“Grassification” of desert shrublands

 

Energy flow and the “grassification” of desert shrublands

by Julio L. Betancourt

in http://www.pnas.org/content/112/31/9504.short?rss=1

Extract

 

In our directionally and continuously changing world, history still matters, and it does so in increasingly novel and important ways. Human adaptation to global change will rely heavily on robust baselines of historic environmental variability and detailed understanding of how both past and modern ecosystems have responded to both individual and multiple stressors. The question of global change has motivated an upsurge in paleoecological studies that span the late Quaternary and the modern era, and has inspired a growing consideration of time as a fundamental axis in ecology (1). A major challenge in developing pertinent ecological baselines remains how to fuse, into continuous time series, observations and experiments from living systems with paleoecological reconstructions from the same sites (2, 3). Tracing and disentangling complex responses to environmental stress from paleological to present-day communities is especially daunting; for example, how climate change; accelerated land use; and biological invasions are influencing the flows of water, nutrients, and energy. The paper by Terry and Rowe in PNAS (4) is a shining example of how modern ecology and paleoecology can be spliced together to decipher how ecological processes unfold over time scales inaccessible to direct observation or experimentation, and how they can be disrupted by human impacts.

The study reports on a multidimensional analysis of bone remains from a cave in North America’s Great Basin to evaluate how energy flow, and not just species distributions and abundances, could be changing fundamentally in the modern era. Terry and Rowe (4) focus on small mammal bones in well-stratified deposits accumulated below an owl’s roost inside Homestead Cave, a wave-constructed cavern near the regressing shoreline of Pleistocene Lake Bonneville and just west of its Holocene remnant, the modern Great Salt …

Read the full article: PNAS