Treesearch

Despite their trophic importance and potential importance as bioindicators of stream condition, benthic algae have not been well studied in California. In particular there are few studies from small streams in the Sierra Nevada. The objective of this study was to determine the standing crop of chlorophyll-a and benthic algal species assemblages present in the small 1st- and 2nd-order streams of the Kings River Experimental Watersheds (KREW, watersheds of Bull, Providence, Duff, and Teakettle Creeks) and determine the associations of these measures with stream habitat. We collected samples...

Nonhost angiosperm volatiles (NAV) and verbenone were tested for their ability to protect individual ponderosa pines, Pinus ponderosa Dougl. ex. Laws., from attack by western pine beetle (WPB), Dendroctonus brevicomis LeConte, and red turpentine beetle (RTB), Dendroctonus valens LeConte (Coleoptera: Curculionidae, Scolytinae). A combination of (
)-verbenone and eight NAVs [benzyl alcohol, benzaldehyde, guaiacol, nonanal, salicylaldehyde, (E)-2-hexenal, (E)-2-hexen-1-ol, and (Z)-2-hexen-1-ol] (NAVV) significantly reduced the density of WPB attacks and WPB successful attacks on attractant-bai...

Depreciative behaviors and other undesirable recreationist actions continue to be a topic of great interest for recreation management (fig. 1). Maintaining park ecosystems involves responding to and preventing damage from depreciative recreationist behavior, and recreation managers are charged with developing and selecting eff ective tools to address the costly and perplexing impacts of undesirable recreationist behavior.

National park staffs rely on sign to inform visitors of a great variety of expected behaviors. Where park rangers or volunteers physically cannot be present to remind visitors of important rules, signs can be especially helpful. However, as any ranger will attest, signs vary in eff ectiveness. The reasons for this are numerous, but message content is a critical factor.

Mechanical thinning and the application of prescribed fire are commonly used tools in the restoration of fire-adapted forest ecosystems. However, few studies have explored their effects on subsequent amounts of bark beetle caused tree mortality in interior ponderosa pine, Pinus ponderosa Dougl. ex P. & C. Laws. var. ponderosa. In this study, we examined bark beetle responses to creation of midseral (low diversity) and late-seral stages (high diversity) and the application of prescribed fire on 12 experimental units ranging in size from 76 to 136 ha. A total of 9500 (5.0% of all trees)...

Psidium cattleianum Sabine (strawberry guava) is one of Hawai‘i’s most disruptive alien plants. Dense stands can suppress growth and establishment of native species, support high populations of crop-damaging fruit flies, and preclude restoration or management of native forests. Our research investigated factors affecting persistence of P. cattleianum seeds in lowland wet forest soils. We collected soil cores from four forested sites immediately after fruit fall and 6.5 months later. We found abundant germination of P. cattleianum seeds immediately after fruit drop. Soil collected under...

Urbanization has profound influences on ecological communities, but our understanding of causal mechanisms is limited by a lack of attention to its component stressors. Published research suggests that at landscape scales, habitat loss and fragmentation are the major drivers of community change, whereas at local scales, human activity and vegetation management are the primary stressors. Little research has focused on whether urbanization stressors may supplant natural factors as dominant forces structuring communities. We used model selection to determine the relative importance of urban...

Urban development typically has extensive and intensive effects on native ecosystems, including vegetation communities and their associated biota. Increasingly, urban planning strives to retain elements of native ecosystems to meet multiple social and ecological objectives. The ecological integrity of native forests in an urbanizing landscape is challenged by a myriad of impacts, such as forest management and invasive species. Environmental protection efforts in the Lake Tahoe basin, spanning the California/Nevada border in the Sierra Nevada mountains, over the past half century have...