**3. Results**

#### **3.1 Impact of climate change on forest type**

Climate change projections indicate that some forests would significantly change while others would not change (**Figure 4**). For instance, the central area and northern area forests would be converted from dry forest in near century to very dry forest in mid-century. The central area forests would further be converted from very dry forest in mid-century to thorn woodland forest in end-century. The lake shore area forests would be converted from very dry forest in near century to thorn woodland forest in mid-century. On the other hand, the shire highlands forest would be converted from dry forest in mid-century to very dry forest in end-century. Interestingly, the shire valley forests would not be affected by climate change.

*Impact of Climate Variability on Forest Vegetation Zones in Malawi DOI: http://dx.doi.org/10.5772/intechopen.106850*

#### **Figure 4.**

*Impact of climate change on forest type using Holdridge Life Zone (HLZ) model under three scenarios, A: Near century (2011–2040); B: Mid-century (2041–2070); and C: End-century (2071–2100).*

#### **3.2 Spatial distribution patterns of vegetations zones**

The results on the spatial distribution pattern of forest zones in Malawi are presented in **Figure 5**. Three forest vegetation zones will be observed in the near century, mid-century and end-century climate change scenarios from the concept framework of Holdridge Life Zone model system. They are dry forest, very dry forest and thorn woodland forest. Under near century (2011–2040) climate conditions, there are two forest vegetation zones occurring in Malawi: dry forest and very dry forest. Under mid-century (2041–2070) climate conditions, one new forest vegetation zone will emerge in Malawi (thorn woodland forest), and dry forest will disappear in under end-century (2071–2100) climate conditions.

### **3.3 Area distribution change of forest vegetations zones**

Summary of the results on the area distribution change of forest vegetation zones in Malawi are presented in **Table 2**. The results show that dry forest vegetation zone shall decrease its area proportion from 60.7% to 15.6% from near century to mid-century. On the other hand, very dry forest vegetation will expand its area proportion from 39.3% to 63.8% under the same climate condition scenario. Most notably is that, thorn woodland forest would shall emerge under the same climate condition scenario. Furthermore, the results indicate that thorn woodland forest would increase its area proportion from 20.5% to 47.1% from the mid-century to the end-century. Consequently, very dry forest would decrease its area proportion from 63.8% to 52.9%, while dry forest will disappear.

#### **3.4 Effect of climate variability on forest living biomass**

Summary of the results on the effect of climate variability on forest living biomass, are presented in **Figure 6**. The results show a significant decrease in forest

#### **Figure 5.**

*Three forest vegetation zones that occurs and that will be observed in Malawi under Holdridge Life Zone model system.*


#### **Table 2.**

*The area of forest vegetation zones under near-century, mid-century and end-century climate change scenario.*

#### **Figure 6.**

*Prediction on the impact of climatic change on forest living biomass for different climatological zone forests in Malawi.*

living biomass from near-century to mid-century for both lake shore area forests (1200 kg ha−1 yr−1) and northern area forests (2300 kg ha−1 yr−1). Likewise, projections show a significant decrease in forest living biomass from mid-century to endcentury for both shire highlands forests (1600 kg ha−1 yr−1) and central area forests (1000 kg ha−1 yr−1). Conversely, the projections show that forest living biomass for shire valley area forests would not be highly affected by climate variability.

## **4. Discussion**

Numerous research studies have been conducted to examine the potential effects of climate change on the distribution of terrestrial vegetation at regional, national and district scales [6, 15–17]. The present study shows that forest vegetation zone responses to climate change are significantly different under the three climate conditions scenarios. It has been demonstrated that dry forest vegetation zone will likely disappear in the end-century. In addition, one new vegetation zones (thorn woodland forest) will appear in the mid-century scenario.

In mid-century and end-century more than 50% of the forest vegetation would be very dry forest. This indicates that mid-century and end-century climate changes will be beneficial for the growth and expansion of the very dry forest. The results reported by Li et al. [6] also support the present findings.

Various climate-vegetation models are used for determining the impact of climate change on forest vegetation type [16]. The present study used HLZ model because of its simplicity, it only needs three parameters to be used, hence more advantageous than other models [6, 18, 19]. Even though the parameters used in HLZ model may sufficiently simulate vegetation patterns, the actual patterns can be described by a function of additional factors that are not clearly considered in the model, which are caused by human [6]. Li et al. [6] and Josa et al. [20] argued that human activities may change the response of vegetation to climate change through transformation of land use types. Therefore, it is said that HLZ model simulates ecosystem potential functions rather than the actual ecosystem structure [6, 20]. Equally, the present study is in agreement to that argument.

The forest vegetation zones simulated under the three climate conditions scenarios in the present study can provide important reference information for policy makers in planning regional vegetation restoration. Some of the strategies that can be used to adapt to the climate change would be promotion of natural regeneration of tree species, promotion of tree site matching, production and promotion of new tree seed varieties; and seed banking for drought resistant tree species.
