Arthropods are not declining but are responsive to disturbance in the Luquillo Experimental Forest, Puerto Rico.

A number of recent studies have documented long-term declines in abundances of important arthropod groups, primarily in Europe and North America. These declines are generally attributed to habitat loss, but a recent study [B.C. Lister, A. Garcia, Proc. Natl. Acad. Sci. USA 115, E10397-E10406 (2018)] from the Luquillo Experimental Forest (LEF) in Puerto Rico attributed declines to global warming. We analyze arthropod data from the LEF to evaluate long-term trends within the context of hurricane-induced disturbance, secondary succession, and temporal variation in temperature. Our analyses demonstrate that responses to hurricane-induced disturbance and ensuing succession were the primary factors that affected total canopy arthropod abundances on host trees, as well as walkingstick abundance on understory shrubs. Ambient and understory temperatures played secondary roles for particular arthropod species, but populations were just as likely to increase as they were to decrease in abundance with increasing temperature. The LEF is a hurricane-mediated system, with major hurricanes effecting changes in temperature that are larger than those induced thus far by global climate change. To persist, arthropods in the LEF must contend with the considerable variation in abiotic conditions associated with repeated, large-scale, and increasingly frequent pulse disturbances. Consequently, they are likely to be well-adapted to the effects of climate change, at least over the short term. Total abundance of canopy arthropods after Hurricane Maria has risen to levels comparable to the peak after Hurricane Hugo. Although the abundances of some taxa have declined over the 29-y period, others have increased, reflecting species turnover in response to disturbance and secondary succession.

Plant science in forest canopies--the first 30 years of advances and challenges (1980-2010).

As an emerging subdiscipline of forest biology, canopy science has undergone a transition from observational, 'oh-wow' exploration to a more hypothesis-driven, experimental arena for rigorous field biology. Although efforts to explore forest canopies have occurred for a century, the new tools to access the treetops during the past 30 yr facilitated not only widespread exploration but also new discoveries about the complexity and global effects of this so-called 'eighth continent of the planet'. The forest canopy is the engine that fixes solar energy in carbohydrates to power interactions among forest components that, in turn, affect regional and global climate, biogeochemical cycling and ecosystem services. Climate change, biodiversity conservation, fresh water conservation, ecosystem productivity, and carbon sequestration represent important components of forest research that benefit from access to the canopy for rigorous study. Although some canopy variables can be observed or measured from the ground, vertical and horizontal variation in environmental conditions and processes within the canopy that determine canopy-atmosphere and canopy-forest floor interactions are best measured within the canopy. Canopy science has matured into a cutting-edge subset of forest research, and the treetops also serve as social and economic drivers for sustainable communities, fostering science education and ecotourism. This interdisciplinary context of forest canopy science has inspired innovative new approaches to environmental stewardship, involving diverse stakeholders.