Conversion of natural forest to loblolly pine plantations has become a common practice on commercial forest land in the central Piedmont of Virginia. To gain insight as to bow habitat conditions for wildlife vary over time, vegetation composition and structure were quantified in 21 converted stands at two state forests. The stands represented three replications of seven developmental stages ranging in age from 1 to 22 years. Six natural forest stands Which typify sites presently being converted were selected for comparison. The seral process can be exemplified by comparing vegetative changes in species richness, evenness, and vegetative coverage in the ground stratum (<1m). Richness and vegetative coverage showed the same trends: high values in stands 1 to 5 years of age followed by a decline from 5 to 15 years, at Which point canopy closure was complete and these variables were relatively stable for the next seven years. Evenness over time was fairly constant, except for three-rear-old stands where a decline occurred due to predominance by <u>Andropogon virginicus</u>. Trends in richness and evenness differed from the old-field successional model due to a diverse reservoir of propagative units at the initiation of succession and the rapid closure of the canopy by co-developing pines and sprout hardwoods. From an analysis of habitat variables, it appeared that one-year-old stands satisfied requirements of bobwhite quail and wild turkey; stands aged three years were deficient in food plants and probably too densely vegetated. Nine-year-old stands still provided browse for white-tailed deer. Post-canopy closure stands (15 to 22 yrs) were of little value to wildlife. In native forest stands (72 yrs), understory forage production was comparable to the post-canopy closure stands, while mast production, as estimated by Oak basal area and density, was more than adequate for good deer and turkey habitat. The present value of converted stands to wildlife depends on their size and interspersion with native forest and other cover types. Their future value could vary significantly depending on the silvicultural treatments applied. / Master of Science

Yes / The mechanisms regulating community composition and local dominance of trees in species-rich forests are poorly resolved, but the importance of interactions with soil microbes is increasingly acknowledged. Here, we show that tree seedlings that interact via root-associated fungal hyphae with soils beneath neighbouring adult trees grow faster and have greater survival than seedlings that are isolated from external fungal mycelia, but these effects are observed for species possessing ectomycorrhizas (ECM) and not arbuscular mycorrhizal (AM) fungi. Moreover, survival of naturally-regenerating AM seedlings over ten years is negatively related to the density of surrounding conspecific plants, while survival of ECM tree seedlings displays positive density dependence over this interval, and AM seedling roots contain greater abundance of pathogenic fungi than roots of ECM seedlings. Our findings show that neighbourhood interactions mediated by beneficial and pathogenic soil fungi regulate plant demography and community structure in hyperdiverse forests. / This research was funded by the National Key Research and Development Program of China (Project No. 2017YFA0605100) and the National Natural Science Foundation of China (NSFC 31770466 to X.L. and 31870403 to M.L.), and partly supported by awards from the UK Natural Environment Research Council (NERC NE/M004848/1 and NE/R004986/1). D.J. is also supported by the N8 AgriFood programme.

No description available.

This project was designed to examine the stability of stream ecosystems in response to forest disturbance and subsequent succession. Stability was defined as the ability of streams to retain particulate organic matter and nutrients during storms. I hypothesized that forest streams are least stable during the intermediate stages of forest succession because particulate organic matter accumulations in streams are lowest at that time. This hypothesis was tested by examining stream stability in relation to forest succession. Stream surveys indicated fewer debris dams and organic matter accumulations in streams draining early and intermediate successional forests compared to reference sites. The abundance of large wood declined within 10 years of forest disturbance and continued to decline for at least 30-40 years through the intermediate stages of forest succession. Comparisons of inputs with standing stocks of organic matter indicated that streams draining early and intermediate successional sites receive less litter from their watersheds and processed it faster. Decreases in stream obstructions combined with changes in litter inputs and processing resulted in relatively high storm transport of fine organic matter from disturbed streams. Storm organic matter export from disturbed streams averaged 4.22 g AFDW/m² and from reference streams averaged 1.83 g AFDW/m². Storm nutrient budgets, constructed by measuring nutrient inputs (soil water, throughfall) and outputs (stream discharge) during individual storms indicated that streams draining early and intermediate successional forest were less retentive of nitrogen and phosphorus than reference sites. Nitrogen loss from disturbed streams averaged 58.04 mg/m²/storm and from reference streams averaged 16.52 mg/m²/storm. Phosphorus loss from disturbed streams averaged 32.52 mg/m²/storm and from reference sites averaged 7.14 mg/m²/storm. A majority of the nitrogen and phosphorus loss was in association with organic particles. There was no difference between disturbed and reference streams in potassium, calcium, or sulfate retention during storms. However, disturbed streams tended to lose more particulate organic potassium and calcium than reference sites. These results indicate that forest disturbance has a Iong-term impact on stream ecosystems by reducing their stability for many years following forest clearing. / Ph. D.

published_or_final_version / Geography and Geology / Master / Master of Philosophy

Monitoring wildlife habitats has become important to forest ecosystem management because it provides valuable information about the response of forests and their species to harvest practices, impacts from recreational use, conservation efforts, and natural and human-caused disturbances. Monitoring is a complex task that requires a variety of abiotic and biotic measurements and decisions about what should be measured, and when and where measurements should be taken. Riparian habitats contain unusually high diversity and are important to land managers. Wildlife assessments of riparian areas have focused on vertebrate species such as amphibians, birds, and mammals, but have largely ignored the arthropod components of the habitats. Arthropods constitute over 85% of all species and posses characteristics that make them valuable for tracking environmental changes. The purpose of this study was to gather site-specific data about epigaeic, riparian beetle community composition of the H.J. Andrews Experimental Forest (HJA). The patterns of beetle distribution, abundance, and diversity were analyzed and the results were used to characterize and compare the riparian and adjacent upslope beetle communities. Almost 8,000 beetle specimens representing about 250 species were collected from 141 pitfall traps placed along 10 transects in 3 different channel morphologies along Lookout Creek in the HJA. Traps were opened during six 30-day sampling periods over 2 years. Riparian and adjacent upslope beetle communities had high diversity measurements. The average difference of the calculated Simpson's Diversity Index between the two communities was 0.0116 and represented about 1% of the average riparian diversity. Analysis of species-curves indicated that the riparian habitats contained a higher total number of species. Multivariate Principal Coordinate Analysis indicated that the two habitats had distinctly different beetle communities. Multigroup Discriminant Analysis correctly classified 89.7% of the sampling units as the habitat group into which they were assigned a priori. Detailed recommendations for monitoring riparian habitats were discussed. / Graduation date: 2000

This study describes the composition of forest landscapes surrounding northern spotted owl (Strix occidentalis caurina) nests in the central Cascade Mountains of Oregon. I compared forest composition around 126 owl nests in 70 pair territories with forest composition around 119 points drawn randomly from all terrestrial cover-types, and around 104 points drawn randomly from the old-forest (closed canopy, > 80 yrs) cover type. All nest sites and random points were drawn from U.S. Forest Service lands and were not drawn from privately owned lands or Wilderness Areas. Forest cover was classified on a Landsat Thematic Mapper image. I quantified the percentage of old-forest within 200 concentric circular plots (0.04-5.0-km radii), centered on each analyzed point, using a geographic information system. I used logistic regression to make spatially-explicit inferences. Owl nests were surrounded by more old-forest when compared to points drawn randomly from all terrestrial cover types: there was significantly (P<0.05) more old-forest around the owl nests in plots as large as 1.79 km in radius. When compared to points drawn randomly from the old-forest cover type, owl nests were surrounded by significantly (P<0.05) more old-forest in plots with 0.17-0.80-km radii. Exploratory analyses suggest that the landscape scales most pertinent to northern spotted owl nest site positioning in this study area appear to be (in descending order): the surrounding 10-15 ha (~200-m radius), the surrounding 25-30 ha (~300-m radius), the surrounding 200 ha (800-m radius), and possibly the surrounding 700 ha (1,500-m radius). This study supports the assertion that northern spotted owls are strongly associated with older forests. The results also indicate that owl nests are most associated with higher proportions of old-forest near the nest implying that the arrangement of habitat is important for nest-site selection/positioning Since spotted owls in the central Cascade Mountains of Oregon are known to have home-ranges that average 1,769 ha, it is important to recognize that these results apply to nest-site selection/positioning on the landscape and not to the amount of habitat necessary for pair persistence or successful reproduction. / Graduation date: 1998

Ten species of bats occur in the Oregon Coast Range and are hypothesized to be associated with late-successional forests. The development of characteristics of late-successional forests in young forest stands can be accelerated through silvicultural practices such as thinning I examined the effects of thinning on the use of forests by bats in the Oregon Coast Range. I used automated ultrasonic detectors to record bat calls in 50- to 100-year-old thinned and =thinned stands as well as in old-growth (2200-year-old) stands in 11 sites in the Oregon Coast Range during the summers of 1994 and 1995. I compared bat activity levels among the 3 stand types. In addition, I classified bat calls into 1 of 5 species groups: Eptes/Las, Myev/vo, Myyu/ca, MythCory, and Mysp. I measured selected vegetation and environmental variables in conjunction with bat activity. I also compared bat activity on roads with activity in the stand interior at 1 site. Bat activity was higher in old growth than in young stands, and higher in thinned than in =thinned stands in 1995 and over both seasons combined. I did not detect a difference in bat activity among stand types in 1994, until I removed 1 site from the analysis. The Mysp and MythCory species groups exhibited differences among stand types. Bat activity along roads was higher than activity within stands. Tree density, tree diameter, tree height, shrub cover, and shrub height varied significantly between old-growth and young stands. Tree density, tree diameter, shrub cover, canopy cover, and crown height varied significantly between thinned and unthinned stands. Bat activity, overall or by species group, was significantly related to structural variables, including mean snag diameter, mean distance from the detector to snags, and percent shrub cover. My results suggest that bats are sensitive to stand structure and that silvicultural practices, such as thinning, which promote development of structural characteristics found in old-growth stands, would benefit bat populations. Further study is needed to clarify the habitat preferences of separate bat species and to specify habitat elements required by bat species. / Graduation date: 1997

Thesis (M.Phil.) -- Griffith University, 2004. / Facsimile of the author's original dissertation. Pagination of document: x, 121 leaves. Includes bibliographical references. Also available online via the World Wide Web.

Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.