Skip to main content
Advanced Search

Filters: Tags: Microclimate (X) > Types: Citation (X)

8 results (24ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
Climate change models envision an increase in summer precipitation in eastern California and adjacent arid regions by 2050, due to anthropogenic activities. Changes in the frequency, intensity and spatial patterns of rainfall pulses are likely to influence seedling recruitment and establishment, and ultimately community composition and dynamics. The effects of altered water availability might be complicated by the effect of adult plants on resources and conditions, potentially altering seedling recruitment success and affecting community succession. We tested the hypotheses that: (1) an experimental pulse representing a 25% increase in summer precipitation would increase photosynthesis for Artemisia tridentata and...
thumbnail
Synopsis: Windbreaks are a major component of successful agricultural landscapes. At the farm scale, they help control erosion and blowing snow, improve animal health and survival under winter conditions, reduce energy consumption of the farmstead, and enhance habitat diversity. At a landscape scale, they provide habitat for various types of wildlife and have the potential to contribute significant benefits to the carbon balance equation, thereby easing the economic burdens associated with climate change. The effectiveness of a windbreak is determined partially by its external structure including its height, length, orientation, continuity, width, and cross-sectional shape and partially by its internal structure...
Hawaii’s high and steep topography leads to pronounced small-scale variations in climate, and this makes comprehensive modeling of the weather and climate particularly challenging. This paper describes a regional model formulation designed for simulations of the microclimates in Hawaii and then documents and analyzes an extended retrospective simulation for near-present-day conditions. Part II will apply the model to projected climate conditions near the end of the present century. A nested version of the Advanced Research version of the Weather Research and Forecasting Model with fine horizontal resolution and improved physics for the Hawaiian region has been configured. A 20-yr triply nested simulation of the...
In the southwestern United States, desert mountain ranges are “islands” of forest in a sea of dry grasslands and desert shrubs. It is likely that this region will face a hotter climate in the future. A particular concern is that many of these tree species (oaks, pines, and junipers) are restricted to higher elevations and that a warming climate will reduce the available habitat causing populations to decline. Although all trees are restricted to mountains in this region, different species prefer different local habitats (for example, one might prefer south slopes, others valley bottoms). This suggests that more than simply elevation determines tree habitat. We took detailed measurements of temperature and soil moisture...
Millions of acres of rangeland in the western United States are now dominated by introduced annual weeds such as cheatgrass (Bromus tectorum L.). The ability to germinate rapidly at low temperatures has been proposed as one of many mechanisms that confer a competitive advantage to this species. Previous studies of this phenomenon, however, have been limited to relatively simple comparisons of total germinability and germination rate under selected constant-temperature treatments. In this study, we germinated seeds of cheatgrass and two native perennial bunchgrass species, bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve] and big squirreltail [Elymus multisetus (J.G. Smith) M.E. Jones], over the temperature...
In order to study the likely effects of global warming on future ecosystems, a method for applying a heating treatment to open-field plant canopies (i.e. a temperature free-air controlled enhancement (T-FACE) system) is needed which will warm vegetation as expected by the future climate. One method which shows promise is infrared heating, but a theory of operation is needed for predicting the performance of infrared heaters. Therefore, a theoretical equation was derived to predict the thermal radiation power required to warm a plant canopy per degree rise in temperature per unit of heated land area. Another equation was derived to predict the thermal radiation efficiency of an incoloy rod infrared heater as a function...
Woody plant encroachment is affecting vegetation composition in arid grasslands worldwide and has been associated with a number of environmental drivers and feedbacks. It has been argued that the relatively abrupt character (both in space and in time) of grassland-to-shrubland transitions observed in many drylands around the world might result from positive feedbacks in the underlying ecosystem dynamics. In the case of the Chihuahuan Desert, we show that one such feedback could emerge from interactions between vegetation and microclimate conditions. Shrub establishment modifies surface energy fluxes, causing an increase in nighttime air temperature, particularly during wintertime. The resulting change in winter...
1. Microclimate was measured and photosynthetic responses to a climate warming manipulation were compared for the evergreen shrub Artemisia tridentata and the herbaceous forb Erigeron speciosus in the Rocky Mountains, Colorado, USA. 2. Soil was warmer and drier under infra-red heaters compared with control plots. 3. Midday xylem pressure potential did not differ for A. tridentata on heated vs control plots but was lower for E. speciosus on heated plots compared with controls. Leaf temperatures did not vary for the two species on heated or control plots. 4. There were no significant treatment or species differences in the diurnal patterns of CO2 assimilation or stomatal conductance to water vapour. Also, there were...
    map background search result map search result map Windbreaks in North American Agricultural Systems Windbreaks in North American Agricultural Systems