Treesearch

Scabland penstemon is a widespread species occurring as scattered populations from central Washington to western Montana and northwestern Wyoming to Nevada and California (Lindgren and Wilde 2003; St. John et al. 2009; LBJWC 2014). Populations are limited to Box Elder County in northwestern Utah (Cronquist et al. 1984; Welsh et al. 2016), the northern two-thirds of Nevada (Cronquist et al. 1984; Hitchcock and Cronquist 2018), and the Klamath, North Coast, Cascade, Sierra Nevada Ranges and Modoc Plateau regions of California (Hickman 1993).

Sharpleaf penstemon occupies a limited range in central Washington, eastern Oregon, southern and east-central Idaho, northwestern Nevada, and northern Utah (Hitchcock et al. 1959; St. John et al. 2009; Hitchcock and Cronquist 2018). It is most common in low-elevation habitats of the Columbia River Basin in Washington and Oregon and the Snake River Plains of southern Idaho (Hitchcock et al. 1959; Holmgren 1979).

Thickleaf beardtongue has a limited distribution, occurring in Utah, east-central Nevada, and northern Arizona. Reports of the species in Wyoming and Colorado are likely referring to mucronate penstemon (Penstemon mucronatus), which was considered a thickleaf beardtongue variety by some taxonomists. Variety pachyphyllus occurs in Carbon, Daggett, Duchesne, Uinta, and Wasatch Counties of Utah. Variety congestus occurs from the calcareous region of east-central Nevada to the Unita Basin in northeastern Utah, and through the Grand Canyon Plateau of northern Arizona (Freeman 2019). Holmgren...

American vetch grows throughout North America. In the United States, it grows in all but the southeastern states, and it is widely distributed west of the Mississippi River (Hickman 1993; Allen and Tilley 2014). It is widespread in the Intermountain Region but becomes less common toward the arid southwestern edge (Barneby 1989). Variety americana occupies the range described for the species (Allen and Tilley 2014; Hitchcock and Cronquist 2018). Variety minor is most common in short-grass prairies and dry woodlands east of the Rocky Mountains, but also occurs in western Montana and eastern...

Mangroves are among the most carbon-rich terrestrial ecosystems, primarily attributable to the soil pool. There are substantial differences in soil carbon (C) and nitrogen (N) due to the disparities in geomorphic settings and ecological drivers, but this insight is drawn primarily from observational studies. An objective inventory of carbon stocks in mangroves of the Rufiji River Delta, Tanzania was conducted. Seventy-five soil cores were collected within a 12,164 ha inventory area, comprising the northern portion of the delta. Cores were collected from intact and dwarf mangroves, agricultu...

All North American ash (Fraxinus spp.) species are threatened by the emerald ash borer(EAB; Agrilus planipennis), an exotic beetle which has already destroyed millions of ash trees in theU.S. and Canada. Although both chemical insecticides and biological control can be effective, andhost resistance appears possible, the speed of the invasion has defied traditional management ap‐proaches. One potential, innovative approach to managing this destructive insect is to develop ahost tree‐induced gene silencing strategy using RNA interference (RNAi) constructs targeting EAB‐specific genes. An...

Pathogens and pests, native or introduced, can cause high levels of damage and mortality in urban and rural forests. In many cases, little can be done to protect standing trees of the affected species; however, there is a growing recognition that host tree resistance can play a role at countering the long-term impacts of such outbreaks. Leveraging tree resistance for forest health requires a commitment to tree breeding such that resistant genotypes can be identified, propagated, and bred to produce resistant populations for replanting the affected species. Successful resistance breeding...