Treesearch

Previous work has demonstrated that epigeal woody invasive plants (with expanding, photosynthetic cotyledons), such as honey mesquite (Prosopis glandulosa L.), respond positively to elevated atmospheric CO2 concentrations in as little as 3 days after emergence. No research has addressed the behavior of larger seeded, hypogeal invasive plants (common in south Texas) exposed to elevated CO2. We studied two such species, guajillo (Acacia berlandieri Benth.) and cat claw acacia (Acacia greggii Gray var. wrightii (G. Bentham) D. Isley), to quantify growth stimulation at a doubled concentration...

The objective of this experiment was to test the hypotheses that 1) simulated herbivory stimulates increased biomass production in spiny hackberry (Celtis pallida), but decreases biomass production in blackbrush acacia (Acacia rigidula) compared to unbrowsed plants and 2) thorn density and length increase in blackbrush acacia to a greater extent than in spiny hackberry in response to tissue removal. Blackbrush acacia shrubs defoliated repeatedly at the 75 percent level produced about 66 percent more biomass than control shrubs, while shrubs receiving 100 percent repeat defoliation treatment...

Long-duration fire activity during the 2006 northern California fire season presented an excellent opportunity to create a temporary air-quality/smoke-monitoring network in the complex terrain across northwestern California. The network was established through cooperative interagency coordination of Federal officials, the California Air Resources Board (CARB), and local Air Pollution Control Districts (APCDs). This network addressed concerns over air quality and potential firefighter- and citizen-health issues. Equipment deployed included real time PM2.5 monitors (EBAMs and DataRAM’s) at...

Alxa desert steppe is one of severely the degraded rangelands in the Northwest China. Shrubs, as the dominant life form in the desert steppe, play an important role in protecting this region from further desertification. Chemical properties of three soil layers (0 to 10, 10 to 20 and 20 to 30 cm) at three locations (the clump center [A], in the periphery of shrub canopies [B], and the inter-shrub space [C], at least one m away from the edge of shrub canopies) were investigated in two prominent shrub communities (Zygophyllum xanthoxylum, Ammopiptanthus monglicus) in Alxa desert steppe. The...

Symbiotic fungi confer multiple benefits such as enhanced photosynthetic rates and drought tolerance in host plants. Shrubs and grasses of southwestern deserts are colonized by symbiotic fungi that cannot be removed by conventional sterilization methods. These fungi were extensively studied in Bouteloua eriopoda (Torr.) Torr. and Atriplex canescens (Pursh) Nutt. over a wide range of locations and environmental conditions. Fungi were intrinsically integrated with cells, tissues, and regenerated plant cultures. These composite plantfungus organisms are comprised of more than one fungal...

The distribution and abundance of plant biomass in space and time are important properties of rangeland ecosystem. Land managers and researchers require reliable shrub weight estimates to evaluate site productivity, food abundance, treatment effects, and stocking rates. Rapid, nondestructive methods are needed to estimate shrub biomass in semi-arid ecosystems. Shrub height and crown diameter are useful non-destructive measures of shrub size. Mariola (Parthenium incanum) is an important shrub that is widely distributed in the Chihuahuan and Sonoran deserts. Mariola is found from the...

Ceratoides lanata (Rydb.) J.T. Howell, common winterfat, is valued for its nutrient content and palatability to livestock; however, the subspecies Ceratoides lanata var. subspinosa (Rydb.) J.T. Howell, (‘subspinosa’) is considered unpalatable. Curiously, observations of ‘subspinosa’ revealed several populations in central New Mexico that were heavily grazed. Volatile terpene profiles are associated with differences in palatability in many plant species. To determine whether differences in volatile profiles between ‘subspinosa’ populations would correlate with apparent differences in...

Invasive annual grasses, such as cheatgrass (Bromus tectorum), create changes in soil microorganism communities and severely limit shrub establishment, a situation that is of considerable inportance to land managers. We examined the effects of biological crustforming algae and arbuscular mycorrhizal fungi on growth and survival of Ephedra viridis (EPVI), Coleogyne ramosissima (CORA), Artemisia filifolia (ARFI), Chrysothamnus nauseosus ssp. hololeucus (CHNA), and Artemisia nova (ARNO), with and without competition from cheatgrass, in a controlled laboratory pot experiment. Shrub survival...

Fire-adapted forest ecosystems make up 95 percent of the historic Coastal Plain vegetation types in the Southeastern United States. Fire suppression over the last century has altered the species composition of these ecosystems, increased fuel loads, and increased wildfire risk. Prescribed fire is one management tool used to reduce fuel loading and restore fire-adapted species, but little information exists on the presettlement extent and location of fire-dependent ecosystems at a level of detail useful to guide land management decisions at the local spatial scale. In an effort to close...

Computational tools have been developed at the National Institute of Standards and Technology (NIST) for modeling fire spread and smoke transport. These tools have been adapted to address fire scenarios that occur in the wildland urban interface (WUI) over kilometer-scale distances. These models include the smoke plume transport model ALOFT (A Large Open Fire plume Trajectory model) and WFDS (Wildland-urban interface Fire Dynamics Simulator) for fire spread and smoke transport in the wildland-urban interface. The visualization tool is called Smokeview. In this paper, an overview of the...