Download or read book Microbial Nitrogen Cycling Response to Calcium and Phosphorus in Northern Hardwood Forest Soils at the Hubbard Brook Experimental Forest New Hampshire written by Kevan Joseph Minick and published by . This book was released on 2009 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthropogenic soil acidification appears to be detrimental to forest health in the northeastern US possibly due to reduced microbial activity influencing plant-available nutrients. In a recent study at the Hubbard Brook Experimental Forest, soil microbial activity was not stimulated by increased pH. Therefore, microbial response to increased pH may depend on the level of calcium added or availability of other nutrients. I tested the effects of Ca and phosphorus additions in the field on microbial nitrogen transformations. High Ca addition reduced net N mineralization. Low Ca addition did not affect N transformations, but the combination of Ca/P addition reduced net N mineralization. Phosphorus addition unexpectedly increased gross nitrification. Results from this study indicate that microbial mineralization is not sensitive to moderate differences in pH or limited by P. Therefore, detrimental effects of acidic deposition to these forests are not likely a result of nutrient deficiencies related to suppression of microbial activity.
Download or read book Soil Nitrogen Cycling Over Two Decades Following Calcium Treatment in Hubbard Brook Experimental Forest NH written by and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A watershed-scale calcium addition experiment at Hubbard Brook Experimental Forest, New Hampshire, was performed in 1999 to better understand how forest ecosystem function and biogeochemistry are affected by changes in pH. Significant increases in forest growth and acid neutralizing capacity of the soil and stream water were reported in the six years following the calcium addition, but the expected stimulation of the nitrogen cycle was not observed. The aims of this study were to 1) examine the 20-year dataset of soil nitrogen dynamics following the experimental calcium addition in the treated watershed and paired reference area to understand longer term trends and effects, and 2) explore connections between soil nitrogen processes and watershed nitrogen export in stream water observed in the calcium-treated watershed since 2013. Since 2002, soil pH was higher in the calcium-treated watershed than the reference, with stronger differences seen in surface horizons, but declined over time and converged toward the reference conditions by 2018, throughout the soil profile. Soil nitrogen cycling measurements were not consistent with the changes in soil pH, and temporal trends were different depending on the variable in question. Differences in temporal trends in nitrogen cycling variables were often more pronounced as a function of soil horizon than Ca treatment. However, interesting trends were seen in certain variables, with effects of Ca treatment diverging from long term trends in the reference area for some variables while converging toward reference conditions for others. There was no strong evidence from microbial nitrogen transformations at the plot scale to explain the nitrate export from the calcium treated watershed observed by other researchers (Rosi-Marshall et al. 2016). Because pathways in soil nitrogen cycling did not show consistent trajectories over time in response to the calcium treatment, understanding how changes in pH and other environmental variables, along with competition for nitrogen between plants and soil microbes, differentially affect these various processes remains a challenge in forest ecosystem science.
Download or read book Microbial Activity in Deeper Mineral Soil Important for Nitrogen Cycling Across Successional Stand Age in a Northern Hardwood Forest written by Bridget Anna Darby and published by . This book was released on 2016 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Little is known about soil processes with depth, as the majority of studies measuring soil nitrogen (N) cycling and microbial activity only measure the top 10-15 cm, where activity is expected to be highest. Microbes play an important role in the extraction of N from the mineral soil through the mineralization of organic N and in the accumulation of N in the mineral soil through immobilization and turnover of N in microbial biomass or in extracellular enzymes. It is also uncertain how these processes vary with successional stand age. To understand how N cycling varies with depth and forest stand age, we measured gross and net N mineralization and nitrification rates, as well as extracellular enzyme activity to 50 cm depth across three sites varying in stand age (45 and 100 years post-harvest and old growth) at and near Hubbard Brook Experimental Forest in central New Hampshire. N- and C- degrading enzyme activity correlated with gross N mineralization rates, but not net N mineralization rate, directly linking microbial activity to the release of N from SOM. Enzyme activity and N cycling rates were expected to decrease with depth in response to decreasing soil C and N concentrations and increasing organic matter age. We found that N cycling rates per g dry soil and g N did decrease with between the forest floor and mineral soil, but decomposition enzyme activity and remained constant relative to decreasing organic matter concentrations with depth. On an areal basis, N cycling in the mineral soil was much larger, flux than in the organic horizon due to the large mass of the mineral soil. We found few differences in activity rates across sites, though net nitrification was significantly higher at the old growth site and enzyme activities were often lower at the 100 year old stand as compared the other two sites. The results from our study demonstrate the underappreciated importance of microbial activity with depth. Although N cycling rates decreased with depth, N turnover remained relatively high throughout the soil profile, highlighting the availability of N in old SOM and the likely importance of deep soil in supplying N to plants and microbes.
Download or read book Biogeochemistry of a Forested Ecosystem written by Gene E. Likens and published by Springer Science & Business Media. This book was released on 2013-08-13 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this Third Edition is to update long-term data presented in earlier editions and to generate new syntheses and conclusions about the biogeochemistry of the Hubbard Brook Valley based on these longer-term data. There have been many changes, revelations, and exciting new insights generated from the longer data records. For example, the impact of acid rain peaked during the period of the HBES and is now declining. The longer-term data also posed challenges in that very marked changes in fluxes occurred in some components, such as hydrogen ion and sulfate deposition, calcium and nitrate export in stream water and biomass accumulation, during the almost 50 years of record. Thus, presenting “mean” or “average” conditions for many components for such a long period, when change was so prominent, do not make sense. In some cases, pentads or decades of time are compared to show these changes in a more smoothed and rational way for this long period. In some cases, a single period, often during periods of rapid change, such as acidification, is used to illustrate the main point(s). And, for some elements a unique mass balance approach, allowing the calculation of the Net Ecosystem Flux (NEF), is shown on an annual basis throughout the study.
Download or read book Early Response of Phosphorus Cycling to an Experimental Addition of Calcium in a Northern Hardwood Forest written by Isabella Fiorentino and published by . This book was released on 2002 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Journal of Forest Research written by and published by . This book was released on 2014 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrogen Cycling in the Northern Hardwood Forest written by Lucas Emil Nave and published by . This book was released on 2007 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Nitrogen (N) is the nutrient most limiting to plant growth (NPP) in temperate forests. In N-limited temperate forests, most of the N required for NPP is recycled between soil and plant N pools by the microbial process of N-mineralization (Nmin). However, human activities have increased atmospheric N deposition (Ndep) to forests in the last 50-100 years, and this surplus N may increase NPP. But, forest responses to Ndep are not satisfactorily understood, and depend on how atmospheric N inputs are partitioned between soils and plants. From my field data collection at a mature forest site, I estimated that NPP required 51 kg N ha−1 yr−1, most of which was used for fine root and leaf production (62% and 31%, respectively). Each year, Nmin supplied 87% of Nreq, and Ndep contributed an additional 13%, 4% of which was due to canopy retention of Ndep (Ncr). Data from my mesocosm 15N-labelling experiment suggested that very little (10%) of Ncr observed in the field was actually taken up by trees, and the majority of Ndep (85%) was assimilated into soil pools. These results suggest that Ndep could not have significantly increased forest NPP at UMBS over the time scale of my studies. My greenhouse experiment corroborated this conclusion, with tree seedlings showing no significant increase in photosynthesis or growth in response to Ndep at ambient rates. However, Ndep to forest ecosystems has been occurring for decades in industrialized regions, and most of the N inputs have been incorporated into soil organic matter (SOM). Research across temperate forests has suggested that forests exposed to large N inputs over time exhibit decreased soil C/N ratios, which are associated with faster Nmin rates. Using meta-analysis, I verified this pattern in the literature, and discovered novel relationships between forest soil properties and their responses to N inputs. My results demonstrated a long-term, quantitative relationship between Ndep and Nmin, and suggest that NPP may increase in temperate forests affected by Ndep.
Download or read book Ecological Society of America Annual Meeting Abstracts written by Ecological Society of America. Meeting and published by . This book was released on 2004 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ecology written by and published by . This book was released on 1984 with total page 1056 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publishes essays and articles that report and interpret the results of original scientific research in basic and applied ecology.
Download or read book Carbon Nitrogen and Phosphorus Cycling in Forest Soils written by Robert G. Qualls and published by MDPI. This book was released on 2019-06-21 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of carbon stored in the soils of the world is stored in forests. The refractory nature of some portions of forest soil organic matter also provides the slow, gradual release of organic nitrogen and phosphorus to sustain long term forest productivity. Contemporary and future disturbances, such as climatic warming, deforestation, short rotation sylviculture, the invasion of exotic species, and fire, all place strains on the integrity of this homeostatic system of C, N, and P cycling. On the other hand, the CO2 fertilization effect may partially offset losses of soil organic matter, but many have questioned the ability of N and P stocks to sustain the CO2 fertilization effect. Despite many advances in the understanding of C, N, and P cycling in forest soils, many questions remain. For example, no complete inventory of the myriad structural formulae of soil organic N and P has ever been made. The factors that cause the resistance of soil organic matter to mineralization are still hotly debated. Is it possible to “engineer” forest soil organic matter so that it sequesters even more C? The role of microbial species diversity in forest C, N, and P cycling is poorly understood. The difficulty in measuring the contribution of roots to soil organic C, N, and P makes its contribution uncertain. Finally, global differences in climate, soils, and species make the extrapolation of any one important study difficult to extrapolate to forest soils worldwide.
Download or read book Impacts of Climate Change on Soil Microorganisms in Northern Hardwood Forests written by Carley Jane Kratz and published by . This book was released on 2014 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: As global climate continues to change, it becomes more important to understand possible feedbacks from soils to the climate system. This dissertation focuses on soil microbial community responses to climate change factors in northern hardwood forests. Two soil warming experiments at Harvard Forest in Massachusetts, and a climate change manipulation experiment with both elevated temperature and increased moisture inputs in Michigan were sampled. The hyphal in-growth bag method was to understand how soil fungal biomass and respiration respond to climate change factors. Our results from phospholipid fatty acid (PLFA) analyses suggest that the hyphal in-growth bag method allows relatively pure samples of fungal hyphae to be partitioned from bacteria in the soil. The contribution of fungal hyphal respiration to soil respiration was examined in climate change manipulation experiments in Massachusetts and Michigan. The Harvard Forest soil warming experiments in Massachusetts are long-term studies with 8 and 18 years of +5 °C warming treatment. Hyphal respiration and biomass production tended to decrease with soil warming at Harvard Forest. This suggests that fungal hyphae adjust to higher temperatures by decreasing the amount of carbon respired and the amount of carbon stored in biomass. The Ford Forestry Center experiment in Michigan has a 2 x 2 fully factorial design with warming (+4-5 °C) and moisture addition (+30% average ambient growing season precipitation). This experiment was used to examine hyphal growth and respiration of arbuscular mycorrhizal fungi (AMF), soil enzymatic capacity, microbial biomass and microbial community structure in the soil over two years of experimental treatment. Results from the hyphal in-growth bag study indicate that AMF hyphal growth and respiration respond negatively to drought. Soil enzyme activities tend to be higher in heated versus unheated soils. There were significant temporal variations in enzyme activity and microbial biomass estimates. When microbial biomass was estimated using chloroform fumigation extractions there were no differences between experimental treatments and the control. When PLFA analyses were used to estimate microbial biomass we found that biomass responds negatively to higher temperatures and positively to moisture addition. This pattern was present for both bacteria and fungi. More information on the quality and composition of the organic matter and nutrients in soils from climate change manipulation experiments will allow us to gain a more thorough understanding of the mechanisms driving the patterns reported here. The information presented here will improve current soil carbon and nitrogen cycling models.
Download or read book Plant and Microbial Mechanisms of Nitrogen Retention in Northern Hardwood Forests Receiving Atmospheric NO3 Deposition written by William C. Eddy and published by . This book was released on 2006 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nutrient Demand and Nitrogen Processing in Streams of the Hubbard Brook Experimental Forest written by Emily Snow Bernhardt and published by . This book was released on 2001 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Link Between Nitrogen Cycling and Soil Microbial Community Composition in Forest Soils of Western Oregon written by Stephanie A. Boyle and published by . This book was released on 2007 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations in forest soils. The first study consisted of a reciprocal transfer experiment where soil cores were transferred between high-elevation forest and adjacent meadow environments. It focused on bacterial denitrifying communities by measuring denitrification enzyme activity and community composition as determined by terminal restriction fragment length polymorphism (T-RFLP) profiles targeting the gene for nitrous oxide reductase (nosZ). Results from this experiment showed that while transferring meadow soils into forests increased denitrification rate, denitrifying community composition did not appear to change after two years. The second study examined N cycling and microbial community composition in soils from 20-year-old experimental tree plantations with pure stands of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in a high- and a low-productivity forest. 15N isotope dilution was combined with antibiotics to assess the roles of bacteria and fungi in N mineralization and nitrification. Data showed that nitrification was a major sink for NH4+ in all soil types and bacteria were the primary nitrifiers. Increased ammonification following antibiotic additions suggested that organic N may be important for the growth of heterotrophic bacteria and fungi. Results of nitrification potential assays showed that most nitrification was acetylene insensitive (autotrophic). Community composition of ammonia-oxidizing bacteria and archaea were assessed by targeting bacterial and archaeal ammonia-monooxygenase (amoA) genes. The composition and population size of ammonia-oxidizing bacteria differed between Douglas fir and red alder and tended to group with Nitrosospira clusters 2 and 4. Archaeal amoA was only amplified from the high-productivity site and grouped with other archaeal clones from soil and estuary sediments. Environmental factors affected rates of N cycling within two years, but community compositional changes responded more slowly, e.g., nitrifying communities differed between 20-year-old tree stands. This suggests that if environmental changes persist they may lead to changes in microbial community composition.
Download or read book Sources of Calcium and Strontium in a Northern Hardwood Ecosystem written by Jennifer L. Bonin and published by . This book was released on 1998 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Drinking Water from Forests and Grasslands written by and published by . This book was released on 2000 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Is Nitrogen Cycling and Bioavailablity Limited by Phosphorus in Northern New England Forest Soils written by Cayce Jo Salvino and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
