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https://www.readbyqxmd.com/read/27918073/dominant-mycorrhizal-association-of-trees-alters-carbon-and-nutrient-cycling-by-selecting-for-microbial-groups-with-distinct-enzyme-function
#1
Tanya E Cheeke, Richard P Phillips, Edward R Brzostek, Anna Rosling, James D Bever, Petra Fransson
While it is well established that plants associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi cycle carbon (C) and nutrients in distinct ways, we have a limited understanding of whether varying abundance of ECM and AM plants in a stand can provide integrative proxies for key biogeochemical processes. We explored linkages between the relative abundance of AM and ECM trees and microbial functioning in three hardwood forests in southern Indiana, USA. Across each site's 'mycorrhizal gradient', we measured fungal biomass, fungal : bacterial (F : B) ratios, extracellular enzyme activities, soil carbon : nitrogen ratio, and soil pH over a growing season...
December 5, 2016: New Phytologist
https://www.readbyqxmd.com/read/27917167/potential-for-sulfate-reduction-in-mangrove-forest-soils-comparison-between-two-dominant-species-of-the-americas
#2
Melike Balk, Joost A Keuskamp, Hendrikus J Laanbroek
Avicennia and Rhizophora are globally occurring mangrove genera with different traits that place them in different parts of the intertidal zone. It is generally accepted that the oxidizing capacity of Avicennia roots is larger than that of Rhizophora roots, which initiates more reduced conditions in the soil below the latter genus. We hypothesize that the more reduced conditions beneath Rhizophora stands lead to more active sulfate-reducing microbial communities compared to Avicennia stands. To test this hypothesis, we measured sulfate reduction traits in soil samples collected from neighboring Avicennia germinans and Rhizophora mangle stands at three different locations in southern Florida...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27915182/using-spatial-metrics-and-surveys-for-the-assessment-of-trans-boundary-deforestation-in-protected-areas-of-the-maya-mountain-massif-belize-guatemala-border
#3
S D Chicas, K Omine, J B Ford, K Sugimura, K Yoshida
Understanding the trans-boundary deforestation history and patterns in protected areas along the Belize-Guatemala border is of regional and global importance. To assess deforestation history and patterns in our study area along a section of the Belize-Guatemala border, we incorporated multi-temporal deforestation rate analysis and spatial metrics with survey results. This multi-faceted approach provides spatial analysis with relevant insights from local stakeholders to better understand historic deforestation dynamics, spatial characteristics and human perspectives regarding the underlying causes thereof...
December 1, 2016: Journal of Environmental Management
https://www.readbyqxmd.com/read/27913865/nitrogen-dynamics-in-subtropical-fringe-and-basin-mangrove-forests-inferred-from-stable-isotopes
#4
Carla Roberta Gonçalves Reis, Gabriela Bielefeld Nardoto, André Luis Casarin Rochelle, Simone Aparecida Vieira, Rafael Silva Oliveira
Mangroves exhibit low species richness compared to other tropical forests, but great structural and functional diversity. Aiming to contribute to a better understanding of the functioning of mangrove forests, we investigated nitrogen (N) dynamics in two physiographic types of mangroves (fringe and basin forests) in southeastern Brazil. Because fringe forests are under great influence of tidal flushing we hypothesized that these forests would exhibit higher N cycling rates in sediment and higher N losses to the atmosphere compared to basin forests...
December 2, 2016: Oecologia
https://www.readbyqxmd.com/read/27912015/invasion-in-patchy-landscapes-is-affected-by-dispersal-mortality-and-mate-finding-failure
#5
Jonathan A Walter, Ariel L Firebaugh, Patrick C Tobin, Kyle J Haynes
Range expansions are a function of population growth and dispersal, and nascent populations often must overcome demographic Allee effects (positive density dependence at low population densities) driven by factors such as mate-finding failure. Given the importance of individual movement to mate finding, links between landscape structure and movement may be critical to range expansion; however, landscape effects on other factors including mortality may be equally or more important. In one of the most comprehensive investigations of the interactions of these processes to date, we combined field experiments, simulation modeling, and analysis of empirical spread patterns to investigate how landscape structure affected the spread of the gypsy moth in Virginia and West Virginia...
December 2016: Ecology
https://www.readbyqxmd.com/read/27912009/resource-stoichiometry-and-the-biogeochemical-consequences-of-nitrogen-deposition-in-a-mixed-deciduous-forest
#6
Meghan G Midgley, Richard P Phillips
Ecosystems often show differential sensitivity to chronic nitrogen (N) deposition; hence, a critical challenge is to improve our understanding of how and why site-specific factors mediate biogeochemical responses to N enrichment. We examined the extent to which N impacts on soil carbon (C) and N dynamics depend on microbial resource stoichiometry. We added N to forest plots dominated by ectomycorrhizal (ECM) trees, which have litter and soil pools rich in organic N and relatively wide C:N ratios, and adjacent forest plots dominated by arbuscular mycorrhizal (AM) trees, which have litter and soil pools rich in inorganic N and relatively narrow C:N ratios...
December 2016: Ecology
https://www.readbyqxmd.com/read/27907261/fitting-state-space-integral-projection-models-to-size-structured-time-series-data-to-estimate-unknown-parameters
#7
J Wilson White, Kerry J Nickols, Daniel Malone, Mark H Carr, Richard M Starr, Flora Cordoleani, Marissa L Baskett, Alan Hastings, Louis W Botsford
Integral projection models (IPMs) have a number of advantages over matrix-model approaches for analyzing size-structured population dynamics, because the latter require parameter estimates for each age or stage transition. However, IPMs still require appropriate data. Typically they are parameterized using individual-scale relationships between body size and demographic rates, but these are not always available. We present an alternative approach for estimating demographic parameters from time series of size-structured survey data using a Bayesian state-space IPM (SSIPM)...
December 2016: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/27907032/genetic-structure-in-the-northern-range-margins-of-common-ash-fraxinus-excelsior-l
#8
Mari Mette Tollefsrud, Tor Myking, Jørn Henrik Sønstebø, Vaidotas Lygis, Ari Mikko Hietala, Myriam Heuertz
During post glacial colonization, loss of genetic diversity due to leading edge effects may be attenuated in forest trees because of their prolonged juvenile phase, allowing many migrants to reach the colonizing front before populations become reproductive. The northern range margins of temperate tree taxa in Europe are particularly suitable to study the genetic processes that follow colonization because they have been little affected by northern refugia. Here we examined how post glacial range dynamics have shaped the genetic structure of common ash (Fraxinus excelsior L...
2016: PloS One
https://www.readbyqxmd.com/read/27904966/treeline-advances-and-associated-shifts-in-the-ground-vegetation-alter-fine-root-dynamics-and-mycelia-production-in-the-south-and-polar-urals
#9
Emily F Solly, Ika Djukic, Pavel A Moiseev, Nelly I Andreyashkina, Nadezhda M Devi, Hans Göransson, Valeriy S Mazepa, Stepan G Shiyatov, Marina R Trubina, Fritz H Schweingruber, Martin Wilmking, Frank Hagedorn
Climate warming is shifting the elevational boundary between forests and tundra upwards, but the related belowground responses are poorly understood. In the pristine South and Polar Urals with shifts of the treeline ecotone documented by historical photographs, we investigated fine root dynamics and production of extramatrical mycorrhizal mycelia (EMM) along four elevational transects reaching from the closed forest to the treeless tundra. In addition, we analysed elevational differences in climate and vegetation structure, and excavated trees to estimate related changes in the partitioning between below- and aboveground biomass...
November 30, 2016: Oecologia
https://www.readbyqxmd.com/read/27903055/local-landscape-effects-on-population-dynamics-of-ixodes-ricinus
#10
Naveed Asghar, Mona Petersson, Magnus Johansson, Patrik Dinnetz
Ixodes ricinus, a common tick in Europe, transmits severe tickborne pathogens (TBPs). In Sweden, both prevalence and incidence of tick-borne infections have increased during the last few decades, and a majority of the cases is reported from the area around Stockholm. Among ticks, transmission of TBPs involves co-feeding of susceptible larvae or nymphs with infected ticks on the same host. Seasonal synchrony of immature stages and total tick abundance are important factors for the probability of horizontal transmission of TBPs...
November 21, 2016: Geospatial Health
https://www.readbyqxmd.com/read/27902716/large-scale-anthropogenic-reduction-of-forest-cover-in-last-glacial-maximum-europe
#11
Jed O Kaplan, Mirjam Pfeiffer, Jan C A Kolen, Basil A S Davis
Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires...
2016: PloS One
https://www.readbyqxmd.com/read/27896478/soil-microbial-communities-buffer-physiological-responses-to-drought-stress-in-three-hardwood-species
#12
Steven A Kannenberg, Richard P Phillips
Trees possess myriad adaptations for coping with drought stress, but the extent to which their drought responses are influenced by interactions with soil microbes is poorly understood. To explore the role of microbes in mediating tree responses to drought stress, we exposed saplings of three species (Acer saccharum, Liriodendron tulipifera, and Quercus alba) to a four week experimental drought in mesocosms. Half of the pots were inoculated with a live soil slurry (i.e., a microbial inoculum derived from soils beneath the canopies of mature A...
November 28, 2016: Oecologia
https://www.readbyqxmd.com/read/27896030/historical-reconstruction-of-climatic-and-elevation-preferences-and-the-evolution-of-cloud-forest-adapted-tree-ferns-in-mesoamerica
#13
Victoria Sosa, Juan Francisco Ornelas, Santiago Ramírez-Barahona, Etelvina Gándara
BACKGROUND: Cloud forests, characterized by a persistent, frequent or seasonal low-level cloud cover and fragmented distribution, are one of the most threatened habitats, especially in the Neotropics. Tree ferns are among the most conspicuous elements in these forests, and ferns are restricted to regions in which minimum temperatures rarely drop below freezing and rainfall is high and evenly distributed around the year. Current phylogeographic data suggest that some of the cloud forest-adapted species remained in situ or expanded to the lowlands during glacial cycles and contracted allopatrically during the interglacials...
2016: PeerJ
https://www.readbyqxmd.com/read/27893926/estimation-of-the-optimal-regime-in-treatment-of-prostate-cancer-recurrence-from-observational-data-using-flexible-weighting-models
#14
Jincheng Shen, Lu Wang, Jeremy M G Taylor
Prostate cancer patients are closely followed after the initial therapy and salvage treatment may be prescribed to prevent or delay cancer recurrence. The salvage treatment decision is usually made dynamically based on the patient's evolving history of disease status and other time-dependent clinical covariates. A multi-center prostate cancer observational study has provided us data on longitudinal prostate specific antigen (PSA) measurements, time-varying salvage treatment, and cancer recurrence time. These data enable us to estimate the best dynamic regime of salvage treatment, while accounting for the complicated confounding of time-varying covariates present in the data...
November 28, 2016: Biometrics
https://www.readbyqxmd.com/read/27893758/multiple-browsers-structure-tree-recruitment-in-logged-temperate-forests
#15
Edward K Faison, Stephen DeStefano, David R Foster, Joshua M Rapp, Justin A Compton
Historical extirpations have resulted in depauperate large herbivore assemblages in many northern forests. In eastern North America, most forests are inhabited by a single wild ungulate species, white-tailed deer (Odocoileus virginianus), and relationships between deer densities and impacts on forest regeneration are correspondingly well documented. Recent recolonizations by moose (Alces americanus) in northeastern regions complicate established deer density thresholds and predictions of browsing impacts on forest dynamics because size and foraging differences between the two animals suggest a lack of functional redundancy...
2016: PloS One
https://www.readbyqxmd.com/read/27893157/brown-world-forests-increased-ungulate-browsing-keeps-temperate-trees-in-recruitment-bottlenecks-in-resource-hotspots
#16
Marcin Churski, Jakub W Bubnicki, Bogumiła Jędrzejewska, Dries P J Kuijper, Joris P G M Cromsigt
Plant biomass consumers (mammalian herbivory and fire) are increasingly seen as major drivers of ecosystem structure and function but the prevailing paradigm in temperate forest ecology is still that their dynamics are mainly bottom-up resource-controlled. Using conceptual advances from savanna ecology, particularly the demographic bottleneck model, we present a novel view on temperate forest dynamics that integrates consumer and resource control. We used a fully factorial experiment, with varying levels of ungulate herbivory and resource (light) availability, to investigate how these factors shape recruitment of five temperate tree species...
November 28, 2016: New Phytologist
https://www.readbyqxmd.com/read/27891619/the-role-of-nutrients-in-drought-induced-tree-mortality-and-recovery
#17
REVIEW
Arthur Gessler, Marcus Schaub, Nate G McDowell
I. II. III. References SUMMARY: Global forests are experiencing rising temperatures and more severe droughts, with consistently dire forecasts for negative future impacts. Current research on the physiological mechanisms underlying drought impacts is focused on the water- and carbon-associated mechanisms. The role of nutrients is notably missing from this research agenda. Here, we investigate what role, if any, forest nutrition plays for survival and recovery of forests during and after drought. High nutrient availability may play a detrimental role in drought survival due to preferential biomass allocation aboveground that (1) predispose plants to hydraulic constraints limiting photosynthesis and promoting hydraulic failure, (2) increases carbon costs during periods of carbon starvation, and (3) promote biotic attack due to low tissue carbon: nitrogen (C : N)...
November 28, 2016: New Phytologist
https://www.readbyqxmd.com/read/27885172/isohydric-species-are-not-necessarily-more-carbon-limited-than-anisohydric-species-during-drought
#18
N Garcia-Forner, C Biel, R Savé, J Martínez-Vilalta
Isohydry (i.e., strong regulation of leaf water potential, Ψl) is commonly associated with strict stomatal regulation of transpiration under drought, which in turn is believed to minimize hydraulic risk at the expense of reduced carbon assimilation. Hence, the iso/anisohydric classification has been widely used to assess drought resistance and mortality mechanisms across species, with isohydric species being hypothetically more prone to carbon starvation and anisohydric species more vulnerable to hydraulic failure...
November 23, 2016: Tree Physiology
https://www.readbyqxmd.com/read/27883190/environmental-control-of-carbon-allocation-matters-for-modelling-forest-growth
#19
Joannès Guillemot, Christophe Francois, Gabriel Hmimina, Eric Dufrêne, Nicolas K Martin-StPaul, Kamel Soudani, Guillaume Marie, Jean-Marc Ourcival, Nicolas Delpierre
We aimed to evaluate the importance of modulations of within-tree carbon (C) allocation by water and low-temperature stress for the prediction of annual forest growth with a process-based model. A new C allocation scheme was implemented in the CASTANEA model that accounts for lagged and direct environmental controls of C allocation. Different approaches (static vs dynamic) to modelling C allocation were then compared in a model-data fusion procedure, using satellite-derived leaf production estimates and biometric measurements at c...
November 24, 2016: New Phytologist
https://www.readbyqxmd.com/read/27878088/dispersal-and-group-formation-dynamics-in-a-rare-and-endangered-temperate-forest-bat-nyctalus-lasiopterus-chiroptera-vespertilionidae
#20
João D Santos, Christoph F J Meyer, Carlos Ibáñez, Ana G Popa-Lisseanu, Javier Juste
For elusive mammals like bats, colonization of new areas and colony formation are poorly understood, as is their relationship with the genetic structure of populations. Understanding dispersal and group formation behaviors is critical not only for a better comprehension of mammalian social dynamics, but also for guiding conservation efforts of rare and endangered species. Using nuclear and mitochondrial markers, we studied patterns of genetic diversity and differentiation among and within breeding colonies of giant noctule bats (Nyctalus lasiopterus), their relation to a new colony still in formation, and the impact of this ongoing process on the regionwide genetic makeup...
November 2016: Ecology and Evolution
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