نتایج جستجو برای: pinus ponderosa
تعداد نتایج: 13623 فیلتر نتایج به سال:
A method is described for predicting the spatial distribution of individual birds using presence data. The approach is demonstrated using a statistical habitat association model developed for resident and migratory birds on a 12 ha plot of ponderosa pine (Pinus ponderosa) heavily infested with southwestern ponderosa pine dwarf mistletoe (Arceuthobium vasinatum subsp. Cryptopodum (Englemann) Haw...
Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nea...
Effects of Ponderosa pine needle ingestion of uterine vascular function in late-gestation beef cows.
Consumption of Ponderosa pine (Pinus ponderosa) needles (PN) by beef cows during late gestation results in premature delivery in association with profound constriction of the caruncular arterial bed. Further, PN extracts and plasma from PN-fed cows increase uterine arterial tone in vitro. Uterine arterial tone is a measure of the arterial resistance to stretch and controls the baseline rate of ...
Understanding seasonal variations of photosynthetic parameters is critical for accurate modeling of carbon dioxide (CO2) uptake by ecosystems. Maximum carboxylation velocity (Vcmax), maximum rate of electron transport (Jmax), leaf respiration in the light (R(day)), light-saturated assimilation (Amax) and maximum quantum yield (Phi) were calculated from leaf gas exchange measurements made monthl...
We examined radial growth rates of locally co-occurring Douglas-fir (PSME e Pseudotsuga menziesii var. glauca) and ponderosa pine (PIPO e Pinus ponderosa var. ponderosa) trees growing within the Northern Rockies to determine if there are differential growth and climatic responses between these species and whether these responses are consistent among topographically and climatologically diverse ...
—Ectomycorrhizal colonization and rooting characteristics were quantified in a mature ponderosa pine (Pinus ponderosa Dougl. ex Laws.) stand in the western Sierra Nevada. Root length totaled 3835.9 m ⋅ m–2 of forest floor surface area, with 96% consisting of the fine-root fraction. Total root dry weight and volume were 2230.4 g ⋅ m–2 and 5807.4 cm3 ⋅ m–2 of forest floor area, respectively, with...
In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-s...
Inductively coupled plasma mass spectrometry (ICP-MS) was used to examine trace element concentration in tree-rings over three and half centuries to assess macro-trends of environmental change. Tree-rings of a 350+ year old mammoth ponderosa pine (Pinus ponderosa) were analyzed for element concentration and evaluated versus local and global historical events. The ponderosa pine was located 100 ...
Understanding patterns of plant population mortality during extreme weather events is important to conservation planners because the frequency of such events is expected to increase, creating the need to integrate climatic uncertainty into management. Dominant plants provide habitat and ecosystem structure, so changes in their distribution can be expected to have cascading effects on entire com...
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