Treesearch

Plant responses to ozone (O3) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux of water. Stomatal measurements are generally obtained at midday when gas exchange is maximal, but these may not be adequate surrogates for stomatal responses observed at other times of day, nor for non-stomatal responses. Here, we find in Pima cotton that stomatal responses to O3 observed at midday do not...

Dam removal is reconnecting rivers, and lessons learned will help water-resource and river management, particularly as removals expand globally and choices become more challenging.

White-headed woodpeckers (Picoides albolarvatus) are important cavity excavators that recently have become the focus of much research because of concerns over population declines. Past studies have focused on nest site selection and survival but information is needed on factors influencing their space use when away from the nest. We examined space use by white-headed woodpeckers during the nesting (May–Jul) and post-nesting (Jul–Oct) periods and compared the role of environmental factors (e.g., landcover) and socio-demographic factors (e.g., age, breeding success) in home range size and...

Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and levelling off downstream as it converges to matchmeteorological conditions.However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature vs distance) for 53 rivers in the PacificNorthwest (USA) using an extensive data set of remotely sensed summertime river temperatures and classified each profile into...

The physiological mechanisms underlying the short maximum height of shrubs are not understood. One possible explanation is that differences in the hydraulic architecture of shrubs compared with co-occurring taller trees prevent the shrubs from growing taller. To explore this hypothesis, we examined various hydraulic parameters, including vessel lumen diameter, hydraulic conductivity and vulnerability to drought-induced embolism, of three co-occurring species that differed in their maximum potential height. We examined one species of shrub, one short-statured tree and one taller tree. We...

Very large fires (VLFs) have important implications for communities, ecosystems, air quality and fire suppression expenditures. VLFs over the contiguous US have been strongly linked with meteorological and climatological variability. Building on prior modelling of VLFs (>5000 ha), an ensemble of 17 global climate models were statistically downscaled over the US for climate experiments covering the historic and mid-21st-century periods to estimate potential changes in VLF occurrence arising from anthropogenic climate change. Increased VLF potential was projected across most historically...

Land use and climate change occur simultaneously around the globe. Fully understanding their separate and combined effects requires a mechanistic understanding at the local scale where their effects are ultimately realized. Here we applied an individual-based model of fish population dynamics to evaluate the role of local stream variability in modifying responses of Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to scenarios simulating identical changes in temperature and stream flows linked to forest harvest, climate change, and their combined effects over six decades. We parameter...

Herbivory can shape the dynamics of plant populations, including effects on survival and reproduction, and is in turn affected by environmental factors that vary in space and time. White-tailed deer are significant herbivores in North America that have been broadly documented to affect plant reproductive success. If variation in the frequency and impact of herbivory by deer correlates with a broad-scale latitudinal gradient, climactic effects may be important for shaping plant–herbivore interactions. Alternatively, a lack of broad-scale gradients would suggest local factors such as plant...

Zucchini yellow mosaic virus (ZYMV) is an economically important pathogen of cucurbits that is transmitted both horizontally and vertically. Although ZYMV is seed-transmitted in Cucurbita pepo, the potential for seed transmission in virus-resistant transgenic cultivars is not known. We crossed and backcrossed a transgenic squash cultivar with wild C. pepo, and determined whether seed-to-seedling transmission of ZYMV was possible in seeds harvested from transgenic backcrossed C. pepo. We then compared these transmission rates to those of non-transgenic (backcrossed and wild) C. pepo.The...