Grassland bird responses to a fire-grazing interaction in a fragmented landscape

Grassland birds have experienced widespread population declines throughout the North American tallgrass prairie region, largely as a result of habitat loss and the homogenization of remaining fragments. Recent work in relatively extensive grasslands has demonstrated that mimicking historic disturbance patterns using a fire-grazing interaction can increase the abundance and diversity of grassland birds by providing more habitat heterogeneity. We examined the efficacy of management that restores a fire-grazing interaction for promoting avian diversity in a fragmented landscape. We examined community and population responses of obligate and facultative grassland bird species at 13 experimental research pastures in the Grand River Grasslands of Iowa and Missouri (USA), divided among three treatments: 1) spatially discrete fires and free access by cattle ( patch-burn grazing ), 2) free access by cattle and a single complete burn ( grazed-and-burned ), and 3) a single complete burn with no cattle ( burned-only ). We expected that patch-burn grazing would produce a bird community intermediate between those of the grazed-and-burned and burned-only treatments, because it would provide habitat for species associated with both. However, community structure on pastures managed using patch-burn grazing instead diverged significantly from both of the other treatments, though most individual species showed few population responses to treatment. Differences in community structure were most highly correlated with visual obstruction and wooded edge density in the landscape, suggesting bird communities are differentiated not only by their structural habitat requirements, but also by the varying degrees of sensitivity to landscape fragmentation of their component species

Analysis of Abrupt Transitions in Ecological Systems

The occurrence and causes of abrupt transitions, thresholds, or regime shifts between ecosystem states are of great concern and the likelihood of such transitions is increasing for many ecological systems. General understanding of abrupt transitions has been advanced by theory, but hindered by the lack of a common, accessible, and data-driven approach to characterizing them. We apply such an approach to 30–60 years of data on environmental drivers, biological responses, and associated evidence from pelagic ocean, coastal benthic, polar marine, and semi-arid grassland ecosystems. Our analyses revealed one case in which the response (krill abundance) linearly tracked abrupt changes in the driver (Pacific Decadal Oscillation), but abrupt transitions detected in the three other cases (sea cucumber abundance, penguin abundance, and black grama grass production) exhibited hysteretic relationships with drivers (wave intensity, sea-ice duration, and amounts of monsoonal rainfall, respectively) through a variety of response mechanisms. The use of a common approach across these case studies illustrates that: the utility of leading indicators is often limited and can depend on the abruptness of a transition relative to the lifespan of responsive organisms and observation intervals; information on spatiotemporal context is useful for comparing transitions; and ancillary information from associated experiments and observations aids interpretation of response-driver relationships. The understanding of abrupt transitions offered by this approach provides information that can be used to manage state changes and underscores the utility of long-term observations in multiple sentinel sites across a variety of ecosystems.Organismic and Evolutionary Biolog

Appendix B. Data collection procedure for all variables of anuran breeding habitat and landscape structure for 61 central Iowa, USA, wetlands surveyed March–July 2005.

Data collection procedure for all variables of anuran breeding habitat and landscape structure for 61 central Iowa, USA, wetlands surveyed March–July 2005

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity