The Topographic Relative Moisture Index (TRMI), designed to indicate the relative soil moisture availability among sites in mountain terrain, is described. The TRMI is a summed scalar index of four slope parameters: topographic position, slope aspect, steepness, and slope configuration. A review of other methods of characterizing site moisture relations, including direct monitoring, water-balance climatology, site index, and other inferential topographic/edaphic indices, reveals that the simple, straightforward application of the TRMI is rapid, inexpensive, and effective in field research. The ability of the TRMI to portray significant patterns of plant response to environment is demonstrated from empirical studies at both the species-level (the ecology of Arizona cypress) and community-level (forest patterns in Yosemite National Park).

Plants have been used throughout history for their medicinal properties. This use has often focused on human health but plants have also been, and still are, applied in ethnoveterinary practice and animal health management.In recent times, the use of synthetic chemicals has become prevalent. Public awareness of the potential environmental and health risks associated with heavy chemical use has also increased. This has put pressure on regulatory bodies to reduce the use of chemicals in agriculture. The most striking example is the 2006 banning of antibiotics in animal feed by the European Union. Moves such as this have increased the drive to find alternatives to synthetic chemicals and research has again turned to the use of plant bioactives as a means of improving animal health.Current scientific evidence suggests there is significant potential to use plants to enhance animal health in general and that of ruminants (cattle, deer, sheep, etc.) in particular. Active areas of research for plant bioactives (particularly saponin and tannin containing plants) include reproductive efficiency, milk and meat quality improvement, foam production/bloat control and methane production. Nematode control is also a significant area of research and the evidence suggests a much broader range of phytochemicals may be effective. This review presents a summary of the literature and examines international research efforts towards the development of plant bioactives for animal health.

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Studies of dune vegetation patterns have emphasized two structuring agents: local environmental gradients that shape the prominent zonation of coastal plant species, and disturbance patches initiated by overwash during coastal storms. For dune systems of two barrier islands in the Georgia Bight, we investigate how the interplay of these two conceptual frames generate patterns in (1) longitudinal (along-shore) and transverse (across-shore) compositional variability and (2) the arrangement of species along transverse gradients. We describe how this interplay constitutes a complex biogeomorphic system in which disturbance and recovery along gradients reinforce one another in positive feedback. Topographic and cover data were sampled within strip transects aligned perpendicular to the shoreline at study sites along a frequently storm-overwashed microtidal (South Core Banks, North Carolina) and an infrequently overwashed mesotidal (Sapelo Island, Georgia) barrier island. Multiresponse permutation procedures revealed that Sapelo has significantly greater transect-level longitudinal and transverse compositional variability. Nonmetric multidimensional scaling indicated that a single dominant transverse species gradient characterizes South Core, versus two spatially intersecting vegetation gradients for Sapelo. On South Core, reduced relief promoted by plant species of horizontally extensive growth forms reinforces the spread of overwash events across the landscape, thus overlaying disturbance and recovery gradients. Species-mediated dune topographic roughness on Sapelo buffers the dune vegetation from potential stand-wide disturbances, thereby juxtaposing disturbance and recovery gradients to a greater extent. We discuss the benefit of incorporating a complex adaptive-systems framework into the reductionist methodologies invoked in field-based biogeographical studies.

The significance of these changes, remains unclear. We have little understanding of how neuroendocrine changes relate to the experience of symptoms, and it is unclear whether these changes are primary, or secondary to behavioural changes in sleep or exercise. Longitudinal studies of populations at risk for CFS will help to resolve these issues.

Land use and physiographic variability influence stream low flows, yet their interactions and relative influence remain unresolved. Our objective was to assess the influence of land use and watershed geomorphic characteristics on low‐flow variability in the southern Blue Ridge Mountains of North Carolina and Georgia. Ten minute interval discharge data for 35 streams (in watersheds from 3 to 146 km2) were measured for two late summer low‐flow seasons, coinciding with a severe drought period in the southeastern United States. Three low‐flow metrics were calculated (1 and 7 day minimum flows and 1st percentile flow) for each low‐flow season (5 August to 12 November 2007 and 1 August to 12 November 2008). A comprehensive suite of watershed characteristics, including factors of topography, channel network morphometry, soils, land use, and precipitation were used in multiple regression analysis of low‐flow variability among the 35 watersheds. Additionally, low flows in groups of lower‐ and higher‐forest cover watersheds were compared. Drainage density, areal coverage of colluvium, topographic variability (as slope standard deviation), and percent of the channel network as first order stream emerged as the most important variables for explaining low‐flow variability. Watershed forest cover demonstrated a consistent, significant positive relationship with low flows, despite the higher evapotranspiration rates associated with forest compared with other land covers and despite the relatively small range of disturbance in this study area. This highlights the importance of infiltration and recharge under undisturbed land cover in sustaining low flows, and it bears noteworthy implications for environmental flows and water resource sustainability.

Spatial autocorrelation analyses of 12 allozyme loci were used to compare genetic structure within populations of two varieties of Pinus clausa. P. clausa var. immuginata populations tend to be unevenaged, with continuous recruitment in small gaps created by wind damage, whereas P. clausa var. clausa populations are more even-aged, with recruitment postdating periodic canopy ®res. Three var. immuginata populations and three matched pairs of var. clausa populations, including both a mature and a nearby recently burned population, were examined. Aggregation of multilocus genotypes at small distances was evident in all young var. clausa populations. Little inbreeding was apparent among juveniles or adults in these populations; their genetic structure is likely to have resulted from limited seed dispersal. Genotypes were not signi®cantly spatially structured in nearby matched mature populations. Genetic structure was less evident in var. immuginata populations. Aggregated genotypes were only apparent in the population where patches included juveniles of similar ages; dense juvenile clumps in the other two var. immuginata populations comprised a variety of ages. Interannual variability in allele frequencies of surviving seedlings may account for the absence of genetic structure in these populations.Keywords: disturbance history, gene dispersal, genetic structure, Pinus clausa, spatial autocorrelation. IntroductionFine-scale genetic structure is evident within populations when the distribution of genetic variation among individuals grouped at increasing spatial scales is nonrandom (McCauley, 1997). A number of evolutionary and ecological processes aect the development of genetic structure within plant populations, including pollen and seed dispersal (Wright, 1943; Latta et al., 1998), microhabitat variation in selection (Linhart et al., 1981; Epperson & Allard, 1989; Slatkin & Arter, 1991), adult population density (Hamrick & Nason, 1996), spatial and temporal patterns of seedling establishment (Ellstrand, 1992;Schnabel & Hamrick, 1995;Hamrick & Nason, 1996), and stand age and history (Knowles et al., 1992; Hamrick et al., 1993; Schnabel et al., 1998). Probably the most widely examined in¯uence on ®ne-scale genetic structure has been gene movement, including both pollen and seed dispersal. Extensive gene movement theoretically osets the in¯uence of microhabitat selection, which may foster ®ne-scale genetic dierentiation within populations. With wind-pollinated and wind-dispersed species, however, gene dispersal generally decreases with increasing interplant distance; and spatial structure may result from genetic drift associated with limited gene¯ow over greater distances (Wright, 1943; Heywood, 1991). These neighbourhoods may become ecologically adapted to their microhabitat through selection, reinforcing genetic structure (Berg & Hamrick, 1995). Although various temperate tree species have been studied to determine whether genetic structure is evident within populations of wind-pollinated and -dispersed species, ...

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