Creating diverse forests for multiple uses is important to natural resource managers and landowners. A study conducted in southwestern Oregon provides forest managers with information that offers choices when managing land for a variety objectives that may include a high level of wood production, a moderate level of wood production with some wildlife habitat features, or low wood production that provides cover and forage for a wider variety of wildlife species.
"Land managers need effective approaches for creating and modifying forest stand structures to satisfy a broad range of objectives," explains Tim Harrington, a research forester at the Forest Service's Pacific Northwest Research Station. "Silvicultural treatments can be used to shift competitive interactions between conifers and hardwoods to create the desired balance between wood production and wildlife habitat."
Harrington and John Tappeiner, an emeritus Oregon State University forestry professor, initiated a study in 1983 in southwestern Oregon on Douglas-fir plantations near Cave Junction and Glendale, Oregon. During the first phase of the study, when the plantations were 1 or 2 years old, a single herbicide treatment was used to reduce hardwood density to several levels. The Douglas-fir were thinned at age 15 to leave densities of 120 to 220 dominant trees per acre.
About 8 years later (ages 23 to 25), the scientists found that:
Three very different stand structures emerged.Highly productive, pure stands of Douglas-fir, 39 to 52 feet tall, occurred where hardwoods were completely removed at age 2 years.
Where the original hardwood density was retained, Douglas-fir and hardwoods occupy the same canopy layer, 26 to 30 feet tall, in mixed stands that are low in productivity but may have the potential to provide cover and forage for a range of wildlife species.Each of the stand structures had different potentials for habitat and for wood production.
It is unknown how long these stand structures will persist given future competitive interactions; however, differences in Douglas-fir yield among the three stand structures are likely to remain stable or even increase as the taller-growing species continues to exert its dominance.
"Managing stands with moderate hardwood densities enables a stratified structure to develop with conifers and hardwoods occupying dominant and intermediate canopy layers, respectively," explains Harrington. "Combining high hardwood densities with precommercial thinning of Douglas-fir creates a codominant stand structure with conifers and hardwoods occupying the same canopy layer. Managers may also want to retain some hardwoods in areas prone to black stain root disease, since the hardwoods may reduce mortality of planted Douglas-fir following thinning."
Read the entire report, Long-term effects of tanoak competition on Douglas-fir stand development, in the April issue of Canadian Journal of Forestry.
Source: Tim Harrington, research forester, (360) 753-7674, email@example.com
The Pacific Northwest Research Station is one of seven research facilities in the USDA Forest Service. The station's headquarters is in Portland, Ore., with 11 locations in Alaska, Oregon, and Washington. The station has about 500 employees.
Sherri Richardson Dodge | EurekAlert!
Fighting a destructive crop disease with mathematics
21.06.2017 | University of Cambridge
Unusual soybean coloration sheds a light on gene silencing
20.06.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology