Treesearch

The related challenges of predictions in ungauged basins and predictions in ungauged climates point to the need to develop environmental models that are transferable across both space and time. Hydrologic modeling has historically focused on modelling one or only a few basins using highly parameterized conceptual or physically based models. However, model parameters and structures have been shown to change significantly when calibrated to new basins or time periods, suggesting that model complexity and model transferability may be antithetical. Empirical space-for-time models provide a...

Swiss needle cast (SNC), a foliage disease of Douglas-fir (Pseudotsuga menziesii), is caused by the physical blockage of the stomata by pseudothecial ascocarps of the fungus Phaeocryptopus gaeumannii. Occlusion of the stomata results in a decrease in the ability of the host to exchange gases with the environment leading to reduced carbon assimilation (Manter et al., 2000). This results in premature foliage loss and subsequent growth reduction due to decreased photosynthetic leaf area (Manter et al., 2003). Prior to the 1980’s, it was known to cause severe disease only in exotic Douglas-fir...

Light Detection and Ranging (LiDAR) has become a common means for predicting key forest structural attributes. The aim of this study was to explore the relationship between individual tree LiDAR-based metrics and field data on tree attributes from a tropical rainforest in Peninsular Malaysia, to assess the correlation between LiDAR and field data at the individual-tree level for aboveground biomass (AGB) estimates. The model was developed using multiple regression analysis, with a non-linear power model being used to fit the predictive models. The AGB model was developed based on estimated...

Post-dispersal seed predators contribute substantially to seed loss across many ecosystems. Most research has focused on understanding sources of variation in seed loss, without appreciating the implications of seed predation for plant coexistence, community assembly and broader community theory. Meanwhile, research aimed at understanding coexistence and community assembly processes in plant communities has focused on axes of dispersal and resource competition and the traits influencing these processes, without accounting for the role of generalist seed predators.

The recent development of an interagency strategy to monitor wilderness character, Keeping It Wild 2: An Updated Interagency Strategy for Monitoring Wilderness Character Across the National Wilderness Preservation System (Landres et al. 2015), allows on-the-ground managers and decision makers to assess whether stewardship actions for an individual wilderness are fulfilling the legislative mandate to “preserve wilderness character.” By using credible data that are consistently collected, one can assess how wilderness character changes over time and evaluate how stewardship actions affect...

Forests worldwide are impacted by a wide variety of disturbances that are happening more frequently with more intensity than in the past due to global climate change. Forest managers, therefore, need to identify new ways to quickly and accurately predict post-disturbance forest landscape composition. We suggest the use of Landsat satellite imagery and an image processing tool to map percent canopy cover (PCC) by species and sub-canopy species counts to be used in adaptive forest management strategies. We used zero-inflated models to successfully predict PCC and sub-canopy counts (number of...

In this study, we extended the spatial weight matrix defined by Getis and Aldstadt (2004) to a more general case to map the distribution of Rosa multiflora, an invasive shrub, across the Upper Midwest counties in a spatial lag model (SLM) context. Both the simulation study and the application to the invasion data of invasive Rosa multiflora collected in 2005-2006 proved that the modified spatial weight matrix outperforms its original case and the contiguity- and nearest distance- based spatial weight matrices in diagnostic statistics and resultant invasion maps. The geographical distributio...

Thurber’s needlegrass (Achnatherum thurberianum [Piper] Barkworth) is a key restoration species in the Great Basin and surrounding areas, yet comprehensive studies of how climate relates to genetic variation and seed zones for restoration projects are lacking. Potentially adaptive phenotypic traits of 66 diverse populations of Thurber’s needlegrass were measured in common gardens at Central Ferry, Washington and Reno, Nevada in 2012 and 2013. Extensive genetic variation was observed among phenology, morphology, and production traits (P < 0.01), and canonical correlation was used to relate...

Wildfire is a key disturbance agent in forests worldwide, but recent large and costly fires have raised urgent questions about how different current fire regimes are from those of the past. Dendroecological reconstructions of historical fire frequency, severity, spatial variability, and extent, corroborated by other lines of evidence, are essential in addressing these questions. Existing methods can infer the severity of individual fires and stand-level fire regimes. However, novel research designs combining evidence of stand-level fire severity with fire extent are now being used to...

This study examined the recovery of both physical and biotic characteristics of small (<0.1 m3 sec-1) headwater stream systems impacted by the Dude Fire, which occurred in central Arizona, USA, in 1990. Data collected prior to the fire from 1986 to1988 was compared to similar data collected at various points after the fire though 2011 in order to assess changes in the geomorphology and macroinvertebrate communities over the 21-year time period. Additionally, several environmental parameters of the impacted streams were compared to neighboring unburned headwater streams in order to determine...