Tropical forests are thermally buffered despite intensive selective logging

Abstract

Tropical rainforests are subject to extensive degradation by commercial selective logging. Despite pervasive changes to forest structure, selectively logged forests represent vital refugia for global biodiversity. The ability of these forests to buffer temperature-sensitive species from climate warming will be an important determinant of their future conservation value, although this topic remains largely unexplored.Thermal buffering potential is broadly determined by: (i) the difference between the "macroclimate" (climate at a local scale, m to ha) and the "microclimate" (climate at a fine-scale, mm to m, that is distinct from the macroclimate); (ii) thermal stability of microclimates (e.g. variation in daily temperatures); and (iii) the availability of microclimates to organisms. We compared these metrics in undisturbed primary forest and intensively logged forest on Borneo, using thermal images to capture cool microclimates on the surface of the forest floor, and information from dataloggers placed inside deadwood, tree holes and leaf litter. Although major differences in forest structure remained 9-12 years after repeated selective logging, we found that logging activity had very little effect on thermal buffering, in terms of macroclimate and microclimate temperatures, and the overall availability of microclimates. For 1°C warming in the macroclimate, temperature inside deadwood, tree holes and leaf litter warmed slightly more in primary forest than in logged forest, but the effect amounted to <0.1°C difference between forest types. We therefore conclude that selectively logged forests are similar to primary forests in their potential for thermal buffering, and subsequent ability to retain temperature-sensitive species under climate change. Selectively logged forests can play a crucial role in the long-term maintenance of global biodiversity.

Canopy structure and topography jointly constrain the microclimate of human‐modified tropical landscapes

“…As a result, we found that even though logging had a profound impact on the height and density of forest canopies (Figure 3; Hardwick et al, 2015;Pfeifer et al, 2016), only under intense logging pressure or following the conversion of forests to oil-palm plantations was microclimate strongly affected. This is broadly consistent with recent work showing that logged forests in the tropics tend to be largely thermally buffered and do not differ substantially in their microclimate to old-growth stands (Senior, Hill, Benedick, et al, 2017;Senior, Hill, González del Pliego, et al, 2017). Yet while previous studies have for the most part been limited to making dichotomous comparisons between logged and unlogged forests, using high-precision ALS data acquired across a landscape where land-use intensity was manipulated experimentally we were able to characterize the effects of forest degradation on microclimate in terms of quantitative changes in forest structure.…”

Occurrence of blood‐feeding terrestrial leeches (Haemadipsidae) in a degraded forest ecosystem and their potential as ecological indicators

“…Certainly, our findings suggest that, in the face of large‐scale habitat degradation in the tropics, logged forests with some degree of canopy will be important for the persistence of terrestrial leeches and other invertebrates. As such, our findings add to the growing body of work that supports the conservation value of selectively logged forest in human‐modified tropical landscapes (Deere et al., ; Edwards et al., ; Senior, Hill, Benedick & Edwards, ) .…”

Seasonal drivers of understorey temperature buffering in temperate deciduous forests across Europe

“…Canopy structure and composition play a key role in regulating the offset of maximum summer temperatures. Forests thus provide highly heterogeneous thermal environments, with maximum temperature conditions that are often much cooler than suggested by available climate layers (Jucker et al, ; Scheffers et al, ; Senior, Hill, Benedick, & Edwards, ). The maximum temperature offsets reported here compare well with the general patterns observed in temperate regions across the globe and might even increase if the forest temperatures were to be measured closer to the forest ground surface (De Frenne et al, ).…”