Climate–land-use dynamics in high and hill country environments: implications for conservation, primary production, rural communities, and ecosystem services
General Context (from MBIE contract)
Climate change will have direct impacts on hill & high country environments via 1) changes to primary production; 2) native forest & shrubland successional dynamics; and 3) increased pressures on sensitive ecosystems such as ephemeral wetlands. It will also have indirect impacts to ecosystem services (e.g. water quantity & quality, soil erosion, carbon dynamics and sequestration). This modelling will explore the potential implications for conservation, forestry, bioenergy, and pastoral sectors including such issues as water allocation and irrigation, risk of wildfires, associated economic costs & benefits, and potential policy responses.
By the middle of this century water and air temperatures are expected to be, on average, around a degree Celsius higher than was the case in the 1990s. Toward the end of the century the mid-range projections are for an increase of 2oC and may be as high as 5oC. Average rainfall is expected to increase in the west and south and decrease in the east and north, and heavy rainfall events may become more severe. This might be expected to influence a range of issues relating to primary productivity, ecosystem services and conservation.
Effects on upland systems will be a combination of direct impacts of climate change, changes in social and economic conditions due to climate change, and impacts of policies for greenhouse gas reductions or climate change mitigation.
Study Area Selected
The Uplands Case Study will encompass iconic areas of high country of the Mackenzie Basin and surrounding watersheds. The study area will be defined as the upper part of the Waitaki River catchment, including all areas draining into the reservoir Lake Waitaki. The case study will use the boundaries of the Upper Waitaki Zone of the Canterbury Water Management Strategy of the Canterbury Regional Council, as the precise definition of the boundaries of the study area (see the Canterbury Water Zone Map).
Potential Impacts of Climate Change
The following impacts of Climate Change are currently under consideration within this Case Study. The final choice of issues, and the emphasis and effort amongst them will be chosen by ongoing input from a range of stakeholders.
- Flow availability and hydrological fluxes for downstream users as well as any other hydrological variables (eg snow cover area, groundwater recharge, surface runoff, evaporation from soil-vegetation-“snow sublimation”) as well as extreme events (eg flood event, drought occurrence).
- Land-use change and its downstream impacts
- Agricultural profitability
- Agriculture and forestry production impacts
- Wilding pines and wildfires
- Shifts in environmental conditions and resulting shifts in ecosystems, including species distributions and exacerbated increased weed invasions
Potential Implications of Climate Change
The case study will attempt to explore the implications of climate change primarily through the use of farm systems and landuse models, with the understanding that there is likely to be a “nesting effect” of impacts and implications. For example, an impact of changes in rainfall and runoff to streams and rivers in the catchment could be a change in the potential to extract and store water for irrigation. This will have implications for pasture productivity in the area, which will have associated implications for farm profitability, which then may have an impact on landuse. This “nested” impacts/implications concept will be explored in this case study.