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Disentangling the relative importance of changes in climate and land-use intensity in driving recent bird population trends.

Eglington SM, Pearce-Higgins JW - PLoS ONE (2012)

Bottom Line: Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance.When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards.Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.

View Article: PubMed Central - PubMed

Affiliation: British Trust for Ornithology, The Nunnery, Thetford, Norfolk, United Kingdom.

ABSTRACT
Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance. However, few studies have disentangled the relative importance of these two drivers in causing recent population declines. We quantify the relative importance of both processes by modelling annual variation in population growth of 18 farmland bird species in the UK as a function of measures of land-use intensity and weather. Modelled together, both had similar explanatory power in accounting for annual fluctuations in population growth. When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards. Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.

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Changes in importance of land-use intensity and climate change in driving farmland bird population growth.Changes in the relative importance of land-use intensity and climate change in driving farmland bird population growth. The graph shows the fit of the land-use (open circles) and weather (black circles) only models to the observed population trend, as assessed from the correlation coefficients between observed and predicted populations for sequential 10-year time-slices, and plotted against the central year.
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pone-0030407-g004: Changes in importance of land-use intensity and climate change in driving farmland bird population growth.Changes in the relative importance of land-use intensity and climate change in driving farmland bird population growth. The graph shows the fit of the land-use (open circles) and weather (black circles) only models to the observed population trend, as assessed from the correlation coefficients between observed and predicted populations for sequential 10-year time-slices, and plotted against the central year.

Mentions: Models of population growth (Table S1) had good explanatory power in retrodicting observed population trends of farmland birds (Figure S1), with a mean coefficient of determination between observed and expected index values of r2 = 0.88±0.03. The mean coefficient of determination of the land-use only models was r2 = 0.79±0.06 and the weather only models r2 = 0.34±0.08. Population trends of the majority of species were therefore much more closely related to land-use change than climate change, with weather only models producing a better fit to the observed trend than land-use only models in only two species. The importance of land-use intensity in explaining the observed farmland bird decline is indicated by the close-fit of the modelled trend in the indicator when based upon both land-use intensity and weather (r2 = 0.99), or just land-use intensity (r2 = 0.98). In the absence of land-use change the coefficient of determination was weak at r2 = 0.19 with only a 7% population decline predicted, rather than the observed 50% (Figure 3). At the start of the time-series, weather only models provided a better fit to the farmland bird population trends than land-use only models, but this switched in 1981 (reflecting correlations from 1976–1985, the period of major population decline). During the 1990s, observed trends were strongly driven by land-use intensity rather than weather (Figure 4). However, in recent years, the gap has narrowed, although contrary to our predictions, climate change has not exceeded land-use intensity as the main driver of farmland bird population trends. The relative performance of both models is now lower than previously, which reflects the recent stability and reduced variation in farmland bird abundance (Figure 3, Figure S1).


Disentangling the relative importance of changes in climate and land-use intensity in driving recent bird population trends.

Eglington SM, Pearce-Higgins JW - PLoS ONE (2012)

Changes in importance of land-use intensity and climate change in driving farmland bird population growth.Changes in the relative importance of land-use intensity and climate change in driving farmland bird population growth. The graph shows the fit of the land-use (open circles) and weather (black circles) only models to the observed population trend, as assessed from the correlation coefficients between observed and predicted populations for sequential 10-year time-slices, and plotted against the central year.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316534&req=5

pone-0030407-g004: Changes in importance of land-use intensity and climate change in driving farmland bird population growth.Changes in the relative importance of land-use intensity and climate change in driving farmland bird population growth. The graph shows the fit of the land-use (open circles) and weather (black circles) only models to the observed population trend, as assessed from the correlation coefficients between observed and predicted populations for sequential 10-year time-slices, and plotted against the central year.
Mentions: Models of population growth (Table S1) had good explanatory power in retrodicting observed population trends of farmland birds (Figure S1), with a mean coefficient of determination between observed and expected index values of r2 = 0.88±0.03. The mean coefficient of determination of the land-use only models was r2 = 0.79±0.06 and the weather only models r2 = 0.34±0.08. Population trends of the majority of species were therefore much more closely related to land-use change than climate change, with weather only models producing a better fit to the observed trend than land-use only models in only two species. The importance of land-use intensity in explaining the observed farmland bird decline is indicated by the close-fit of the modelled trend in the indicator when based upon both land-use intensity and weather (r2 = 0.99), or just land-use intensity (r2 = 0.98). In the absence of land-use change the coefficient of determination was weak at r2 = 0.19 with only a 7% population decline predicted, rather than the observed 50% (Figure 3). At the start of the time-series, weather only models provided a better fit to the farmland bird population trends than land-use only models, but this switched in 1981 (reflecting correlations from 1976–1985, the period of major population decline). During the 1990s, observed trends were strongly driven by land-use intensity rather than weather (Figure 4). However, in recent years, the gap has narrowed, although contrary to our predictions, climate change has not exceeded land-use intensity as the main driver of farmland bird population trends. The relative performance of both models is now lower than previously, which reflects the recent stability and reduced variation in farmland bird abundance (Figure 3, Figure S1).

Bottom Line: Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance.When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards.Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.

View Article: PubMed Central - PubMed

Affiliation: British Trust for Ornithology, The Nunnery, Thetford, Norfolk, United Kingdom.

ABSTRACT
Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance. However, few studies have disentangled the relative importance of these two drivers in causing recent population declines. We quantify the relative importance of both processes by modelling annual variation in population growth of 18 farmland bird species in the UK as a function of measures of land-use intensity and weather. Modelled together, both had similar explanatory power in accounting for annual fluctuations in population growth. When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards. Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.

Show MeSH
Related in: MedlinePlus