Treesearch

The oomycete Phytophthora ramorum is a plant pathogen with an unusually broad host range. Recognized in 2000 as a previously unknown and likely introduced species, this pathogen has become established in central and northern coastal California, southwestern Oregon, and Western Europe. Tree species that may be killed by stem cankers include true oaks (Quercus agrifolia Née, Q. kelloggii Newb., Q. parvula var. shrevei (C.H. Muller) Nixon, and Q. chrysolepis Liebm.), and tanoaks (Notholithocarpus densiflorus Hook. and Arn.), in North America; and Japanese larch (Larix kaempferi (Lam.)...

A 8-wheel forwarder was observed while transporting pinyon pine (P. edulis) and Utah juniper (J. osteosperma) from woods to landing in southern Utah. The forwarder was part of a 2-machine system used to treat pinyon-juniper stands. Trees were felled using a rubber tracked skid steer with a shear head, then transported to a collection point with a Ponsse Buffalo King 20-ton forwarder. A total of 47 cycles of the forwarder operating were captured on video and evaluated using time-and-motion study methods. The forwarder averaged 25.8 minutes per cycle at a mean total distance of 786 feet....

Extended working hours can increase the number of hours that equipment is available to perform work, but how effective are workers during those additional evening/night hours? A study was conducted in Alabama to compare daytime and nighttime production rates of a feller-buncher. The study was installed in a first thinning of a single-aged loblolly pine (Pinus taeda) plantation. A single operator was observed during both daylight and dark hours. Data indicates that the number of stems cut per accumulation was similar between the shifts. However, bunches created during the night shift were...

Invasive plant species threaten biological communities globally. However, relatively little is known about how evolutionary processes vary over the course of an invasion. To evaluate the importance of historical and adaptive drivers of range expansion, we compare the performance of North American populations of invasive Lonicera japonica from areas established 100-150 years ago, now the southern core of the range, to populations from the northern range margin, established within the last 65 years. Growth and survival of individuals from 17 core and 14 margin populations were compared in...

Previous studies have debated the flammability of young regenerating stands, especially those in a matrix of mature forest, and no consensus has emerged as to whether young stands are inherently prone to high-severity wildfire. This topic has recently been addressed using spatial imagery, and weak inferences were made given the scale mismatch between the coarse resolution of spatial imagery and the fine resolution of mechanisms driving fire severity. We collected empirical stand and fire-severity data from 44 regenerating stands that are interspersed in mature, mid-elevation forests in the...

The existence of non-serotinous, non-sprouting species in fire regimes where serotiny confers an adaptive advantage is puzzling, particularly when these species recruit poorly from soil seed banks or from burn edges. In this paper, white spruce (Picea glauca (Moench) Voss) was used to show that the timing of fire relative to seed development can control aerial seed bank availability for non-serotinous species. To estimate seed survival in closed cones during crown fires, cone heating was simulated using a one-dimensional conduction model implemented in a computational fluid dynamics...

Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry)...

Forest dynamics in the United States differ substantially from those in the developing world and thus present unique monitoring requirements. While deforestation and conversion to semipermanent agriculture dominate tropical forest dynamics, the area of forest land in the United States has remained fairly constant for the last 50-60 years (Birdsey and Lewis 2003). Although the United States experienced rapid deforestation during the eighteenth and nineteenth centuries, much of the eastern clearing regrew during the twentieth century as marginal agricultural land was abandoned.

Lidar height data collected by the Geosciences Laser Altimeter System (GLAS) from 2002 to 2008 has the potential to form the basis of a globally consistent sample-based inventory of forest biomass. GLAS lidar return data were collected globally in spatially discrete full waveform "shots," which have been shown to be strongly correlated with aboveground forest biomass. Relationships observed at spatially coincident field plots may be used to model biomass at all GLAS shots, and well-established methods of model-based inference may then be used to estimate biomass and variance for specific...