Treesearch

Simulating the influence of intensive management and annual weather fluctuations on tree growth requires a shorter time step than currently employed by most regional growth models. High-quality data sets are available for several plantation species in the Pacific Northwest region of the United States, but the growth periods ranged from 2 to 12 years. Measurement periods of varying length complicate efforts to fit growth models because observed growth rates must be interpolated to a common length growth period or those growth periods longer or shorter than the desired model time step must...

We present an evaluation of the ecological roles ("key ecological functions" or KEFs) of 618 wildlife species as one facet of subbasin assessment in the Columbia River basin (CRB) of the United States and Canada. Using a wildlife-habitat relationships database (IBIS) and geographic information system, we have mapped KEFs as levels of functional redundancy (numbers of species with particular KEF categories) that may occur within subbasins and subwatersheds historically and at present. Natural levels of functional redundancy are presumed to be desirable for contributing to resilient ecosystem...

We used spatial predictions from gradient models to examine the influence of environment, disturbance, and ownership on patterns of forest vegetation biodiversity across a large forested region, the Oregon Coast Range (USA). Gradients in tree species composition were strongly associated with physical environment, especially climate, and insensitive to disturbance. In contrast, forest structure was strongly correlated with disturbance measures and only weakly with environmental gradients, and several attributes of forest structure differed among ownerships. Differences among ownerships were...

Soil disturbance is a visually apparent result of using heavy equipment to harvest trees. Subsequent consequences for growth of remaining trees, however, are variable and seldom quantified. We measured tree growth 7 and 11 years after thinning of trees in four stands of coast Douglas-fir (Pseudotsuga menziesii var. menziesii(Mirb.) Franco) where soil disturbance was limited by using planned skid trails, usually on dry soils. The three younger stands had responded to nitrogen fertilizer in the 4 years before thinning, but only one stand showed continued response in the subsequent 7- or...

The characteristic decline in height growth that occurs over a tree's lifespan is often called "age-related decline." But is the reduction in height growth in aging trees a function of age or of size? We grafted shoot tips across different ages and sizes of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees to determine whether the decline in height growth is mediated by tree size or by the age of the apical meristem. We also evaluated whether reduced carbon assimilation plays an important role in height growth decline. In one experiment we cut shoot tips from old-growth, young-mature...

Under certain environmental conditions, nocturnal transpiration can be relatively high in temperate and tropical woody species. In nutrient-poor systems such as the Brazilian Cerrado, nocturnal transpiration may enhance delivery of nutrients to roots. We compared nocturnal transpiration of three dominant Cerrado tree species growing in unfertilized plots and plots to which nitrogen (N) and phosphorus (P) had been added twice yearly from 1998 to 2005. The fertilized trees had lower nocturnal transpiration. The results were consistent with the idea that enhancing nutrient uptake by allowing...

We characterized headwater stream habitats, fish, and amphibian fauna, in and along 106 headwater stream reaches at 12 study sites within managed forest stands 40 to 70 years old in western Oregon. Headwater stream types in our sample included perennial, spatially intermittent, and dry reaches. We captured 454 fish of three species groups and 1,796 amphibians of 12 species. Using canonical correlation, nonmetric multidimensional scaling ordination, and generalized linear models, we identified species and assemblages associated with reach hydrologic type (e.g., perennial, intermittent,...

Biophysical characteristics of sapwood and outer parenchyma water storage compartments were studied in stems of eight dominant Brazilian Cerrado tree species to assess the impact of differences in tissue capacitance on whole-plant water relations. Both the sapwood and outer parenchyma tissues played an important role in regulation of internal water deficits of Cerrado trees. Relationships between minimum leaf water potential and water storage capacity across the different species suggested that daily fluctuations in water deficits were substantially reduced in species with large capacitance...

Although many scientists recommend adaptive management for large forest tracts, there is little evidence that its use has been effective at this scale. One exception is the 10-million-hectare Northwest Forest Plan, which explicitly included adaptive management in its design. Evidence from 10 years of implementing the plan suggests that formalizing adaptive steps and committing to monitoring worked better than allocating land to adaptive management areas. Clearly, some of the problems in implementing any new strategy should have been expected and probably would have been avoided if the plan...

We review the policies and management approaches used in U.S. Pacific Northwest planted forest to address biodiversity protection. We provide a case-study watershed design from southern Oregon, integrating various stand-to-landscape biodiversity-management approaches.