Temperature sensitivity of community-level physiological profiles (CLPPs) was examined for two semiarid soils from the southwestern United States using five different C-substrate profile microtiter plates (Biolog GN2, GP2, ECO, SFN2, and SFP2) incubated at five different temperature regimes. The CLPPs produced from all plate types were relatively unaffected by these contrasting incubation temperature regimes. Our results demonstrate the ability to detect CLPP differences between similar soils with differing physiological parameters, and these differences are relatively insensitive to incubation temperature. Our study also highlights the importance of using both bacterial and fungal plate types when investigating microbial community differences by CLPP. Nevertheless, it is unclear whether or not the differences in CLPPs generated using these plates reflect actual functional differences in the microbial communities from these soils in situ.

Belowground interactions can affect plants either directly or indirectly via their associated mycorrhizal fungi. However, few studies have experimentally examined the consequences of interspecific root interactions for these important mutualists in the field. We used a trenching experiment to examine how belowground interactions between pinyon pine and one‐seed juniper affected the ectomycorrhizal (EM) fungal communities of pinyon pine. Three major findings emerged: (1) pinyons responded to the reduction of juniper roots with a near doubling of fine root biomass in just two years, (2) this increase in pinyon roots translated into a potential two‐fold increase in EM abundance, and (3) the EM fungal communities of trenched trees differed significantly from controls largely due to a decrease in ascomycete fungi. Because species of EM fungi vary in the benefits they provide, changes in EM communities could have long‐term consequences for host‐plant establishment, growth, and survival. Belowground interactions with juniper may contribute to the high mortality of pinyons and the reduced diversity of EM fungi associated with recent droughts.

Summary 1.Burning of slash (woody debris) piles resulting from the harvest of fuel wood is a common management technique designed to reduce fire risk and increase establishment of understorey vegetation in many semi-arid woodlands. However, the consequences of slash burning on plant communities and their below-ground fungal mutualists are poorly understood. 2. We examined how the burning of slash piles affected understorey plant communities and arbuscular mycorrhizal (AM) fungi in a pinyon-juniper woodland in northern Arizona, USA, 5 years after harvesting. We analysed plant communities and AM inoculum potential along 16 transects in: (i) burned slash pile sites; (ii) interspaces between burned slash piles; (iii) non-burned canopy sites; and (iv) non-burned interspaces. We quantified AM colonization of dominant native and exotic plants in burned and non-burned areas. 3. Burned areas had significantly fewer understorey plant species than non-burned areas, and exotic species were four times more abundant at burned slash sites than at other sites. 4. Exotic plants from burned and non-burned areas exhibited levels of AM colonization that were 50% greater than native plants. Bioassay and field-collected plants exhibited similar levels of AM colonization and there were no significant treatment differences. 5. The total biomass of bioassay plants grown in soil from burned slash sites averaged 19% greater than plant biomass from other sites, and had 27% more phosphorus in their shoot tissue; however, tissue nitrogen contents were similar. 6. Synthesis and applications . These results suggest that either fire did not reduce AM inoculum potential, or that AM fungal populations recovered in the 5 years after the slash was burned. Changes in understorey plant communities and increases in exotic species with burning could result from other soil changes (e.g. species of AM fungi present), reduction of native species in the seed bank or greater dispersal ability of exotic plants compared with native plant species. We suggest that burning slash piles as a management tool in pinyon-juniper woodlands can result in plant communities that are persistently dominated by exotic species. Management approaches that utilize fuel wood harvest alone or that incorporate seeding of native plants may achieve the desired results.

Low-elevation islands face threats from sea level rise (SLR) and increased storm intensity. Evidence of endangered species' population declines and shifts in vegetation communities are already underway in the Florida Keys. SLR predictions indicate large areas of these habitats may be eliminated in the next century. Using the Florida Keys as a model system, we present a process for evaluating conservation options for rare and endemic taxa. Considering species characteristics and habitat, we assess central issues that influence conservation options. We contrast traditional and controversial options for two animal and two plant species giving special emphasis to perceptions of ecological risk and safety from SLR and suggest courses of action. Multiple strategies will be required to spread extinction risk and will be effective for different time periods. Global climate change presents an uncertain, perhaps no-analog future that will challenge land managers and practitioners to re-evaluate equilibrium-state-conceived laws and policies not only for these taxa, but for many facing similar threats. To embrace conservation in a changing world will require a new dialogue that includes controversial ideas, a review of existing laws and policies, and preparation for the oncoming change.

The ability of seedlings to establish can depend on the availability of appropriate mycorrhizal fungal inoculum. The possibility that mycorrhizal mutualists limit the distribution of seedlings may depend on the prevalence of the plant hosts that form the same type of mycorrhizal association as the target seedling species and thus provide inoculum. We tested this hypothesis by measuring ectomycorrhizal (EM) fine root distribution and conducting an EM inoculum potential bioassay along a gradient of EM host density in a pinyon-juniper woodland where pinyon is the only EM fungal host while juniper and other plant species are hosts for arbuscular mycorrhizal (AM) fungi. We found that pinyon fine roots were significantly less abundant than juniper roots both in areas dominated aboveground by juniper and in areas where pinyon and juniper were co-dominant. Pinyon seedlings establishing in pinyon-juniper zones are thus more likely to encounter AM than EM fungi. Our bioassay confirmed this result. Pinyon seedlings were six times less likely to be colonized by EM fungi when grown in soil from juniper-dominated zones than in soil from either pinyon-juniper or pinyon zones. Levels of EM colonization were also reduced in seedlings grown in juniper-zone soil. Preliminary analyses indicate that EM community composition varied among sites. These results are important because recent droughts have caused massive mortality of mature pinyons resulting in a shift towards juniper-dominated stands. Lack of EM inoculum in these stands could reduce the ability of pinyon seedlings to re-colonize sites of high pinyon mortality, leading to long-term vegetation shifts.