Although temperate forests are generally thought of as N-limited, resource optimization theory predicts that ecosystem productivity should be co-limited by multiple nutrients. These ideas are represented in the Multi-Element Limitation (MEL) model (Rastetter et al. 2012). To test the patterns of resource limitation predicted by MEL, we are conducting nutrient manipulations in three study sites in New Hampshire: Bartlett Experimental Forest (BEF), Hubbard Brook Experimental Forest (HBEF), and Jeffers Brook in the White Mountain National Forest. We are monitoring stem diameter, leaf area, sap flow, foliar chemistry, leaf litter production and chemistry, foliar nutrient resorption, root biomass and production, mycorrhizal associations, soil respiration, heterotrophic respiration, N and P availability, N mineralization, soil phosphatase activity, soil carbon and nitrogen, nutrient uptake capacity of roots, and mineral weathering. These data can be found in the EDI repository, using the search term "MELNHE" (http://portal.edirepository.org), and through the data catalog on https://hubbardbrook.org, using the same search term. This data package is referenced by the MELNHE datasets, and includes a datatable of site descriptions and a pdf file with the project description, and diagrams of plot configuration. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
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Estimates of productivity and multiple measures of biodiversity at Bartlett and Hubbard Brook Experimental Forests
In ecosystems dominated by grasses and other small-statured plants, biodiversity and productivity have generally been found to be positively correlated. However, studies in forested ecosystems have found mixed results. Biodiversity in forests has typically been characterized using indices of species diversity, but recent studies have shown that other measures of biodiversity can also play an important role. Several indices of biodiversity were calculated using local-scale inventory measurements and aircraft Light Detecting and Ranging data from Bartlett (BEF) and Hubbard Brook Experimental Forests (HBEF) in New Hampshire, USA to look at relationships between different measures of biodiversity (species, functional, phylogenetic, and structural diversity) and site productivity. For this dataset, a total of 22 biodiversity indices were calculated using the 2001-2003 BEF and 1995-1998 HBEF inventory datasets. These biodiversity indices include three species diversity indices, five functional diversity indices, five phylogenetic diversity indices, and 12 structural diversity indices. In addition, measurements of wood growth and foliar nitrogen for a select number of plots previously collected in another study (Smith et al 2005) were used to represent plot productivity. Site characteristics and land use such as topography, management history, and forest type were also included.
Hubbard Brook Experimental Forest and the Bartlett Experimental Forest are both operated and maintained by the USDA Forest Service, Northern Research Station.
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- NSF-PAR ID:
- 10491723
- Publisher / Repository:
- Environmental Data Initiative
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The MELNHE study looks at patterns of resource limitation through nutrient manipulations in three study sites in New Hampshire: Bartlett Experimental Forest, Hubbard Brook Experimental Forest, and Jeffers Brook, located in the White Mountain National Forest. The investigation is monitoring stem diameter, leaf area, sap flow, foliar chemistry, leaf litter production and chemistry, foliar nutrient resorption, root biomass and production, mycorrhizal associations, soil respiration, heterotrophic respiration, N and P availability, N mineralization, soil phosphatase activity, soil carbon and nitrogen, nutrient uptake capacity of roots, and mineral weathering. This data set includes phosphate, nitrate and ammonium availability measured using resin exchange strips. Additional detail on the MELNHE project, including a datatable of site descriptions and a pdf file with the project description and diagram of plot configuration can be found in this data package: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-hbr&identifier=344 These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. The following papers describe and make use of these data: Fisk MC, Ratliff TJ, Goswami S, Yanai RD. 2014. Synergistic soil response to nitrogen plus phosphorus fertilization in hardwood forests. Biogeochemistry 118:195-204. https://doi.org/10.1007/s10533-013-9918-1 Goswami S, Fisk MC, Vadeboncoeur MA, Johnston M, Yanai RD, and Fahey TJ. 2018. Phosphorus limitation of aboveground production in northern hardwood forests. Ecology 99: 438-449. https://doi.org/10.1002/ecy.2100 Shan S, Fisk MC, Fahey TJ. 2018. Contrasting effects of N on rhizosphere processes in two northern hardwood species. Soil Biology and Biochemistry 126: 219-227. https://doi.org/10.1016/j.soilbio.2018.09.007 Shan S, Devens H, Fahey TJ, Yanai RD, Fisk MC. 2022. Fine root growth increases in response to nitrogen addition in phosphorus-limited northern hardwood forests. Ecosystems, https://doi.org/10.1007/s10021-021-00735-4 Gonzales KE, Yanai RD, Fahey TJ, Fisk MC. 2023. Evidence for P limitation in eight northern hardwood stands: Foliar concentrations and resorption by three tree species in a factorial N by P addition experiment. Forest Ecology and Management 529: 120696. https://doi.org/10.1016/j.foreco.2022.120696 Li S, Fisk MC, Yanai RD, Fahey TJ. 2023. Co-limitation of root growth by nitrogen and phosphorus in early successional northern hardwood forest. Ecosystems. https://10.1007/s10021-023-00869-7more » « less
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Abstract The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Department of Agriculture, Forest Service out of concerns about the effects of logging increasing flooding and erosion. To address this issue, within the HBEF hydrological and micrometeorological monitoring was initiated in small watersheds designated for harvesting experiments. The Hubbard Brook Ecosystem Study (HBES) originated in 1963, with the idea of using the small watershed approach to study element fluxes and cycling and the response of forest ecosystems to disturbances, such as forest management practices and air pollution. Early evidence of acid rain was documented at the HBEF and research by scientists at the site helped shape acid rain mitigation policies. New lines of investigation at the HBEF have built on the long legacy of watershed research resulting in a shift from comparing inputs and outputs and quantifying pools and fluxes to a more mechanistic understanding of ecosystem processes within watersheds. For example, hydropedological studies have shed light on linkages between hydrologic flow paths and soil development that provide valuable perspective for managing forests and understanding stream water quality. New high frequency in situ stream chemistry sensors are providing insights about extreme events and diurnal patterns that were indiscernible with traditional weekly sampling. Additionally, tools are being developed for visual and auditory data exploration and discovery by a broad audience. Given the unprecedented environmental change that is occurring, data from the small watersheds at the HBEF are more relevant now than ever and will continue to serve as a basis for sound environmental decision‐making.
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Abstract Ecosystems are changing in complex and unpredictable ways, and analysis of these changes is facilitated by coordinated, long‐term research. Meeting diverse societal needs requires an understanding of what populations and communities will be dominant in 20, 50, and 100 yr. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long‐Term Ecological Research (LTER) network addressing the LTER core research area of populations and communities. This analysis revealed that each LTER site had at least one compelling story about what their site would look like in 50 or 100 yr. As the stories were prepared, themes emerged, and the stories were grouped into papers along five themes for this special issue: state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the resilience theme and includes stories from the Baltimore (urban), Hubbard Brook (northern hardwood forest), Andrews (temperate rain forest), Moorea (coral reef), Cedar Creek (grassland), and North Temperate Lakes (lakes) sites. The concept of resilience (the capacity of a system to maintain structure and processes in the face of disturbance) is an old topic that has seen a resurgence of interest as the nature and extent of global environmental change have intensified. The stories we present here show the power of long‐term manipulation experiments (Cedar Creek), the value of long‐term monitoring of forests in both natural (Andrews, Hubbard Brook) and urban settings (Baltimore), and insights that can be gained from modeling and/or experimental approaches paired with long‐term observations (North Temperate Lakes, Moorea). Three main conclusions emerge from the analysis: (1) Resilience research has matured over the past 40 yr of the LTER program; (2) there are many examples of high resilience among the ecosystems in the LTER network; (3) there are also many warning signs of declining resilience of the ecosystems we study. These stories highlight the need for long‐term studies to address this complex topic and show how the diversity of sites within the LTER network facilitates the emergence of overarching concepts about this important driver of ecosystem structure, function, services, and futures.
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Abstract Decades of theory and empirical studies have demonstrated links between biodiversity and ecosystem functioning, yet the putative processes that underlie these patterns remain elusive. This is especially true for forest ecosystems, where the functional traits of plant species are challenging to quantify. We analyzed 74,563 forest inventory plots that span 35 ecoregions in the contiguous USA and found that in ~77% of the ecoregions mixed mycorrhizal plots were more productive than plots where either arbuscular or ectomycorrhizal fungal-associated tree species were dominant. Moreover, the positive effects of mixing mycorrhizal strategies on forest productivity were more pronounced at low than high tree species richness. We conclude that at low richness different mycorrhizal strategies may allow tree species to partition nutrient uptake and thus can increase community productivity, whereas at high richness other dimensions of functional diversity can enhance resource partitioning and community productivity. Our findings highlight the importance of mixed mycorrhizal strategies, in addition to that of taxonomic diversity in general, for maintaining ecosystem functioning in forests.more » « less
