Treesearch

Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high-severity fire, forest recovery may be compromised by lack of tree seed sources, warmer and drier postfire climate, or short-interval reburning. A potential outcome of the loss of resilience is the conversion of the prefire forest to a different forest type or nonforest vegetation. Conversion implies major, extensive, and enduring changes in dominant species, life forms, or functions, with impacts on ecosystem services. In the present article, we synthesize a growing body of evidence of...

Obtaining accurate and widespread measurements of the vertical structure of the Earth’s forests has been a long-sought goal for the ecological community. Such observations are critical for accurately assessing the existing biomass of forests, and how changes in this biomass caused by human activities or variations in climate may impact atmospheric CO2 concentrations. Additionally, the three-dimensional structure of forests is a key component of habitat quality and biodiversity at local to regional scales. The Global Ecosystem Dynamics Investigation (GEDI) was launched to the International...

A central challenge in global change research is the projection of the future behavior of a system based upon past observations. Tree-ring data have been used increasingly over the last decade to project tree growth and forest ecosystem vulnerability under future climate conditions. But how can the response of tree growth to past climate variation predict the future, when the future does not look like the past? Space-for-time substitution (SFTS) is one way to overcome the problem of extrapolation: the response at a given location in a warmer future is assumed to follow the response at a...

Land managers face a mounting variety of challenges, including how to efficiently dispose of excessive woody residues on forest sites (especially in the Western United States), maintain and improve soil productivity, improve forest resilience to changes in climate (especially as it pertains to drought and fire), and increase the effectiveness of reforestation activities. The use of biochar, a charcoal that is not readily degraded and is made specifically for land application, may have a role in meeting these challenges. Moreover, biochar may provide nursery managers with opportunities to...

In northern California, United States, a cut-to-length (CTL) system was recently used for the first time to harvest young redwood (Sequoia sempervirens (Lamb. ex D. Don) Endl.) forests. Landowners and public agencies in this region have been concerned about the potential negative impacts of CTL on soils during wet-season harvest operations. To determine soil impacts, we measured changes in soil bulk density (BD) and hydraulic conductivity (HC) after CTL operations in May and August. Soil samples were collected at two locations (track and center) along forwarder trails and at a reference...

Forest soil disturbances are unavoidable in ground-based skidding operations and it is well-known that the extent, duration, and severity of disturbances increase with increasing trafficking from harvest equipment and slope gradient. It is unclear, however, how different types of harvest equipment affect the extent of disturbance along the margins of skid trails. The aim of this study was to investigate changes in topsoil (0–10 cm depth) physical properties beyond the margins of skid trails in mountainous terrain in response to skidding with three different skidder types with varying tire...

Nettleleaf giant hyssop (Agastache urticifolia [Benth.] Kuntze) belongs to the Lamiaceae or mint family, Mentheae tribe, and Nepetinae subtribe (Drew and Sytsma 2012). The Agastache genus is comprised of two sections, Agastache (syn: Chiastandra) and Brittonastrum, which are geographically distinct. Nettleleaf giant hyssop is part of the more northerly distributed Agastache section (Lint and Epling 1945; Vogelmann 1985). Taxonomy for this review follows Cronquist et al. (1984).

Nakedstem sunray occurs in Idaho, Utah, Nevada, Arizona, and California (Curtis 2006). It is widespread throughout the Great Basin (Clark 1998) and occurs as restricted populations in southwestern and central Idaho, northern Arizona’s Mohave and Coconino counties, and southeastern California’s Inyo and San Bernardino counties (Cronquist et al. 1994).

Springsnails (genus Pyrgulopsis, hereafter pyrgs) are small freshwater aquatic gastropods that occur in isolated springs in western North America. Pyrgs are species of conservation concern, but patterns of occupancy and speciation are complex. We investigated patterns of occurrence for pyrgs in the Spring Mountains, Clark County, Nevada. We were primarily concerned with identifying springs containing the species P. deaconi, the Spring Mountains pyrg, and P. turbatrix, the southeast Nevada pyrg. We identified species through genetic analysis of the COI-1 mitochondrial region and examined...

Limestone hawksbeard is a western species occurring in southern British Columbia, Alberta, Saskatchewan, and south to northern New Mexico, Arizona, and central California (Bogler 2006; USDA NRCS 2019). It occurs primarily east of the Cascade Mountains in the Pacific Northwest (Hitchcock and Cronquist 2018). Populations are most abundant in northern California and southern Oregon, becoming local and infrequent eastward (Babcock and Stebbins 1938).