Adaptation of Mountain Ecosystems to Global Climate Change

#### **Chapter 1**

## Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan Region: Potential for Achieving Multiple Benefits

*Roshan M. Bajracharya, Deepak K. Gautam, Ngamindra R. Dahal and Him Lal Shrestha*

#### **Abstract**

Land management and forests are crucial to tackling the concurrent issues of sustainable food production and climate change. Conventional modern agriculture, converting forests and naturally vegetated landscapes to farms and rangelands, contributes significantly to elevate carbon in the atmosphere. Agroforestry systems offer potential for local communities to meet livelihood needs while simultaneously adapting to and mitigating climate change. Data from several studies conducted in nine districts of central Nepal between 2007 and 2017 were analyzed. Forests and agroforestry systems in three central Nepal districts had significantly higher total carbon stocks than agricultural soils (2–5 times) due to high above and below-ground biomass carbon and SOC stocks. The application of improved FYM compost, cattle urine and biochar in four districts increased average SOC by 2.75% over 6 years, translating to an increase of nearly 100 t ha<sup>1</sup> in SOC stock. Along with soil quality benefits, biochar and FYM compost improved the yields of soybean, potato, millet and Swertia chirayita yields which were significantly higher than in untreated plots. The flux of N2O was significantly lower in biochar-amended soil compared to non-biochar. Crop diversification incorporating high-value horticultural and medicinal crops enhance economic returns as indicated by higher benefit-cost ratios for vegetable and Swertia chirayita than for cereals.

**Keywords:** agroforestry, diversified cropping, climate change, biochar, farmyard manure, sustainable soil management

#### **1. Introduction**

Farming communities in the hill and mountain regions of the Himalayas depend to a large extent on the soil and forest resources for their survival and livelihoods. The past several decades have witnessed ever-increasing pressures upon the land-based

resources due to increased human and livestock populations. Intensified and commercial agricultural production with increased reliance on chemical fertilizers and pesticides has led to adverse ecological consequences of these unsustainable farming practices. Soil degradation and productivity decline are widespread in many parts of South Asia [1]. Moreover, the impacts of global climate change, causing higher mean annual temperatures and erratic, intense rainfall events, further threaten the livelihoods of small-holder mountain farmers [2, 3]. Therefore, approaches and systems to enhance and sustain production, while also improving resilience to climate change impacts are urgently needed in the Himalayan region. A combination of practices holds considerable potential to provide multiple benefits related to sustainable production along with supporting climate change adaptation and mitigation. These include crop diversification, incorporation of agroforestry species, use of biochar in conjunction with local farmyard manure and the adoption of appropriate soil and water conservation measures [4, 5].

Due to the increasing demands for food and fiber of a growing population, intensification of agriculture is unavoidable. Agricultural intensification can be defined as any cropping or animal husbandry system that increases the intensity or frequency of use of the same parcel of land, for instance, by growing a greater number of crops per year or grazing a higher number of livestock on the same land area than previously [6, 7]. If such intensification of production is done through the adoption of agrochemical use and mono-culture cropping, then over a period of a few decades, the organic matter content and fertility of the soil becomes depleted, leading to diminishing quality and productivity of the land. On the other hand, if intensification can be achieved in a sustainable manner, maintaining ecological balance, then both the livelihoods of farming communities and the environment could be preserved [5, 8, 9].

Agroforestry involves the inclusion of perennial plants on farm land in combination with annual crops. Often trees, such as, fruit or fodder species, are planted within or on the borders of the crop land with other annual cereal or vegetable crops grown in between. Agroforestry systems offer considerable potential as a climate adaptive strategy due to the diverse nature of crops with varying degrees of tolerance to soil, water, nutrient and climatic conditions [5, 10, 11]. Furthermore, the inclusion of perennial crops enables complimentary, as well as, synergistic effects in terms of productivity, while also capturing and storing carbon, thereby contributing to climate change mitigation [12–14]. These systems are likely to be particularly appropriate for mountain farming due to the steep topography, often shallow depth of soils and limited scope for supplemental irrigation.

In addition to diversified cropping strategies through agroforestry, another environmentally friendly and sustainable approach for enhancing production while aiding in carbon sequestration is the use of on-site farmyard manure and locally prepared biochar. While the use of biochar in soils dates back thousands of years in South America and Australia [15, 16], its potential for promoting soil microbial activity, improving plant nutrient availability, increasing water retention and, thereby enhancing production has only gained scientific recognition in recent decades [3, 17, 18]. The beneficial effects of biochar reportedly arise from its high porosity, stability and longevity in soils, serving as a catalyst for increased microbial activity along with high water and nutrient retention capacity [17–19]. In the Himalayan region, biochar prepared from locally available waste biomass feedstock, such as, crop residues and weeds, could offer a low-cost, sustainable option to improve soil quality and livelihoods through increased crop productivity. Layek et al. [9] point out that in the Eastern Himalayas of India, where a type of slash-and-burn

agriculture is practiced, the use of biochar could improve soil quality and crop production while also enhancing carbon sequestration. Even greater benefits of biochar to enhance crop yields may be achieved through the application of biochar enriched in nutrients such as nitrogen, phosphorous and potassium [20, 21].

#### **2. Approach and methods**

The present chapter is a compilation and re-analysis of the data and salient aspects of several studies carried out in the lower and mid-hills regions of Nepal located in the Central Himalayas. The studies were conducted in nine different districts of the central and mid-western development regions of Nepal during the period from 2007 to 2017. The study districts and locations are shown within the map of the country in **Figure 1**. Brief descriptions of the field trials and studies examined are provided below.

The effects of agroforestry and community-managed forests on the accumulation of carbon in both soil and biomass compared to conventional agriculture were evaluated in a study conducted in three districts of central Nepal. Four field plots each in three land use types, namely, agriculture (AG), agroforestry systems (AF) and community forests (CF), were sampled in Chitwan, Gorkha and Rasuwa districts [22]. These districts represented different agro-climatic zones with Chitwan in the tropical zone (100–300 m elevation range), Gorkha situated in the warm subtropical zone (at 1000–1200 m elevation) and Rasuwa lying in the warm temperate zone (at 1800– 2000 m elevation). Soil organic carbon (SOC) and dry bulk density (BD) were determined using dry combustion [23] and core methods [24], respectively, for samples taken at four soil depths down to 1 m or bedrock, whichever was shallower. These included topsoil at 0–0.15 m depth, and three sub-soil layers at 0.15–0.30 m, 0.30–0.60 m and > 0.60 m depths. Using the SOC percent and soil BD, the total soil

#### **Figure 1.**

*Map of Nepal showing the study districts (shaded in gray).* Source: *https://www.worldatlas.com/r/w960-q80/ upload/d6/7b/0c/provinces-of-nepal-map.png.*

OC stocks were calculated using Eq. (1) [25]. The above and below-ground biomass carbon stocks were also determined using the allometric method according to Chave et al. [26]. The above-ground tree biomass (AGBT) was calculated using the diameter at breast height (DBH) and the total height of the tree (h) as given in Eq. (2).

The biomass carbon of leaf-litter, herbs and grasses was determined by destructive sampling over an area of 1 m<sup>2</sup> , and oven drying in the laboratory; calculations were done according to the formula in Eq. (3). The below-ground root biomass was taken according to the root-to-shoot ratio of 1:5 as suggested in MacDicken [27].

$$\text{SOC stock } \left(\text{t } \text{ha}^{-1}\right) = \text{SOC}^\* \text{ BD}^\* \text{ H}^\* \ \mathbf{10}^4 \tag{1}$$

Where, SOC = soil OC %; BD = soil dry bulk density (Mg/m<sup>3</sup> ); H = thickness of soil layer sampled.

$$\text{AGTB} - \text{C stock} \left(\text{t} \,\text{ha}^{-1}\right) = 0.059^{\circ} \,\text{ } \text{\(\text{DBH}^2\text{\*}\,\text{ h}\)}\tag{2}$$

Where, δ = wood specific gravity (g cm<sup>3</sup> ); DBH = diameter of tree at breast height (cm); h = tree height (m).

$$\mathbf{LHGB} - \mathbf{C stock} \left(\mathbf{t} \,\mathrm{ha}^{-1}\right) = \mathbf{Wf}^\* \,\mathrm{Wd}^\* \,\mathbf{10}^4/\mathrm{A}^\* \,\mathrm{Ws} \tag{3}$$

Where, Wf = fresh weight of leaf-litter-herb-grass sample; Ws = wet weight of subsample; Wd = oven dried weight of subsample; A = sampled area (m<sup>2</sup> ).

The use of sustainable soil management practices, such as, improved compost and farmyard manure (FYM), cattle urine, crop residue mulching and biochar are reported to have beneficial effects on soil quality and fertility. This ultimately translates to increased productivity and higher crop yields, which contribute to greater incomes and better livelihoods for farming communities. A study in four districts of central and mid-western Nepal evaluated the increase in soil organic carbon over a period of 6 years of adoption of these practices by farmers [28]. Soil from 16 farmer fields in Baglung, Kavrepalanchok, Sindhupalchok and Syangja districts was sampled at 0–0.15 m and 0.15–0.3 m depths representing the crop rooting zone. The soils were air-dried, sieved through a 2 mm sieve and analyzed for SOC using the loss-on-ignition dry combustion method. The increase in SOC contents over the six-year period was calculated and the potential for carbon sequestration was determined.

In separate trials in five districts of central Nepal, the application of biochar prepared from locally available crop residues, weeds and grass biomass in combination with FYM compost was studied. The quality of biochar made by pyrolysis at low temperatures (350 to 470°C) using different feed stocks, namely, coffee pulp and husks, leaf-litter/grass, rice straw, Eupatorium sp., and wood sawdust, along with the quality of local FYM compost was determined. The organic C contents, pH, total N, available P, available K and cation exchange capacity (CEC) were determined for biochar, FYM and soil from the farm fields using standard methods. The effects of the local biochar and FYM on soil properties, as well as, crop growth and yields were evaluated for coffee agroforestry and vegetable crops in Bhaktapur, Kavrepalanchok, Lalitpur, Rasuwa and Sindhupalchok districts of central Nepal between 2012 and 2017 [29, 30].

An economic analysis was done to determine the benefits to farm income of cultivating vegetable crops and medicinal plants in smallholder farm fields in Rasuwa district during 2016–2017. Cost-benefit analyses were done for crops including millet (the main cereal crop grown in the district), radish, garlic and Swertia chirayita (medicinal plant). The benefit-cost ratio was calculated to determine the estimated profitability of each crop type.

#### **3. Results and discussion**

Based on sampling and quantification of carbon stocks under agricultural fields, agroforestry systems and community forest plots, it was observed that the total carbon stocks accumulated in forests were expectantly highest (by 2 to 5 times), followed by agroforestry systems (approximately 2–3 times higher than agriculture) and least in agricultural lands in three districts in central Nepal (**Table 1**). While soil carbon stocks were variable, with farm fields in Chitwan having significantly higher SOC stocks than the other two districts, biomass carbon stocks were highest for community forests, followed by agroforestry plots. Agricultural plots, on the other hand, did not accumulate biomass carbon as the fields are planted to annual crops which are harvested and all biomass removed each cropping season. The variability of SOC stocks may be due to farming practices, amounts of organic residues returned to the soil and farmyard manure applied, as well as, the soil depth, which was highest in Chitwan district. The influence of organic matter management under different agricultural practices and variability in soil OC contents and stocks have been reported in a number of studies [4, 9, 22, 31, 32].

As shown in **Figure 2**, the distribution of below-ground carbon stocks, including root-biomass carbon and SOC, depended on the depth of sampling. Although the total below-ground carbon stocks were generally higher for forest soils, the difference was not significant when topsoil (0–0.3 m) alone was considered. However, when quantified to greater depths, the below-ground carbon stocks were considerably higher for both community forest and agroforestry plots. This is presumably due to the contribution of root biomass carbon of perennial crops and trees under agroforestry systems and in forests. Increased SOC contents under agroforestry systems have been observed in other studies as well [13, 33–35].


#### **Table 1.**

*Carbon stocks (t ha<sup>1</sup> ) under three land uses in three central districts of Nepal.*

**Figure 2.**

*Distribution of below-ground carbon stocks at different depths within the topsoil (0–0.3 m), in Rasuwa district, left; and the entire soil profile, right, in Chitwan district.*

Farm fields in four districts of central and mid-western Nepal, namely, Kavrepalanchok, Sindhupalchok, Baglung and Syangja, were monitored over a period of 6 years to evaluate the effect of sustainable soil management practices that focused on organic and nature-based approaches to increase soil organic matter and fertility. As shown in **Table 2**, the mean baseline SOC contents of the four study districts were low, ranging from less than 1 percent to about 2.3 percent. After 6 years of adoption of the improved FYM/compost and cattle urine application practices on the farm plots, mean SOC contents increased significantly in all districts from about 2.5 to more than 6 percent. This represented a range of about 2-fold to more than 4-fold increase in SOC contents in the farm fields over the 6-year period. Assuming an average soil bulk density of 1.2 Mg m�<sup>3</sup> , the average increase in SOC stock in the topsoil (0.3 m layer) would amount to nearly 100 t ha�<sup>1</sup> over 6 years. The results indicate that such sustainable soil management practices can improve not only the quality and fertility of agricultural soils but also contribute significantly to carbon capture and sequestration. Such improvements in soil properties and increased carbon accumulation as a consequence of restorative soil management practices have been shown in numerous other studies [3, 16, 29, 36].

Other studies examining the properties and influence of locally prepared biochar on both the soil and crop production suggested improvements over conventional farming practices. The local biochar was made using a variety of different waste biomass feed stocks such as coffee waste, weeds (Eupatorium sp.), leaf-litter, grass and wood sawdust. Pyrolysis at low temperatures in a locally constructed dual chamber biochar stove over periods ranging from 3 to 10 hours (depending on moisture contents of feed stock) yielded 35 to 50 percent by weight of the resultant biochar as can be seen from **Table 3**. The highest quantities of biochar resulted from leaf-litter and grass, as well as, coffee pulp and rice husk feed stocks at about 50 percent of the initial weight of the biomass.

Biochar has a number of beneficial effects when applied to the soil. This can be seen from the properties of the biochar given in **Table 4**. Biochar tends to be alkaline in nature and hence can moderate the soil pH in acidic soils. The highest pH was observed for biochar made from Eupatorium sp., a local nuisance weed, which resulted in pH greater than 10. The next best feed stock from a pH standpoint was leaf-litter and grass, which yielded biochar with about 9.5 pH. With regard to best overall properties including organic matter, nitrogen and phosphorus levels, Eupatorium along with leaf-litter and grass, as well as, wood sawdust biochar appeared to be favorable (**Table 4**). It should be noted, however, that biochar does

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*


#### **Table 2.**

*Soil organic carbon contents in the crop root zone (0–0.3 m depth) over 6 years of sustainable soil management practices in four districts of Nepal (n = 16).*


#### **Table 3.**

*Biochar is produced from various feedstock types under the low-temperature pyrolysis (temperature range maintained at 350–470°C).*

not provide nutrients directly to crops, rather, it enhances microbial activity by providing sites with high nutrient and moisture contents for their growth, thereby, enabling the release of nutrients for crop use. Furthermore, due to the high OM contents of biochar and the stability of this OM, biochar can enhance carbon sequestration in soils over extended periods of time. The beneficial effects of biochar on soil properties have also been reported by other researchers [31, 37–40].

Farmers in the hills and mountains of the Himalayas have traditionally used locally prepared farmyard manure or compost as a means of fertilizing and replenishing the soil with organic matter and crop nutrients. In recent decades, however, increasing


#### **Table 4.**

*Biochar properties are produced from five types of biomass feed stocks.*

reliance on chemical fertilizers in order to produce commercial crops around the year with an intensified cropping cycle has led to declining soil quality and productivity. Research in several districts of central Nepal, including Lalitpur, Kavrepalanchok, Sindhupalchok, Bhaktapur and Rasuwa, has suggested that the application of a combination of FYM compost and biochar could improve soil quality, while simultaneously enhancing crop yields, particularly those of vegetable crops and medicinal plants.

Analyses of locally prepared FYM compost samples from three districts revealed that this organic form of fertilizer is rich in macro- as well as micro-nutrients (**Table 5**). Apart from having high amounts of organic matter ranging from about 15 to 65 percent, the FYM compost is also high in nitrogen, available phosphorus and available potassium, which are the three most common nutrients required by plants in large amounts. The values in FYM ranged from about 4000 to 7000 mg kg�<sup>1</sup> for total N, about 5300 to 12,000 mg kg�<sup>1</sup> for available P and approximately 200 to 300 mg kg�<sup>1</sup> for available K. These values are considered high to very high as a source of plant available macro-nutrients. Moreover, the analyzed FYM samples also contained considerable amounts of iron, manganese, copper and zinc, which are micro-nutrients required in only trace amounts by crops.

The properties of soils after 2 years of amendment with biochar as compared to soil in control (non-biochar) plots clearly indicate improvements in a number of soil properties (**Table 6**). The SOC content, soil pH and CEC of biochar treated soils were significantly higher than for untreated soils as seen from the analysis of variance F-test and P values. The bulk density was weakly significantly lower (P < 0.10) for biocharamended soil compared to the control. The crop macro nutrients, namely, total N, available P and available K were not statistically significantly different for biocharamended soil, but the values were, nonetheless, somewhat higher than for the control soil (**Table 6**).

The above results indicate, therefore, that the use of FYM compost prepared onfarm from animal manure mixed with crop residues, leaf-litter and used animal bedding materials serves as an environmentally friendly and sustainable means of restoring soil fertility and overall quality. The enhancement of crop yields due to the application of biochar and organic fertilizers is corroborated by many studies around


#### **Table 5.**

*Properties of farm yard manure compost prepared locally by farmers.*

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*


#### **Table 6.**

*Selected properties for biochar-amended and non-biochar (control) soil in three districts of Central Nepal (n = 12).*

the world [39, 41–44]. While increasing the rate of biochar application to soil generally led to increased yields, an optimum application rate of 15 t ha<sup>1</sup> was proposed by Pandit et al. [45]; as the cost increased with higher rates, the incremental yield did not support the application of higher amounts of biochar.

A field trial on smallholder farm fields in Rasuwa district indicated that the application of FYM compost at a rate of 20 t ha<sup>1</sup> mixed with biochar at a rate of 5 t ha<sup>1</sup> had significant effects on increasing the yield of a number of crops over the application of FYM alone to the soil (**Table 6**). Yields of mustard seed were highly significantly (P < 0.01) different between the two treatments, while those of potato and the medicinal plant Swertia chirayita were significantly different (P < 0.05). Although the yields of garlic and radish were only weakly significantly different (P < 0.10) between biochar+FYM and FYM alone, the yield values were notably higher for the former by about 25 to 66 percent (**Table 7**).

Another trial in Bhaktapur district also indicated that the combination of FYM compost with low rates of biochar applied to the soil prior to planting led to generally higher yields for crops like garlic, chili, radish and soybean (**Figure 3**). The yield of soybeans grown in soil with biochar+FYM applied was significantly higher, by about 56 percent, than that of soybeans grown in soil with FYM compost only. While the yield differences for the other crops, namely, garlic, chili and radish, were not significant, the yields of the crops grown in soil with biochar+FYM were slightly higher


#### **Table 7.**

*Yields of different crops grown with farmyard manure compost alone and with biochar plus FYM compost in Rasuwa district.*

#### **Figure 3.**

*Yields of vegetable crops grown with and without biochar in Bhaktapur district.*

than that for crops grown in soil with only FYM compost (**Figure 3**). Similar results have been reported by researchers in other studies [36, 39, 41, 46]. The application of low doses of biochar enhanced by treating with cattle urine was also found to be effective in increasing yields of a number of vegetable and cereal crops by Schmidt et al. [42, 43].

Apart from the yield benefits of the use of biochar in agricultural and agroforestry soils, another study in Bhaktapur district where biochar was applied to farm plots at low rates (4 to 8 t ha�<sup>1</sup> ) showed a distinct reduction in the emission of greenhouse gases. The monitoring of carbon dioxide, nitrous oxide and methane, using the static chamber method over a period of 2 months during the early growing season, showed lower emissions of the gases from biochar-applied soil than from control plots that received no biochar (**Figure 4**). While the results were not statistically significantly different for CO2 and CH4, the emission of N2O was significantly higher (P < 0.05) from soil in non-biochar plots as compared to biochar-amended plots. Other studies have also shown significant reductions in NO2 and CO2 from biochar applied soils as reported by Stavi and Lal [4]. On the other hand, increased N2O emissions from agricultural soils and acidification have been shown to result from intensified crop production with the use of chemical fertilizers [47]. Therefore, the amendment of the intensively cultivated soils with biochar could be a potential measure to alleviate excessive GHG emissions.

Considerable research and scientific evidence have established that agroforestry systems and the incorporation of perennial plant species in agriculture have many environmental and ecological benefits in terms of soil quality, biodiversity, climate mitigation, etc. However, less work has been done evaluating the economic advantages of agroforestry crops, especially, high-value medicinal plants. A study in smallholder farm fields of Rasuwa district in central Nepal compared the total revenues from and costs of cultivating a number of different crops including cereal crops, vegetables and medicinal plants. The results clearly showed that medicinal plant cultivation, such as Swertia chirayita, gave significantly higher returns with a benefitto-cost ratio of 2.45. On the other hand, growing common cereal crops like maize and millet actually led to a loss, whereas, vegetable crops such as radish were marginally

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*

#### **Figure 4.**

*Emissions of three greenhouse gases from soil with and without biochar amendment in Bhaktapur district.*


#### **Table 8.**

*Cost–benefit analysis for various crops produced by smallholder farmer in Rasuwa district.*

profitable (**Table 8**). The economic benefits of diversified cropping and inclusion of horticultural crops have also been reported by Shah et al. [44].

#### **4. Conclusions**

The results of a number of field trials conducted in several districts in central Nepal demonstrate that agroforestry, crop diversification and the adoption of various sustainable soil management practices hold considerable potential for enhancing land productivity, increasing crop yields and improving the livelihoods of local farming communities. Agroforestry systems are particularly suitable for mountainous regions and can contribute to climate change adaptation and resilience of hill communities while also increasing SOC accumulation and carbon stocks, thereby, helping to mitigate climate change. Trees outside of forest have been reported to substantially enhance carbon sequestration whether as traditional agroforestry practices or simply trees planted on farms and homesteads [48]. Forests and agroforestry systems

typically contained significantly higher total carbon stocks than agricultural soils (by 2 to 5 times) due to the high above and below-ground biomass carbon as well as SOC stocks.

Sustainable soil management practices such as the application of improved FYM compost, cattle urine and biochar in four districts led to an increase in SOC contents by 2.75 percent on average, which could amount to nearly 100 t ha�<sup>1</sup> of increase in SOC stocks over a 6-year period. In addition to soil quality benefits, the application of biochar and FYM compost improved the yields of a variety of crops with soybean, potato, mustard and Swertia chirayita yields being significantly higher than for untreated plots. Biochar has the potential to contribute to the mitigation of climate change by enhancing carbon sequestration in soil due to its inert nature and longevity in soils, as well as, by helping to reduce emissions of greenhouse gases from soil [49]. The flux of N2O was observed to be significantly lower in biochar-amended soil as compared to non-biochar soil. This was presumably due to the effect of biochar on soil chemistry, moisture conditions and microbial activity [4, 32].

The adoptability of sustainable agricultural practices depends to a large extent on economic returns. Diversifying crops with the inclusion of high-value horticultural and medicinal crops could lead to better economic returns as seen from the relatively higher benefit-cost ratios for vegetable and Swertia chirayita than for cereal crops. Therefore, adequate technical, financial and institutional support to farmers in developing countries and mountainous regions are needed to encourage and promote climate resilient and environmentally sound agricultural and land use practices.

#### **Acknowledgements**

The unreserved cooperation and assistance of the hill farmers in our study districts is gratefully acknowledged.

#### **Conflict of interest**

The authors declare no conflict of interest.

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*

#### **Author details**

Roshan M. Bajracharya<sup>1</sup> \*, Deepak K. Gautam<sup>2</sup> , Ngamindra R. Dahal<sup>3</sup> and Him Lal Shrestha<sup>4</sup>

1 Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel, Nepal

2 Nepal Agroforestry Foundation, Kathmandu, Nepal

3 Nepal Water Conservation Foundation, Kathmandu, Nepal

4 Kathmandu Forestry College, Kathmandu, Nepal

\*Address all correspondence to: roshan.bajracharya@gmail.com

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Lal R. Soil degradation and food security in South Asia. In: Lal R, Sivakumar MVK, Faiz SMA, Rahman AHMM, Islam KR, editors. Climate Change and Food Security in South Asia. Dordrecht, The Netherlands: Springer; 2011. pp. 137-152

[2] Pachauri RK. Climate change and agroforestry. In: Nair PKR, Garrity D, editors. Agroforestry - The Future of Global Land Use. Advances in Agroforestry No. 9. Dordrecht, The Netherlands: Springer Science & Business Media; 2012. pp. 13-16

[3] Bajracharya RM. Regenerative approach for sustainability and climate resilience of mountain agroecosystems. In: Bajracharya RM, Sitaula BK, Raut N, Gurung S, editors. Sustainable Natural Resource Management in the Himalayan Region: Livelihood and Climate Change. New York: Nova Science Publ. Inc.; 2021. pp. 42-56

[4] Stavi I, Lal R. Agroforestry and biochar to offset climate change: A review. Agronomy for Sustainable Development. 2013;**33**:81-96

[5] Bajracharya RM. Sustainable land use, landscape management and governance. In: Shit PK, Adhikary PP, Bhunia GS, Sengupta D, editors. Soil Health and Environmental Sustainability: Application of Geospatial Technology. Switzerland: Springer-Nature; 2022. pp. 423-436

[6] Carswell G. Agricultural intensification and rural sustainable livelihoods: A "think piece". IDS Working Paper No. 64. 2011

[7] Bajracharya RM, Dahal BM. Agricultural Intensification. The Berkshire Encyclopedia of Sustainability: Ecosystem Management and Sustainability. New York, NY, USA: Berkshire Publishing Group; 2012. pp. 7-10

[8] Tilman D, Balze C, Hill J, Befort BL. Global food demand and the sustainable intensification of agriculture. PNAS. 2011;**108**(50):20260-20264

[9] Layek J, Narzari R, Hazarika S, Das A, Rangappa K, Devi S, et al. Prospects of biochar for sustainable agriculture and carbon sequestration: An overview for eastern Himalayas. Sustainability. 2022; **14**(11):6684. DOI: 10.3390/su14116684

[10] Leakey R. Environmental resilience and agroforestry. In: Nair PKR, Garrity D, editors. Agroforestry - The Future of Global Land Use. Advances in Agroforestry No. 9. Dordrecht, The Netherlands: Springer Science & Business Media; 2012. pp. 11-12

[11] Synnot P. Climate change, agriculture, and food security in Nepal - Developing adaptation strategies and cultivating resilience. Report, Mercy Corps Nepal; 2012. 53 p

[12] Bajracharya RM, Atreya K. Carbon sequestration in upland farming systems of the Nepal mid-hills. In: Paper Presented at the National Conference on Environment. Kathmandu, Nepal: Tribhuvan University; 2007

[13] Cardinael R, Chevallier T, Cambou A, Beral C, Barthes BG, Dupraz C, et al. Increase of soil organic carbon stock under agroforestry: A survey of different sites in France. In: 3rd European Agroforestry Conference, Montpellier, France; May 23-25, 2016

[14] Bishaw B, Soolanayakanahally R, Karki U, Hagan E. Agroforestry for

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*

sustainable production and resilient landscapes. Agroforestry Systems. 2022; **96**:447-451. DOI: 10.1007/s10457-022- 00737-8

[15] Sandor JA, Eash NS. Ancient agricultural soils in the Andes of southern Peru. Soil Science Society of America Journal. 1995;**59**:170-179

[16] Downie AE, Van Zwieten L, Smernik RJ, Morris S, Munroe RR. Terra Preta Australis: Reassessing the carbon storage capacity of temperate soils. Agriculture, Ecosystems and Environment. 2011;**140**:137-147

[17] Regeneration International. What Is Biochar? San Francisco, CA, USA: Regeneration International; 2018. Available from: http://www. regenerationinternational.org/whatis-biochar/

[18] Novak J, Ro K, Ok YS, Sigua G, Spokas K, Uchimiya S, et al. Biochar's multifunctional role as a novel technology in the agricultural, environmental, and industrial sectors. Chemosphere (Amsterdam, The Netherlands: Elsevier). 2016;**142**:1-3

[19] IBI Biochar. New Jersey, USA: International Biochar Initiative; 2012. Available from: http://www.biocharinternational.org/

[20] Sohi SP. Carbon storage with benefits. Science. 2012;**338**:1034-1035. Publ. on-line by AAAS, Washington, D.C.; 2012. Available from: http://www.sciencemag.org/cgi/ collection/ecology

[21] Karim AA, Kumar M, Singh E, Kumar A, Kumar S, Ray A, et al. Enrichment of primary macronutrients in biochar for sustainable agriculture: A review. Critical Reviews in Environmental Science and Technology. 2022;**52**(9):1449-1490. DOI: 10.1080/ 10643389.2020.1859271

[22] Shrestha HL, Bajracharya RM, Sitaula BK. Soil organic carbon and soil properties for REDD implementation in Nepal: Experience from different land use management in three districts of Nepal. In: Bhadouria R, Singh S, Tripathi S, Singh P, editors. Understanding Soils of Mountain Landscapes, Sustainable Use of Soil Ecosystems Services and Management. Amsterdam, The Netherlands: Elsevier; 2023. pp. 267-278. DOI: 10.1016/B978-0- 323-95925-4.00002-9

[23] Nelson DWW, Sommers L. Total carbon, organic carbon, and organic matter. Methods of soil analysis. Part 2. In: Chemical and Microbiological Properties, Agronomy Monographs. 2nd ed. Madison, WI, USA: ASA; SSSA; 1982, 1982. pp. 539-579

[24] Blake GR, Hartge KH. Bulk density, Methods of soil analysis part 1. In: Page AL, editor. Physical and Mineralogical Methods, Agronomy Monographs. 2nd ed. Madison, WI, USA: ASA; SSSA; 1986. pp. 425-442

[25] Pearson TRH, Brown SL, Bridsey RA. Measurement guidelines for the sequestration of forest carbon. Gen. Tech. Rept. NRS–18. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station; 2007. 42 p

[26] Chave J, Andalo C, Brown S, Cairns MA, Chambers JQ, Eamus DE, et al. Tree allometry and improved estimation of carbon stocks and balance in tropical forests. Oecologia. 2005;**145**: 87-99. DOI: 10.1007/s00442-005-0100-x

[27] MacDicken KG. A guide to monitoring carbon storage in forestry and agroforestry projects. In: Forest

Carbon Monitoring Program. Arlington, VA, USA: Winrock International Institute for Agricultural Development; 1997. p. 87

[28] Bajracharya RM, Atreya K. Carbon sequestration in upland farming systems of the Nepal mid-hills. In: Paper Presented at the National Conference on Environment. Kirtipur, Kathmandu, Nepal: Tribhuvan University; 2007

[29] Dahal N, Bajracharya RM. Effects of sustainable soil management practices on distribution of soil organic carbon in upland agricultural soils of mid-hills of Nepal. Nepal. Journal of Science and Technology. 2012;**13**(1):133-141

[30] Gautam DK, Bajracharya RM, Sitaula BK. Effects of Biochar and farm yard manure on soil properties and crop growth in an agroforestry system in the Himalaya. Sustainable Agriculture Research. 2017;**7**(4):74-82. Available from: https://www.ccsenet.org/journal/ index.php/sar/article/view/69546

[31] Khan N, Shah Z, Ahmed N, Ahmad S, Mehmood N, Junaid M. Effect of integrated use of biochar, FYM and nitrogen fertilizer on soil organic fertility. Pure and applied Biology. 2013; **2**(2):42-47

[32] Semida W, Beheiry H, Setamou M, Simpson C, Ali T, Rady M, et al. Biochar implications for sustainable agriculture and environment: A review. South African Journal of Botany. 2019; **127**:333-347. DOI: 10.1016/j. sajb.2019.11.015

[33] Dahal N, Bajracharya RM, Wagle LM. Biochar effects on carbon stocks in the coffee agroforestry systems of the Himalayas. Sustainable Agricultural Research. 2018;**7**(4): 103-114. DOI: sar.v7n4p103

[34] Ofosu E, Bazrgar A, Coleman B, et al. Soil organic carbon enhancement in diverse temperate riparian buffer systems in comparison with adjacent agricultural soils. Agroforestry Systems. 2022;**96**:623-636. DOI: 10.1007/ s10457-021-00691-x

[35] Noponen MRA, Healey JR, Soto G, Haggar JP. Sink or source-the potential of coffee agroforestry systems to sequester atmospheric CO2 into soil organic carbon. Agriculture, Ecosystems and Environment. 2013;**175**:60-68. DOI: 10.1016/j.agee.2013.04.012

[36] Fan M, Shen J, Yuan L, et al. Improving crop productivity and resource use efficiency to ensure food security and environmental quality in China. Journal of Experimental Botany. 2013;**63**(1):13-24

[37] Pudasaini K, Ashwath N, Walsh K, Bhattarai T. Biochar improves plant growth and reduces nutrient leaching in red clay loam and sandy loam. In: Proc. Int'l. Conf. Water, Food Security and Climate Change in Nepal. Spl. Issue, J. Water Energy and Environ. Kathmandu, Nepal: HydroNepal; 2012. pp. 86-90

[38] Ścisłowska M, Włodarczyk R, Kobyłecki R, Bis Z. Biochar to improve the quality and productivity of soils. Journal of Ecological Engineering. 2015; **16**(3):31-35. DOI: 10.12911/22998993/ 2802

[39] Njoku C, Uguru BN, Chibuike CC. Use of biochar to improve selected soil chemical properties, carbon storage and maize yield in an ultisol in AbakalikiEbonyi state, Nigeria. International Journal of Environmental and Agricultural Research. 2016;**2**(1): 15-22

[40] Pandit NR, Mulder J, Hale SE, Martinsen V, Schmidt HP,

*Diversified Agroforestry for Climate Change Adaptation and Mitigation in the Himalayan… DOI: http://dx.doi.org/10.5772/intechopen.113157*

Cornelissen G. Biochar improves maize growth by alleviation of nutrient stress in a moderately acidic low- input Nepalese soil. Science of the Total Environment. 2016;**625**:1380-1389

[41] Akhtar SS, Li G, Andersen MN, Liu F. Biochar enhances yield and quality of tomato under reduced irrigation. Agricultural Water Management. 2014; **138**:37-44

[42] Schmidt HP, Pandit BH, Cornelissen G, Kammann CI. Biochar based fertilization with liquid nutrient enrichment: 21 field trials covering 13 crop species in Nepal. Land Degradation and Development. 2017;**28**(8): 2324-2342. DOI: 10.1002/ldr.2761

[43] Schmidt HP, Pandit BH, Martinsen V, Cornelissen G, Conte P, Kammann CI. Four-fold increase in pumpkin yield in response to low dosage root zone application of urine-enhanced biochar to a fertile tropical soil. Agriculture. 2015;**5**(3):723-741. DOI: 10.3390/agriculture5030723

[44] Shah AK, Kori AK, Kumar K, et al. Yield performance and economic evaluation of mustard varieties under mango based Agri-horticulture practice in semi-arid tropics. Agroforestry Systems. 2022;**96**:651-657. DOI: 10.1007/ s10457-021-00712-9

[45] Pandit NR, Mulder J, Hale SR, Zimmerman AR, Pandit BH, Cornelissen G. Multi-year double cropping biochar field trials in Nepal: Finding the optimal biochar dose through agronomic trials and costbenefit analysis. Science of the Total Environment. 2018;**637-638**:1333-1341. DOI: 10.1016/j.scitotenv.2018.05.107

[46] Schulz H, Glaser B. Effects of biochar compared to organic and inorganic fertilizers on soil quality and plant growth in a greenhouse experiment. Journal of Plant Nutrition and Soil Science. 2012;**175**:410-422

[47] Raut N, Dorsch P, Sitaula BK, Bakken LR. Soil acidification by intensified crop production in South Asia results in higher N2O/(N2 + N2O) product ratios of denitrification. Soil Biology and Biochemistry. 2012;**55**: 104-112

[48] Skole DL, Mbow C, Mugabowindekwe M, Brandt MS, Samek JH. Trees outside of forests as natural climate solutions. Nature Climate Change. 2021;**2021**(11):1013-1016. DOI: 10.1038/s41558-021-01230-3

[49] Gogoi N, Sarma B, Mondal SC, Kataki R, Garg A. Use of Biochar in sustainable agriculture. In: Farooq M, Pisante M, editors. Innovations in Sustainable Agriculture. Cham: Springer; 2019. DOI: 10.1007/978-3- 030-23169-9\_16

#### **Chapter 2**

## Fire and Climate Change in the North American Great Lakes Pine Transition Forest

*Steven I. Apfelbaum and Alan Haney*

#### **Abstract**

This chapter explores potential changes in fire regimes and biodiversity given projected changes in climate in the Great Lakes Pine Transition Forest (GLPF), a portion of the southern boreal forest. We have studied how forest structure, composition, and biodiversity changed over nearly 500 years by comparing communities on comparable edaphic locations of various ages since stand-replacing disturbance. Our interpretation of probable future changes is based on how these ecosystems have reassembled after wildfire, blowdown, and insect disturbances in the past and projections of climate change in the next 75 years. Rapid climate change is now introducing different conditions from those to which this ecosystem was historically adapted, and therefore, projections of future change are more subjective.

**Keywords:** boreal forest, great lake pine forest formation, forest carbon, peat carbon, wildfire climate risk, fire and climate change

#### **1. Introduction**

The boreal ecosystem is one of the most extensive with a circumboreal distribution accross North America, Europe, and Asia. This is also one of the largest fire maintained forested systems on earth. In this chapter we evaluate future trajectories for the Great Lakes Pine Transition Forest (GLPF), a southern extension of the Boreal forest system bordering the Great Lakes in North America. This forested system has an long fire record from tree ring, soil carbon-charcoal, and palenological analyses by others. In this chapter we used our nearly forty years of field measurements of forest structure, standing crop biomass, among other measurements to make informed projections of future changes in this ecosystem [1, 2].

#### **2. Ecosystem description and historic response to disturbance**

The GLPF, as with most of North America's ecosystems, was historically adapted to periodic fire. With Indo-European settlement in the mid-to-late 1700s essentially all ecosystems of North America were altered increasingly as populations

and technology advanced. Those not directly affected by timber harvests or forest removal, cultivation, or hydrologic alterations were altered by fire suppression and introduction of exotic species. Rapid climate change threatens to further change ecosystems, often unstable because of previous stresses, including loss of species. Although the GLPF has not lost many species, if any, the relative abundance and relationships have been altered. Ecosystems such as the GLPF, adapted to fire regimes that changed slowly over nearly 10,000 years, now must adapt to changes in fire regimes in a matter of several decades. Moreover, increased fire frequency and intensity, that now appears inevitable, will contribute more greenhouse gases emissions in a negative feedback loop.

The GLPF lies between the Boreal Forest Region in North America, which extends from Newfoundland to Alaska to the Great Lakes–St. Lawrence Forest Region, as defined by Rowe [3]. Circumpolar boreal ecosystems, of which the GLPF is a segment, are the largest remaining intact forested ecosystem on the planet [4]. The GLPF is distinguished most obviously by presence of red pine (*Pinus resinosa*) that sometimes occurs in nearly pure natural stands, but more often, when present, is a co-dominant. Eastern white pine (*Pinus strobus*) is also a signature species of the GLPF, although its range extends much farther south, well beyond the boreal forest biome. Otherwise, most of the trees common to at least the central boreal forest of North America coexists in the GLPF. Typical associates of red-and-white pine are jack pine (*Pinus banksiana*), balsam fir (*Abies balsamifera*), white-and-black spruce (*Picea alba and P. mariana*), paper birch (*Betula papyrifera*), tamarack (*Larix laricina*), northern white cedar (*Thuja occidentalis*), quaking aspen (*Populus tremuloides*), and balsam poplar (*Populus balsamifera*), proportions varying according to edaphic characteristics, and type and time since the disturbance that gave rise to the current community.

A classification of 13 upland plant communities found in the GLPF was developed by Ohmann and Ream [5] and Grigal and Ohmann [6]. Classification of lowland communities was developed by Heinselman [7] and Dean [8]. These eight lowland community types plus the 13 upland community types provide a baseline for predicting changes associated with climate change. Both the upland and lowland communities have abundant carbon present in standing vegetation and peat substrates, much of which might be released by increased fire.

The tree species listed above are dominant or codominant in all except three community types: lichen communities on exposed rocky outcrops; alder-willow shrub communities, primarily along streams or in frequently flooded areas; and marsh and open muskeg. A fourth wetland community is dominated by black ash (*Fraxinus nigra*) and American elm (*Ulmus americana*) that is becoming less common because of disease. The composition, structure, and diversity of all upland communities are strongly influenced by the intensity and extent of wildfire [1].

Lowland communities, historically, burned, usually after exceptionally dry periods, often several successive years with below-average precipitation. Under conditions of low humidity and high wind, crown fires can sweep across lowland communities even without prolonged drought. With drought, even substrates burn. In extreme cases, peat-filled depressions can become open ponds. Despite only covering around 3% of land surface area, peatlands are responsible for storing up to one-thirds of the world's soil carbon [9, 10]. This is twice as much carbon as in all the world's forest biomass combined. Peatlands play a critical role in filtering and storing water. They improve water quality and reduce floods [11, 12]. They are home to many rare and

*Fire and Climate Change in the North American Great Lakes Pine Transition Forest DOI: http://dx.doi.org/10.5772/intechopen.110734*

unique species. Following fire, pines, especially jack pine, typically dominate upland sites and spruce and fir or aspen dominates sites with deeper soil and more reliable moisture.

Strong straight-line winds are a secondary disturbance in the GLPF. High wind often results in extensive blowdown. Aspen is a vigorous root-sprouter, and when present in predisturbance communities, will dominate after blowdown or clearcutting, especially on deeper soils with adequate moisture [1, 13–15]. Aspen, with wind-blown seed also can invade extensive burns from surviving parent trees that may be located well outside the burn. Aspen is intolerant and relatively shortlived; consequently, following blowdown, aspen dominance slowly gives way to more tolerant spruce and fir, although surviving aspen may persist as a scattered overstory for 100 years or more. In the long-term absence of disturbance, sprucefir forests eventually replace aspen on deeper and more mesic sites. Where seed sources are present, white and red pine may also become established and persist into old-growth, 250 or more years [1]. Red pine more often regenerates after fire, whereas the more tolerant white pine may regenerate after fire or wind-throw. Both white and red pine develop thick bark that can withstand fire after 30 to 50 years, and they can survive for 400 or more years under favorable conditions, creating an overstory above spruce, fir, or jack (pine). Such old-growth communities are rare, in part not only because the commercial value of mature white-and-red pine led to widespread harvesting but also because intense fire associated with periodic drought regenerated forest communities, with or without white-and-red pine depending on whether parent trees survived long enough afterward to release viable seed.

Our studies have focused on vegetation and breeding birds [16] and blowdown [13–15], and corresponding breeding bird communities and species associated with the vegetation structure and compositional responses [17–20]. A synopsis of some likely changes include a decline in diversity of bryophytes and other understory vegetation is likely. Breeding bird diversity in jack pine-black spruce communities declines as these even-aged communities mature. As for several postfire years, diversity is higher, frequent fire might favor bird diversity. After intense stand-replacing crown fires in upland jack pine communities, a homogeneous jack pine or jack pine-black spruce is regenerated. The relatively low diversity of the bird community, dominated primarily by bark-gleaning and tree-foliage-searching foraging guilds, in the rather homogeneous jack pine forest stand is replaced by species that include ground brush foragers that feed on seeds and insects, tree foliage and brush foliage searchers that feed on insects, fly catching birds that sally forage for flying insects across the openings and open for structure of a newly burned site, woodpeckers that nest in the dead and dying trees and forage forest bark beetles, and numerous raptors that arrive in search of grouse another bird foraging on the lush insect and seed production at the ground story.

The presence of abundant aspen saplings provides food and cover for much wildlife, especially important for charismatic species such as moose and beaver. Food chains in young aspen is indicated by heavily browsed saplings and presence of fecal material of moose and snowshoe hare, associated with fecal material of wolves which contain the hair from these herbivores. Northern Goshawk (*Accipiter gentilis*) localize their nest around recent burns, where they actively have been documented to pursue their primary foodstuff, ruffed grouse (*Bonasa umbellus*) and where we have observed and documented their nesting [18, 21, 22].

#### **3. Past and future regional climate**

With projected climate changes, both blowdown and fire will become more frequent, and likely will become more extensive given higher temperatures and more extreme climatic events, especially thunderstorms. Although there are excellent records of climate change over the past 50 or more years, and very good models of how climate will change in the next 50 years, the relationship between climate and fire characteristics is much more nebulous. Much of the anticipated change in climate and projections of associated impacts for the Great Lakes Region is provided in a report (An Assessment of the Impacts of Climate Change on the Great Lakes) by the Environmental Law and Policy Center [23] prepared by 18 climate scientists with expertise in the region. That report, however, did not include a discussion of how climate change might affect forest ecology and fire.

Climate is changing faster in the Great Lakes region than averages over the rest of United States. Averaged over 1985–2016 relative to 1901–1960, in the Great Lakes Basin the temperature has increased 1.6°F (0.53°C). This is faster than the 1.2°F (0.4°C) increase for United States [24]. Teasing these trends apart reveals an average increase across Wisconsin, for example, of over 4°F (1.3°C) in winter and 1°F (3.0°C) in summer. Total annual days of ice-cover for Lake Mendota in Madison, Wisconsin, where good records have been kept since 1860, shows a steady decrease from around 120 days to a present five-year running average of around 80 days. Arguably more important than averages is the increase in year-to-year variation. For example, the maximum percent of Great Lakes covered by ice has remained very close to the 50-year average of about 50%. The year-to-year variation, however, has increased substantially, with higher and lower extremes. Averaged over the same time periods, annual precipitation increased in the Great Lakes Basin by 10%, but much of the increase fell in winter and early spring where it has less effect on fire regimes. Summer precipitation in the Basin is predicted to decrease by 5–15% by the end of the century [25]. Again, the variation has increased with greater and lower amounts and more prolonged droughts.

Globally, extreme weather events are expected to become more common. In North America, heat waves and drought have become more frequent since the 1960s [24]. When comparing average annual daily mean temperatures for the 1976–2005 period to that predicted for the 2070–2099 period, an increase of 5.8–10.1°F (1.9–3.4°C). is projected for the Great Lakes Basin [23]. The range reflects two different scenarios; the lower scenario is based on optimistic reduction in greenhouse gas (ghg) emissions while the higher scenario is based on a projection of current trends in ghg emissions. Extremely warm days (those with temperatures exceeding 90° F (32.2°C)) are projected to increase by 17–40 days by the end of the century, the range reflecting the low- and high-ghg emission scenarios. Wintertime warming is expected to increase proportionately more than summertime high increases, as documented for Wisconsin above. The frost-free period will increase substantially. Days with minimal temperature exceeding 32°F (0°C) in the Great Lakes Basin are projected to increase by 27 and 42, with the low and high scenario models, respectively. These highly probable climate changes can only result in more frequent and more severe fire.

Based on historic fire patterns, conservative fire projections can be offered. Historic fire return intervals vary depending on cycles of drought and landform position, but average 70–110 years [1]. It has been rare that any upland forest escaped fire for more than 250 years. A few pockets of old growth up to 450 years have survived

#### *Fire and Climate Change in the North American Great Lakes Pine Transition Forest DOI: http://dx.doi.org/10.5772/intechopen.110734*

when protected by sheltering topography (e.g., draws, lakes, rock escarpments). There can be little doubt that with even the most optimistic climate projections for higher summer temperature, drier conditions, and more severe storms for the next 50 years, fire frequency will increase. Because this region is often where cold dry arctic air masses clash with warm, moist Gulf air masses, thunderstorms with substantial lightning are typical and, not infrequently, derechos develop with hurricane-force straight-line winds. Even under current conditions, winds associated with thunderstorms commonly exceed 60 mph (96.6 km/hr).

Lightning in the region is primarily generated by frontal and convective activity [26]. On average 27 thunderstorms occur annually in the Great Lakes region. Lightning occurs mostly mid-May to mid-September. Although forest conditions become increasingly dry as the growing season progresses, exposure to lightning decreases.

Prolonged dry periods, often extending over several consecutive years, have led to more widespread and more severe fires in the past [1]. Such drought periods are likely to continue and become more severe. Droughts may become so severe as to be the cause of the death of trees and dramatically reduce lake levels. Even one or 2 months with little to no precipitation during spring or early summer can set the stage for severe fires [1]. For example, the region experienced below normal precipitation from 1929 through 1936 and extreme high temperatures were recorded in 1936 leading to outbreak of many severe fires in the region. It is during such droughts that lowland communities often burned.

#### **4. Projections of how climate change will alter the GLPF**

Heinselman [1] developed forest stand-origin maps of extensive portions of the GLPF using dendrochronology to determine forest tree ages. Fire scars and tree growth ring measurements have been used to identify periods of drought associated with wildfire patterns. Swain [27] used charcoal and other pyrolyzed material in annual lake varves to examine fire frequencies. These data were used to document return intervals and relationship of different communities to fire. Fire with return intervals of 65–100 years on upland sites have led to jack pine and aspen dominance over much of the region. In fire-protected draws such as lake margins and wetlands, white and red pine, spruce, and many species of shrubs may escape fire for 100–200 or more years. Many wetlands burned only during the most severe droughts [1].

Heinselman [1] found many, but not all, fire scars to be associated with major fire years, where intense crown-fires resulted in stand-replacement. However, during intervening years, ground fires that under-burned forests of multiple age-classes and origins, confused the interpretation of stand ages. For example, during droughts, peat becomes combustible and, once ignited, can retain fire for months, even into winter. The resulting patterns of vegetation largely reflect the combustibility of fuel, especially the difference between those fuels able to carry crown-fires and wetlands or protected areas more prone to lighter, ground fires.

#### **5. Fires and biodiversity**

Fire largely shapes vegetation composition which, in turn, largely controls the breeding and overwintering birds, mammals, insects, amphibians, and reptiles that persist in each community. In addition to biodiversity, fire and postfire succession shapes the structure of the vegetation [1]. Wind or insect outbreaks also influence which dominant species of trees and shrubs will develop, but fire can, and often does, trump those disturbances.

Addressing the most common community types, we can project the responses likely with climate change. Based primarily on Heinselman' s work [1, 28, 29], the most common community types in the GLPF are fir-birch (16%), jack pine-black spruce (11%), black spruce bog (7%), maple-aspen-birch-fir (6%), aspen-birch (6%), jack pine-fir (6%), and black spruce-feather moss (6%). Here, we summarize forest community changes likely with the projected climate changes.


#### *Fire and Climate Change in the North American Great Lakes Pine Transition Forest DOI: http://dx.doi.org/10.5772/intechopen.110734*

This community type often includes extensive shallow peat substrates with a shallow 15 cm depth which contains ~60–90 tons of carbon/hectare [30]. Using these tonnages for estimation and the acreage of GLPF and southern boreal forest in Ontario (26 million ha of forested peatlands), this conservatively suggests ~1500– 2300 million tons of carbon to be present in the peat. If this burns, it releases 1.65 to 1.8 times this, or 2400 to 4140 million tons of CO2 equivalent, or 0.2 to 0.4 gigatons of GHG emissions. More emissions would be expected if fires burned deeper peat deposits with increased summer heating and drought. Peatlands in this small example from Ontario represent a very small percentage of the estimated 600,000 million metric tons of peat estimated to be present across on earth [9, 11].


#### **6. Future fire and climate relationships**

At the scale of the landscape, the following fire and ecosystem-scale changes are likely:


incidence of lightning ignition. Although thunderstorms are less frequent in summer, they do occur and with warmer, drier conditions, lightning ignition will likely increase.


#### **7. System changes**

Durability and longevity of carbon on the landscape in standing or downed woody biomass will decrease. GHG's emissions, in time, will decline as future fires burn through younger stands with less woody biomass, and most vulnerable peat in wetlands is burned.

Biodiversity, especially of understory species and neotropical birds will continue to go down. Habitat loss and climate change are already reducing migrant bird species. A recent report by the National Audubon Society estimates that two-thirds of North American birds are endangered species of extinction by the end of the century. In the GLPF, birds that nest or feed in open ground and that utilize brush and young postfire jack pine stands will be less impacted by changing fire regimes. Mourning Warblers, Chestnut-sided Warblers, Yellow-rumped warblers, and Ruffed Grouse are examples of birds that will be favored [18, 19]. Species that will decline during the replacement of mid-age and older stands by these younger stands will be the tree-foliage-searching guild, such as Solitary and Red-eyed Vireo, Parula, Canada and Black-throated Green Warblers, Ruby-crowned Kinglets, Spruce Grouse, Hooded Merganser, and Northern Goshawk [21, 22]. Woodpeckers, including northern black-backed and arctic threetoed woodpeckers, pileated and downy and hairy woodpeckers are all envisioned to increase and colonize burned settings with dead standing trees. Flycatchers are expected to increase as the dense stands open after fire with canopy mortality, foraging species that sally (e.g., olive sided flycatcher, least flycatcher), while species that forage on-wing (e.g., night-hawks, chimney swifts, tree swallows) would increase.

Plant species shifts will occur, but in our experience, no species is lost from the landscape following fire [2, 16]. Native graminoids (*Carex, Calamagrostis*, etc.) will increase as will species of more open sites such as berries (blueberry-*Vaccinium*,

Blackberry and raspberry (*Rubus* spp), and bearberry (*Arctostaphylos* sp). Mountain ash (*Sorbus americana*), mountain maple (*Acer spicatum*), Haws (*Viburnum* spp) are also likely to increase. Species of bryophytes, especially mosses, leafy liverworts, and ferns of deep-forested settings, especially arboreal species found on the trunks of living trees are likely to decline.

#### **8. Climate and fire**

Climate change can acerbate effects that have not previously been considered. One such feedback loop is the changing fire regime and ghg emissions from carbon contained in the standing and downed timber and peat substates. To understand the differences in the magnitude of the GHG emissions as an example, we compare the carbon present in the forest cover and forested peatlands in Ontario [11].

*Peatland carbon*. Boreal forests comprise 83% of all North American forests. The above Ontario example (covering 26 million ha) only represents ~30% of all peatlands in Ontario's boreal region [9, 11]. Just in this region, as fires become more frequent and intense, 24–41 million tons of CO2 equivalent could be released to the atmosphere from combusted peats.

*Forest Carbon*. Ontario forests containing 193–214 mega-tons of carbon/ha (MgC/ ha) accrue additional carbon at rates of 2.1–3.7 MgC/ha-yr [30]. An additional 40% (or 193 MgC/ha × 1.40) is found in the roots, as below-ground carbon (or 77 MgC/ ha). Using the same Ontario forested peatlands acreage as above, >7 million tons (5,043,090,000 MgC above-ground, and 2,012,010,000 MgC below-ground in roots) could be combusted with increased frequency and intensity of wildfires in this Ontario landscape.

#### **9. Summary and considerations**

Changes in climate and wildfire regimes are predicted to result in large impacts in the GLPF and release of carbon may have even more profound impact, especially when scaled to the entire boreal ecosystem. Significant increases in fire intensity, frequency, and the acreage burned are predicted in this ecosystem with climate change predictions [11, 12, 31].

Release of carbon from the biome may well influence future climate change, altering climate significantly more than the current predictions. This suggests several considerations for forest/ecosystem management as follows:


and with this a decline in regional diversity is likely. The use of preemptive prescribed burning in forest communities around the locations with mid- and older-age communities may help reduce the risk of spread of regional fires to these older communities.


*Fire and Climate Change in the North American Great Lakes Pine Transition Forest DOI: http://dx.doi.org/10.5772/intechopen.110734*

#### **Author details**

Steven I. Apfelbaum1 \* and Alan Haney2

1 Applied Ecological Institute, Inc., Brodhead, WI, USA

2 University of Wisconsin, Stevens Point, WI, USA

\*Address all correspondence to: steve@aeinstitute.org

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Heinselman M. The Boundary Waters Wilderness Ecosystem. Minneapolis: University of MN Press; 1996. p. 334

[2] Apfelbaum SI, Haney A, Wang F, Carlson J. Old-growth southern boreal forest stability response to a standreplacing wildfire. Natural Areas Journal. 2017;**37**(4):474-488

[3] Rowe JS. Forest Regions of Canada. Canadian Dept. of Environment: Canadian Forest Service Publ; 1972. p. 1300

[4] Collinson AS. Introduction to World Vegetation. Springer; 1978

[5] Ohmann LF, Ream RR. Wilderness Ecology: Virgin Plant Communities of the Boundary Waters Canoe Area. U.S. Forest Service res. Paper NC-63; 1971

[6] Grigal DF, Ohmann LF. Classification, description, and dynamics of upland plant communities within a Minnesota wilderness area. Ecological Monographs. 1975;**45**:389-407

[7] Heinselman M. Landscape evolution, peatland types, and the environment in the Lake Agassiz peatlands natural area, Minnesota. Ecological Monographs. 1970;**40**:235-261

[8] Dean JL. Wetland Forest Communities of the Eastern Boundary Waters Canoe Area. University of Minnesota; 1971. M.S. thesis. (Cited from Heinselmann, 1996)

[9] Joosten H. The Global Peatland CO2 Picture: Peatland Status and Drainage Related Emissions in all Countries of the World. Ede: Wetlands International; 2009. Available from: https://unfccc.int/sites/ default/files/ draftpeatlandco2report.pdf

[10] Scharlemann JP, Tanner EV, Hiederer RR, Kapos V. Global soil carbon: Understanding and managing the largest terrestrial carbon pool. Carbon Management. 2014;**5**(1):81-91. DOI: 10.4155/cmt.13.77

[11] United Nations Environment Programme. 2022. Global Peatlands Assessment: The State of the World's Peatlands

[12] International Union for Conservation of Nature. Securing the Future for Global Peatlands. Hawaii: World Conservation Congress Resolution WCC-2016-Res-043-EN; 2016. Available from: https://portals.iucn.org/ library/sites/library/filesresrecfiles/ WCC\_2016\_RES\_043\_EN.pdf

[13] Burris JM, Haney AW. Bird communities after blowdown in a late-successional Great Lakes sprucefir forest. The Wilson Bulletin. 2005;**117**(4):341-352

[14] Burris JM, Haney AW. Bird communities before and after a catastrophic blowdown in a Great Lakes pine forest. Bird Populations. 2006;**7**:10-20

[15] Lain EJ, Haney A, Burris JM, Burton J. Response of vegetation and birds to severe wind disturbance and salvage logging in a southern boreal forest. Forest Ecology and Management. 2008;**256**(5):863-871

[16] Apfelbaum SI, Haney A. Bird populations before and after wildfire in a Great Lakes pine forest. The Condor. 1981;**83**(347):354

[17] Apfelbaum SI, Haney A. Nesting and foraging activity of the Brown creeper in Northeastern Minnesota. The Loon. 1977;**49**(2):78-80

*Fire and Climate Change in the North American Great Lakes Pine Transition Forest DOI: http://dx.doi.org/10.5772/intechopen.110734*

[18] Apfelbaum SI, Haney A. Changes in bird populations during succession following fire in the northern Great Lakes wilderness. In: Proceedings – National Wilderness Research Conference: Current Research, 10-16. General Technical Report INT GTR-212. Forest Service: Intermountain Research Station: U.S. Department of Agriculture; 1985;**6**

[19] Apfelbaum SI, Haney A. Bird population changes in recovering conifer forests documented (Minnesota and Ontario). Restoration and Management Notes. 1985;**3**(1):34-35

[20] Haney A, Apfelbaum S, Burris JM. Thirty years of post-fire succession in a southern boreal forest bird community. American Midland Naturalist. 2008;**159**(2):421-433

[21] Apfelbaum SI, Seelbach P. Nest tree, habitat selection, and productivity of seven north American raptor species based on the Cornell University Nest record card program. Raptor Research. 1983;**17**(4):97-113

[22] Apfelbaum SI, Haney A. Note of foraging and nesting habits of goshawks. The Loon. 1984;**56**(132):133

[23] ELPC, (Environmental Law and Policy Center). An Assessment of the Impacts of Climate Change on the Great Lakes2019. p. 70

[24] USGCRP, (US Global Climate Change Research Program). 4th National Review and Report. 1800 G Street, NW, Suite 9100, Washington, DC, 20006, USA; 2017. Available from: Globalchange.gov

[25] Byun K, Hamlet AF. Projected changes in future climate over the Midwest and Great Lakes region using downscaled CMIP5 ensembles. International Journal of Climatology. 2018;**38**:e531-e553

[26] Baker DG, Hines DA, Strub JH Jr. Precipitation facts, normal, and extremes. Climate of Minnesota, Part V, University of Minnesota Agricultural Experiment Station Tech. Bull. 1967:254

[27] Swain AM. A history of fire and vegetation in northeastern Minnesota as recorded in lake sediments. Quaternary Research. 1973;**3**:383-396

[28] Heinselman M. Fire and succession in the conifer forests of northern North America. In: West DC, Shugart HH, Botkin DB, editors. Forest Succession, Concepts, and Applications. New York, N.Y: Springer-Verlag; 1981. pp. 374-405

[29] Heinselman M. Fire intensity and frequency as factors in the distribution and structures of northern ecosystems. 1981:7-57. in H.A. Mooney, T.M. Bonnicksen N. L. Christensen, J.E. Lotan, and W.A. Reiners, coordinators Fire regimes and ecosystem properties. Proc. Of conference Honolulu, Hawaii, 1978. USDA Forest Service Gen. Tech. Rept. WO-26

[30] Natural Resources Canada. Canadian Forest Service. Frontline Express: Great Lakes Forestry, Bulletin #84

[31] Intergovernmental Panel on Climate Change. In: Hiraishi T, Krug T, Tanabe K, Srivastava N, Baasansuren N, Fukuda M, et al., editors. Supplement to the 2006 IPCC Guidelines for National Greenhouse gas Inventories: Wetlands: Methodological Guidance on Lands with Wet and Drained Soils, and Constructed Wetlands for Wastewater Treatment. Geneva, Switzerland; 2014. Available from: https://www.ipcc. ch/publication/2013-supplement-tothe-2006- IPCC-guidelines-for-nationalgreenhouse-gas-inventories wetlands/

### Section 2
