Treesearch

This regional summary addresses the effects of climate change on soils of seven of the eight main Hawaiian islands (Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Kaho‘olawe, Maui, and Hawai‘i), the territories of Guam and American Samoa, the Commonwealth of the Northern Mariana Islands, and the freely associated Republic of Palau, Federated States of Micronesia, and Republic of the Marshall Islands. The distribution of soil types in Hawai‘i and the US Affliated Pacifc Islands (USAPI), and their sensitivity to climate change, is determined as elsewhere by soil-forming factors and their interactions...

Dissolved organic carbon (DOC) flux is an important mechanism to convey soil carbon (C) from aboveground organic debris (litter) to deeper soil horizons and can influence the formation of stable soil organic C compounds. The magnitude of this flux depends on both infiltration and DOC production rates which are functions of the climatic, soil, topographic and ecological characteristics of a region. Aboveground litter quantity and quality was manipulated for 20 years in an old-growth Douglas fir forest under six treatments to study relationships among litter inputs, DOC production and flux,...

Head abnormalities are not uncommon in turtles and are often characterized by swelling in portions of the head, particularly the tympanic area (e.g., aural abscesses). These can be due to nutritional deficiencies and/or bacterial infections.

Clonal plantations of Eucalyptus are among the most productive forests in the world, with intensification of silviculture and genetic breeding doubling the wood mean annual increments over the past four decades. The TECHS Project demonstrated that even with intensive silviculture, wood production varies by more than twofold across environmental gradients, and growth of highly selected clones differs by more than two-fold within a site. Wood production accounts for less than half of the photosynthesis of a forest, and we tested two hypotheses about the relation between wood production and...

Severe wildfires combust most above ground vegetation and detritus layers, altering the content and chemical composition of soil organic matter (SOM). To evaluate the lasting effects of wildfire on SOM and the recovery of burned soils, we sampled surface (Oa horizon) and mineral soils (0-5 and 5-15 cm depths) in unburned areas and areas burned at moderate and high severity 14 years after the 2002 Hayman Fire, in Colorado, USA. We characterized SOM using Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC-MS) and identified 106 pyrolysates within eight chemical classes [aromatic hydrocarbo...

Understanding the mechanisms governing drought tolerance in highly productive clonal Eucalyptus plantations in Brazil will become increasingly important with climate change driven increases in temperature and drought events. We quantified how leaf water potential, hydraulic safety margin (mid-day - pre-dawn leaf water potential, Ψδ) and the physiological parameters obtained from standard pressure-volume curves differed between four contrasting Eucalyptus genotypes across a temperature and water availability gradient in Brazil. We hypothesized that genotypes developed in dry areas were more...

The slow-moving flameless burning of wildland fuels (i.e. smouldering) can be difficult to detect and challenging to extinguish. Although previous research involving the smouldering of organic fuels (e.g. cotton, cellulose, peat) has investigated the influence of various fuel characteristics (e.g. moisture content, inorganic content, bulk density) on spread rate and surface temperatures, the smouldering behaviour of other common fuels is not well understood. This study expands on previous research to better understand how fuel characteristics influence the smouldering behaviour of duff...

Novel forms of drought are emerging globally, due to climate change, shifting teleconnection patterns, expanding human water use, and a history of human influence on the environment that increases the probability of transformational ecological impacts. These costly ecological impacts cascade to human communities, and understanding this changing drought landscape is one of today’s grand challenges. By using a modified horizon-scanning approach that integrated scientists, managers, and decision-makers, we identified the emerging issues in ecological drought that represent key challenges to...

In many fire-prone watersheds, wildfire threatens surface drinking water sources with eroded contaminants. We evaluated the potential to mitigate the risk of degraded water quality by limiting fire sizes and contaminant loads with a containment network of manager-developed Potential fire Operational Delineations (PODs) using wildfire risk transmission methods to partition the effects of stochastically simulated wildfires to within and out of POD burning. We assessed water impacts with two metrics - total sediment load and frequency of exceeding turbidity limits for treatment - using a...

We examined the influence of stand density and genotype on transpiration and water use efficiency in high productivity plantations. Three widely planted Eucalyptus clones that differ in drought tolerance and productivity (E. urophylla, E. urophylla x E. grandis and E. grandis x E. camaldulensis, clones IP, B2 and C3, respectively) were measured at four densities (590, 1030, 1420, and 2950 trees ha-1). Over the 1-year study period (1.5-2.5 years after planting), individual biomass increment decreased with increasing density, from 21 kg tree-1 at 590 trees ha-1 to 6 kg tree-1 at 2950 trees...