Declining old-forest species as a legacy of large trees lost

作者：Jones Gavin M.^*; Keane John J.; Gutierrez R. J.; Peery M. Zachariah

来源：Diversity and Distributions, 2018, 24(3): 341-351.

DOI：10.1111/ddi.12682

• declining population paradigm
• forest management
• forest restoration
• logging
• occupancy modelling
• spotted owl

Aim: Global declines in large old trees from selective logging have degraded old-forest ecosystems, which could lead to delayed declines or losses of old-forest-associated wildlife populations (i.e., extinction debt). We applied the declining population paradigm and explored potential evidence for extinction debt in an old-forest dependent species across landscapes with different histories of large tree logging.
Location: Montane forests of the Sierra Nevada, California, USA.
Methods: We tested hypotheses about the influence of forest structure on territory extinction dynamics of the spotted owl (Strix occidentalis) using detection/non-detection data from 1993 to 2011 across two land tenures: national forests, which experienced extensive large tree logging over the past century, and national parks, which did not.
Results: Large tree/high canopy cover forest was the best predictor of extinction rates and explained 26%-77% of model deviance. Owl territories with more large tree/high canopy cover forest had lower extinction rates, and this forest type was similar to 4 times more prevalent within owl territories in national parks ((x) over bar = 19% of territory) than national forests ((x) over bar = 4% of territory). As such, predicted extinction probability for an average owl territory was similar to 2.5 times greater in national forests than national parks, where occupancy was declining ((sic) < 1) and stable ((sic) = 1), respectively. Large tree/high canopy cover forest remained consistently low, but did not decline, during the study period on national forests while owl declines were ongoing-an observation consistent with an extinction debt.
Main conclusions: In identifying a linkage between large trees and spotted owl dynamics at a regional scale, we provide evidence suggesting past logging of large old trees may have contributed to contemporary declines in an old-forest species. Strengthening protections for remaining large old trees and promoting their recruitment in the future will be critical for biodiversity conservation in the world's forests.

• 出版日期2018-3