Kara Nicole Youngentob

Climate change, conservation and management: an assessment of the peer-reviewed scientific journal literature

Recent reviews of the conservation literature indicate that significant biases exist in the published literature regarding the regions, ecosystems and species that have been examined by researchers. Despite the global threat of climatic change, similar biases may be occurring within the sub-discipline of climate-change ecology. Here we hope to foster critical thought and discussion by considering the directions taken by conservation researchers when addressing climate change. To form a quantitative basis for our perspective, we assessed 248 papers from the climate change literature that considered the conservation management of biodiversity and ecosystems. We found that roughly half of the studies considered climate change in isolation from other threatening processes. We also found that the majority of surveyed scientific publications were conducted in the temperate forests of Europe and North America. Regions such as Latin America that are rich in biodiversity but may have low adaptive capacity to climate change were not well represented. We caution that such biases in research effort may be distracting our attention away from vulnerable regions, ecosystems and species. Specifically we suggest that the under-representation of research from regions low in adaptive capacity and rich in biodiversity requires international collaboration by those experienced in climate-change research, with researchers from less wealthy nations who are familiar with local issues, ecosystems and species. Furthermore, we caution that the propensity of ecologists to work in essentially unmodified ecosystems may fundamentally hamper our ability to make useful recommendations in a world that is experiencing significant global change.

Foliage Chemistry Influences Tree Choice and Landscape Use of a Gliding Marsupial Folivore

The chemical quality of forage may determine landscape use and habitat quality for some herbivorous species. However, studies that investigate the relationship between foliar chemistry and foraging choices in wild vertebrates are rare. Petauroides volans (the greater glider) is unique among Australian marsupial folivores because it glides. It also frequently consumes foliage from both major Eucalyptus subgenera, Eucalyptus (common name “monocalypt”) and Symphyomyrtus (common name “symphyomyrtle”), which differ markedly in their foliar chemistry. Such differences are thought to be a product of co-evolution that also led to guild-specific plant secondary metabolite (PSM) specialization among other marsupial eucalypt folivores. To explore whether foliar chemistry influences tree use, we analyzed foliage from eucalypt trees in which we observed P. volans during a radio tracking study and from eucalypt trees in which animals were never observed. We used a combination of chemical assays and near infrared spectrophotometry (NIRS) to determine concentrations of nitrogen (N), in vitro available nitrogen (AvailN), and in vitro digestible dry matter (DDM) from foliage sampled from the monocalypt and symphyomyrtle species, and total formylated phloroglucinol compounds (FPCs) and sideroxylonals (a class of FPCs) from the symphyomyrtle species (FPCs do not occur in monocalypts). Tree size and spatially-dependent, intraspecific variations in sideroxylonals and DDM concentrations in the symphyomyrtle foliage and of N, AvailN, and DDM in the monocalypt species were important indicators of tree use and habitat suitability for P. volans. The results i) demonstrate that guild-specific PSMs do not always lead to guild-specific foraging; ii) provide a compelling co-evolutionary case for the development of gliding in P. volans; and iii) have implications for the management and conservation of this and other folivorous species.

Bark chewing reveals a nutrient limitation of leaves for a specialist folivore

Mineral micronutrients are critical for basic physiological function, and variable availability of minerals over the landscape can influence foraging decisions. Sodium is essential for nerve function and osmotic balance; however, it can be limiting in some environments, such as those at high elevations. Koalas (Phascolarctos cinereus) living in subalpine regions have been observed eating Eucalyptus mannifera bark, an unusual food choice for a folivore. We hypothesized that sodium may be deficient in leaves at high-elevation sites, and that the bark from trees could be a potential sodium source. We compared the mineral content of eucalypt bark and leaves in 3 areas where koalas chew bark and in leaves of a preferred food tree of koalas, E. viminalis, across a range of elevations. Individual chewed trees were rare compared to non-chewed conspecifics and patchily distributed. Bark from chewed E. mannifera trees had significantly higher concentrations of sodium than plant parts from non-chewed neighboring conspecifics and other Eucalyptus species trees. We also found that E. viminalis foliage had significantly less sodium at higher elevations than lowland populations. We propose that koalas have developed the unusual bark-eating behavior to meet sodium requirements in an otherwise sodium-poor landscape. Given the physiological importance of sodium, behavioral adaptations such as these may be critical to the ability of mammalian herbivores to survive in nutrient-deficient landscapes.