Treesearch

The timing of births in ungulates has significant implications for juvenile survival and population growth. For North American elk (Cervus elaphus), typical parturition season ranges from late May to early Jun., and juveniles born outside of this peak characteristically exhibit lowered survival. We observed abnormally long parturition seasons in free-ranging elk populations in Missouri and South Dakota during 2012. Both populations exhibited late births; the last known births occurred on 26 Sep. in Missouri and 4 Sep. in South Dakota. Duration of parturition season was 112 and 119 d in...

Landscape fire succession models (LFSMs) predict spatially-explicit interactions between vegetation succession and disturbance, but these models have yet to fully integrate ungulate herbivory as a driver of their processes. We modified a complex LFSM, FireBGCv2, to include a multi-species herbivory module, GrazeBGC. The system is novel in that it explicitly accommodates multiple herbivore populations, inter- and intra-specific spatial forcing of their forage demands, and site-specific dietary selectivity to interactively modify biomass, fuels and fire behavior across a landscape and over...

Droughts can influence forest composition directly by limiting water or indirectly by intensifying other stressors that affect establishment, growth, and mortality. Using community assemblages of eastern US tree species and drought tolerance characteristics assessed from literature, we examine recent drought conditions in relation to the spatial distribution of species and their tolerance to drought. First we calculate and compare a cumulative drought severity index (CDSI) for the conterminous US for the periods 1960-1986 and 1987-2013 using climate division Palmer Drought Severity Index...

The genus Liancalus Loew is revised for the Nearctic Region. Seven species are documented from this region including two new species: Liancalus genualis Loew, L. hydrophilus Aldrich, L. limbatus Van Duzee, L. pterodactyl sp. n., L. querulus Osten Sacken, L. similis Aldrich, and L. sonorus sp. n. Lectotypes are designated for the following species: L. genualis, L. hydrophilus, L. querulus, and L. similis. The species are illustrated, a key to males and females is provided, and their distributions mapped. Adults of Liancalus are some of the largest species of Dolichopodidae and commonly...

Open space lands are provided by a variety of entities from private individuals to the federal government and these entities make management decisions based on a very broad range of priorities. The net benefits of additional open space depend on the number, quality, and composition of existing open space in the vicinity. In areas where open space is abundant and there is a significant proportion that is federally owned, the net benefits are not well understood. In this study, the marginal willingness to pay for proximity to public open space is estimated using the hedonic property method...

The replacement of native C4-dominated grassland by C3-dominated shrubland is considered an ecological state transition where different ecological communities can exist under similar environmental conditions. These state transitions are occurring globally, and may be exacerbated by climate change. One consequence of the global increase in woody vegetation may be enhanced ecosystem carbon sequestration, although the responses of arid and semiarid ecosystems may be highly variable. During a drier than average period from 2007 to 2011 in the northern Chihuahuan Desert, we found established...

This resource update provides an overview of forest resources in Virginia. Information for this factsheet was updated by means of the Forest Inventory and Analysis (FIA) annualized sample design. Each year, 20 percent of the sample plots (one panel) in Virginia are measured by field crews, the data compiled, and new estimates produced.

Hardwood forests of the Great Lakes Region have evolved without earthworms since the Last Glacial Maximum, but are now being invaded by exotic earthworms introduced through agriculture, fishing, and logging. These exotic earthworms are known to increase soil mixing, affect soil carbon storage, and dramatically alter soil morphology. Here we show, using an active earthworm invasion chronosequence in a hardwood forest in northern Minnesota, that such disturbances by exotic earthworms profoundly affect inorganic nutrient cycles in soils. Soil nutrient elemental concentrations (Ca, Mg, K, and...

Bioenergy production can have positive or negative impacts on soil and water. To best understand these impacts, the effects of bioenergy systems on water and soil resources should be assessed as part of an integrated analysis considering environmental, social and economic dimensions. Bioenergy production systems that are strategically integrated in the landscape to address soil and water problems should be promoted where their establishment does not cause other negative impacts that outweigh these benefits (Figure 18.1). While standardized metrics, such as footprints and water- and...

Fire is a natural component of forest ecosystems in parts of North America, South America, Europe, Australia, Africa and the Mediterranean region. These fires are usually uncontrolled wildfires in areas of ignitable vegetation but can also be prescribed fires set for vegetation management purposes. Wildfires are commonly characterised based on cause of ignition, physical properties (e.g. propagation rate), fuel material and weather conditions. The four major natural causes of wildfire ignitions are lightning, volcanic eruptions, sparks from rockfalls and spontaneous combustion. Among the...