The Experts below are selected from a list of 477 Experts worldwide ranked by ideXlab platform
Peter S. Curtis - One of the best experts on this subject based on the ideXlab platform.
-
forest structure in space and time biotic and abiotic determinants of canopy complexity and their effects on net primary productivity
Agricultural and Forest Meteorology, 2018Co-Authors: Alexander T Fotis, T H Morin, Robert T Fahey, Brady S Hardiman, Gil Bohrer, Peter S. CurtisAbstract:Abstract The structural dynamics of forest canopies involve complex interactions among the abiotic environment, stand structure, species composition and disturbance regimes. How the re-arrangement of tree canopies in space and time affects forest aboveground net primary productivity (ANPP) remains poorly understood, however. In this study, we analyzed a long-term dataset from a temperate deciduous forest in Northern Michigan, USA, to investigate two primary objectives: 1) what abiotic and biotic factors influence canopy complexity and its inter-annual variability, and 2) the direct and indirect effects that abiotic, biotic and canopy complexity variables have on ANPP. We hypothesized that inter-annual variability in canopy complexity would be lower in high complexity canopies and that temporal variability in complexity metrics would be inversely related to ANPP. We found that canopy complexity was highest in more taxonomically diverse stands with high variability in tree diameters and in stands dominated by Populus tremuloides and Populus grandidentata. Canopy complexity was lowest in stands dominated by Quercus rubra and Pinus strobus, which also had lower ANPP. Stands with a high stem density had lower inter-annual variation in canopy complexity, exhibited more height growth and an increase in canopy open space, which in turn enhanced ANPP. Our results provide novel empirical evidence linking temporal stability in canopy complexity to ANPP, and suggest that variability in canopy complexity over time, in addition to the overall mean canopy complexity, may be important when considering drivers of forest carbon uptake.
-
Moderate Disturbance Has Similar Effects on Production Regardless of Site Quality and Composition
MDPI AG, 2018Co-Authors: Benjamin T. Sagara, Christoph S Vogel, Peter S. Curtis, Alexander T Fotis, Robert T Fahey, Christopher M GoughAbstract:Moderate severity disturbances, which only kill a subset of canopy trees (e.g., via insects, pathogens, and windthrow), are increasingly widespread in North America, and can alter forest structure and production. Whether the net primary production (NPP) of forest stands differing in pre-disturbance site quality and composition respond similarly to moderate severity disturbance, however, is unknown, but critical to understanding the disturbance response dynamics of patchy landscapes. We experimentally disturbed three, 2-ha stands varying in pre-disturbance primary production and community composition, temporarily reducing live stand basal area by 38% to 66% through the stem girdling of all mature early successional aspen (Populus tremuloides Michx. and Populus grandidentata Michx.) and birch (Betula papyrifera Marshall). Disturbance significantly altered stand-scale physical and biological structure and prompted a similar decade-long pattern of wood NPP decline and recovery. All stands exhibited an initial reduction in wood NPP, followed by a recovery period and eventual return to pre-disturbance levels within eight years, with the most productive stand exhibiting an increase in primary production following recovery. Following wood NPP recovery, more biologically diverse forest canopies with higher leaf area indexes intercepted more light, and, consequently, had higher rates of wood NPP. We conclude that, despite substantial pre-disturbance differences in productivity and community composition, relative wood NPP recovery patterns can be similar, though long-term post-recovery primary production may trend higher in more productive and compositionally diverse stands. We suggest that improved mechanistic understanding of different forest ecosystems’ responses to disturbances remains critical to informing management decisions across diverse landscape mosaics
-
phenological and temperature controls on the temporal non structural carbohydrate dynamics of Populus grandidentata and quercus rubra
Forests, 2010Co-Authors: Christopher M Gough, Charles E. Flower, Christoph S Vogel, Peter S. CurtisAbstract:Temporal changes in plant tissue non-structural carbohydrates (NSC) may be sensitive to climate changes that alter forest phenology. We examined how temporal fluctuations in tissue NSC concentrations of Populus grandidentata and Quercus rubra relate to net and gross primary production (NPP, GPP) and their climatic drivers in a deciduous forest of Michigan, USA. Tissue NSC concentrations were coupled with NPP and GPP phenologies, declining from dormancy until GPP initiation and then increasing following NPP cessation. Warmer autumns extended the temporal gap between NPP and GPP cessation, prolonging the period of NSC accumulation. These results suggest that tissue NSC concentrations may increase with climate change.
-
whole ecosystem labile carbon production in a north temperate deciduous forest
AGUFM, 2008Co-Authors: Christopher M Gough, Charles E. Flower, D Dragoni, Christoph S Vogel, Peter S. CurtisAbstract:Labile carbon (C), which is principally comprised of non-structural carbohydrates, is an essential intermediary between C assimilation and structural growth in deciduous forests. We developed a new approach that combined meteorological and biometric C cycling data for a mixed deciduous forest in Michigan, USA, to provide novel estimates of whole-ecosystem labile C production and reallocation to structural net primary production (NPP). We substantiated inferred seasonal patterns of labile C production and reallocation to structural NPP with measurements of Populus grandidentata and Quercus rubra wood non-structural carbohydrate concentration and mass over two years. Our analysis showed that 55% of annual net canopy C assimilate (Ac) was first allocated to labile C production rather than to immediate structural NPP. Labile C produced during the latter half of summer later supported dormant- season structural growth and respiration, with 34% of structural NPP in a given year requiring labile C stored during previous years. Seasonal changes in wood non-structural carbohydrate concentration and mass generally corroborated inferred temporal patterns of whole-ecosystem labile C production and reallocation to structural NPP. Our findings confirm that disparities can arise between same-year meteorological and biometric net ecosystem production when meteorologically measured C assimilation and biometrically measured growth are asynchronous because of temporary photosynthate allocation to labile C storage. We conclude that a broader understanding of labile C production and reallocation at the ecosystem scale is important to interpreting lagged canopy C cycling and structural growth processes.
-
environmental controls on sap flow in a northern hardwood forest
Tree Physiology, 2005Co-Authors: B D Bovard, Christoph S Vogel, Peter S. Curtis, H B Su, H P SchmidAbstract:Our objective was to gain a detailed understanding of how photosynthetically active radiation (PAR), vapor pressure deficit (D) and soil water interact to control transpiration in the dominant canopy species of a mixed hardwood forest in northern Lower Michigan. An improved understanding of how these environmental factors affect whole-tree water use in unmanaged ecosystems is necessary in assessing the consequences of climate change on the terrestrial water cycle. We used continuously heated sap flow sensors to measure transpiration in mature trees of four species during two successive drought events. The measurements were scaled to the stand level for comparison with eddy covariance estimates of ecosystem water flux (F w ). Photosynthetically active radiation and D together explained 82% of the daytime hourly variation in plot-level transpiration, and low soil water content generally resulted in increased stomatal sensitivity to increasing D. There were also species-specific responses to drought. Quercus rubra L. showed low water use during both dry and wet conditions, and during periods of high D. Among the study species, Acer rubrum L. showed the greatest degree of stomatal closure in response to low soil water availability. Moderate increases in stomatal sensitivity to D during dry periods were observed in Populus grandidentata Michx. and Betula papyrifera Marsh. Sap flow scaled to the plot level and F w demonstrated similar temporal patterns of water loss suggesting that the mechanisms controlling sap flow of an individual tree also control ecosystem evapotranspiration. However, the absolute magnitude of scaled sap flow estimates was consistently lower than F w . We conclude that species-specific responses to PAR, D and soil water content are key elements to understanding current and future water fluxes in this ecosystem.
Donald R Zak - One of the best experts on this subject based on the ideXlab platform.
-
biomass accumulation and soil nitrogen availability in an 87 year old Populus grandidentata chronosequence
Forest Ecology and Management, 2004Co-Authors: Laura L White, Donald R Zak, Burton V BarnesAbstract:Abstract The Upper Lake States region is marked by major disturbances of fire and logging over 100 years ago that created a landscape mosaic of early successional forests. Given the intimate link between soil N availability and forest growth in this region, it is important to understand how temporal changes in soil N constrain the rate at which forest biomass accumulates following a stand-destroying disturbance. Bigtooth aspen (Populus grandidentata Michx.) currently dominates sites where primarily old-growth pine–hemlock–oak forests once thrived, which provides an opportunity to observe nearly 100 years of succession following severe disturbance. In this study, we examine the relationship between soil N availability and biomass accrual in a series of plots undergoing secondary succession following logging and burning. Our results demonstrate that total aboveground biomass and nitrogen accrual patterns are strongly and positively related on a highly disturbed, bigtooth aspen-dominated ecosystem in northern Lower Michigan. Nitrogen mineralization and nitrification were highest immediately following disturbance, and then decreased over the next approximately 20 years of succession. Following this short-term decrease, these processes increased and attained a maximum value after 70 years of forest succession. Understory biomass accumulation showed the opposite trend of nutrient availability, with highest values during the first 20 years of succession, followed by a dramatic decrease for the next 70 years. Understory biomass began to decrease as plants grew into the overstory or died. Total aboveground biomass was correlated with N mineralization (r=0.894; P=0.041) and nitrification (r=0.782; P=0.118) and appears to be increasing steadily to some maximum that has not yet been reached.
-
soil microbial communities beneath Populus grandidentata grown under elevated atmospheric co2
Ecological Applications, 1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
Populus grandidentata grown under elevated atmospheric c021
1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
above and belowground response of Populus grandidentata to elevated atmospheric co2 and soil n availability
Plant and Soil, 1994Co-Authors: Peter S. Curtis, Kurt S. Pregitzer, Donald R Zak, James A TeeriAbstract:Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with l5N to trace the flux of N within the plant-soil system. Above— and belowground growth, CO2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems, and leaves were analyzed for total N and 15N.
-
elevated atmospheric co2 and feedback between carbon and nitrogen cycles
Plant and Soil, 1993Co-Authors: Donald R Zak, Peter S. Curtis, Kurt S. Pregitzer, James A Teeri, Robert Fogel, Diana L RandlettAbstract:We tested a conceptual model describing the influence of elevated atmospheric CO2 on plant production, soil microorganisms, and the cycling of C and N in the plant-soil system. Our model is based on the observation that in nutrient-poor soils, plants (C3) grown in an elevated CO2 atmosphere often increase production and allocation to belowground structures. We predicted that greater belowground C inputs at elevated CO2 should elicit an increase in soil microbial biomass and increased rates of organic matter turnover and nitrogen availability. We measured photosynthesis, biomass production, and C allocation of Populus grandidentata Michx. grown in nutrient-poor soil for one field season at ambient and twice-ambient (i.e., elevated) atmospheric CO2 concentrations. Plants were grown in a sandy subsurface soil i) at ambient CO2 with no open top chamber, ii) at ambient CO2 in an open top chamber, and iii) at twice-ambient CO2 in an open top chamber. Plants were fertilized with 4.5 g N m−2 over a 47 d period midway through the growing season. Following 152 d of growth, we quantified microbial biomass and the availabilities of C and N in rhizosphere and bulk soil. We tested for a significant CO2 effect on plant growth and soil C and N dynamics by comparing the means of the chambered ambient and chambered elevated CO2 treatments.
Kurt S. Pregitzer - One of the best experts on this subject based on the ideXlab platform.
-
soil microbial communities beneath Populus grandidentata grown under elevated atmospheric co2
Ecological Applications, 1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
Populus grandidentata grown under elevated atmospheric c021
1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
Height Growth of Advance Regeneration Under an Even-Aged Bigtooth Aspen (Populus grandidentata) Overstory
American Midland Naturalist, 1995Co-Authors: Brian J. Palik, Kurt S. PregitzerAbstract:-Height and age structures and recent height growth rates of white pine (Pinus strobus) and red maple (Acer rubrum) advance regeneration were examined in an even-aged bigtooth aspen ecosystem to determine if height growth inhibition in the understory is characteristic of these systems, as is suggested in general for even-aged forests. We hypothesized that the overstory was inhibiting height growth of understory stems and that the degree of inhibition would vary with overstory basal area and the relative contribution to total basal area of species differing in light-attenuating ability. The study was conducted in a mature bigtooth aspen forest on a dry-mesic site in which little density-independent mortality in the overstory had yet occurred. Correlations between age and height of advance regeneration on replicate plots were significant in 14 of 16 cases, but were highly variable and, on average, not very high. Correlations were stronger for white pine, indicating more consistent height growth than for red maple. However, red maple advance regeneration had greater mean height growth rates than white pine. Height distributions of advance regeneration, distributions of relative height increment over 5 yr, and mean 5-yr relative height increment were unrelated to plot-level measures of total overstory basal area and relative basal area of bigtooth aspen. These results indicate that height growth of advance regeneration was occurring in this forest, but height growth rates varied among individuals and species. The degree of inhibition in height growth was unrelated to plot-level measures of total overstory competition, as reflected in basal area. Further, variation in height growth rate was unrelated to the relative contribution to total basal area of canopy species differing in light-attenuating ability. The results of this study indicate that large overstory gaps are not required to promote establishment and height growth of advance regeneration in all even-aged aspen forests and that controls other than overstory structure may lead to variation in height growth rates of advance regeneration.
-
above and belowground response of Populus grandidentata to elevated atmospheric co2 and soil n availability
Plant and Soil, 1994Co-Authors: Peter S. Curtis, Kurt S. Pregitzer, Donald R Zak, James A TeeriAbstract:Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with l5N to trace the flux of N within the plant-soil system. Above— and belowground growth, CO2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems, and leaves were analyzed for total N and 15N.
-
elevated atmospheric co2 and feedback between carbon and nitrogen cycles
Plant and Soil, 1993Co-Authors: Donald R Zak, Peter S. Curtis, Kurt S. Pregitzer, James A Teeri, Robert Fogel, Diana L RandlettAbstract:We tested a conceptual model describing the influence of elevated atmospheric CO2 on plant production, soil microorganisms, and the cycling of C and N in the plant-soil system. Our model is based on the observation that in nutrient-poor soils, plants (C3) grown in an elevated CO2 atmosphere often increase production and allocation to belowground structures. We predicted that greater belowground C inputs at elevated CO2 should elicit an increase in soil microbial biomass and increased rates of organic matter turnover and nitrogen availability. We measured photosynthesis, biomass production, and C allocation of Populus grandidentata Michx. grown in nutrient-poor soil for one field season at ambient and twice-ambient (i.e., elevated) atmospheric CO2 concentrations. Plants were grown in a sandy subsurface soil i) at ambient CO2 with no open top chamber, ii) at ambient CO2 in an open top chamber, and iii) at twice-ambient CO2 in an open top chamber. Plants were fertilized with 4.5 g N m−2 over a 47 d period midway through the growing season. Following 152 d of growth, we quantified microbial biomass and the availabilities of C and N in rhizosphere and bulk soil. We tested for a significant CO2 effect on plant growth and soil C and N dynamics by comparing the means of the chambered ambient and chambered elevated CO2 treatments.
Diana L Randlett - One of the best experts on this subject based on the ideXlab platform.
-
soil microbial communities beneath Populus grandidentata grown under elevated atmospheric co2
Ecological Applications, 1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
Populus grandidentata grown under elevated atmospheric c021
1996Co-Authors: Donald R Zak, Kurt S. Pregitzer, Diana L Randlett, David B Ringelberg, David C White, Peter S. CurtisAbstract:In most terrestrial ecosystems, the amount of substrate entering the soil from plant litter production is only sufficient to meet the maintenance requirements of soil microorganisms, allowing for no net annual growth. However, the rising atmospheric CO2 concentration has the potential to alter such a balance by increasing plant litter production, and hence the amount of substrate available for heterotrophic metabolism in soil. In a recent experiment, we observed that greater belowground plant litter production at elevated at- mospheric CO2 significantly increased the biomass of soil microorganisms in both rhizo- sphere and non-rhizosphere soil. Because soil microorganisms differ in their ability to convert substrate into biomass, we hypothesized that greater plant litter production at elevated CO2 should shift community composition as fungal populations increase in re- sponse to greater substrate availability. We used a molecular technique, phospholipid fatty acid (PLFA) analysis, to gain insight into the composition of soil microbial communities beneath Populus grandidentata growing at ambient and twice-ambient atmospheric CO2. PLFAs extracted from rhizosphere and non-rhizosphere soil were derivatized and identified using gas chromatography and mass spectrometry. After one growing season the proportions of bacterial, actinomycetal, and fungal PLFAs were not significantly influenced by elevated atmospheric CO2 in either rhizosphere or non-rhizosphere soil. However, clear differences were present between microbial communities in rhizosphere and non-rhizosphere soil. Al- though enhanced belowground plant litter production under elevated atmospheric CO2 in- creased the biomass of soil microorganisms, we have no evidence to suggest that such an increase occurred through a shift in community composition, at least in the short term.
-
elevated atmospheric co2 and feedback between carbon and nitrogen cycles
Plant and Soil, 1993Co-Authors: Donald R Zak, Peter S. Curtis, Kurt S. Pregitzer, James A Teeri, Robert Fogel, Diana L RandlettAbstract:We tested a conceptual model describing the influence of elevated atmospheric CO2 on plant production, soil microorganisms, and the cycling of C and N in the plant-soil system. Our model is based on the observation that in nutrient-poor soils, plants (C3) grown in an elevated CO2 atmosphere often increase production and allocation to belowground structures. We predicted that greater belowground C inputs at elevated CO2 should elicit an increase in soil microbial biomass and increased rates of organic matter turnover and nitrogen availability. We measured photosynthesis, biomass production, and C allocation of Populus grandidentata Michx. grown in nutrient-poor soil for one field season at ambient and twice-ambient (i.e., elevated) atmospheric CO2 concentrations. Plants were grown in a sandy subsurface soil i) at ambient CO2 with no open top chamber, ii) at ambient CO2 in an open top chamber, and iii) at twice-ambient CO2 in an open top chamber. Plants were fertilized with 4.5 g N m−2 over a 47 d period midway through the growing season. Following 152 d of growth, we quantified microbial biomass and the availabilities of C and N in rhizosphere and bulk soil. We tested for a significant CO2 effect on plant growth and soil C and N dynamics by comparing the means of the chambered ambient and chambered elevated CO2 treatments.
Christopher M Gough - One of the best experts on this subject based on the ideXlab platform.
-
Wood Decay Characteristics and Interspecific Interactions Control Bacterial Community Succession in Populus grandidentata (Bigtooth Aspen)
Frontiers Media S.A., 2019Co-Authors: Eiko E. Kuramae, Christopher M Gough, Marcio F. A. Leite, Afnan K. A. Suleiman, Buck T. Castillo, Lewis Faller, Rima B. Franklin, John SyringAbstract:Few studies have investigated bacterial community succession and the role of bacterial decomposition over a continuum of wood decay. Here, we identified how (i) the diversity and abundance of bacteria changed along a chronosequence of decay in Populus grandidentata (bigtooth aspen); (ii) bacterial community succession was dependent on the physical and chemical characteristics of the wood; (iii) interspecific bacterial interactions may mediate community structure. Four hundred and fifty-nine taxa were identified through Illumina sequencing of 16S rRNA amplicons from samples taken along a continuum of decay, representing standing dead trees, downed wood, and soil. Community diversity increased as decomposition progressed, peaking in the most decomposed trees. While a small proportion of taxa displayed a significant pattern in regards to decay status of the host log, many bacterial taxa followed a stochastic distribution. Changes in the water availability and chemical composition of standing dead and downed trees and soil were strongly coupled with shifts in bacterial communities. Nitrogen was a major driver of succession and nitrogen-fixing taxa of the order Rhizobiales were abundant early in decomposition. Recently downed logs shared 65% of their bacterial abundance with the microbiomes of standing dead trees while only sharing 16% with soil. As decay proceeds, bacterial communities appear to respond less to shifting resource availability and more to interspecific bacterial interactions – we report an increase in both the proportion (+9.3%) and the intensity (+62.3%) of interspecific interactions in later stages of decomposition, suggesting the emergence of a more complex community structure as wood decay progresses
-
Data_Sheet_1_Wood Decay Characteristics and Interspecific Interactions Control Bacterial Community Succession in Populus grandidentata (Bigtooth Aspen).docx
2019Co-Authors: Eiko E. Kuramae, Christopher M Gough, Marcio F. A. Leite, Afnan K. A. Suleiman, Buck T. Castillo, Lewis Faller, Rima B. Franklin, John SyringAbstract:Few studies have investigated bacterial community succession and the role of bacterial decomposition over a continuum of wood decay. Here, we identified how (i) the diversity and abundance of bacteria changed along a chronosequence of decay in Populus grandidentata (bigtooth aspen); (ii) bacterial community succession was dependent on the physical and chemical characteristics of the wood; (iii) interspecific bacterial interactions may mediate community structure. Four hundred and fifty-nine taxa were identified through Illumina sequencing of 16S rRNA amplicons from samples taken along a continuum of decay, representing standing dead trees, downed wood, and soil. Community diversity increased as decomposition progressed, peaking in the most decomposed trees. While a small proportion of taxa displayed a significant pattern in regards to decay status of the host log, many bacterial taxa followed a stochastic distribution. Changes in the water availability and chemical composition of standing dead and downed trees and soil were strongly coupled with shifts in bacterial communities. Nitrogen was a major driver of succession and nitrogen-fixing taxa of the order Rhizobiales were abundant early in decomposition. Recently downed logs shared 65% of their bacterial abundance with the microbiomes of standing dead trees while only sharing 16% with soil. As decay proceeds, bacterial communities appear to respond less to shifting resource availability and more to interspecific bacterial interactions – we report an increase in both the proportion (+9.3%) and the intensity (+62.3%) of interspecific interactions in later stages of decomposition, suggesting the emergence of a more complex community structure as wood decay progresses.
-
Moderate Disturbance Has Similar Effects on Production Regardless of Site Quality and Composition
MDPI AG, 2018Co-Authors: Benjamin T. Sagara, Christoph S Vogel, Peter S. Curtis, Alexander T Fotis, Robert T Fahey, Christopher M GoughAbstract:Moderate severity disturbances, which only kill a subset of canopy trees (e.g., via insects, pathogens, and windthrow), are increasingly widespread in North America, and can alter forest structure and production. Whether the net primary production (NPP) of forest stands differing in pre-disturbance site quality and composition respond similarly to moderate severity disturbance, however, is unknown, but critical to understanding the disturbance response dynamics of patchy landscapes. We experimentally disturbed three, 2-ha stands varying in pre-disturbance primary production and community composition, temporarily reducing live stand basal area by 38% to 66% through the stem girdling of all mature early successional aspen (Populus tremuloides Michx. and Populus grandidentata Michx.) and birch (Betula papyrifera Marshall). Disturbance significantly altered stand-scale physical and biological structure and prompted a similar decade-long pattern of wood NPP decline and recovery. All stands exhibited an initial reduction in wood NPP, followed by a recovery period and eventual return to pre-disturbance levels within eight years, with the most productive stand exhibiting an increase in primary production following recovery. Following wood NPP recovery, more biologically diverse forest canopies with higher leaf area indexes intercepted more light, and, consequently, had higher rates of wood NPP. We conclude that, despite substantial pre-disturbance differences in productivity and community composition, relative wood NPP recovery patterns can be similar, though long-term post-recovery primary production may trend higher in more productive and compositionally diverse stands. We suggest that improved mechanistic understanding of different forest ecosystems’ responses to disturbances remains critical to informing management decisions across diverse landscape mosaics
-
phenological and temperature controls on the temporal non structural carbohydrate dynamics of Populus grandidentata and quercus rubra
Forests, 2010Co-Authors: Christopher M Gough, Charles E. Flower, Christoph S Vogel, Peter S. CurtisAbstract:Temporal changes in plant tissue non-structural carbohydrates (NSC) may be sensitive to climate changes that alter forest phenology. We examined how temporal fluctuations in tissue NSC concentrations of Populus grandidentata and Quercus rubra relate to net and gross primary production (NPP, GPP) and their climatic drivers in a deciduous forest of Michigan, USA. Tissue NSC concentrations were coupled with NPP and GPP phenologies, declining from dormancy until GPP initiation and then increasing following NPP cessation. Warmer autumns extended the temporal gap between NPP and GPP cessation, prolonging the period of NSC accumulation. These results suggest that tissue NSC concentrations may increase with climate change.
-
whole ecosystem labile carbon production in a north temperate deciduous forest
AGUFM, 2008Co-Authors: Christopher M Gough, Charles E. Flower, D Dragoni, Christoph S Vogel, Peter S. CurtisAbstract:Labile carbon (C), which is principally comprised of non-structural carbohydrates, is an essential intermediary between C assimilation and structural growth in deciduous forests. We developed a new approach that combined meteorological and biometric C cycling data for a mixed deciduous forest in Michigan, USA, to provide novel estimates of whole-ecosystem labile C production and reallocation to structural net primary production (NPP). We substantiated inferred seasonal patterns of labile C production and reallocation to structural NPP with measurements of Populus grandidentata and Quercus rubra wood non-structural carbohydrate concentration and mass over two years. Our analysis showed that 55% of annual net canopy C assimilate (Ac) was first allocated to labile C production rather than to immediate structural NPP. Labile C produced during the latter half of summer later supported dormant- season structural growth and respiration, with 34% of structural NPP in a given year requiring labile C stored during previous years. Seasonal changes in wood non-structural carbohydrate concentration and mass generally corroborated inferred temporal patterns of whole-ecosystem labile C production and reallocation to structural NPP. Our findings confirm that disparities can arise between same-year meteorological and biometric net ecosystem production when meteorologically measured C assimilation and biometrically measured growth are asynchronous because of temporary photosynthate allocation to labile C storage. We conclude that a broader understanding of labile C production and reallocation at the ecosystem scale is important to interpreting lagged canopy C cycling and structural growth processes.