After severe wildfires, pine recovery depends on ectomycorrhizal (ECM) fungal spores surviving an... more After severe wildfires, pine recovery depends on ectomycorrhizal (ECM) fungal spores surviving and serving as partners for regenerating forest trees. We took advantage of a large, severe natural forest fire that burned our long-term study plots to test the response of ECM fungi to fire. We sampled the ECM spore bank using pine seedling bioassays and high-throughput sequencing before and after the California Rim Fire. We found that ECM spore bank fungi survived the fire and dominated the colonization of in situ and bioassay seedlings, but there were specific fire adapted fungi such as Rhizopogon olivaceotinctus that increased in abundance after the fire. The frequency of ECM fungal species colonizing pre-fire bioassay seedlings, post-fire bioassay seedlings and in situ seedlings were strongly positively correlated. However, fire reduced the ECM spore bank richness by eliminating some of the rare species, and the density of the spore bank was reduced as evidenced by a larger number of...
Background/Question/Methods Tree species richness in forests is associated with higher levels of ... more Background/Question/Methods Tree species richness in forests is associated with higher levels of ecosystem services and greater resilience in the face of anthropogenic global change. California’s Sierra Nevada mixed conifer forests have historically been a uniquely resilient system due to the evenness of their mixed composition. However, fire exclusion in the region has led to changes in the physical structure of the forest as well as a sharp decrease in the species richness of recruits in the forest understory. This shift from a mixed to homogenous system is likely to increase the susceptibility of the ecosystem to perturbations and to slow recovery after disturbance, resulting in decreased resilience of the forest in the face of natural and anthropogenic disturbances. What are the drivers of this forest reorganization? Answering this question allows us to more accurately model forest trajectories and better manage for a desired resilient state. We measured changes in forest compos...
Background/Question/Methods A major source of uncertainty in the calculation of nutrient budgets ... more Background/Question/Methods A major source of uncertainty in the calculation of nutrient budgets results from imprecise and inaccurate soil sampling techniques. Traditional methods of soil sampling, such as soil coring and excavation of quantitative soil pits, are limited by rocky soil conditions. In addition, the removal of soil for analysis prevents repeated sampling in sites that may have high spatial variability. To improve these limitations, we are testing two novel methods of soil collection and analysis at the Bartlett Experimental Forest in New Hampshire, Bear Brook Watershed in Maine, and Mt. Ascutney in Vermont. We tested a gas-powered, diamond-bit drill which can core through large roots and rocks to a depth of 90 cm or more, thereby eliminating the depth and density biases of manual coring. The samples we collected with this technique were compared to soils collected from quantitative soil pits located within 2 m of the core to determine if exchangeable cation concentrat...
Background/Question/Methods Anthropogenic nitrate deposition is altering soil nitrogen enrichment... more Background/Question/Methods Anthropogenic nitrate deposition is altering soil nitrogen enrichment and acidification, affecting biogeochemical processes in northern hardwood forests. High nitrogen availability can influence organic matter (SOM) cycling by depressing degradation of recalcitrant soil organic matter. In some ecosystems, available P limits decomposer activity and this may be linked to SOM quality. We need to better understand responses by microbial decomposer organisms to these important nutrients, because of their potential influence on ecosystem carbon sequestration. We manipulated N&P availability in laboratory microcosms that were amended with several different C sources of varying complexity. Organic horizon material was collected in mid-July from 3 beech-dominated mature plots in the Hubbard Brook Experimental Forest (Thornton, NH) and incubated with factorial N, P, dextrose, cellulose, xylan and sawdust additions. Carbon mineralization was measured intensively, at...
Background/Question/Methods Long-term elemental budgets for watersheds at the Hubbard Brook Exper... more Background/Question/Methods Long-term elemental budgets for watersheds at the Hubbard Brook Experimental Forest (HBEF) have provided new insights into the integration of biogeochemistry and ecology. These budgets have shown how forest disturbance from timber harvest, acid deposition, and climate disturbance (e.g., ice storms) alters the elemental dynamics of forested ecosystems. The element budgets have been analyzed, knowing that inherent uncertainties exist and their approximate magnitudes, however detailed propagation of uncertainty through the inputs, outputs, and net hydrologic flux has not been attempted. We have analyzed uncertainty in multiple element budgets at HBEF in order to identify the major sources of uncertainty in each input-output budget and how those sources of uncertainty have changed. Through uncertainty analysis we can gain a greater understanding of the ecosystem change over time and how to optimally monitor the ecosystem to reduce uncertainty in the future. T...
Background/Question/Methods Ecosystem budgets often report elemental pools and fluxes without ful... more Background/Question/Methods Ecosystem budgets often report elemental pools and fluxes without fully accounting for the uncertainty in these estimates, making it difficult to evaluate the significance of findings or to compare results across ecosystems. Some sources of uncertainty are well understood and commonly reported, such as the variability reflected in replicate plots. Other aspects of uncertainty are rarely reported, such as the spatial variation in precipitation measurements, the temporal uncertainty in sampling stream water concentrations, or the regression equations used to estimate the biomass of tree components. We recently developed and demonstrated a Monte Carlo approach to propagating uncertainty in an ecosystem nitrogen budget, focusing on tree biomass. The objective of this study is to quantify the uncertainty in phosphorus pools and fluxes in a northern hardwood forest using data from the Hubbard Brook Ecosystem Study, New Hampshire, USA. ","serif";&...
Background/Question/Methods Air pollutants such as nitrogen oxides, sulfur dioxide, and mercury h... more Background/Question/Methods Air pollutants such as nitrogen oxides, sulfur dioxide, and mercury have had significant impacts on the quality of lakes, rivers, soils, biota, and tree health throughout the Northeastern US. Some areas of New York State are particularly susceptible to environmental degradation, such as the Adirondack and Catskill regions, which receive some of the highest rates of acid and mercury deposition in the country. Long-term monitoring (LTM) efforts have produced data sets that have been extremely valuable for evaluating changes over time in air pollution loads and effects on the environment. It is important to reevaluate LTM programs to ensure that these programs remain efficient and effective. To our knowledge, a comprehensive evaluation of state-wide long-term monitoring of acid and mercury deposition has never been undertaken in New York State. These monitoring efforts include projects funded by a variety of federal and state agencies, private non-profit org...
Background/Question/Methods Uncertainty analyses can be used to improve efficiency in ecosystem m... more Background/Question/Methods Uncertainty analyses can be used to improve efficiency in ecosystem monitoring efforts. We illustrate four methods of data analysis appropriate to four types of monitoring designs, using examples from northeastern North America. • To analyze a long-term record from a single site, we applied a general linear model to stream chemistry at Biscuit Brook in the Catskill Mountains. Biscuit Brook has been monitored continuously on a weekly basis since 1999; we simulated reduced sampling efforts and evaluated confidence in the detection of change over time. • To analyze a one-time survey, we applied a detectable difference analysis to loon tissue mercury concentrations, illustrating effect of sampling intensity on statistical power and the selection of a sampling interval likely to detect an expected change over time. • To analyze sampling intensity at one point in time, we subsampled forest inventory plots from the Hubbard Brook Experimental Forest, illustrating...
Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at t... more Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at the scale of a small-watershed ecosystem. We used data from the Gomadansan Experimental Forest, Japan, Hubbard Brook Experimental Forest, USA, and Coweeta Hydrologic Laboratory, USA, to evaluate many sources of uncertainty, including the precision and accuracy of measurements, selection of models, and spatial and temporal variation. Uncertainty in the analysis of stream chemistry samples was generally small but could be large in relative terms for solutes near detection limits, as is common for ammonium and phosphate in forested catchments. Instantaneous flow deviated from the theoretical curve relating height to discharge by up to 10% at Hubbard Brook, but the resulting corrections to the theoretical curve generally amounted to <0.5% of annual flows. Calibrations were limited to low flows; uncertainties at high flows were not evaluated because of the difficulties in performing calibrations during events. However, high flows likely contribute more uncertainty to annual flows because of the greater volume of water that is exported during these events. Uncertainty in catchment area was as much as 5%, based on a comparison of digital elevation maps with ground surveys. Three different interpolation methods are used at the three sites to combine periodic chemistry samples with streamflow to calculate fluxes. The three methods differed by <5% in annual export calculations for calcium, but up to 12% for nitrate exports, when applied to a stream at Hubbard Brook for 1997-2008; nitrate has higher weekly variation at this site. Natural variation was larger than most other sources of uncertainty. Specifically, coefficients of variation across streams or across years, within site, for runoff and weighted annual concentrations of calcium, magnesium, potassium, sodium, sulphate, chloride, and silicate ranged from 5 to 50% and were even higher for nitrate. Uncertainty analysis can be used to guide efforts to improve confidence in estimated stream fluxes and also to optimize design of monitoring programmes.
ABSTRACT Selective browsing by Odocoileus virginianus (White-tailed Deer) has shifted plant commu... more ABSTRACT Selective browsing by Odocoileus virginianus (White-tailed Deer) has shifted plant communities in the Northeast, but the effects of seed dispersal by deer on forest seed banks are unknown. We used data from deer exclosures in hunted and unhunted properties in southeastern New York to determine whether deer browsing and different deer management histories have altered composition and/or abundance of forest saplings and seed banks. Results indicate that deer did not alter species richness, abundance, or composition in seed banks in either hunted or unhunted areas. Deer did, however, decrease sapling density and richness at the unhunted site but not at the hunted site. We conclude that impacts of unmanaged deer populations are greater on sapling recruitment than on seed banks.
ABSTRACT Leaf litterfall represents an important nutrient flux in forests, but separating leaves ... more ABSTRACT Leaf litterfall represents an important nutrient flux in forests, but separating leaves by species and collecting fresh litter annually for nutrient analysis is time-consuming and expensive. To quantify the sources of variation in litterfall nutrient estimates and guide optimal allocation of research effort, we analyzed nutrient concentration (5 years) and mass (6 years) of leaf litter for nine tree species in 13 northern hardwood sites. Coefficients of variation (CVs) in nutrient concentration were higher across sites than over time within sites for most elements; phosphorus was especially variable across sites (56% CV). Thus, to estimate litterfall nutrient fluxes accurately in forests of this type, nutrient analyses should be site-specific as well as species-specific but may not need to be repeated annually (CVs over time averaged 17% for calcium, 21% for magnesium, 28% for potassium, and 32% for phosphorus concentration). Total leaf litterfall mass varied considerably from year to year, ranging from 234 to 370 g·m–2 averaged over 13 sites. We recommend that litter collectors be elevated above the ground to avoid oversampling during extreme wind events. Use of species-specific allometric equations, or even basal area, to estimate the species composition of total litter mass may obviate the need to sort litter by species.
... Yanai 1 , Mark B. Green 3 , Mary Beth Adams 4 , Douglas A. Burns 5 , Donald C. Buso 6 , Mark ... more ... Yanai 1 , Mark B. Green 3 , Mary Beth Adams 4 , Douglas A. Burns 5 , Donald C. Buso 6 , Mark E. Harmon 7 , Shannon ... 1)Forest and Natural Resources Management, SUNY College of Environmental Science and Forestry, Syracuse, NY, (2)USDA Forest Service, Durham, NH, (3 ...
Statistical uncertainty analyses can be used to improve the efficiency of environmental monitorin... more Statistical uncertainty analyses can be used to improve the efficiency of environmental monitoring, allowing sampling designs to maximize information gained relative to resources required for data collection and analysis. In this paper, we illustrate four methods of data analysis appropriate to four types of environmental monitoring designs. To analyze a long-term record from a single site, we applied a general linear model to weekly stream chemistry data at Biscuit Brook, NY, to simulate the effects of reducing sampling effort and to evaluate statistical confidence in the detection of change over time. To illustrate a detectable difference analysis, we analyzed a one-time survey of mercury concentrations in loon tissues in lakes in the Adirondack Park, NY, demonstrating the effects of sampling intensity on statistical power and the selection of a resampling interval. To illustrate a bootstrapping method, we analyzed the plot-level sampling intensity of forest inventory at the Hubbard Brook Experimental Forest, NH, to quantify the sampling regime needed to achieve a desired confidence interval. Finally, to analyze time-series data from multiple sites, we assessed the number of lakes and the number of samples per year needed to monitor change over time in Adirondack lake chemistry using a repeated-measures mixed-effects model. Evaluations of time series and synoptic long-term monitoring data can help determine whether sampling should be re-allocated in space or time to optimize the use of financial and human resources.
After severe wildfires, pine recovery depends on ectomycorrhizal (ECM) fungal spores surviving an... more After severe wildfires, pine recovery depends on ectomycorrhizal (ECM) fungal spores surviving and serving as partners for regenerating forest trees. We took advantage of a large, severe natural forest fire that burned our long-term study plots to test the response of ECM fungi to fire. We sampled the ECM spore bank using pine seedling bioassays and high-throughput sequencing before and after the California Rim Fire. We found that ECM spore bank fungi survived the fire and dominated the colonization of in situ and bioassay seedlings, but there were specific fire adapted fungi such as Rhizopogon olivaceotinctus that increased in abundance after the fire. The frequency of ECM fungal species colonizing pre-fire bioassay seedlings, post-fire bioassay seedlings and in situ seedlings were strongly positively correlated. However, fire reduced the ECM spore bank richness by eliminating some of the rare species, and the density of the spore bank was reduced as evidenced by a larger number of...
Background/Question/Methods Tree species richness in forests is associated with higher levels of ... more Background/Question/Methods Tree species richness in forests is associated with higher levels of ecosystem services and greater resilience in the face of anthropogenic global change. California’s Sierra Nevada mixed conifer forests have historically been a uniquely resilient system due to the evenness of their mixed composition. However, fire exclusion in the region has led to changes in the physical structure of the forest as well as a sharp decrease in the species richness of recruits in the forest understory. This shift from a mixed to homogenous system is likely to increase the susceptibility of the ecosystem to perturbations and to slow recovery after disturbance, resulting in decreased resilience of the forest in the face of natural and anthropogenic disturbances. What are the drivers of this forest reorganization? Answering this question allows us to more accurately model forest trajectories and better manage for a desired resilient state. We measured changes in forest compos...
Background/Question/Methods A major source of uncertainty in the calculation of nutrient budgets ... more Background/Question/Methods A major source of uncertainty in the calculation of nutrient budgets results from imprecise and inaccurate soil sampling techniques. Traditional methods of soil sampling, such as soil coring and excavation of quantitative soil pits, are limited by rocky soil conditions. In addition, the removal of soil for analysis prevents repeated sampling in sites that may have high spatial variability. To improve these limitations, we are testing two novel methods of soil collection and analysis at the Bartlett Experimental Forest in New Hampshire, Bear Brook Watershed in Maine, and Mt. Ascutney in Vermont. We tested a gas-powered, diamond-bit drill which can core through large roots and rocks to a depth of 90 cm or more, thereby eliminating the depth and density biases of manual coring. The samples we collected with this technique were compared to soils collected from quantitative soil pits located within 2 m of the core to determine if exchangeable cation concentrat...
Background/Question/Methods Anthropogenic nitrate deposition is altering soil nitrogen enrichment... more Background/Question/Methods Anthropogenic nitrate deposition is altering soil nitrogen enrichment and acidification, affecting biogeochemical processes in northern hardwood forests. High nitrogen availability can influence organic matter (SOM) cycling by depressing degradation of recalcitrant soil organic matter. In some ecosystems, available P limits decomposer activity and this may be linked to SOM quality. We need to better understand responses by microbial decomposer organisms to these important nutrients, because of their potential influence on ecosystem carbon sequestration. We manipulated N&P availability in laboratory microcosms that were amended with several different C sources of varying complexity. Organic horizon material was collected in mid-July from 3 beech-dominated mature plots in the Hubbard Brook Experimental Forest (Thornton, NH) and incubated with factorial N, P, dextrose, cellulose, xylan and sawdust additions. Carbon mineralization was measured intensively, at...
Background/Question/Methods Long-term elemental budgets for watersheds at the Hubbard Brook Exper... more Background/Question/Methods Long-term elemental budgets for watersheds at the Hubbard Brook Experimental Forest (HBEF) have provided new insights into the integration of biogeochemistry and ecology. These budgets have shown how forest disturbance from timber harvest, acid deposition, and climate disturbance (e.g., ice storms) alters the elemental dynamics of forested ecosystems. The element budgets have been analyzed, knowing that inherent uncertainties exist and their approximate magnitudes, however detailed propagation of uncertainty through the inputs, outputs, and net hydrologic flux has not been attempted. We have analyzed uncertainty in multiple element budgets at HBEF in order to identify the major sources of uncertainty in each input-output budget and how those sources of uncertainty have changed. Through uncertainty analysis we can gain a greater understanding of the ecosystem change over time and how to optimally monitor the ecosystem to reduce uncertainty in the future. T...
Background/Question/Methods Ecosystem budgets often report elemental pools and fluxes without ful... more Background/Question/Methods Ecosystem budgets often report elemental pools and fluxes without fully accounting for the uncertainty in these estimates, making it difficult to evaluate the significance of findings or to compare results across ecosystems. Some sources of uncertainty are well understood and commonly reported, such as the variability reflected in replicate plots. Other aspects of uncertainty are rarely reported, such as the spatial variation in precipitation measurements, the temporal uncertainty in sampling stream water concentrations, or the regression equations used to estimate the biomass of tree components. We recently developed and demonstrated a Monte Carlo approach to propagating uncertainty in an ecosystem nitrogen budget, focusing on tree biomass. The objective of this study is to quantify the uncertainty in phosphorus pools and fluxes in a northern hardwood forest using data from the Hubbard Brook Ecosystem Study, New Hampshire, USA. ","serif";&...
Background/Question/Methods Air pollutants such as nitrogen oxides, sulfur dioxide, and mercury h... more Background/Question/Methods Air pollutants such as nitrogen oxides, sulfur dioxide, and mercury have had significant impacts on the quality of lakes, rivers, soils, biota, and tree health throughout the Northeastern US. Some areas of New York State are particularly susceptible to environmental degradation, such as the Adirondack and Catskill regions, which receive some of the highest rates of acid and mercury deposition in the country. Long-term monitoring (LTM) efforts have produced data sets that have been extremely valuable for evaluating changes over time in air pollution loads and effects on the environment. It is important to reevaluate LTM programs to ensure that these programs remain efficient and effective. To our knowledge, a comprehensive evaluation of state-wide long-term monitoring of acid and mercury deposition has never been undertaken in New York State. These monitoring efforts include projects funded by a variety of federal and state agencies, private non-profit org...
Background/Question/Methods Uncertainty analyses can be used to improve efficiency in ecosystem m... more Background/Question/Methods Uncertainty analyses can be used to improve efficiency in ecosystem monitoring efforts. We illustrate four methods of data analysis appropriate to four types of monitoring designs, using examples from northeastern North America. • To analyze a long-term record from a single site, we applied a general linear model to stream chemistry at Biscuit Brook in the Catskill Mountains. Biscuit Brook has been monitored continuously on a weekly basis since 1999; we simulated reduced sampling efforts and evaluated confidence in the detection of change over time. • To analyze a one-time survey, we applied a detectable difference analysis to loon tissue mercury concentrations, illustrating effect of sampling intensity on statistical power and the selection of a sampling interval likely to detect an expected change over time. • To analyze sampling intensity at one point in time, we subsampled forest inventory plots from the Hubbard Brook Experimental Forest, illustrating...
Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at t... more Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at the scale of a small-watershed ecosystem. We used data from the Gomadansan Experimental Forest, Japan, Hubbard Brook Experimental Forest, USA, and Coweeta Hydrologic Laboratory, USA, to evaluate many sources of uncertainty, including the precision and accuracy of measurements, selection of models, and spatial and temporal variation. Uncertainty in the analysis of stream chemistry samples was generally small but could be large in relative terms for solutes near detection limits, as is common for ammonium and phosphate in forested catchments. Instantaneous flow deviated from the theoretical curve relating height to discharge by up to 10% at Hubbard Brook, but the resulting corrections to the theoretical curve generally amounted to <0.5% of annual flows. Calibrations were limited to low flows; uncertainties at high flows were not evaluated because of the difficulties in performing calibrations during events. However, high flows likely contribute more uncertainty to annual flows because of the greater volume of water that is exported during these events. Uncertainty in catchment area was as much as 5%, based on a comparison of digital elevation maps with ground surveys. Three different interpolation methods are used at the three sites to combine periodic chemistry samples with streamflow to calculate fluxes. The three methods differed by <5% in annual export calculations for calcium, but up to 12% for nitrate exports, when applied to a stream at Hubbard Brook for 1997-2008; nitrate has higher weekly variation at this site. Natural variation was larger than most other sources of uncertainty. Specifically, coefficients of variation across streams or across years, within site, for runoff and weighted annual concentrations of calcium, magnesium, potassium, sodium, sulphate, chloride, and silicate ranged from 5 to 50% and were even higher for nitrate. Uncertainty analysis can be used to guide efforts to improve confidence in estimated stream fluxes and also to optimize design of monitoring programmes.
ABSTRACT Selective browsing by Odocoileus virginianus (White-tailed Deer) has shifted plant commu... more ABSTRACT Selective browsing by Odocoileus virginianus (White-tailed Deer) has shifted plant communities in the Northeast, but the effects of seed dispersal by deer on forest seed banks are unknown. We used data from deer exclosures in hunted and unhunted properties in southeastern New York to determine whether deer browsing and different deer management histories have altered composition and/or abundance of forest saplings and seed banks. Results indicate that deer did not alter species richness, abundance, or composition in seed banks in either hunted or unhunted areas. Deer did, however, decrease sapling density and richness at the unhunted site but not at the hunted site. We conclude that impacts of unmanaged deer populations are greater on sapling recruitment than on seed banks.
ABSTRACT Leaf litterfall represents an important nutrient flux in forests, but separating leaves ... more ABSTRACT Leaf litterfall represents an important nutrient flux in forests, but separating leaves by species and collecting fresh litter annually for nutrient analysis is time-consuming and expensive. To quantify the sources of variation in litterfall nutrient estimates and guide optimal allocation of research effort, we analyzed nutrient concentration (5 years) and mass (6 years) of leaf litter for nine tree species in 13 northern hardwood sites. Coefficients of variation (CVs) in nutrient concentration were higher across sites than over time within sites for most elements; phosphorus was especially variable across sites (56% CV). Thus, to estimate litterfall nutrient fluxes accurately in forests of this type, nutrient analyses should be site-specific as well as species-specific but may not need to be repeated annually (CVs over time averaged 17% for calcium, 21% for magnesium, 28% for potassium, and 32% for phosphorus concentration). Total leaf litterfall mass varied considerably from year to year, ranging from 234 to 370 g·m–2 averaged over 13 sites. We recommend that litter collectors be elevated above the ground to avoid oversampling during extreme wind events. Use of species-specific allometric equations, or even basal area, to estimate the species composition of total litter mass may obviate the need to sort litter by species.
... Yanai 1 , Mark B. Green 3 , Mary Beth Adams 4 , Douglas A. Burns 5 , Donald C. Buso 6 , Mark ... more ... Yanai 1 , Mark B. Green 3 , Mary Beth Adams 4 , Douglas A. Burns 5 , Donald C. Buso 6 , Mark E. Harmon 7 , Shannon ... 1)Forest and Natural Resources Management, SUNY College of Environmental Science and Forestry, Syracuse, NY, (2)USDA Forest Service, Durham, NH, (3 ...
Statistical uncertainty analyses can be used to improve the efficiency of environmental monitorin... more Statistical uncertainty analyses can be used to improve the efficiency of environmental monitoring, allowing sampling designs to maximize information gained relative to resources required for data collection and analysis. In this paper, we illustrate four methods of data analysis appropriate to four types of environmental monitoring designs. To analyze a long-term record from a single site, we applied a general linear model to weekly stream chemistry data at Biscuit Brook, NY, to simulate the effects of reducing sampling effort and to evaluate statistical confidence in the detection of change over time. To illustrate a detectable difference analysis, we analyzed a one-time survey of mercury concentrations in loon tissues in lakes in the Adirondack Park, NY, demonstrating the effects of sampling intensity on statistical power and the selection of a resampling interval. To illustrate a bootstrapping method, we analyzed the plot-level sampling intensity of forest inventory at the Hubbard Brook Experimental Forest, NH, to quantify the sampling regime needed to achieve a desired confidence interval. Finally, to analyze time-series data from multiple sites, we assessed the number of lakes and the number of samples per year needed to monitor change over time in Adirondack lake chemistry using a repeated-measures mixed-effects model. Evaluations of time series and synoptic long-term monitoring data can help determine whether sampling should be re-allocated in space or time to optimize the use of financial and human resources.
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Papers by Carrie Levine