Increased vulnerability of alpine and high elevation native forest ecosystems and implications for pest management and tourism
General Context (from MBIE Contract)
Climate change will influence vegetation dynamics (e.g., seed masting) hydrology (e.g., snow cover) and pest dynamics (e.g., rats & stoats) in novel ways that threaten the resilience of New Zealand’s alpine and high elevation forested ecosystems. This modelling, in partnership with DOC, will explore potential implications for ecosystem resilience & functioning, pest management, and tourism.
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 with an upper range of 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. Several broad areas of impacts in the alpine areas may be foreseen, including changes in the amount and distribution of snowpacks and permanent snow and ice, changes in the volume and timing of stream flows from alpine areas, changes in primary productivity in alpine ecosystems and high elevation forests, with cascading impacts on populations of invasive mammals and their indigenous prey species.
This case study, in partnership with DOC, will explore potential implications for conservation management and tourism in alpine areas. It is linked to other case studies in Research Aim 2 because major river systems originate in alpine areas, and therefore water yield to areas at lower elevation will be affected by changes in climate in alpine areas.
This case study has strong support from the Department of Conservation (DOC) because substantial areas of conservation land occur in alpine and high elevation forest ecosystems where management of invasive mammals is required to mitigate impacts on native species. In addition, changes in climate might affect the ability of DOC to provide public access and support recreational use of alpine areas. In general, the tourism industry in alpine areas is highly dependent on weather conditions, and the financial viability of this industry is likely to be affected by changes in climate.
Potential Impacts of Climate Change
- Changes in primary production
- Tree-line shift and resulting changes in habitat area and location
- Invasive mammals
- Impacts of invasive mammals on native species
- Management of invasive mammals
- Other Case Studies
Potential Implications of Climate Change
The implications of climate change for alpine ecosystems have yet to be determined. Overseas studies have predicted major consequences for industries such as forestry (for example due to shifting tree-lines at high latitudes; e.g. Soja et al. 2006) and agriculture (changing glacial meltwater reducing and/or increasing supply to irrigation systems; e.g. Li et al. 2007). In New Zealand, the potential for shifts in tree-lines is uncertain and, in any case, this could have minor consequences for the conservation of native species relative to other threats (McGlone and Walker 2011). However, Tompkins et al. (2013) have predicted substantial changes in the ability of management programmes to achieve effective control of invasive mammals if the frequency of masting (episodes of very high seeding) increases. Given that predation by invasive mammals is one of the most serious threats to native fauna, DOC and other agencies might be forced to re-assess the effectiveness of current pest control strategies. Based on previous studies (e.g. Innes et al. 1999), non-linear relationships between threats, such as predation, and persistence of vulnerable native species could easily result in critical step changes in conservation outcomes, requiring major shifts in conservation policy.
Impacts of climate change on tourism are yet to be assessed in detail but, given the importance of this industry, the implications for local and national economies are likely to be significant.
Highlights of RA2 Alpine Case Study Synthesis Report
New Zealand’s alpine and sub-alpine systems are characterised by plant communities that occasionally produce very large seed crops (masts). Masts result in irruptions of rodents and their predators, primarily stoats, with subsequent severe predation impacts on native fauna. Masts can be predicted using the difference in successive summer temperatures, i.e. the ΔT model (Kelly et al. 2013). Historic, current and projected summer temperature data were used in the ΔT model to predict the timing and extent of masts in forest dominated by beech (Fuscospora spp.).
- Masts are often synchronised over very large areas of beech forest, i.e. at regional scales.
- Mega-masts, i.e. masts occurring over >50% of beech-dominated forest, have occurred 11 times over the last 40 years.
- Virtual Climate Station Network (VCSN) temperature data were used to correctly forecast mega-masts in 2014 and 2016. These forecasts contributed to planning for DOC’s high-profile pest control programme, ‘Battle for our Birds’.
- Spatially explicit forecasts of masts will help Department of Conservation (DOC) managers identify those areas of high conservation value that coincide with a high probability of a mast and therefore are threatened by a pest irruption in any particular year.
- Climate projections up to 2100 suggest mega-masts, and hence wide-scale pest irruptions, are likely to continue to occur episodically regardless of Representative Concentration Pathway (RCP). This indicates that provision of contingency funds for managing mast-induced irruptions of pests could be based on approaches used for other natural events such as wildfires, floods and earthquakes.
- Differences between General Circulation Models (GCMs) mask any significant differences between RCPs in their predicted effects on the frequency of mega-masts during the 21st century.
- The approach of combining spatial climate projections with a climate-based model for beech masts could be used for predicting the effects of climate change on other masting ecosystems worldwide.
- Actuarial or other risk-management approaches are likely to be required in the future to better manage periodic pest irruptions.
Click here to download the RA2 Alpine Case Study Synthesis Report.
- Innes, J., Hay, R., Flux, I., Bradfield, P., Speed, H. and Jansen, P. (1999) Successful recovery of North Island kokako Callaeas cinerea wilsoni populations, by adaptive management. Biological Conservation 87: 201–214.
- Li, W., Chen, Y., Hao, X., Huang, X. and Chen, Y. (2007) Responses of streamflow to climate change in the northern slope of Tianshan Mountains in Xinjiang: A case study of the Toutun River basin. Science in China Series D: Earth Sciences 50 (Supp. 1), 42–48.
- McGlone, M. and Walker, S. (2011) Potential effects of climate change on New Zealand’s terrestrial biodiversity and policy recommendations for mitigation, adaptation and research. Science for Conservation 312.
- Soja, A.J., Tchebakova, N.M., French , N.H.F., Flannigan, M.D., Shugart, H.H., Stocks, B.J., Sukhinin, A.I., Parfenova, E.I., Chapin, F.S. and Stackhouse, P.W. (2007) Climate-induced boreal forest change: Predictions versus current observations. Global and Planetary Change56: 274–296.
- Tompkins, D.M., Byrom, A.E. and Pech, R.P. (2013) Predicted responses of invasive mammal communities to climate-related changes in mast frequency in forest ecosystems. Ecological Applications
- Image 1: Beech Forest Alpine View by Rowan Buxton
- Image 2: Radio Collared Rat by Andrea Byrom