Risk = [Exposure x Vulnerability] x Hazard

Why interactions between climate and landscape change matter for conservation priorities

It was becoming increasingly clear that an approach to conservation that deals with threats one by one without considering how those threats interact is inadequate when biodiversity is threatened by multiple, co-occurring stressors. For example, in Decision Point #57 I showed how species in areas with high temperatures and where average rainfall has decreased over time will likely suffer greater impacts from habitat loss fragmentation.

Three years on, EDG researchers have now taken this understanding of synergistic interactions one step further, and assessed the future risk of global biodiversity loss due to climate change and land-cover interactions. Understanding the role of multiple stressors (eg, climate change and habitat loss) on biodiversity is essential for identifying policy responses and managing the impact of global change on biodiversity. Our study addresses this critical issue and provides new insights into global investment in conservation priority ‘hotspots’.

Figure 1: The steps taken to calculate the risk of biodiversity loss from habitat loss.

Figure 1: The steps taken to calculate the risk of biodiversity loss from
habitat loss.

The team from UQ (CEED), CSIRO, Microsoft Research, University of Saskatchewan, and the Sapienza University of Rome ran a risk analysis to model the interaction between habitat loss and climate to quantify the implications of these interactions on birds and mammals globally. Climate scenarios for the fourth assessment report of the intergovernmental panel on climate change were used along with the projected land-cover change scenarios of human development from the Millennium Ecosystem Assessment.

The vulnerability model depended on climate projections according to an empirical model derived from a previous global meta-analysis (see Decision Point #57). Risk was calculated as the number of species of birds and mammals impacted by habitat loss from future land-cover change with and without the interaction (Figure 1).

Climate change will exacerbate the risk of mammal and bird declines due to future land-cover change by up to 24% for mammals and 43% for birds.

Impacts on mammals and birds

Our analysis found that climate change will exacerbate the risk of mammal and bird declines due to future land-cover change by up to 24% for mammals and 43% for birds. Orange and dark red in Figure 2 indicate areas where the interaction between climate change and habitat loss increases in risk from future land-cover change, whereas light to dark green indicate areas where risk either declines or remains unchanged.

Our ever changing landscapes: pictured here is a mural in the town of Sheffield in Tasmania showing a Tasmanian landscape with the now extinct Tasmanian tiger and the threatened Tasmanian devil. The Tasmanian tiger went extinct due to a number of stresses including over hunting, habitat loss and disease. Dealing with any of these threats individually probably wouldn’t have saved this species just as dealing with climate change or land-cover change separately may not save many of today’s threatened species into the future. The key lies in understanding the interactions between the multiple stressors. (Photo by Chrystal Mantyka-Pringle)

Our ever changing landscapes: pictured here is a mural in the town of Sheffield in Tasmania showing a Tasmanian landscape with the now extinct Tasmanian tiger and the threatened Tasmanian devil. The Tasmanian tiger went extinct due to a number of stresses including over hunting, habitat loss and disease. Dealing with any of these threats individually probably wouldn’t have saved this species just as dealing with climate change or land-cover change separately may not save many of today’s threatened species into the future. The key lies in understanding the interactions between the multiple stressors.
(Photo by Chrystal Mantyka-Pringle)

Birds are systematically more impacted because the effects of climate on vulnerability is relatively larger than they are for mammals. Risk for mammals and birds increases the most in areas where temperature change is predicted to increase the most. In contrast, risk declines most in areas where mean precipitation is expected to increase the most.

We also revealed that 15–32% of terrestrial biodiversity hotspots change by their ranking when they are ranked according to their risk of species impacted with and without interactions.

Is this important for decision-making?

Such an interaction may modify the spatial patterns of declines and lead to shifts in conservation priorities that would otherwise be missed if they are ignored. For example, if the outcome of an interaction is negative in your conservation area of interest, there may be opportunities to reduce the impacts through adaptation strategies or actions such as increasing habitat quality and extent.

For communities that are unlikely to be able to migrate to suitable environments elsewhere (eg, alpine and freshwater communities), it may be possible to minimize interactions through the protection or installation of climate refuges or buffer strips or by manipulating vegetation structure, composition, or disturbance regimes (see Mantyka-Pringle et al, 2014 and Decision Point #78). Other adaptation strategies may include translocating vulnerable species to novel habitats, altering fire regimes, or mitigating other threats such as invasive species, habitat fragmentation and pollution.

Policy-makers and planners should therefore optimize management actions as well as protected area placement in areas where biodiversity and endangered species are at most risk. In contrast, if the outcome of an interaction is positive, limited conservation effort may be warranted and scarce resources can be re-allocated to other regions identified as priorities for conservation.

The take away message from our analysis is that conservation efforts need to take into account the interaction between a changing climate and land-cover change if we are to develop cost-effective conservation policies and strategies.

Figure 2: A map showing the effect of the interaction between climate change and habitat loss on the risk of species being impacted from future land-cover change (and across biodiversity hotspots) for terrestrial mammals and birds. Values represent the percent change in the number of species affected after considering the interaction with climate for different climate change and land-cover change scenarios.

Figure 2: A map showing the effect of the interaction between climate change and habitat loss on the risk of species being impacted from future land-cover change (and across biodiversity hotspots) for terrestrial mammals and birds. Values represent the percent change in the number of species affected after considering the interaction with climate for different climate change and land-cover change scenarios.


Climate change AND land-cover change

Climate change can interact with land-cover change by exacerbating the impact of habitat loss and fragmentation on biodiversity. It does this by increasing the susceptibility of fragmented biological populations to extinction risks connected with random events (like fires or disease outbreaks). Climate change can also hinder the ability of species to cope with modified land-cover. If climate change depresses population sizes or causes increased variability in population dynamics, for example as a consequence of increased incidents of extreme events, then habitat networks may require larger patches and improved connectivity to maintain populations. Loss and fragmentation of habitat may also hinder the movement of species and their ability to cope with climate change through tracking of suitable climatic conditions. Even relatively intact landscapes are at risk, particularly where landscape heterogeneity is low, forcing species to move potentially large distances to track suitable climatic conditions. Population responses to extreme climatic events, such as fire and flooding, are also likely to be affected by habitat quality, area and heterogeneity. Interactions between climate change and land-cover change may therefore be widespread phenomena and have the potential to fundamentally alter the magnitude and spatial patterns of declines in biodiversity.


More info: Chrystal Mantyka-Pringle c.mantyka-pringle@usask.ca

References

Mantyka-Pringle C, TG Martin & JR Rhodes (2012). Interactions between climate and habitat loss effects on biodiversity: a systematic review and meta-analysis. Global Change Biology 18:1239-1252.

Mantyka-Pringle CS, TG Martin, DB Moffatt, S Linke & JR Rhodes (2014). Understanding and Predicting the Combined Effects of Climate Change and Land-Use Change on Freshwater Macroinvertebrates and Fish. Journal of Applied Ecology 51: 572-581.

Mantyka-Pringle CS, P Visconti, M Di Marco, TG Martin, C Rondinini & JR Rhodes (2015). Climate change modifies risk of global biodiversity loss due to land-cover change. Biological Conservation 187: 103- 111. http://www.sciencedirect.com/science/article/pii/S0006320715001615

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