iind Sabin, T. E. 1998. [decomposition and nutrient dynamics of oak Quercu.s spp. logs after five years of decomposition. Efogniphy 21: 3-10.Decomposition of oak Quercus spp. logs (25 ^5 cm diameter, 3 tn long) was compared among log substrates in Oregon, Minnesota. Kansas and Norlh Carolina during the first five years on the groimcl. Decomposition of whole logs (weighted by substrate) averaged 0.069 yr"' (±0.16 SD). but followed a 2-cxponential model (k = 0.12 yr ' year 1 and k = 0.06 yr ' years 2 5), reflecting qualitative differences among log substrates (outer and inner bark, sapwood and hearlwood). Rapid loss from bark substrates contributed to the initial rapid decay rate. Sapwood decay rate averaged 0.15 yr ' and dominated Uie second log decny rate. Heartwood lost only 6% mass during the first five years, for an overall decay rate of 0.012 yr ' thai likely will represent a longer-term third exponential decay rate.Carbon loss amounted to ca 5 kg yr ' per 170 kg log. Nutrient concentrations generally declined during the first five years, but nitrogen, sulfur, and sodium accumulated in sapwood and heartwood during ihis period. Sulfur content increased in all substrates and doubled in whole logs during this 5-yr period. Complex patlerns of nutrient content suggest patterns of'microbial colonization and nutrient utilization. Polynomial models were developed to describe rates of carbon and nutrient flux in log substrates.
In western Oregon, we created snags by sawing tops off live Douglas-fir (Pseudotsuga menziesii) (n = 821) trees and monitored their condition and use by cavity-nesting birds. We created snags in three silvicultural treatments: modified clearcut stands, two-story stands, and small-patchgroup-selection stands. We used two snag patterns: clumped and scattered. Created snags averaged 3.8/ha in density, 17 m in height, and 75 cm in diameter. Chainsaw-topped snags were used by cavity nesters within 5 yr of creation. Abundance of excavated cavities increased in all silvicultural treatments (P = 0.0001) and was higher in two-story and clearcut stands than in small-patch stands (P ≤ 0.0004). We did not, however, find that snag pattern (clumped v. scattered) affected use by cavity-nesting birds based on abundance of excavated cavities (P > 0.6). We observed excavated cavities in five hardwood species indicating that hardwoods represented an important resource for cavity-nesting birds. Creating conifer snags by topping and retaining hardwoods may retain or increase populations of cavity nesters in areas with low natural snag density. West. J. Appl. For. 12(3):93-97.
Application. Vector diagrams can be used to demonstrate the subtle relationships between various watering regimes and a seedling's growth responses such as shifts in nutrient levels and biomass. A watering regime that optimizes growth and bud developmentcan be developed through close monitoring of seedlings.Abstract. Containerized Douglas-fir (Pseudotsuga menziesii [Mirb.] France) seedlings were subjected to six moisture-stress treatments (ranging from 7 to 65% soil water content by volume) for 12 weeks. At the end of this period, there were significant differences in phenological, physiological, and morphological responses among the seedlings in the various moisture-stress treatments. In general, seedlings grown under very high or very low soil moisture conditions were adversely affected, while those grown under moderate conditions (29 to 53% soil water content) exhibited optimum growth, bud development, and nutrient and starch reserves. The use of vector analysis was found to be helpful in data interpretation. The results indicate the importance of closely monitoring nursery moisture regimes in order to achieve the best seedling quality.
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