Download or read book Effects of Silviculture Systems on Arthropod Community Structure written by B Lindgren (Staffan) and published by . This book was released on 1999 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Silviculture Systems on Arthropod Community Structure written by B. Staffan Lindgren and published by . This book was released on 1998 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Community Level Impacts of Microstegium Vimineum on Arthropod Community Structure and Foodweb Dynamics in a Temperate Deciduous Forest written by Judith L. Metcalf and published by . This book was released on 2013 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Invasion by non-native primary producers are generally expected to lead to a decline in native species richness, however in some cases, these invasions can actually lead to an increase in diversity and abundance of certain groups of organisms. Arthropods are extremely sensitive to changes in the plant community, particularly herbivores, and the response of these primary consumers can influence predator populations. Microstegium vimineum is an invasive C4 grass that has developed strong populations in the understory of temperate deciduous forests along the east coast of the U.S. This work evaluates the influence that this invader may have on insect and spider abundance and diversity, including changes at the trophic group and functional guild levels. Additionally we evaluate the impacts of both an increase in invasion density and a decrease in native plant diversity on arthropod community structure. In general, we find a significant increase in herbivore abundance, primarily as a result in the increased abundances of concealed chewers, free-living chewers and free-living sap feeders. Free-living sap-feeders also showed an increase in biomass. Spider abundance and diversity also increased in association with invasion by M. vimineum. Both active hunters and sit-and-wait predators showed significant increases in invaded sites. The ratio of adult:immature spiders however had a negative relationship with invasion. These changes in the arthropod community appear to be related to both changes in vegetation structure as well as changes in plant biomass. We found increased abundances in our treatments in which invasion density increased and decreases in the arthropod community in sites where native plants were removed from the system. We also show some support for the idea that carnivores, specifically spiders, may respond more strongly to changes in vegetative complexity, while herbivores, specifically leaf hoppers, may respond more strongly to changes in plant biomass.

Download or read book Correlation Between Structural Heterogeneity and Arthropod Biodiversity written by Stephanie Lee Madson and published by . This book was released on 1998 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: The "old-growth controversy" in the Pacific Northwest recognized thinning as the primary silvicultural practice for land managers to produce wildlife habitat while continuing to produce timber. For the foreseeable future, forest stands will be harvested to produce forest gaps and a patchwork of trees of different ages. In order to evaluate the effect of thinning on biodiversity, nine 15-year-old harvests of this type (age=70 years) were paired with adjacent old-growth and even-aged, unthinned "pole" stands. Since soil is the crucible of terrestrial biodiversity, it is critical to contrast the effects upon the forest floor of this future practice with current management. Soil and litter fauna were monitored along 250 meter transects (pitfall and Berlese sampling at ten-meter intervals) to meet the following objectives: 1) to determine biological diversity on public lands, per federal mandate, and use diversity as a management tool; 2) compare levels of biodiversity between three management strategies; 3) determine best methods to assay arthropod diversity; and 4) identify structural and environmental determinants of arthropod diversity and abundance. The study's hypotheses were: 1) old-growth forests will have greater arthropod diversity than thinned stands; 2) thinned stands will have greater arthropod diversity than unthinned stands; and 3) species found within old-growth stands, but not within unthinned pole stands, will also be found in thinned stands. This study contrasted nine Western Hemlock/Douglas-fir sites each with contrasting old-growth, thinned and unthinned pole management stands. Sites were equally blocked in Southern Oregon, the Coast Range, and the Cascade Mountains. No segment of the arthropod fauna. (i.e., pitfall-trapped epigeic macroarthropods, Berlese-extracted litter-dwelling meso- and microarthropods, or soil-dwelling microarthropods) exhibited a management (treatment) effect throughout the entire region. When the regional blocking was removed, within-region analysis generally revealed that old-growth was most distinct. Old-growth stands had the highest abundance of individuals, but were comprised of the fewest species. Thinned stands were characterized by the highest species richness. Within-region analysis revealed an interaction of management effects and specific locale effects; locale effects dominated for soil microarthropods and epigeic macroarthropods, while management options dominated for litter arthropods. Within the Southern Oregon region, I attempted to correlate arthropod community structure (canonical correspondence analysis (CCA) of within-stand samples) with a suite of soil chemical and microbiological descriptors. Full analysis of twelve variables within one exemplary stand revealed several potential trends (negative: dissolved organic carbon, soil moisture, distance from the beginning of the transect; positive: total CO2 field respiration, mineralizable nitrogen, water-induced respiration, substrate-induced respiration). Relatively shallow slopes and very low r-value coefficients of correlation characterized all statistical tests. Few of the trends apparent at one site were paralleled at more than one other site; at all sites potential correlates had very low r-values. No community revealed separate clouds in CCA analysis, indicating distinct "micro-communities" of arthropods inhabiting distinct micro-habitats. Lack of distinctive species assemblages and lack of correlation with microhabitat variables indicated that arthropods respond on different temporal and/or spatial scales then the microbial-oriented variables, and that each taxon is responding in an individual manner.

Download or read book Effects of Land use Intensity on Arthropod Diversity and Community Structure in Grassland written by Nadja Katharina Simons and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Community level Effects of Vegetation Architecture and Prey Availability written by Mary E. Pendergast and published by . This book was released on 2011 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes to vegetation architecture within a natural habitat can have profound impacts upon ecological community function, but the relative influence of vegetation architecture itself and potential indirect influences of associated food resources are often difficult to disentangle. I present the results of a three-year study designed to address the community level impacts of changes in big sagebrush (Artemisia tridentata) architecture and associated prey availability upon the ground-dwelling arthropod community. Three experimental sagebrush architecture treatments (low, intermediate, and high foliage density) and two levels of prey insect availability treatment (natural and baited/increased prey availability) were imposed in a sage-steppe ecosystem. The ground-dwelling spider (top predators) and insect (prey) response to all combinations of the six treatments were assessed through abundances in pitfall traps. Chapter 2 demonstrates that changes in a single shrub's architecture did not markedly impact prey arthropod availability on the ground, though an overall increase in arthropod abundance was detected within baited shrubs. This indicates changes to vegetation architecture do not impact prey insect availability for ground-dwelling spiders. Thus, changes in shrub architecture and not the associated prey base directly alter the ground-dwelling spider community. Chapter 3 shows that architectural manipulation of a single sagebrush directly influences the ability of certain ground-dwelling spider guilds to persist beneath the shrub. Data within Chapters 2 and 3 support the conclusion that vegetation architecture directly affects ground-dwelling spider community structure and composition. Finally, Chapter 4 explores how the relative impacts of vegetation architecture and prey availability upon ecological communities can shift depending upon the spatial context in which the manipulations take place, given the differences in mobility of species within the grounddwelling spider and insect prey communities. Within this study, Diurnal and Nocturnal Wanderers responded to manipulations in prey availability at a larger spatial context (patches of 15 shrubs) while more stationary Trappers and Ambushers did not. Through simultaneous manipulation of vegetation architecture (Artemisia tridentata, big sagebrush) and associated insect prey base in different spatial contexts, this dissertation demonstrates that vegetation architecture directly affects ground-dwelling spider community organization at the species and guild levels of diversity. Shifts in spider (predator) functional diversity can ultimately impact arthropod decomposer and herbivore populations, influencing fundamental ecosystem processes such as decomposition and productivity.

Download or read book Community Structure of Canopy Arthropods Associated with Abies Amabilis Branches in a Variable Retention Forest Stand on Vancouver Island British Columbia Canada written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Clearcut harvesting can create conditions unfavourable to forest regeneration. In response, variable retention harvest methods are being investigated in montane forests on Vancouver Island, Canada. The effect of this overstory removal is unknown for canopy microarthropods, especially oribatid mites. As mites contribute significantly to nutrient cycling and decomposition processes in the canopy, changes in community structure and abundance may have dramatic effects on forest productivity. I studied the effects of two variable retention treatments, patch-cut and shelterwood systems, on arthropod communities associated with Abies amabilis (amabilis fir) branches and lichens. Changes in community structure were evident among the treatments and an old-growth control site. I also investigated the use of lichen abundance as a surrogate for oribatid mite abundance because it is time consuming and laborious to collect, count and identify microarthropods. Lichen abundance was a good predictor of mites in the old-growth and shelterwood, but not in the patch-cuts. Lichen abundance estimates should not replace biotic inventories, but can he used as an indicator when rapid biodiversity assessments are required.

Download or read book Effects of Agricultural Conservation Practices on Fish and Wildlife written by and published by . This book was released on 2008 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The bibliography is a guide to recent scientific literature covering effects of agricultural conservation practices on fish and wildlife. The citations listed here provide information on how conservation programs and practices designed to improve fish and wildlife habitat, as well as those intended for other purposes (e.g., water quality improvement), affect various aquatic and terrestrial fauna"--Abstract.

Download or read book Community Structure of Canopy Arthropods Associated with Abies Amabilis Branches in a Variable Retention Forest Stand on Vancouver Island British Columbia Canada written by Stacey Lee Wilkerson and published by . This book was released on 2005 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Creating a Forestry for the 21st Century written by Kathryn A. Kohm and published by Island Press. This book was released on 1997 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, a sea change has occurred in the field of forestry. A vastly increased understanding of how ecological systems function has transformed the science from one focused on simplifying systems, producing wood, and managing at the stand-level to one concerned with understanding and managing complexity, providing a wide range of ecological goods and services, and managing across broad landscapes.Creating a Forestry for the 21st Century is an authoritative and multidisciplinary examination of the current state of forestry and its relation to the emergent field of ecosystem management. Drawing upon the expertise of top professionals in the field, it provides an up-to-date synthesis of principles of ecosystem management and their implications for forest policy. Leading scientists, including Malcolm Hunter, Jr., Bruce G. Marcot, James K. Agee, Thomas R. Crow, Robert J. Naiman, John C. Gordon, R.W. Behan, Steven L. Yaffee, and many others examine topics that are central to the future of forestry: new understandings of ecological processes and principles, from stand structure and function to disturbance processes and the movement of organisms across landscapes challenges to long-held assumptions: the rationale for clearcutting, the wisdom of short rotations, the exclusion of fire traditional tools in light of expanded goals for forest landscapes managing at larger spatial scales, including practical information and ideas for managing large landscapes over long time periods the economic, organizational, and political issues that are critical to implementing successful ecosystem management and developing institutions to transform knowledge into action Featuring a 16-page center section with color photographs that illustrate some of the best on-the-ground examples of ecosystem management from around the world, Creating a Forestry for the 21st Century is the definitive text on managing ecosystems. It provides a compelling case for thinking creatively beyond the bounds of traditional forest resource management, and will be essential reading for students; scientists working in state, federal, and private research institutions; public and private forest managers; staff members of environmental/conservation organizations; and policymakers.

Download or read book The Effect of Vertical Stratification and Forest Management on Beetle Insecta written by Jessica Turgeon and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Forest canopies may harbour up to 50% of the world's diversity and since the canopy and forest floor have different architectures, the structure of arthropod assemblages may vary by stratum. This has implications for forest management since long-term logging practices can change the composition and structure of northeastern North American forests, and arthropods are sensitive to these differences. While canopy sampling is becoming more common, the interaction between forest management and vertical stratification in temperate forests in North America has remained relatively unexplored. The objective of this thesis is to explore and quantify the structure of arthropod communities in two strata within the context of forest management (time-since harvest and silvicultural technique). I used beetles (Coleoptera) and spiders (Araneae), important components of forest ecosystems, to test effects of vertical stratification and forest management effects on biodiversity and community structure. I collected 586 species of beetles and spiders, representing 11 137 individuals, over two field seasons in a deciduous hardwood forest in Southern Québec. Beetle diversity was influenced by height, with the understorey harbouring a higher abundance and species richness than the upper canopy. Spider diversity was not affected by height or forest management. Both beetle and spider community compositions were strongly affected by height, with each stratum supporting a different community. Beetle assemblages differed between forest management sites (both time-since harvest and silvicultural technique treatments), but this was largely influenced by the Latridiidae, the most commonly collected family. Spider assemblages did not change with forest management treatment. Responses were taxon dependent, at both the Order and Family level. I suggest that ongoing biodiversity assessments and future ecological work in temperate forests should include canopy sampling, as omitting it might lead to an inaccurate representation of forest systems. Forest management should also be limited in frequency (time-since harvest) and intensity (silvicultural techniques), since canopy closure seems to be an important factor in shaping arthropod communities. " --

Download or read book Effects of Land Use Transformation on Microarthropod Community Structure in Mediterranean Area written by Lucia Santorufo and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of human-mediated activities on soil quality and functioning have been assessed. Composition and changes in arthropod community structure and laboratory bioassays were performed on urban soils in order to understand the roles of metal contamination on soil organism activities and distribution. Then, comparison of urban, agricultural, industrial and forest soils were performed, monitoring Collembola species and functional traits composition, in order to assess if the impact of urban environment is greater than other kinds of anthropization. Soil organism community was analysed twice a years for evaluating the role of seasonality on anthropic impacted soils. The different kinds of anthropization firstly affected the abiotic properties of the sites. Agricultural and urban soils were the most impacted soils by human activities, which cause changes in vegetation cover, organic matter amounts and accumulation of hazardous elements and compounds. Soils organisms responded to soil abiotic modifications. In particular, in urban environment soil organisms were strongly reduced at high level of metal contamination, whereas organic matter content and climatic conditions played the main role at low-intermediate soil contamination. Collembola community showed a strong reduction in species richness in agricultural soils, with a consequent domination of few tolerant species. Collembola functional trait distribution was mainly affected by the presence and the type of litter and inputs of contaminants. In particular, agricultural environment favoured organisms with traits adapted to soil life surface, whereas forest soils favoured organisms with euedaphic characteristics. Industrial and urban soils showed organisms with both epiedaphic and euedaphic characteristics.

Download or read book Effects of Management on Arthropod Communities in Organic and Conservation Agricultural Systems in Pennsylvania and Mexico written by Ariel Rivers and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conservation agriculture, a system relying on crop rotations, mulch, and minimal soil disturbance, is widely recognized for benefits to soil quality, stabilizing crop yields, and altering plant-insect interactions. In particular, each of these practices affects the soil-dwelling arthropod assemblage in a particular way by influencing the microenvironment at the soil surface, with potential consequences for predatory and pest arthropods. To better understand the effects of conservation agriculture practices on local arthropod assemblages, biological control potential, and crop damage, here I compare two North American conservation agriculture cropping systems: a soybean (Glycine max L. Merr.), wheat (Triticum aestivum L.), and corn (Zea mays L.) rotation grown under organic management in central Pennsylvania, U.S.A, and a rotation of corn and wheat in central Mexico. In both systems, primary inversion tillage was reduced compared to conventional practices for the area. In Pennsylvania, the cash crops were no-till planted into a rolled cover crop mulch of either hairy vetch (Vicia villosa Roth) and triticale (x Triticosecale Wittmack) planted together preceding corn, or cereal rye (Secale cereale L.) preceding soybean. Additionally, in Pennsylvania, the cover crops were managed by a roller-crimper at three dates (early, middle, or late) relative to standard dates for the area to allow for cash crop planting. In Mexico, the cash crops were planted into the previous years' crop residue, which was cut and left in the field after harvest. In both systems, we measured arthropod activity-density by pitfall trap, biological control potential (predation) by implementing sentinel traps baited with live waxworms (Galleria mellonella F.), density of herbivorous arthropods at the soil surface, and damage by herbivorous invertebrates to the cash crops. Predatory arthropods in particular were affected by the conservation agriculture practices in both systems, with the type of residue affecting the activity-density, diversity, and function of particular predators, including ground and tiger beetles (Coleoptera: Carabidae) in Pennsylvania, and ants in Mexico (Hymenoptera: Formicidae). Predation rates were relatively high in both systems, with differences within systems depending on year, crop, and residue. Herbivore density and plant damage also depended on crop, but lower herbivore density correlated with higher predator activity-density in Pennsylvania. Likewise, certain types of crop damage, in particular cutting by lepidopteran larva, decreased with increased activity-densities of predatory arthropods. In Pennsylvania in particular, certain practices had a stronger influence on results than others; for instance, predatory arthropod activity-density was significantly greater in corn planted into a rolled mat of hairy vetch-triticale as compared to soybean planted into a rolled mat of cereal rye. In contrast, shallow high residue cultivation in corn and soybean was not a strong factor influencing the local arthropod assemblage at the time we sampled in Pennsylvania. The comparison of these two systems allows for an opportunity to understand the complexities of conservation agriculture and the potential for this system to conserve and augment predatory arthropods while contributing to pest control in low-input agricultural systems in North America.

Download or read book Edge Effects of Clearcut Harvesting on Ground Arthropod Species Composition and Predator Community Structure in Old growth Douglas fir Forests written by Timothy Theron Work and published by . This book was released on 2000 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edge effects resulting from forest fragmentation are likely to alter the distributions and interactions of resident species. I evaluated changes in species composition, species turnover, and relative abundance of ground arthropods across replicated transects extending from regenerating clearcuts into old-growth Douglas-fir forests. Arthropods were collected from 3-August to 14-September in 1997 and 23-May 1998 to 31-July 1998 using pitfall traps. Pitfall traps were positioned at 75 m (in the clearcut), -25, 0 (forest edge), 50, 100 and 200 m into the forest in 1997. In 1998, traps were repositioned at 25, 0, 25, 50,lOO, and 200 m into the forest. Changes in species composition and relative abundance were compared using non-metric multidimensional scaling ordination. Two-hundred, five species representing 24,178 individuals were collected. Edge effects on species composition and relative abundance were apparent up to 100 m into old-growth forests. Species were characterized as edge-phobic (interior forest associates), edge-philic, edge-insensitive or as edge-input (clearcut associates). The majority of species were characterized as either edge-phobic or edge-input species. Seasonal patterns in activity are also reported. To further address the impacts of edges on community structure, changes in species abundance of predator taxa across the edge-forest gradient were compared to four models of resource partitioning. Observed patterns of species abundance did not differ across the edge-forest gradients and were consistent with a model of random assortment (or non-equilibrium) where an individual predator species utilizes resources independently of other predators. This pattern was consistent whether species abundance was expressed as numerical abundance or biomass. This study suggests that edge effects resulting from forest fragmentation alter species composition and may negatively affect interior forest species. Furthermore, although species composition changes across forest edges, this study suggests that resource partitioning by a trophic group such as predators remains unaffected by forest edges.

Download or read book Effect of Leaf Shape on Microhabitat Selection and Community Structure of Selected Forest Litter Arthropods written by Bruce G. Stevenson and published by . This book was released on 1980 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Arthropod Response to Cover Crop Based Reduced Tillage Organic Cropping Systems written by Karly Regan and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Although all farmers face potential trade-offs between management tactics such as chemical usage, tillage, crop rotation, and other aspects of their production system, these trade-offs can be especially challenging to balance for organic producers. Conservation of natural enemies can be one of the most important tactics for managing invertebrate pests that is available to organic producers (NOP 2005). Through this dissertation, I investigated the response of arthropod pests and predators to organic cropping systems incorporating cover crops and reducing tillage, as well as reviewing broader effects of tillage on pests and predators.My dissertation addresses multiple objectives through five chapters. Chapter 1 is a general introduction that reviews organic field crop production, tillage as a soil management practice, the use of winter cover crops, and how these agricultural practices influence arthropod pest and predator populations. Chapter 2 assesses the effects of tillage on arthropod populations, particularly predator populations, through a review and meta-analysis conducted in collaboration with Elizabeth Rowen. In addition to comparing the effects of conventionally managed systems with frequent and/or intensive tillage to no-till systems, the meta-analysis examines the effects of reduced or conservation tillage practices on arthropod communities in these systems. Chapter 3 investigates the effects of winter cover crop species, tillage, and interseeding of cover crops into standing corn on the soil-dwelling arthropod community, with a focus on arthropod predators, in an organic agronomic crop rotation. Characterizing the soil-associated invertebrate community allows us to understand the effects of these practices on arthropod abundance, diversity, and community composition, and the roles that invertebrates play in these systems. I examine the relationship between different predator groups and the response of the predator community to four organic cropping systems that vary in the frequency, intensity, and timing of disturbance. I also quantify predation exerted by the predator community in the same four cover crop-based, reduced-tillage cropping systems using sentinel prey assays to evaluate the effects of these cropping systems and their associated management practices on the conservation of beneficial predators and enhancement of predation. Chapter 4 investigates the effects of cropping systems that vary in disturbance on damage from common early and late season invertebrate pests of corn in the Mid-Atlantic US. Through assessment of pest damage, I evaluate risks that producers face when implementing cover crops or reducing tillage in an organic cropping system. Chapter 5 examines the effects of tillage and cover crop management on a pest of large-seeded crops, Delia platura (Diptera: Anthomyiidae), through 6 years of management in an organic cropping system. Lastly, Chapter 6 serves as a conclusion, in which I summarize the results presented throughout the dissertation and their relevance to agronomic production in Pennsylvania, the surrounding region, and in organic systems more broadly. I also propose suggestions for future research directions.

Download or read book Forest Macro arthropods as Potential Indicators of Ecosystem Conditions in Western Idaho written by Margaret E. Ruby and published by . This book was released on 2001 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive ecosystem management is a new paradigm for managing federal forests which requires regular monitoring of ecosystem function and diversity to measure the effects of management. Managers need new strategies and tools to help them assess their progress in maintaining healthy, productive and biologically diverse forests. Biomonitoring of select forest macro-arthropod species can provide useful information on the effects of management on forest biodiversity and ecosystem function. The purpose of this study was threefold: (1) to inventory the macro-arthropod community and important environmental variables in the Bear Creek and Indian Creek study area within the Payette National Forest (PNF) in Western Idaho; (2) to compare measures of community composition, diversity, and structure in forest macro-arthropod communities between patches of different sizes and treatment; and (3) to assist PNF managers in their ecosystem management efforts by providing principles to guide the use of macro-arthropods as indicators of changing forest conditions. Transects with pitfall traps were used to collect macro-arthropods at 22 sites in the Bear Creek and Indian Creek study area during the summer of 1994. Five forest patch types in Abies grandis habitat types were sampled. Intact forest patches of 100 or more hectares, and large patches of 50-100 hectares, ranged in age between 50 and 250 years old with multistoried structure. Small patches up to 10 hectares were remnants or fragments of formerly intact forest isolated by logging. A plantation patch was 15 years old with patchy understory and forb cover. Clearcut patches had little or no overstory, and variable understory, and forb layers. At each transect, soil samples were collected and six environmental descriptor variables were analyzed according to patch treatment and patch size. These site descriptors were: basal area (ft2/acre); percent canopy cover for the overstory, understory; and forb layers; litter depth (cm), and percent soil moisture content. Differences detected using an ANOVA and T-tests are discussed in the Results section. Arthropod community composition, diversity, and structure were described according to relative abundance, and four measures of diversity. They were also described by membership in seventeen orders and/or super-families; ten functional groups; two disperser classes (long or short distance); and three species indicator classes. A total of 5455 macro-arthropod individuals, representing 17 orders and/or super-families and 219 species were collected in the Bear Creek and Indian Creek study area. While macro-arthropod fauna relative abundance did not vary significantly by treatment (ANOVA p