Treesearch

The interplay of past management practices, higher temperatures, extended drought, and insectoutbreaks has resulted in unprecedented levels of tree mortality across the southern Sierra Nevada Mountains ofCalifornia. To characterize patterns in tree mortality, we collected repeated forest measurements on 255 variableradiusplots during 2015 and 2016. From initial measurements in spring 2015, sugar pine (Pinus lambertiana) andponderosa pine (P. ponderosa) mortality increased from 30 percent to 80 percent by summer 2016. Incense cedar(Calocedrus decurrens) mortality remained relatively stable...

In this experiment, 15N-labelled fertilizers were used to trace nitrogen uptake, assimilation, and fate in four loblolly pine (Pinus taeda) stands fertilized with 224 kg ha-1 of elemental nitrogen (N) in the Southeastern United States. The fertilizer treatments included a non-fertilized control, urea, and three different enhanced efficiency N fertilizers. Two years after fertilization, soil from the upper 15 cm in each of five treatments from four different locations was collected. A greenhouse study was established to examine the availability of the residual fertilizer N in the soil. Two...

Dispersal of seeds by scatter-hoarding rodents is common among tropical and temperate tree species, including chestnuts in the genus Castanea. Backcrossed (BC) interspecific hybrid chestnuts exhibit wide variation in seed traits: as the parent species (Castanea dentata and C. mollissima) have distinct seed phenotypes and tend to be handled differently by seed dispersers, phenotypic variation in BC trees is likely due to inheritance of genes that have undergone divergent evolution in the parent species. To identify candidate genomic regions for interspecific differences in seed dispersal,...

There is an increasing emphasis on using natural processes, including riparian forest restoration, to enhance the ecological, hydrological and geomorphological functioning of watercourses. However, we have insufficient knowledge on how the supply and retention of in-channel wood from riparian forest stands changes with age, with inferences typically based on data from terrestrial forests. This presents a challenge in estimating the efficacy and functional lifespan of restoration projects. In this paper, we use a riparian forest growth model to show there is a lag of up to 40–50 years...

Within the southern US forest products industry, the sawmill sector has experience a high rate of mill exits. Between 1999 and 2011, the number of operating sawmills dropped by 77%. However, average mill sawlog consumption increased during the same period. Changes in the number and consumption capacity of sawmills pose questions related to resulting shifts in the spatial distribution of active sawmills in Tennessee for 1999 and 2011. We also investigated the effect of new location patterns on roundwood production across the state. Mill information was obtained from the US Department of...

Stand growth and productivity during the first decade for two groups of yield plots established in managed loblolly pine plantations growing in the Southeastern United States were compared. Both groups were established on site-prepared areas in operational stands growing under intensive management. Group 1 plots represented stands established during the 1990s with open pollinated single family or multi-family stock and received silvicultural treatments typical of the period. Group 2 plots were established approximately 10 years later in the same physiographic region with clones and...

Diameter-based maximum size-density measures are useful to estimate stand basal area carrying capacity. In this study, we used an alternate formulation of relative spacing by replacing average dominant tree height with quadratic mean diameter, denoted diameter-based relative spacing (RSD). We compared the efficacy of RSD and Reineke’s (1933) self-thinning rule for estimation of stand basal area carrying capacity. Data from a loblolly pine spacing trial, with planting density ranging from 6727 to 747 trees/ha, were used to estimate the coefficients of both measures. RSD largely eliminated...

When it comes to testing for differences in seedling survival, researchers sometimes make Type II statistical errors due to the inherent variability associated with survival in tree planting studies. For example, in one trial (with five replications) first-year survival of seedlings planted in October (42 percent) was not significantly different (alpha=0.05) from those planted in December (69 percent). Did planting in a dry October truly have no effect on survival? Authors who make a Type II error might not be aware that as seedling survival decreases (up to an overall average of 50...

Loblolly pine (Pinus taeda L.) is the most widely planted pine species in the Southern United States due to its ability to grow well on many different sites. After a tree is planted, insects and disease can have an impact by reducing growth that sometimes leads to mortality. Parasitic plants can also reduce the growth of loblolly pine by attaching to the roots. Over the years, several publications have documented the devastating impact Seymeria (Seymeria cassioides Orobanchaceae) can have on loblolly pine. The related fascicled gerardia or purple false foxglove (Agalinis fasciculata...

The repetitious use of diameter-limit harvesting in upland hardwoods has led to low-valued stands with heavy midstory and understory canopy layers containing mostly shade-tolerant species. Limited documentation is available on the means to successfully regenerate these impoverished areas into stands of more desirable, shade-intolerant species. The objective of this study is to evaluate the effectiveness of various herbicides and application methods to accelerate the growth (size) of small natural oak (Quercus spp.) and yellow-poplar (Liriodendron tulipifera) reproduction after harvest that...