Treesearch

Chaparral, among the most stable and resilient vegetation types in California, has shown signs of degradation by altered fire frequency, drought, non-native species, recreation, urban development, and possibly anthropogenic nitrogen deposition in southern California. Restoration has been practiced less frequently in chaparral than other, more extensively disturbed vegetation types, but recent degradation suggests that restoration may be important for the maintenance of ecosystem services such as slope stabilization, carbon sequestration, biodiversity conservation, and scenic beauty. Most...

Thousand Cankers Disease (TCD) of Juglans and Pterocarya (Juglandaceae) involves a fungal pathogen, Geosmithia morbida, and a primary insect vector, Pityophthorus juglandis. TCD was described originally from dying Juglans nigra trees in the western United States (USA), but it was reported subsequently from the eastern USA and northern Italy. The disease is often difficult to diagnose due to the absence of symptoms or signs on the bark surface of the host. Furthermore, disease symptoms can be confused with those caused by other biotic and abiotic agents. Thus, there is a critical need for a...

To address uncertainty in biomass estimates across spatial scales, we determined aboveground biomass (AGB) in Californian forests through the use of individual tree detection methods applied to small-footprint airborne LiDAR. We propagated errors originating from a generalized allometric equation, LiDAR measurements, and individual tree detection algorithms to AGB estimates at the tree and plot levels. Larger uncertainties than previously reported at both tree and plot levels were found when AGB was derived from remote sensing. On average, per-tree AGB error was 135% of the estimated AGB,...

A prediction that has gained considerable traction in the American pika (Ochotona princeps) literature is that because of climate change, high mortality is likely to occur in winters of low or early snowmelt and cause extirpation of local populations. The basis for this prediction is the perception that the absence of an insulative layer of snow to protect pikas from severe winter cold temperatures may cause animals to utilize metabolic reserves through excessive thermoregulation before the spring emergence of fresh vegetation, or die directly from exposure to extreme winter temperatures....

Flame and mass loss data for chaparral, a mixture of shrub plants from the Mediterranean climate zone of southwestern North America, from five previously reported experiments were used to evaluate several published models relating flame characteristics to mass loss and heat release rates. These data are unique with fuel moisture content ranging from 0.36 to 0.94 (dry basis); the study used mass loss rates which included water loss. Fit of the data to Froude number correlations developed by Albini, Byram, Nelson and Thomas and heat release rate—flame length correlations by Heskestad,...

Aim Global declines in large old trees from selective logging have degraded old‐forest ecosystems, which could lead to delayed declines or losses of old‐forest‐associated wildlife populations (i.e., extinction debt). We applied the declining population paradigm and explored potential evidence for extinction debt in an old‐forest dependent species across landscapes with different histories of large tree logging. Location Montane forests of the Sierra Nevada, California, USA. Methods We tested hypotheses about the influence of forest structure on territory extinction dynamics of the spotted...

The Black-backed Woodpecker (Picoides arcticus) is a snag-associated species that colonizes and utilizes patches of burned forests typically within 10 years of fire. Previous research has indicated that salvage logging, the removal of dead and dying trees from burned forests, has a negative effect on nesting densities of Black-backed Woodpeckers. One strategy proposed to ameliorate the impacts of dead tree removal on Black-backed Woodpeckers is to retain patches, or islands, of dense snags within the salvage matrix, but this approach remains largely untested. Following the Angora fire of...

Climate refugia are locations where decoupled climate processes enable species to persist despite unfavorable climate changes in surrounding landscapes. Despite theoretic bases and paleo-ecological evidence, refugia have not been widely characterized under modern conditions in mountain regions. Conifers in the Great Basin, USA, provide an opportunity to evaluate the potential of low-elevation ravine and riparian (LERR) contexts to function as climate refugia. We provide evidence for significantly higher than expected occurrence of limber pine (Pinus flexilis E. James) in LERR contexts...

Fire creates challenges and opportunities for wildlife through rapid destruction, modification and creation of habitat. Fire has spatially variable effects on landscapes; however, for species that benefit from the ephemeral resource patches created by fire, it is critical to understand characteristics of fires that promote postfire colonization and persistence and the spatial scales on which they operate. Using a model postfire specialist, the black‐backed woodpecker (Picoides arcticus), we examined how colonization and persistence varied across two spatial scales as a function of four...

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