Time-delayed responses to land-use changes reveal a window of opportunity for biodiversity

SEMPER-PASCUAL, ASUNCIÓN; MATIAS BAUMANN; BLENDINGER, PEDRO; DECARRE, JULIETA; GOMEZ VALENCIA, BIBIANA; KUEMMERLE, TOBIAS; MASTRANGELO, MATIAS; SABATINI, FRANCESCO; MACCHI, LEANDRO

Congreso; ICCB ECCB; 2017

1. Habitat loss is the primary cause of local extinctions. Yet, there is considerableuncertainty regarding how fast species do respond to habitat loss, and how timedelayed responses vary spatially.2. We focused on the Argentine Dry Chaco (ca. 32 million ha), a global deforestationhotspot, and tested for time-delayed response of birds and mammals to landscapetransformation, based on an extensive field dataset. We quantified the magnitude ofextinction debt by modeling contemporary species richness as a function of eithercontemporary or past (2000 and 1985) landscape patterns. We then mappedextinction debt by predicting equilibrium richness at these points in time.3. We found strong evidence for an extinction debt: landscape structure from 2000explained contemporary species richness of birds and mammals better thancontemporary and 1985-landscapes. This suggests time-delayed responses between10 and 25 years. Extinction debt was especially strong for forest species.4. Projecting our models into space highlighted areas where future local extinctions arelikely to occur due to unpaid extinction debt. Areas recently converted to agriculturehad highest extinction debt, regardless of the post-conversion land-use. Few localextinctions were predicted in areas with remaining large forest patches.5. Synthesis and applications: The strong evidence for an unpaid extinction debt in theArgentine Dry Chaco provides a substantial window of opportunity for averting localbiodiversity losses through habitat restoration. This window may close rapidlythough, and conservation planning should therefore act swiftly. Mapping extinctiondebt allows for spatial prioritization of such conservation activities