Treesearch

Predicting long-term consequences of climate change on hydrologic processes has been limited due to the needs to accommodate the uncertainties in hydrological measurements for calibration, and to account for the uncertainties in the models that would ingest those calibrations and uncertainties in climate predictions as basis for hydrological predictions. We implemented a hierarchical Bayesian (HB) analysis to coherently admit multiple data sources and uncertainties including data inputs, parameters, and model structures to identify the potential consequences of climate change on soil...

Inequality in reproductive success has important implications for ecological and evolutionary dynamics, but lifetime reproductive success is challenging to measure in long-lived species such as forest trees. While seed production is often used as a proxy for overall reproductive success, high mortality of seeds and the potential for trade-offs between seed number and quality draw this assumption into question. Parentage analyses of established seedlings can bring us one-step closer to understanding the causes and consequences of variation in reproductive success. In this paper, we demonstra...

Increasing the diversity of species and structure of red pine (Pinus resinosa) is often a management goal in stands simplified by practices such as fire suppression and plantation management in many areas of the Great Lakes Region. One approach to diversification is to convert predominantly even-aged, pure red pine stands to multi-cohort, mixed-species forests through variable overstory retention at harvest. Based on limited empirical evidence, pathologists have advised against this multi-cohort approach in stands where pathogens causing damaging shoot blight diseases are established. We...

The Douglas-fir beetle, Dedroctonus pseudotsugae (Coleoptera: Curculionidae) is a major pest of Douglas-fire, Pseudotsuga menziesii (Mirb.) in British Columbia (Humphreys 1995). An operational trap lure for D. pseudotsugae could be useful in an integrated pest management program to minimize mortality of Douglas-fir, particularly in conjunction with anti-aggregation pheromones (Lindgren et al. 1988; Ross and Daterman 1995a). The principal pheromone of D. pseudotsugae is frontalin (1,5- dimethyl-6,8-dioxyabicyclo [3.2.1] octane), which is produced by male and female beetles and attracts both...

Well-functioning food webs are fundamental for sustaining rivers as ecosystems and maintaining associated aquatic and terrestrial communities. The current emphasis on restoring habitat structure-without explicitly considering food webs-has been less successful than hoped in terms of enhancing the status of targeted species and often overlooks important constraints on ecologically effective restoration. We identify three priority food web-related issues that potentially impede successful river restoration: uncertainty about habitat carrying capacity, proliferation of chemicals and contaminan...

Fuel reduction treatments are increasingly used to mitigate future wildfire severity in dry forests, but few opportunities exist to assess their effectiveness. We evaluated the influence of fuel treatment, tree size and species on tree mortality following a large wildfire event in recent thin-only, thin and prescribed burn (thin-Rx) units. Of the trees that died within the first 3 years, most died in the first year regardless of treatment. First-year mortality was much higher in control and thin-only units than in thin-Rx units. Cumulative third-year mortality followed a similar trend....

Everglades freshwater marshes were once carbon sinks, but human-driven hydrologic changes have led to uncertainty about the current state of their carbon dynamics. To investigate the effect of hydrology on CO2 exchange, we used eddy covariance measurements for 2 years (2008-2009) in marl (short-hydroperiod) and peat (long-hydroperiod) wetlands in Everglades National Park. The importance of site, season, and environmental drivers was evaluated using linear and nonlinear modeling, and a novel method was used to test for temporally lagged patterns in the data. Unexpectedly, the long-hydroperio...

Global patterns in soil, plant, and fungal stable isotopes of N (15N) show promise as integrated metrics of N cycling, particularly the activity of ectomycorrhizal (ECM) fungi. At small spatial scales, however, it remains difficult to differentiate the underlying causes of plant 15N variability and this limits the application of such measurements to better understand N cycling. We conducted a landscape-scale analysis of 15N values from 31 putatively N -limited monospecific black spruce (Picea mariana) stands in central Alaska to assess the two main hypothesized sources of plant 15N...

Despite the complexity of the relationship between stomatal sensitivity, water loss and vulnerability to embolism, the goal of teasing apart the subtleties is a necessary one. As Litvak et al. (2012) mention, determining transpiration patterns based on vulnerability to embolism would be much easier than the lengthy and potentially expensive processes involved in sap flux or eddy flux measurements. Water loss from trees is a large component of the water cycle in natural systems, and an important cost (in terms of irrigation) and benefit (in terms of temperature mitigation) in urban environme...

White pine blister rust (WPBR) is caused by the fungal pathogen Cronartium ribicola. The pathogen is native to Eurasia and was introduced to North America early in the 20th century and is still spreading destructively throughout the range of native western white pines (Douglas ex D. Don) (McDonald and Hoff 2001). All of the North American five-needle (white) pines are susceptible to the pathogen and the disease is currently present in native populations of each species, except Pinus longaeva D.K. Bailey (Schwandt et al. 2010, Sniezko et al. 2011).