Treesearch

Juniper savanna and pinon-juniper woodland communities collectively represent a widespread and diverse vegetation type that occupies foothill and mesa landforms at middle elevations in semi-arid portions of the American Southwest. Ecological understanding and proper management of these juniper and pinon types requires local knowledge of component species, site history and potential, set within a regional floristic and climatic context. The wide distribution and broad ecological amplitude of this vegetation type across a six-state area of the southwestern United States is best appreciated...

The purpose of this study was to gain reliable information on the distribution of aboveground biomass of an important component of the woodlands of north-central New Mexico, and to develop prediction equations that may be used to quickly compute biomass from relatively simple field measurements. Improved understanding of and ability to predict aboveground biomass distribution in open-grown pinon pine will provide a framework of information that will allow improved understanding of ecosystem processes.

Paleoecological reconstructions from two lakes in the U.S. northern Rocky Mountain region of Idaho and Montana revealed the presence of bark beetle elytra and head capsules (cf. Dendroctonus spp., most likely D. ponderosae, mountain pine beetle). Occurrence of these macrofossils during the period of time associated with the 1920/1930 A.D. mountain pine beetle outbreak at Baker Lake, Montana suggest that when beetle populations reach epidemic levels, beetle remains may be found in the lake sediments. In addition to the beetle remains found at Baker Lake during the 20th century, remains were...

Prescribed fire is an important tool in the management of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests, yet effects on bark beetle (Coleoptera: Curculionidae, Scolytinae) activity and tree mortality are poorly understood in the southwestern U.S. We compared bark beetle attacks and tree mortality between paired prescribed-burned and unburned stands at each of four sites in Arizona and New Mexico for three growing seasons after burning (2004­2006). Prescribed burns increased bark beetle attacks on ponderosa pine over the first three post-fire years from 1.5 to 13% of all trees,...

Many natural processes in the riparian cottonwood (Populus deltoides) forest of the Middle Rio Grande (MRG) in the southwestern United States have been disrupted or altered, allowing non-native plants such as saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) to establish. We investigated reptilian responses to restoration efforts by sampling communities of lizards at 12 study sites invaded by non-native plants along the MRG in New Mexico for 7 years (2000-2006). Sites within three regions were randomly assigned to one of the three treatments to remove non-native plants...

1) Adult wheat stem sawflies Cephus cinctus, pests of cultivated cereals that also infests wild grasses, migrate into wheat fields where they oviposit in elongating, succulent stems. 2) Volatiles released by wheat plants at susceptible stages were analyzed to determine potential semiochemical compounds. Seven major compounds were identified and quantified. 3) A Y-tube bioassay was developed to evaluate upwind orientation of adult sawflies in response to an airstream that passed over elongated wheat plants. The bioassay was also conducted with synthetic volatile compounds. The compounds...

Considerable research has examined plant responses to concurrent attack by herbivores and pathogens, but the effects of attack by parasitic plants, another important class of plant-feeding organisms, on plant defenses against other enemies has not been explored. We investigated how attack by the parasitic plant Cuscuta pentagona impacted tomato (Solanum lycopersicum) defenses against the chewing insect beet armyworm (Spodoptera exigua; BAW). In response to insect feeding, C. pentagona-infested (parasitized) tomato plants produced only one-third of the antiherbivore phytohormone jasmonic...

The concentrations of sediment and turbidity in stream water were monitored during culvert removals to determine the short term effects of road obliteration. Sediment concentration was measured at 11 stream crossings among two locations in Idaho and one in Washington. Sediment concentration immediately below the culvert outlet exceeded levels above the culvert outlet by at least three orders of magnitude at all stream crossings. Sediment yields ranged from 170 to less than 1 kg in the 24-h period following culvert removal. Turbidity exceeded the regulatory limits during culvert removal at...

Our group of wilderness campers perched on the rocks, enjoying the sounds of the nearby waterfall and the tide stealing in across the flats. Granite walls soared thousands of feet in the air; icebergs floated by on their way from calving glacier to the open sea. Loons called, and a rustling in the woods across the channel meant that a bear or deer might step out onto the beach at any moment. We were more than 30 miles (48 km) by boat into the Tracy Arm-Fords Terror Wilderness, and it was easy to feel that we were far removed from civilization. The possibilities for discovery were endless....

When crafting the U.S. Wilderness Act, Howard Zahniser selected the word untrammeled rather than undisturbed to describe wilderness (Harvey 2005). This reflected his belief that places that had been disturbed by humans should be considered for wilderness designation because impaired ecosystems could be restored. Like many others, he hoped that restoration could be accomplished simply by leaving the wilderness alone. This was reflected in his famous declaration that wilderness stewards should be guardians rather than gardeners. In recent decades, it has become increasingly clear that human...