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Full-Text Articles in Forest Sciences

Fine Characterization Of Leafing Phenology In The Brazilian Atlantic Forest By Optical And Microwave Remote Sensing, James B. Bell Jan 2023

Fine Characterization Of Leafing Phenology In The Brazilian Atlantic Forest By Optical And Microwave Remote Sensing, James B. Bell

Dissertations and Theses

Tropical forests provide important ecosystem functions in the global biosphere, but they remain among the most poorly understood elements of land surface models, especially with regard to their seasonal dynamics. For instance, in seasonally dry forests, the pattern of the annual green-up in their canopies closely follows annual patterns of rainfall. The same, however, does not occur in wet forest canopies which are dominated by evergreen trees. In the latter, water is not scarce enough to limit leaf photosynthetic function. Canopy leafing phenology in these forests is therefore poorly characterized by optical remote sensing methods which are not sensitive to …


Post-Fire Tree Mortality And Regeneration Patterns As Proxies Of Conifer Forest Resilience, Sebastian Upton Busby Dec 2021

Post-Fire Tree Mortality And Regeneration Patterns As Proxies Of Conifer Forest Resilience, Sebastian Upton Busby

Dissertations and Theses

Shifting wildfire patterns and climate conditions, magnified by anthropogenic climate change, are threatening the resilience of conifer forests in North America and more specifically, the western US. If native conifer species are functionally maladapted to novel fire patterns and post-fire climate conditions, large-scale shifts in conifer forest structure, composition, and extent may occur as warming intensifies. Forest resilience in the context of fire and climate can be understood and quantified by the survival of trees through fire events and success of trees to regenerate post-fire and maintain population levels. In this dissertation, I use field observations and remote sensing to …


Are Weevils Picky Eaters? Community Structure And Host Specificity Of Neotropical Saproxylic Beetles (Coleoptera: Curculionidae), Jhunior A. Morillo Jan 2017

Are Weevils Picky Eaters? Community Structure And Host Specificity Of Neotropical Saproxylic Beetles (Coleoptera: Curculionidae), Jhunior A. Morillo

Dissertations and Theses

Abstract Primary saproxylic beetles play a major role in forest nutrient cycling and making deadwood accessible to other decomposers. Understanding beetle host preferences and patterns of community assembly is critical for their conservation, and for predicting which species might become invasive. This project aims to investigate the ecological and host specificity, as well as the community composition of curculionids in a mosaic of old-growth (OG) and secondary forest on the Osa Peninsula, Costa Rica. The subfamily Scolytinae was expected to be the most species-rich and abundant. Ambrosia beetles were expected to have more generalist species than other curculionids. Old growth …


Evaluating The Effects Of Road Crossing Structures On Stream-Associated Amphibians In The Wilson River Watershed, Tillamook State Forest, Oregon, Sara Erin Twitchell Mar 2013

Evaluating The Effects Of Road Crossing Structures On Stream-Associated Amphibians In The Wilson River Watershed, Tillamook State Forest, Oregon, Sara Erin Twitchell

Dissertations and Theses

As replacement and removal of undersized culverts gains momentum as an effective technique for restoring natural stream flows and removing fish passage barriers, it is important to evaluate the benefits of these efforts on the in-stream and adjacent riparian habitat for other species of potential concern. This study compares stream-associated amphibian (SAA) occurrence in streams adjacent to different road crossing structures on unpaved forest roads in the Wilson River watershed located within the Tillamook State Forest, Oregon. Surveys were conducted at road crossing structures for three taxa of SAA; Pacific giant salamander (Dicamptodon tenebrosus), coastal tailed frog (Ascaphus truei), and …


Mutual Exclusion Between Salmonberry And Douglas-Fir In The Coast Range Of Oregon, Kenneth Ray Still Jan 1972

Mutual Exclusion Between Salmonberry And Douglas-Fir In The Coast Range Of Oregon, Kenneth Ray Still

Dissertations and Theses

One serious problem faced by the forest industry in the Pacific Northwest is poor regeneration of commercial trees on land which is harvested and subsequently dominated by brush species. In Coastal Oregon, salmonberry is one of these brush species. Detailed investigations of field sites indicate that light intensity in the brush stands was low but sufficient for germination and early growth of Douglas-fir seedlings and soil moisture percentages and nutrient levels were high enough to support early Douglas-fir growth. Laboratory tests demonstrated the presence of leachable phytotoxins in the leaves of salmonberry. The hypothesis resulting from this study is that …


A Taxonomic Study Of Two Nominal Subspecies Of Pikas (Ochotona Princeps) In The Cascade Mountains Of Oregon, Richard M. Coots Jan 1972

A Taxonomic Study Of Two Nominal Subspecies Of Pikas (Ochotona Princeps) In The Cascade Mountains Of Oregon, Richard M. Coots

Dissertations and Theses

Pikas from four colonies in the Cascade Mountains of Oregon were examined. Two colonies were chosen from within the geographical distribution of two nominal subspecies. A discriminate analysis of morphological measurements taken from the specimens showed that each colony could be distinguished from each other. Each colony studied showed more intra-colony similarity than inter-colony similarity regardless of distance separating the colonies or subspecies designations. The results indicate that the validity of subspecies designations for this species can be questioned.