Research Briefs

Short accounts of papers from EDG researchers.

Are protected areas maintaining bird diversity?

Evaluating the effectiveness of protected areas for sustaining biodiversity is crucial to achieving conservation outcomes. While studies of effectiveness have improved our understanding of protected-area design and management, few investigations (<5%) have quantified the ecological performance of reserves for conserving species. In an effort to increase our knowledge in this area, Laura Rayner and colleagues from ANU have presented an empirical evaluation of protected-area effectiveness using long-term measures of a vulnerable assemblage of species. They compared forest and woodland bird diversity in the Australian Capital Territory over 11 years on protected and unprotected areas located in temperate eucalypt woodland (matched by key habitat attributes). They examined separately the response of birds to protected areas established prior to 1995 and after 1995 when fundamental changes were made to regional conservation policy. Bird diversity was measured in richness, occurrence of vulnerable species, individual species trajectories and functional trait groups.

They found that protected areas were effective in maintaining woody vegetation cover in the study region, but were less effective in the protection of the target bird species assemblage. Protected areas were less species rich than unprotected areas, with significant declines in richness across sites protected prior to 1995. Small, specialised and vulnerable species showed stronger associations with unprotected areas than protected areas. Their findings indicate that recently established reserves (post-1995) are performing similarly to unprotected woodland areas in terms of maintaining woodland bird diversity, and that both of these areas are more effective in the conservation of woodland bird populations than reserves established prior to 1995.

The study demonstrates that the conservation value of protected areas is strongly influenced by the physical characteristics, as well as the landscape context, of a given reserve and can diminish with changes in surrounding land use over time. Both protected areas and off-reserve conservation schemes have important roles to play in securing species populations.

Reference

L Rayner, DB Lindenmayer, JT Wood, P Gibbons, AD Manning (2013). Are protected areas maintaining bird diversity? Ecography. doi: 10.1111/j.1600-0587.2013.00388.x

 

Time preference for invasive species management

Time preference describes how people value (or prefer) outcomes occurring in the present compared to outcomes occurring in the future. Tracy Rout and Terry Walshe have recently published research on why it’s important to factor in time preference when deciding between options for the management of invasive species.

Invasive species have all sorts of different impacts that occur over different time frames. Managing invasive species involves costs that (again) occur over different time frames. In their paper, they illustrated this with an example of invasive vertebrate animals in Australia. These species show a typical difference in the way impacts are estimated – agricultural impacts were considered for 30 years into the future, while environmental impacts were considered over a much longer time frame of 100 years into the future. Their research explores how different time frames have been, and should be, dealt with in multi-criteria decision analyses for invasive species management.

Multi-criteria decision analysis (MCDA) is a structured method of decision support for problems where the decision-maker must balance multiple conflicting objectives. For a decision-maker choosing to allocate funds between controlling foxes, goats, and cats, the budget they allocate to each species would depend on the importance they place on agricultural impacts versus environmental impacts. A multi-criteria decision analyst would leave these impacts in their natural units, and elicit from the decision-maker a weight for type of impact based on its perceived importance. The analyst could then use these elicited weights (or ‘preferences’) to compare alternatives, and find the decision with the best expected outcome for the decision-maker

When Tracy and Terry looked at previous applications of MCDA to invasive species management, they found that these analyses routinely ignore the timeframe over which impacts occur. This is bad news, because ignoring time means assumptions are being made about the decision-maker’s preferences that may or may not be true. For example, not using any form of discounting effectively assumes the decision-maker is indifferent to impacts occurring immediately and those occurring decades or even generations into the future.

By showing how and why time preference should be incorporated into MCDAs, the researchers hope their paper will pave the way for better decision making in invasive species management.

References

Rout TM & Walshe T (2013). Accounting for Time Preference in Management Decisions: An Application to Invasive Species. J. Multi-Crit. Decis. Anal. http://onlinelibrary.wiley.com/doi/10.1002/mcda.1490/full

Or see Tracy’s blog on this paper at http://tracyroutresearch.wordpress. com/2013/03/18/how-people-value-the-future-a-tale-of-two-disciplines/

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