Do ecological contrasts explain the effectiveness of conservation management?
Submitted by editor on 6 August 2015.
Get the paper! Photo of common linnet (Linaria cannabina) photographed at Sallandse Heuvelrug, the Netherlands by J. Swiebe (waarneming.nl).
by Martijn Hammers
Some conservation programs are more successful than others, but we still have little understanding why this is the case. Understanding the mechanisms explaining the effectiveness of conservation measures is very important to guide conservation management.
In this study we tested the recently proposed hypothesis that the effectiveness of conservation management is predicted by the magnitude of the contrast in habitat quality that is created by implementing conservation measures. We call this difference in habitat quality created by conservation management an ‘ecological contrast’. This hypothesis predicts that conservation is more effective in low-quality than in high-quality areas, because a larger ecological contrast is created in low-quality areas.
We performed a landscape-scale experiment to test this ‘ecological contrast hypothesis’. We used a community of over-wintering farmland bird as our model system and examined their responses to experimentally increased availability of a key food resource in low- and high-quality areas. We found that over-wintering farmland bird abundance and species richness were strongly positively related to food availability. In line with the ecological contrast hypothesis, the responses of wintering farmland birds in experimental areas relative to control areas increased with increasing conservation induced contrast in a key limiting resource.
Our results indicate that the contrast in landscape quality created by conservation management explains the response of wintering farmland birds to conservation management. The visualisation of ecological contrasts as done in this paper may be a very useful tool for conservationists as it urges considering the key ecological factors limiting population growth, which will result in better informed recommendations for conservation management.