13,181 research outputs found

    Stand Dynamics and Disturbance History of Champlain Valley Clayplain Forests

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    Studies of stand dynamics can explain how species interactions and disturbances drive forest structure and recruitment patterns of tree species. It is difficult to generate an understanding of stand dynamics and successional trends of forests in areas that have a long history of intense land use such as the Champlain Valley of Vermont, where over 230 years of agricultural activity has acutely and permanently influenced the landscape. The valley clayplain forest, a rare natural community containing endangered herbaceous plants and overstory tree species assemblages that are rare in Vermont, has been fragmented by agricultural use of the Champlain Valley. This study used dendroecological methods and assessments of forest structural conditions to describe the tree recruitment history and structural dynamics of two old-growth valley clayplain forest patches. Our results indicate that the valley clayplain forest has a species composition and recruitment history that has been heavily influenced by human land use throughout at least the past 230 years. We found that Quercus spp., typically considered characteristic of the valley clayplain forest, are being replaced by late-successional species such as Tsuga canadensis. Additionally, other human influences such as invasive species threaten to further alter the composition and dynamics of valley clayplain forests in the near future

    Global analysis of the sugarcane microtranscriptome reveals a unique composition of small RNAs associated with axillary bud outgrowth

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    Axillary bud outgrowth determines shoot architecture and is under the control of endogenous hormones and a fine-tuned gene-expression network, which probably includes small RNAs (sRNAs). Although it is well known that sRNAs act broadly in plant development, our understanding about their roles in vegetative bud outgrowth remains limited. Moreover, the expression profiles of microRNAs (miRNAs) and their targets within axillary buds are largely unknown. Here, we employed sRNA next-generation sequencing as well as computational and gene-expression analysis to identify and quantify sRNAs and their targets in vegetative axillary buds of the biofuel crop sugarcane (Saccharum spp.). Computational analysis allowed the identification of 26 conserved miRNA families and two putative novel miRNAs, as well as a number of trans-acting small interfering RNAs. sRNAs associated with transposable elements and protein-encoding genes were similarly represented in both inactive and developing bud libraries. Conversely, sequencing and quantitative reverse transcription-PCR results revealed that specific miRNAs were differentially expressed in developing buds, and some correlated negatively with the expression of their targets at specific stages of axillary bud development. For instance, the expression patterns of miR159 and its target GAMYB suggested that they may play roles in regulating abscisic acid-signalling pathways during sugarcane bud outgrowth. Our work reveals, for the first time, differences in the composition and expression profiles of diverse sRNAs and targets between inactive and developing vegetative buds that, together with the endogenous balance of specific hormones, may be important in regulating axillary bud outgrowth

    A Maple Wood Wasp, \u3ci\u3eXiphydria Maculata,\u3c/i\u3e and its Insect Enemies (Hymenoptera: Xiphydriiade)

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    A xiphydriid wood wasp, Xiphydria mandata, is very common in branches ofAeer spp. in Indiana. and is frequently the proximate cause of branches falling from shade trees. X. maculata is attacked by seven parasitoids: Alliaells bllrquei (Aulacidae), A. digitalis, Rhyssella nitida (Ichneumonidae), Xiphydriophagus meyerinckii (Pteromalidae), Coeloides rossicus betulae (Braconidae), Spathills elegans (Braconidae), and Orussus sp. (Orussidae). The latter three parasitoids prior to this study had no confirmed hosts; Xiphydriophagus is new to N. America. This parasitoid complex is compared with that of the Palaearctic Xiphydria camelus, showing a series of pairs of closely related Palaearctic and Nearctic forms

    Leaf Optical Responses to Light and Soil Nutrient Availability in Temperature Deciduous Trees

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    Leaf optical parameters influence light availability at the cellular, leaf, and canopy scale of integration. While recent studies have focused on leaf optical responses to acute plant stress, the effects of changes in plant resources on leaf optics remain poorly characterized. We examined leaf optical and anatomical responses of five temperate deciduous tree species to moderate changes in nutrient and light availability. Spectral reflectance in the visible waveband generally increased at high light, but decreased with increased nutrient availability. Patterns of both spectral reflectance and absorptance were primarily determined by chlorophyll concentration although carotenoid concentration was also influential. While most anatomical features did not explain residual variation in reflectance, cuticle thickness was significantly related to reflectance at complementary angles compared to the angle of incidence. Absorptance did not change with light environment; however, absorption efficiency per unit biomass increased by approximately 40% under low light, due to reduced leaf mass per area. We conclude that changes in resource availability differentially influence leaf optical properties and that such changes are driven primarily by changes in pigment concentrations. The magnitude of leaf optical responses to moderate changes in resource availability was comparable to those of acute stress responses and varied among species

    Leaf Mining Insects and Their Parasitoids in the Old-Growth Forest of the Huron Mountains

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    Leaf mining insects in an old-growth forest along the south central shore of Lake Superior in Michigan are documented. We present the results of a 13-year survey of leaf mining species, larval hosts, seasonal occurrence, and parasitoids, as well as report biological observations. Representative larvae, mines, adults, and parasitoids were preserved. Among the larval host associations, 15 are reported as new. Additionally, 42 parasitoid taxa were identified resulting in six first reports from the New World and 32 new host associations. Two undescribed species (Gelechiidae and Figitidae) discovered through this research were described in earlier publications

    Annotated List of Indiana Scolytidae (Coleoptera)

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    A list of 80 species of Indiana Scolytidae (bark and ambrosia beetles) is presented. Notes on known Indiana hosts and distribution in the state are included for each species

    Diversity of plant growth-promoting bacteria associated with sugarcane

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    The sugarcane (Saccharum spp) presents economic importance, mainly for tropical regions, being an important Brazilian commodity. However, this crop is strongly dependent on fertilizers, mainly nitrogen (N). This study assessed the plant growth-promoting bacteria (PGPB) associated with sugarcane that could be used as a potential inoculant to the crop. We evaluated the genetic diversity of PGPB in the plant tissue of sugarcane varieties (RB 867515, RB 1011, and RB 92579). The primer BOX-A1R was used to differentiate the similar isolated and further sequencing 16S rRNA ribosomal gene. The 16S rRNA gene showed the presence of seven different genera distributed into four groups, the genus Bacillus, followed by Paenibacillus (20%), Burkholderia (14%), Herbaspirillum (6%), Pseudomonas (6%), Methylobacterium (6%), and Brevibacillus (3%). The molecular characterization of endophytic isolates from sugarcane revealed a diversity of bacteria colonizing this plant, with a possible biotechnological potential to be used as inoculant and biofertilizers

    The Aquatic Biota and Groundwater Quality of Springs in the Lincoln Hills, Wisconsin Driftless, and Northern till Plains Sections of Illinois

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    ID: 8307INHS Technical Report prepared for Environmental Protection Trust Fund Commission and Illinois Department of Natural Resources Division of Energy and Environmental AssessmentU of I OnlyRestriction applied due to concern over geolocation information of springs on private property
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