Treesearch

Wildfire is a topic that raises much controversy in the context of forests and forest management in Europe. Fire is often viewed as a natural disaster that is harmful, yet fire is also a natural process and an important component of the disturbance regime in some forest ecosystems. A long history of land use has made it difficult to unravel the natural role of fire in European forests. Land use changes and past forestry practices have also increased fuels and fire hazard in some areas. In recent times a warming and increasingly drought-prone climate are raising concerns that fires are...

Four undescribed species or subspecies of Reticulitermes Holmgren 1913 in northern California have been identified by chemotaxonomic and phylogenetic analyses of voucher specimens used for chemotaxonomy. To date, useful morphological keys do not exist. We present eight direct and 22 derived measures and indices of soldier head capsules of multiple colonies of each of five cuticular hydrocarbon (CHC) phenotypes. Our objective was to identify one or more morphological measurements of soldier head capsules that would unequivocally separate taxa previously identified by CHCs and phylogenetic...

It can be challenging to deploy and monitor biocontrol for invasive species, particularly in remote forest settings. One of the most abundant and disruptive invasive tree species in Hawai‘i and across the Pacific is Psidium cattleyanum Sabine (strawberry guava), which replaces native vegetation and negatively impacts forest structure and ecosystem services. A Brazilian leaf-galling insect named Tectococcus ovatus Hempel (Homoptera: Eriococcidae) is an approved biocontrol for strawberry guava, but its introduction to date has been restricted to areas with established road and trail networks...

Native dry forest habitat is one of the most threatened and rare ecosystems in the Hawaiian Islands. The Ka‘ūpūlehu Dry Forest Preserve, on the west coast of Hawai‘i Island, is one of the few remaining intact examples of this low elevation habitat. To aid restoration efforts, flowering phenology of nine native species was estimated monthly from 2001 to 2007. Some species flowered prolifically, others seldom. Two dioecious tree species are in the survey, one only has female flowering trees, the second has both male and female trees. Each gender is treated as a separate species, making ten...

Mangrove forests are the dominant ecosystems on tropical and subtropical coasts, subjected to widespread degradation and land conversion, such as aquaculture. To restore mangrove cover, mangrove seedlings were planted in coastal fringes and abandoned ponds. Most restoration reports were focused on seedling survival and growth rates. However, physiological conditions of mangrove seedlings, in terms of photosynthetic characteristics under field conditions has seldom been studied. Mangrove seedlings from restored “planted” (5 ,8, 15, and 30 yr old) and recolonized (5 and 20 yr old) stands...

Elevated soil temperatures resulting from reintroduction of prescribed fire into long unburnt stands have been associated with unintended tree mortality. Several models exist to predict soil temperatures resulting from soil heating by fire; however, data to develop and validate these models are limited. A model to predict soil temperature at depths up to 25 inches (0.63 m) was developed from a data set from 46 prescribed burns in coniferous forests in national forests and parks in Arizona and California. Soil temperature was less than 140 °F (60 °C) at depths greater than 6 inches (0.15 m)...

Historical fire exclusion, intensive logging of large trees of fire-tolerant species, and even-aged management have contributed to widespread decline of mature/old-growth coniferous forests across the Western USA. To investigate silvicultural approaches for reducing disturbance risk while accelerating restoration of mature/old-growth forest characteristics, we used 20-year data from the Goosenest Adaptive Management Area study in Northern California, USA. Established to evaluate the alternatives for reducing fuels and accelerating the development of late-seral characteristics in ponderosa...

Many non-native tree species are recognized as problematic to ecosystems they have invaded, and subsequent control efforts have met with varying levels of success. Falcataria falcatais a fast-growing, N-fixing tree that has aggressively invaded landscapes across the Hawaiian Archipelago. Due to their ability to alter Hawaiʻi’s native forest ecosystems, large stature at maturity, and potential for catastrophic tree fall, F. falcatastands pose threats to Hawaiʻi’s native forests, residential communities, and agricultural lands. We investigated responses to chemical control of F. falcatastands...

In forested, seasonally dry watersheds, winter rains commonly replenish water storage deficits in the vadose zone before recharging underlying hillslope groundwater systems that sustain streamflow. However, the relative inaccessibility of the subsurface limits our understanding of how groundwater recharge is moderated by vadose zone storage deficits generated by plant-water uptake. Here, we compare groundwater recharge inferred from the storage-discharge relationship with independent, distributed estimates of deficits across 12 undisturbed California watersheds. We find accrued dry season...

The southwestern pine beetle, Dendroctonus barberi Hopkins (Coleoptera: Curculionidae: Scolytinae), is a significant pest of ponderosa pine (Pinus ponderosa) in the Southwestern United States. Pinyon pine (Pinus edulis) and Douglas-fir (Pseudotsuga menziesii var. glauca) have also been recorded as occasional hosts. The southwestern pine beetle occurs in Arizona, Colorado, New Mexico, Nevada, Utah, and Texas, and in the Mexican States of Chihuahua, Coahuila, Durango, Nuevo Leon, and Tamaulipas. Its largest impacts occur in Arizona, New Mexico, and Texas. Southwestern pine beetles play a...