Treesearch

Hawai‘i’s most widespread native tree, ‘ōhi‘a lehua (Metrosideros polymorpha), has been dying across large areas of Hawai‘i Island mainly due to two fungal pathogens (Ceratocystis lukuohia and Ceratocystis huliohia) that cause a disease collectively known as Rapid ‘Ōhi‘a Death (ROD). Here we examine patterns of positive detections of C. lukuohia as it has been linked to the larger mortality events across Hawai‘i Island. Our analysis compares the environmental range of C. lukuohia and its spread over time through the known climatic range and distribution of ‘ōhi‘a. Analyses show this fungal...

Forests are an important part natural ecosystems, by for example providing food, fiber, habitat, and biodiversity, all of which contribute to stable natural systems. Assessing and modeling the structure and characteristics of forests, e.g., Leaf Area Index (LAI), volume, biomass, etc., can lead to a better understanding and management of these resources. In recent years, Terrestrial Laser Scanning (TLS) has been recognized as a tool that addresses many of the limitations of manual and traditional forest data collection methods. In this study, we propose a density-based approach for...

To explore the history of California roach (Hesperoleucus symmetricus) in the Eel River, we compiled mitochondrial DNA data for the putatively introduced Eel River population and comparative collections from throughout the native range. Consistent with an introduction scenario, we found that: 1) one haplotype occurred at high frequency in the Eel River, Russian River and Clear Lake populations, making the Russian River and Clear Lake likely source areas, and 2) the introduced population exhibited reduced haplotype diversity in comparison to populations from the native range. However, we...

Liquid moisture evaporation and pyrolysis of a biomass fuel slab subject to heating were computationally investigated in a one-dimensional domain where the fuel shrinkage was accounted for. The evaporation dynamics was separately represented by equilibrium and Arrhenius models. The equilibrium model describes evaporation as a thermodynamic process whereas the Arrhenius model treats it as a chemical reaction. For calculations, Gpyro, a pyrolysis computational framework, was used after its source code was revised to include the equilibrium model. By default, Gpyro is only capable of operating...

Disease dynamics are governed by variation of individuals, species, and environmental conditions across space and time. In some cases, an alternate reservoir host amplifies pathogen loads and drives disease transmission to less competent hosts in a process called pathogen spillover. Spillover is frequently associated with multi‐host disease systems where a single species is more tolerant of infection and more competent in pathogen transmission compared to other hosts. Pathogen spillover must be driven by biotic factors, including host and community characteristics, yet biotic factors...

An important property of wildfire behaviour is rate of spread (ROS). The objectives of this study are to evaluate the uncertainty of landscape-scale ROS estimates derived from repetitive airborne thermal infrared (ATIR) georeferenced imagery and the utility of such estimates for understanding fire behaviour and controls on spread rates. Time-sequential ATIR image data were collected for the Cedar, Detwiler, and Rey Fires, which burned in California during summers of 2016 and 2017. We analyse error, uncertainty, and precision of ROS estimates associated with co-location accuracy, delineation...

Managing forests to store carbon has focused on increasing forested area, decreasing area lost to logging and clearing, and increasing forest carbon density. Warming, drought, and wildfires challenge the stability of carbon stored in forests. What has been missing is the explicit use of disturbance ecology to factor tree mortality risk. For wildfire and other impactful disturbances, our understanding is sufficient to incorporate these risks into policy mechanisms that enhance forest carbon storage. Doing so would substantially improve global forest carbon policy for climate mitigation....

Recently burned coniferous forests host wildlife communities that respond to variation in burn severity, post-fire habitat structure, and patch configuration. Habitat selection theory predicts that birds inhabiting these variable post-fire landscapes will select nesting locations that confer an adaptive advantage through increased fitness and reproductive success. Understanding the effect of post-fire habitat on avian nesting ecology can provide valuable information to guide restoration and management after wildfire. The Black-backed Woodpecker (Picoides arcticus) is strongly associated...

Landscapes and ecosystems in the Mediterranean basin (MB) have been profoundly modified after a long history of land use and deforestation, which has caused extensive land degradation. In the last third of the 20th century, extensive land abandonment occurred in European Mediterranean countries, which dramatically increased fuel load and continuity in landscape and, consequently, large wildfires. As a response to land degradation, the forest services of MB countries already promoted large afforestations in the late 19th century. After the breakout of large wildfires and the new social...

A wide range of disturbances including recreation, utility corridors, too frequent fire and invasive plants have led to the type conversion of native chaparral habitats to non-native grasslands on the Angeles National Forest. These often compounding disturbances have led to the recent planning, implementation and monitoring of a wide variety of restoration techniques across the forest. Restoration techniques have included imprinting, hydroseeding, container planting and aggressive weed control with a variety of results. Factors influencing these results are adequacy of planning, timelines,...