Treesearch

Longleaf pine (Pinus palustris Mill.) is an important tree species of the southeast U.S. Currently there is no comprehensive stand-level growth and yield model for the species. The model system described here estimates site index (SI) if dominant height (Hdom) and stand age are known (inversely, the model can project Hdom at any given age if SI is known). The survival (N) equation was dependent on stand age and Hdom, predicting greater mortality on stands with larger Hdom. The function that predicts stand basal area (BA) for unthinned stands was dependent on N and Hdom. For thinned stands...

Parasitoids have recently been introduced from Asia to aid in biological control in the United States of the invasive, highly damaging, emerald ash borer, Agrilus planipennis. Three introduced parasitoids have established and field biological studies are underway to improve our understanding of niche partitioning among them. Here we report one such investigation, a field experiment conducted to determine how outer bark thickness of ash trees might affect parasitism by one introduced (Tetrastichus planipennisi) and one native parasitoid (Atanycolus spp.). We found that T. planipennisi was...

Estimating soil C stock in a peatland is highly dependent on accurate measurement of the peat volume. In this study, we evaluated the uncertainty in calculations of peat volume using high-resolution data to resolve the three-dimensional structure of a peat basin based on both direct (push probes) and indirect geophysical (ground-penetrating radar) measurements. We compared volumetric estimates from both approaches, accounting for potential sources of error, with values from the literature. Approximate uncertainty of 14 to 23% was observed in the basin volume, and the total uncertainty...

Longleaf pine once was present on 90 million acres of the southern landscape, ranging from coastal Virginia to east Texas and from central Florida to the mountains of Alabama. On nearly two-thirds of that area, longleaf pine grew in nearly pure (single-species) stands maintained by frequent, low-intensity surface fires of both natural and human origin. The remaining one-third of that area was still dominated by longleaf pine but experienced slightly longer intervals between fires and consisted of mixed pine-hardwood stands on uplands and mixed pine stands on flatwoods sites. Today longleaf...

Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm3 soil)-1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial...

This study characterizes the seed bank prior to and immediately following dormant-season prescribed fire in mature, mixed-Quercus spp. (oak) forests in the southern Appalachian Mountains. Thirty samples from the litter/duff (LD) and the top 5 cm of the mineral soil (MS) were collected from five 5-ha burn units (6 plots per experimental unit) before and immediately after low-intensity prescribed fires, where maximum fire temperatures varied from

Forest landowners are seeing increased pressure from threats like fire, insects, disease, extreme weather, and drought on their land and resources. The last decade has brought record droughts to North Carolina, increasing wildfires, expanding insect and plant invasions, and more intense hurricane and tornado events. Scientists predict increases in temperature and changes in rainfall patterns that can make these threats occur more often, with more intensity, and/or for longer durations. However, there are forest management strategies that can be used to decrease the risk from these threats.

Ecohydrology has advanced rapidly in the past few decades. A search of the topic “ecohydrology” in the Web of Science showed an exponential growth of both publications and citations. The number of publications and citations increased from 7 and 6, respectively in 2000 to 65 and 1262 by 26 November 2012 (Fig. 1). Even with slightly different focus and definitions among scientists, ecohydrology is essentially a science dealing with the interactions between ecological and hydrological processes (e.g. Kundzewicz, 2002). Different from traditional hydrology, ecohydrology focuses more on the...

Bioclimatic models predict large reductions in native trout across the Rocky Mountains in the 21st century but lack details about how changes will occur. Through five case histories across the region, we explore how a changing climate has been affecting streams and the potential consequences for trout. Monitoring records show trends in temperature and hydrographs consistent with a warming climate in recent decades. Biological implications include upstream shifts in thermal habitats, risk of egg scour, increased wildfire disturbances, and declining summer habitat volumes. The importance of...

China is exceptionally rich in biodiversity, with more than 30000 vascular plant species that include many endemic genera, species of ancient origin, and cultivated plants (Yang et al. 2005). Because of rapid economic development, population growth, pollution, and continuing resource exploitation, China’s plant diversity faces severe threats. According to the Chinese National Report on Biodiversity, 15–20% of the animal and plant species in China are now threatened. In the past 50years in China, about 200 species have become extinct, and about 4000–5000 vascular plants are currently...