**4.1 Adaptations of grasslands**

Grassland then adapt to the change in climate by controlling on the opening of the stomata to optimise the balance between photosynthesis and transpiration. With the extended period of change in climatic condition, C3 plants2 will no longer have the ability to flourish in such an environment and dormant C4 plants3 seeds or any vegetative parts that is in the soil will flourish and take over the area. Hence, the vegetation shift. The shift in vegetation may not be just the end of the story. As the carbon dioxide levels in the atmosphere continue to rise, carbon, water and nitrogen cycles would also be affected in the grasslands. Gas exchange in the plants is a key player in these cycles. The reduced transpiration level will lead to a reduced mass flow from the soil to the roots and leaves, causing reduced nitrogen uptake and feedback to weaken photosynthetic capacity. The increase in carbon dioxide in the atmosphere has reacted to the change in climate by exhibiting their decreased nitrogen nutrition status [1]. Hence, the change in Earth's energy budget has impacted grassland by causing reduced stomatal conductance and significant reduction in yields.

For a single plant to strive in the environment, it requires certain criteria to grow. Without the criterion, the plant could have stunted growth, slow growth, discoloration and every other possibility. Apart from the observable morphology signs or poor health, they would also display poor yield. The application of chemical and/or organic fertilisers may not be effective as some plants just simply require concentrations that are readily available in the atmosphere. Thus, the instance stated above, where C4 plants are affected by the change have demonstrated that even if there is a shift in vegetation, if the area is deem inhabitable, the area will continue to remain dry and arid. Therefore, it is a relatively simple concept to comprehend – plants with poor health would then be highly susceptible to other diseases. The complexity of plant physiology is affected by the change due to the imbalance in earth's energy budget and to ensure the continuity of its own species.

<sup>1</sup> Vegetation shifts meant that plants that are C3, where carbon fixation takes place on a fix place and C4 plants where the carbon fixation takes place in both the mesophyll cells and in the bundle sheath cells.

<sup>2</sup> C3 plants utilise the Calvin cycle in the dark reaction of photosynthesis. Photosynthesis in these plants only take place when the stomata are open.

<sup>3</sup> C4 plants utilise the Hatch-slack pathway during dark reaction and have chloroplasts that are dimorphic. Photosynthesis in these plants will continue to occur even when the stomata are closed.

As mentioned earlier, climate change has affected grasslands with the change in temperature and precipitation patterns. In tropical grassland, the change of 1 Undercounter Temperature (uC) to 4 uC, will have grasslands experiencing increased aridity which reduces the productivity of soil organic carbon. It would also have plants experiencing increased water stress, therefore, altering the distribution pattern of grassland communities. There would also be decreased palatability of herbage and increased flammability. Drought tolerance species would then dominate and potentially lead to the extinction of other plant species. The carbon cycle in the tropical grassland would be affected as it will no longer be a carbon sink but it will be a source of emitting carbon dioxide. Grassland that is dominated by the C4 grasses will have enhanced biomass production because of the increase in soil moisture. When the grassland have low nitrogen availability, the response to elevated carbon dioxide will be suppressed. This would cause both long and short term effect. Impact of elevated carbon dioxide can be neglected during a short period of time with the increase in efficacy of nutrient-use and increased nutrient uptake due to higher root biomass at the elevated carbon dioxide.

Temperate grassland have similar changes experienced by the tropical grassland. Similar conditions such as increased drought due to the change in seasonal water regimes. The climate variability has then caused water stress. The water stress would cause reduced forage which then affects grazing livestock and also other animals that graze on the grassland. Grasslands have the capability to provide a buffer against climate variability [14]. The changes in temperate grassland will affect agriculture and grazing animals as compared to tropical grassland at the temperature variability is greater (**Figure 3**).

#### **4.2 Impact of climate change**

The model above was predicted on what will likely to happen in the year 2050. In this present day, the grassland ecosystem is already under serious threat. In the next 50 to 100 years, grasslands have been predicted to have lose between 8 to 10% of the vascular plant (the differences between these estimates are driven by different socioeconomic scenario). The effect of the loss of biodiversity in grasslands and its effects on the carbon cycle would be an example of the synergism of global change drivers where biodiversity loss would constrain grassland ability to cope with the effect of other stressors such as climate change and ozone pollution [10]. The drastic change in

#### **Figure 3.**

*Scenarios of biodiversity change for different biomes for the years 2020 and 2050. Bars represent relative losses of biodiversity of vascular plants through habitat loss for different biomes for two scenarios: (a) order from strength and (b) Adapting mosaic. Losses of biodiversity would occur when populations reach equilibrium with habitat available in 2050 and are relative to 1970 values. Darker bars represent scenarios for 2020 and lighter bars for 2050. Adapted from original Figure 10.6 in [15].*

grassland would be impacted by human activities the greatest as the soil conditions are suitable for agriculture and the mild climate in the biome. However, this would then be driven by the increase in food security as the climate changes and the socio-economic status of natis widens. Hence, climate change do not only have direct threats on the grassland ecosystem, it also causes the change in mindset and management regimes.
