**Abstract**

Agroforestry an established practice for centuries is the deliberate combination of perennials with food crops and/or livestock either simultaneously or sequentially. Agroforestry systems are bio-diverse and are associated in numerous ways for combating desertification and mitigating climate change. Agroforestry practice is a possible way of reducing deforestation and forest degradation and can alleviate resource-use pressure on natural conservation areas. Among many other reasons responsible for climate change, our traditional approaches towards forest management have failed thereby giving way to a drastic climate change, which slowly but has indeed harbingered the cataclysmic future that awaits us if we do not act now. This paper thus acquaints the readers with the role of agroforestry in mitigating the soil erosion, rehabilitation of degraded lands, improving water conservation and replenishment of soil fertility. Besides, the role of agroforestry in improving the soil health and overall ecosystem has also been discussed. This paper furthermore, attempts to recognize the role that agroforestry can play in mitigating the repercussions of climate change apart from improving natural resource sustainability and future food security issues.

**Keywords:** Agroforestry, carbon, climate change mitigation, ecosystem services

### **1. Introduction**

Population explosion worldwide is putting huge pressure on natural resources, which is creating our planet a precarious place to live. It is expected that by the end of the 21st century the world population will reach 8 billion and food required to feed the entire population will be about 120 M tons. It is estimated that by the year 2050 food demand will increase by 60% globally and 100% for the developing countries. Therefore, there is a pressing need to conserve natural resources like soil, water, and vegetation for future demands to accommodate the ever-increasing population growth. Climate change is threatening our very existence and is accepted as a vital issue in the 21st century. Increased emissions of greenhouse gasses due to anthropogenic factors are responsible for average increase in earth temperature and global climate change. Agroforestry has immense potential in mitigating climate change concerns by lessening global warming since vegetation assimilates the CO2 gas in the process of photosynthesis which is one of the main contributors to greenhouse gases.

Agroforestry is a farming system that integrates crops and or livestock with trees and shrubs [1]. Agroforestry provides many benefits that includes favorable microclimate, reduction in erosion, enhanced biodiversity, increased water quality, more infiltration leading to effective groundwater recharge, enhanced and elongated dry flow, improvement in habitat, soil fertility, etc. Agroforestry is promising for a sustainable solution in response to soil conservation, land degradation, and also can bridge the gaps between climate change and mitigation strategies. Agroforestry has the immense capacity to provide sustainable agricultural benefits and approximately 1.2 billion people of the world is practicing agroforestry one way or the other way [2]. It has high potential to balance between the demands and requirements of population growth and natural degradation. The present review investigated the potential and opportunities of agroforestry in combating soil and water degradation and the role of agroforestry in climate change mitigation.

#### **2. Mitigation of soil erosion through agroforestry**

Topsoil on earth is the most productive, as essential macronutrients (N, P, K, Ca, Mg and S) and micronutrients (B, Cl, Fe, Cu, Zn, etc.) for plants are mostly found in topmost layers of the soil. These essential nutrients are required for completing the life cycle of plants. Soil erosion is a process in which topsoil is displaced from its location by different agents mainly water and wind. Globally, about 24 billion tonnes of fertile soil is lost annually through water erosion [3]. The soil pool loses 1100 Mt. C into the atmosphere as a result of soil erosion and another 300–800 Mt. C annually to the ocean through erosion-induced transportation [4].

It is expected that rainfall pattern will vary greatly due to global climate change and the effect of climate change will increase soil erosion. In India, the annual rainfall amount along with the frequency of high-intensity storm events will increase by 2030 compared to the baseline i.e. 1970 which will accelerate erosion and runoff. Nearing et al. [5] reported that an increase of soil erosion and rainfall amount is of the order of 1.70. Lee et al. [6] reported 2°C increase in annual temperature which will increase wind erosion by 15–18%. Therefore, without some improved practices like agroforestry, wind erosion is expected to accelerate in arid and semiarid regions. Windbreaks, alley cropping, and riparian buffers are especially designed to reduce wind erosion [7]. Thus, agroforestry will give more flexibility in socioeconomic and environmental service perspective in changing climatic situations. Vegetation with its canopy cover reduces the kinetic energy of the rainfall. The energy left with the falling raindrops depends on the height of canopy cover from the ground surface. It is reported that 4-meter canopy height decreases the kinetic energy by 80% [8]. Plant litter absorbs the rest of the energy of the falling rainfall which reduces the soil erosion to a certain level. The plant litter reduces the runoff by improving the infiltration and water holding capacity of the soils. The decomposition of plant litter, root decay, and exudation from the rhizosphere increases the organic matter content in soil and enhances the soil structure which is less prone to erosion.

Protecting the topsoil from erosion is of high priority for ensuring sustainable food production and food security. Agroforestry systems are widely accepted and agreed around the globe due to its influence on soil erosion control. Studies reported in the past concluded that developing countries have well-adopted agroforestry systems for controlling soil erosion from the steep slopes [9–14]. Alley cropping reduces soil loss to a great extent mainly due to its dense canopy cover which reduces the kinetic energy of falling rain. Alley cropping system is very effective in absorbing almost the entire energy of rain as the trees used in this system are mostly

**63**

**Figure 1.**

*Average soil deposition for different alley cropping system.*

**Table 1.**

*Potential and Opportunities of Agroforestry Practices in Combating Land Degradation*

of short stature or shrubby. The shrubs form a barrier to runoff and take more time to infiltrate into the soil and thus less runoff. Soil loss is proportional to the square root of runoff volume, the less the volume of the runoff, the less is the transporta-

In Nigeria in an alley cropping system consisting of maize with Leucaena hedge results in soil loss only 76 kg ha−1 in comparison to No-till condition without Leucaena where soil loss was 10737 kg ha−1 [16]. In an experiment in north-western Himalaya at Dehradun, India (rainfall 1740 mm), the effectiveness of different barrier hedges, trees, and grasses on runoff and soil loss at 4% slope was studied (**Table 1**). Grasses were very effective in reducing soil loss despite with higher runoff (**Table 1**). Tree alleys are also effective in reducing the soil loss and runoff. Soil deposited in front of Leucaena based agroforestry system and Eucalyptus based system is represented in **Figure 1**, which represents that average deposition ranged from 15.77–28.5 t ha−1 in front of Leuceana hedges [17]. In Rwanda and Burundi

**Treatment Runoff (%) Soil loss (t ha−1 yr.−1)**

Corn on contour 40 21 Leucaena hedges 21.3 12.1 Panicum (0.75 m wide) 36.7 7.0 Eulaliopsis (0.75 m wide) 42.7 10.0 Veteveria (0.75 m wide) 39.6 8.1 Leucaena trees (6–8 years) 20.4 8.4 Eucalyptus trees (6–8 years) 16.3 5.8

*Effect of different barrier hedges, trees, and grasses on runoff and soil loss.*

*DOI: http://dx.doi.org/10.5772/intechopen.97843*

tion power of the runoff [15].

#### *Potential and Opportunities of Agroforestry Practices in Combating Land Degradation DOI: http://dx.doi.org/10.5772/intechopen.97843*

of short stature or shrubby. The shrubs form a barrier to runoff and take more time to infiltrate into the soil and thus less runoff. Soil loss is proportional to the square root of runoff volume, the less the volume of the runoff, the less is the transportation power of the runoff [15].

In Nigeria in an alley cropping system consisting of maize with Leucaena hedge results in soil loss only 76 kg ha−1 in comparison to No-till condition without Leucaena where soil loss was 10737 kg ha−1 [16]. In an experiment in north-western Himalaya at Dehradun, India (rainfall 1740 mm), the effectiveness of different barrier hedges, trees, and grasses on runoff and soil loss at 4% slope was studied (**Table 1**). Grasses were very effective in reducing soil loss despite with higher runoff (**Table 1**). Tree alleys are also effective in reducing the soil loss and runoff. Soil deposited in front of Leucaena based agroforestry system and Eucalyptus based system is represented in **Figure 1**, which represents that average deposition ranged from 15.77–28.5 t ha−1 in front of Leuceana hedges [17]. In Rwanda and Burundi


#### **Table 1.**

*Agroforestry - Small Landholder's Tool for Climate Change Resiliency and Mitigation*

tion and the role of agroforestry in climate change mitigation.

C annually to the ocean through erosion-induced transportation [4].

**2. Mitigation of soil erosion through agroforestry**

Agroforestry is a farming system that integrates crops and or livestock with trees and shrubs [1]. Agroforestry provides many benefits that includes favorable microclimate, reduction in erosion, enhanced biodiversity, increased water quality, more infiltration leading to effective groundwater recharge, enhanced and elongated dry flow, improvement in habitat, soil fertility, etc. Agroforestry is promising for a sustainable solution in response to soil conservation, land degradation, and also can bridge the gaps between climate change and mitigation strategies. Agroforestry has the immense capacity to provide sustainable agricultural benefits and approximately 1.2 billion people of the world is practicing agroforestry one way or the other way [2]. It has high potential to balance between the demands and requirements of population growth and natural degradation. The present review investigated the potential and opportunities of agroforestry in combating soil and water degrada-

Topsoil on earth is the most productive, as essential macronutrients (N, P, K, Ca, Mg and S) and micronutrients (B, Cl, Fe, Cu, Zn, etc.) for plants are mostly found in topmost layers of the soil. These essential nutrients are required for completing the life cycle of plants. Soil erosion is a process in which topsoil is displaced from its location by different agents mainly water and wind. Globally, about 24 billion tonnes of fertile soil is lost annually through water erosion [3]. The soil pool loses 1100 Mt. C into the atmosphere as a result of soil erosion and another 300–800 Mt.

It is expected that rainfall pattern will vary greatly due to global climate change and the effect of climate change will increase soil erosion. In India, the annual rainfall amount along with the frequency of high-intensity storm events will increase by 2030 compared to the baseline i.e. 1970 which will accelerate erosion and runoff. Nearing et al. [5] reported that an increase of soil erosion and rainfall amount is of the order of 1.70. Lee et al. [6] reported 2°C increase in annual temperature which will increase wind erosion by 15–18%. Therefore, without some improved practices like agroforestry, wind erosion is expected to accelerate in arid and semiarid regions. Windbreaks, alley cropping, and riparian buffers are especially designed to reduce wind erosion [7]. Thus, agroforestry will give more flexibility in socioeconomic and environmental service perspective in changing climatic situations. Vegetation with its canopy cover reduces the kinetic energy of the rainfall. The energy left with the falling raindrops depends on the height of canopy cover from the ground surface. It is reported that 4-meter canopy height decreases the kinetic energy by 80% [8]. Plant litter absorbs the rest of the energy of the falling rainfall which reduces the soil erosion to a certain level. The plant litter reduces the runoff by improving the infiltration and water holding capacity of the soils. The decomposition of plant litter, root decay, and exudation from the rhizosphere increases the organic matter content in soil and enhances the soil structure which is less prone to

Protecting the topsoil from erosion is of high priority for ensuring sustainable food production and food security. Agroforestry systems are widely accepted and agreed around the globe due to its influence on soil erosion control. Studies reported in the past concluded that developing countries have well-adopted agroforestry systems for controlling soil erosion from the steep slopes [9–14]. Alley cropping reduces soil loss to a great extent mainly due to its dense canopy cover which reduces the kinetic energy of falling rain. Alley cropping system is very effective in absorbing almost the entire energy of rain as the trees used in this system are mostly

**62**

erosion.

*Effect of different barrier hedges, trees, and grasses on runoff and soil loss.*

**Figure 1.** *Average soil deposition for different alley cropping system.*

in ferrallitic soils (Ultisol) with rainfall, erosivity ranges from 250 to 700 on 20 to 60% slopes, soil loss ranges from 300 to 700 t ha−1 yr.−1 in the form of sheet and rill erosion. However, surprisingly the runoff rate was only 10 to 30% of the rainfall. In these circumstances, agroforestry practices have been found suitable in reducing soil loss and produced enough biomass to mulch the surface as well as to increase soil fertility.

Numerous studies on soil loss and runoff for different agroforestry models have been carried out in Shivalik Himalayas in India. The soil loss and runoff of the agroforestry models i.e. Eucalyptus + bhabar grass, *Acacia catechu* + napier grass, Leucaena + napier grass, Teak + leucaena+ bhabar grass, Eucalyptus + leucaena + turmeric, poplar + leucaena + bhabar, Sesamum + rape seed are compared with cultivated fallow. The maximum and minimum soil loss and runoff were found in the case of Sesamum + rape seed and Eucalyptus + bhabar grass of 2.69 t ha−1, 20.50% and 0.07 t ha−1 0.05% respectively. For cultivated fallow land, the soil loss and runoff was 5.65 t ha−1 and 23% which was much more than the agroforestry models. The N loss was found minimum in Eucalyptus + bhabar grass model (0.46 kg ha−1) and maximum in Sesamum + rape seed (42.50 kg ha−1) whereas K loss was minimum in *Acacia catechu* + napier grass (0.52 kg ha−1) and maximum in Sesamum + rape seed (3 kg ha−1) respectively. In cultivated fallow land, the N and K loss was 51.30 kg ha−1 and 5.00 kg ha−1respectively [18]. A study to understand the effectiveness of different pasture management techniques in reducing soil loss, runoff and nutrient loss (N & K) was conducted in Bundelkhand region of Central India. Runoff, soil loss and nutrient loss from pasture systems such as natural grassland, improved pasture, sown pasture and 3-tier silvopasture have been compared with respect to bare land. Results showed that among the pasture systems runoff, soil and nutrient loss was found maximum from the natural grassland i.e., 11.6%, 2.50 t ha−1, 3.75 kg ha−1 yr.−1 and 4.00 kg ha−1 yr.−1 respectively and minimum soil and nutrient loss was found for 3-tier silvopasture system i.e., 1.27 t ha−1, 1.27 kg ha−1 yr.−1 and 2.10 kg ha−1 yr.−1 respectively whereas runoff i.e., 9% was minimum for sown pasture.

Windbreaks/shelterbelts are very effective in arid and semi-arid regions specifically for wind erosion-prone areas. They comprised of single/multi rows/belt of trees which are planted in orientation perpendicular to the direction of wind. The belts of trees are very effective in ameliorating the microclimate and improving growth and yield of associated annual crops. Shelterbelt comprising of castor on the windward and shorter tree in leeward direction increased the yield of lady's finger and cowpea by 41% and 21% respectively than the control [19]. From different studies, it has been reported that shelterbelts reduce soil erosion by 50% [20].

Home gardens are also very effective in reducing soil erosion. Study conducted in Kerala (India) revealed that cardamom, pepper and mixed home gardens with coconut trees remarkably reduces the soil loss to 0.65, 3.55 and 1.45 t ha−1 respectively in comparison to soil loss 130 t ha−1 from land after removing forest canopy [21]. In an experiment in Nilgiris in India, runoff and soil loss was measured for 5 years (1959 to 1963) on 16% sloping land under five different vegetation cover viz., blue gum, black-wattle plantation, slola, broom, and indigenous grass. The runoff and soil loss data showed that blue gum cover produced the highest (1.08%) and grassland produced almost nil (0.018%) runoff.

#### **3. Rehabilitation of degraded lands through agroforestry**

Land degradation means the gradual deterioration of land quality in terms of agricultural productivity. An assessment by United Nations Development Programme (UNDP) showed that globally 40% of the land area comes under

**65**

**Table 2.**

*Potential and Opportunities of Agroforestry Practices in Combating Land Degradation*

dryland out of which 29.7%, 44.3%, and rest falls in arid, semiarid, and dry sub-humid region respectively. The Food and Agricultural Organization (FAO) estimated that 43% of rangelands and 20% of cropping lands are degraded while Sub-Saharan Africa has the highest rate of land degradation. About 46% of land in Africa is affected by land degradation which suggests productivity loss of 20% over the last 40 years. About 68% of the land in Australia is under degradation while as in Asia about 25% of the land is vulnerable to degradation and will likely increase

Increase in vegetation coverage is the fundamental approach to control land degradation. UNCCD (2004) revealed that forests and tree cover have potential combat land degradation and desertification by stabilizing soils, reducing water and wind erosion and maintaining nutrient cycling in soils. Different agroforestry systems have been designed after years of research for different categories of degraded lands. These agroforestry systems not only provide higher productivity but are also capable of conserving the resources efficiently. Silvipasture systems have been found to be very successful on degraded lands. Eucalyptus trees in combination with *Eulaliopsis binnata* harnessed almost all the runoff and trapped all soil inside the field except in 1988 when rainfall was extremely high than other years (**Table 2**). In the reclamation of the salt-affected area some of the tree species such as *Acacia farenesiana*, *Tamarix articulate*, *Propsopis juliflora*, *Pithecellobium dulce* and *Parkinsonia aculeate* were found to very effective [22]. In the reclamation of alkali soil, *Prosopis juliflora* (2 mx 2 m) + *Leptochloa fusca* was found most effective alone with the production of 161 t biomass and 56 t ha−1 grass in six years [22]. However, in alkaline soils at Dhipura (Madhya Pradesh, India), it was found *P. juliflora* not only increased the OC content but also enhanced the essential mineral content to great extent after 9 years. *Propopis chilensis* (Mesquite) tree was found to be effective in reducing pH, EC, and exchangeable Na level and increasing infiltration characteristics, OC, total N, available P, exchangeable Ca, Mg and K levels [23, 24]. Eucalyptus tree as reported with high transpiration rates was found very effective in

Natural causes like forest fire, avalanches, landslides, flooding, and anthropogenic activities such as deforestation, overgrazing, construction works, unscientific farming in hills resulted in excess soil erosion and land degradation [25, 26]. A 4 ha landslide-prone area at Nalotanala on Dehradun-Mussoorie road in India, agroforestry plantation of *Ipomoea carnea*, *Vitex negundo* and napier with *Erythrino suberosa*, *Dalbergia sissoo* and *Acacia catechu* successfully stabilized the area after 10 years of practice. [27]. Acharya and Kafle [28] reported that due to continuous soil erosion

Air dry grass yield (t ha−1) 1.2 8.6 1.5 5.1 4.1 Mean Eucalyptus height (m) 1.5 4.7 6.7 8.4 10.5 Mean Eucalyptus DBH (cm) 1.2 4.3 5.5 6.6 7.4 Runoff (mm) — — — 10.01 — Soil loss (t ha−1) — — — 0.17 — Monsoon rainfall (mm) 686 905 313 1586 934

**1985 1986 1987 1988 1989**

**Parameters Years**

*Different parameters related to Eucalyptus and Bhabar agroforestry system.*

of the land worldwide is degraded

was caused by water. Many studies pertaining to agrofor-

*DOI: http://dx.doi.org/10.5772/intechopen.97843*

due to climate change issues. About 19.65 Mkm2

estry have been carried out in to tackle land degradation.

out of which 10.94 Mkm2

reclaiming waterlogged areas [24].

#### *Potential and Opportunities of Agroforestry Practices in Combating Land Degradation DOI: http://dx.doi.org/10.5772/intechopen.97843*

dryland out of which 29.7%, 44.3%, and rest falls in arid, semiarid, and dry sub-humid region respectively. The Food and Agricultural Organization (FAO) estimated that 43% of rangelands and 20% of cropping lands are degraded while Sub-Saharan Africa has the highest rate of land degradation. About 46% of land in Africa is affected by land degradation which suggests productivity loss of 20% over the last 40 years. About 68% of the land in Australia is under degradation while as in Asia about 25% of the land is vulnerable to degradation and will likely increase due to climate change issues. About 19.65 Mkm2 of the land worldwide is degraded out of which 10.94 Mkm2 was caused by water. Many studies pertaining to agroforestry have been carried out in to tackle land degradation.

Increase in vegetation coverage is the fundamental approach to control land degradation. UNCCD (2004) revealed that forests and tree cover have potential combat land degradation and desertification by stabilizing soils, reducing water and wind erosion and maintaining nutrient cycling in soils. Different agroforestry systems have been designed after years of research for different categories of degraded lands. These agroforestry systems not only provide higher productivity but are also capable of conserving the resources efficiently. Silvipasture systems have been found to be very successful on degraded lands. Eucalyptus trees in combination with *Eulaliopsis binnata* harnessed almost all the runoff and trapped all soil inside the field except in 1988 when rainfall was extremely high than other years (**Table 2**). In the reclamation of the salt-affected area some of the tree species such as *Acacia farenesiana*, *Tamarix articulate*, *Propsopis juliflora*, *Pithecellobium dulce* and *Parkinsonia aculeate* were found to very effective [22]. In the reclamation of alkali soil, *Prosopis juliflora* (2 mx 2 m) + *Leptochloa fusca* was found most effective alone with the production of 161 t biomass and 56 t ha−1 grass in six years [22]. However, in alkaline soils at Dhipura (Madhya Pradesh, India), it was found *P. juliflora* not only increased the OC content but also enhanced the essential mineral content to great extent after 9 years. *Propopis chilensis* (Mesquite) tree was found to be effective in reducing pH, EC, and exchangeable Na level and increasing infiltration characteristics, OC, total N, available P, exchangeable Ca, Mg and K levels [23, 24]. Eucalyptus tree as reported with high transpiration rates was found very effective in reclaiming waterlogged areas [24].

Natural causes like forest fire, avalanches, landslides, flooding, and anthropogenic activities such as deforestation, overgrazing, construction works, unscientific farming in hills resulted in excess soil erosion and land degradation [25, 26]. A 4 ha landslide-prone area at Nalotanala on Dehradun-Mussoorie road in India, agroforestry plantation of *Ipomoea carnea*, *Vitex negundo* and napier with *Erythrino suberosa*, *Dalbergia sissoo* and *Acacia catechu* successfully stabilized the area after 10 years of practice. [27]. Acharya and Kafle [28] reported that due to continuous soil erosion


#### **Table 2.**

*Different parameters related to Eucalyptus and Bhabar agroforestry system.*

*Agroforestry - Small Landholder's Tool for Climate Change Resiliency and Mitigation*

in ferrallitic soils (Ultisol) with rainfall, erosivity ranges from 250 to 700 on 20 to 60% slopes, soil loss ranges from 300 to 700 t ha−1 yr.−1 in the form of sheet and rill erosion. However, surprisingly the runoff rate was only 10 to 30% of the rainfall. In these circumstances, agroforestry practices have been found suitable in reducing soil loss and produced enough biomass to mulch the surface as well as to increase

Numerous studies on soil loss and runoff for different agroforestry models have

been carried out in Shivalik Himalayas in India. The soil loss and runoff of the agroforestry models i.e. Eucalyptus + bhabar grass, *Acacia catechu* + napier grass, Leucaena + napier grass, Teak + leucaena+ bhabar grass, Eucalyptus + leucaena + turmeric, poplar + leucaena + bhabar, Sesamum + rape seed are compared with cultivated fallow. The maximum and minimum soil loss and runoff were found in the case of Sesamum + rape seed and Eucalyptus + bhabar grass of 2.69 t ha−1, 20.50% and 0.07 t ha−1 0.05% respectively. For cultivated fallow land, the soil loss and runoff was 5.65 t ha−1 and 23% which was much more than the agroforestry models. The N loss was found minimum in Eucalyptus + bhabar grass model (0.46 kg ha−1) and maximum in Sesamum + rape seed (42.50 kg ha−1) whereas K loss was minimum in *Acacia catechu* + napier grass (0.52 kg ha−1) and maximum in Sesamum + rape seed (3 kg ha−1) respectively. In cultivated fallow land, the N and K loss was 51.30 kg ha−1 and 5.00 kg ha−1respectively [18]. A study to understand the effectiveness of different pasture management techniques in reducing soil loss, runoff and nutrient loss (N & K) was conducted in Bundelkhand region of Central India. Runoff, soil loss and nutrient loss from pasture systems such as natural grassland, improved pasture, sown pasture and 3-tier silvopasture have been compared with respect to bare land. Results showed that among the pasture systems runoff, soil and nutrient loss was found maximum from the natural grassland i.e., 11.6%, 2.50 t ha−1, 3.75 kg ha−1 yr.−1 and 4.00 kg ha−1 yr.−1 respectively and minimum soil and nutrient loss was found for 3-tier silvopasture system i.e., 1.27 t ha−1, 1.27 kg ha−1 yr.−1 and 2.10 kg ha−1 yr.−1

respectively whereas runoff i.e., 9% was minimum for sown pasture.

and grassland produced almost nil (0.018%) runoff.

**3. Rehabilitation of degraded lands through agroforestry**

Land degradation means the gradual deterioration of land quality in terms of agricultural productivity. An assessment by United Nations Development Programme (UNDP) showed that globally 40% of the land area comes under

Windbreaks/shelterbelts are very effective in arid and semi-arid regions specifically for wind erosion-prone areas. They comprised of single/multi rows/belt of trees which are planted in orientation perpendicular to the direction of wind. The belts of trees are very effective in ameliorating the microclimate and improving growth and yield of associated annual crops. Shelterbelt comprising of castor on the windward and shorter tree in leeward direction increased the yield of lady's finger and cowpea by 41% and 21% respectively than the control [19]. From different studies, it has been reported that shelterbelts reduce soil erosion by 50% [20].

Home gardens are also very effective in reducing soil erosion. Study conducted in Kerala (India) revealed that cardamom, pepper and mixed home gardens with coconut trees remarkably reduces the soil loss to 0.65, 3.55 and 1.45 t ha−1 respectively in comparison to soil loss 130 t ha−1 from land after removing forest canopy [21]. In an experiment in Nilgiris in India, runoff and soil loss was measured for 5 years (1959 to 1963) on 16% sloping land under five different vegetation cover viz., blue gum, black-wattle plantation, slola, broom, and indigenous grass. The runoff and soil loss data showed that blue gum cover produced the highest (1.08%)

**64**

soil fertility.

in up-hills in Nepal, the bed levels of *Terai* river were increasing 35–45 cm annually [29]. Govt. of Nepal has leased the degraded forest lands and the tax-free lands to families below the poverty level for the reclamation of the degraded lands [30].
