Long-Term Ecological Research Project Research Articles

Graduate student experiences and perspectives related to conducting thesis research within long-term ecological projects

Long-term ecological research (LTER) projects are considered valuable training grounds for graduate student researchers, yet student voices are largely absent from discussions of LTER merits in the literature. We aimed to identify benefits and challenges encountered by current and former graduate students in conducting graduate research within LTER projects. To explore graduate student experiences and perspectives, we conducted a survey comprising both closed-ended questions (i.e., multiple choice and Likert scale) and open-ended questions. From the responses, we identified emergent categories related to positive and negative experiences using sentiment analysis. We found agreement with purported benefits in areas including networking and access to established field sites and protocols. However, participants also identified data accessibility, authorship decisions, communication, and interpersonal conflicts as significant sources of challenges. We synthesized survey results with existing literature to provide actionable recommendations for principal investigators in four main areas (data, authorship, communication, and management) through an LTER lens. In addition to providing longitudinal data, LTER projects offer graduate students both physical and methodological infrastructure that can serve as the scaffold for new research questions to be developed. However, the likelihood of success of student research, as well as the success of the students themselves, can be improved when the needs of graduate students are prioritized.

A Convolutional Neural Network to Classify Phytoplankton Images Along the West Antarctic Peninsula

AbstractHigh-resolution optical imaging systems are quickly becoming universal tools to characterize and quantify microbial diversity in marine ecosystems. Automated classification systems such as convolutional neural networks (CNNs) are often developed to identify species within the immense number of images (e.g., millions per month) collected. The goal of our study was to develop a CNN to classify phytoplankton images collected with an Imaging FlowCytobot for the Palmer Antarctica Long-Term Ecological Research project. A relatively small CNN (~2 million parameters) was developed and trained using a subset of manually identified images, resulting in an overall test accuracy, recall, and f1-score of 93.8, 93.7, and 93.7%, respectively, on a balanced dataset. However, the f1-score dropped to 46.5% when tested on a dataset of 10,269 new images drawn from the natural environment without balancing classes. This decrease is likely due to highly imbalanced class distributions dominated by smaller, less differentiable cells, high intraclass variance, and interclass morphological similarities of cells in naturally occurring phytoplankton assemblages. As a case study to illustrate the value of the model, it was used to predict taxonomic classifications (ranging from genus to class) of phytoplankton at Palmer Station, Antarctica, from late austral spring to early autumn in 2017‐2018 and 2018‐2019. The CNN was generally able to identify important seasonal dynamics such as the shift from large centric diatoms to small pennate diatoms in both years, which is thought to be driven by increases in glacial meltwater from January to March. This shift in particle size distribution has significant implications for the ecology and biogeochemistry of these waters. Moving forward, we hope to further increase the accuracy of our model to better characterize coastal phytoplankton communities threatened by rapidly changing environmental conditions.

A Convolutional Neural Network to Classify Phytoplankton Images Along the West Antarctic Peninsula

Abstract High-resolution optical imaging systems are quickly becoming universal tools to characterize and quantify microbial diversity in marine ecosystems. Automated classification systems such as convolutional neural networks (CNNs) are often developed to identify species within the immense number of images (e.g., millions per month) collected. The goal of our study was to develop a CNN to classify phytoplankton images collected with an Imaging FlowCytobot for the Palmer Antarctica Long-Term Ecological Research project. A relatively small CNN (~2 million parameters) was developed and trained using a subset of manually identified images, resulting in an overall test accuracy, recall, and f1-score of 93.8, 93.7, and 93.7%, respectively, on a balanced dataset. However, the f1-score dropped to 46.5% when tested on a dataset of 10,269 new images drawn from the natural environment without balancing classes. This decrease is likely due to highly imbalanced class distributions dominated by smaller, less differentiable cells, high intraclass variance, and interclass morphological similarities of cells in naturally occurring phytoplankton assemblages. As a case study to illustrate the value of the model, it was used to predict taxonomic classifications (ranging from genus to class) of phytoplankton at Palmer Station, Antarctica, from late austral spring to early autumn in 2017‐2018 and 2018‐2019. The CNN was generally able to identify important seasonal dynamics such as the shift from large centric diatoms to small pennate diatoms in both years, which is thought to be driven by increases in glacial meltwater from January to March. This shift in particle size distribution has significant implications for the ecology and biogeochemistry of these waters. Moving forward, we hope to further increase the accuracy of our model to better characterize coastal phytoplankton communities threatened by rapidly changing environmental conditions.

Structure and Functionality of the Mesozooplankton Community in a Coastal Marine Environment: Portofino Marine Protected Area (Liguria)

This research is part of the LTER (Long-Term Ecological Research) project, a network of terrestrial, freshwater, transitional water and marine sites, on which ecological research is conducted on a multi-decade scale. LTER studies ecosystems, their dynamics and evolution, the relationships between biodiversity and ecological functionality, water quality, productivity, the role of resource availability, the effects of pollution and climate change. The research focuses on the study of the variability of zooplankton groups in the Portofino marine protected area, in Punta Faro. The samplings were carried out in the years 2018–2019, and the results were compared with the values of the years 2003–2005, interesting from a meteorological climatic and biological point of view. The plankton community of the Punta Faro system was analyzed by means of a modeling approach to obtain information on the functionality and health status of the system and to verify whether this has undergone any alterations in the last decade. The analyses carried out show a clear difference between the three-year period 2003–2005 and the two-year period 2018–2019, highlighting how environmental changes, such as the increase in temperature, have led to higher costs of system functioning in the last two years. The mesozooplankton community has changed both in terms of abundance of organisms and in terms of organization and functionality.

Asynchrony Drives Plant and Animal Community Stability in Mediterranean Coastal Dunes

Substantial evidence now suggests that a positive diversity–stability relationship exists. Yet few studies examine the facets of biodiversity that contribute to this relationship, and empirical research is predominantly conducted on grassland communities under controlled conditions. We investigate the roles of species richness, environmental condition (vegetation cover), asynchrony, and weighted population stability in driving community stability across multiple taxa. We used data from a Long-term Ecological Research project to investigate temporal stability of annual plants, beetles, reptiles, and rodents in Nizzanim Coastal Sand Dune Nature Reserve in Israel. All four taxa had a strong positive relationship between asynchrony and community stability. Only rodents showed a positive richness–stability relationship. Perennial plant cover had a significant relationship with community stability for three taxa, but the direction of the correlation varied. Asynchrony had a stronger relationship with perennial plant cover than it did with richness for both plants and beetles. We suggest that community stability is driven by asynchrony for flora as well as fauna. Stability appears to be determined by species’ interactions and their responses to the environment, and not always by diversity. This has important consequences for understanding the effects of environmental degradation on ecosystem stability and productivity, which have destabilizing consequences beyond biodiversity loss.

Coastal Futures Conservatory

AbstractThis article develops an account of listening as a model for integrating inquiries into rapid environmental change from arts, sciences, and humanities. The account is structured around interpretation of the Coastal Futures Conservatory (CFC), an initiative for integrating arts and humanities into the Long-Term Ecological Research Project at the Virginia Coast Reserve. The CFC organizes collaborative inquiry and public engagement around several kinds of listening, from field recordings and designed listening stations as practices of attentiveness to scientific data by sonifying data sets, across disciplines by commissioning convergent lines of research from humanities and sciences, and across political boundaries by creating cross-coastal exchanges. Working from reflection on CFC practices, the author evaluates the potential and the limits of a pivot from ocular to aural metaphors of creating environmental knowledge as well as the potential and limits of listening as a model for integrating that knowledge. The author then questions integration as metaphor for multidisciplinary collaboration by testing its openness to listening beyond human worlds. The article closes by arguing for the role of contemplative practices in developing “transformative listening” as a way to connect environmental sciences with processes of moral and political formation.

Antarctica during the Pandemic

Oscar Schofield, a Rutgers University professor who is also a coprincipal investigator (PI) for the Palmer Antarctica Long-Term Ecological Research (LTER) site, was on a research cruise off the West Antarctic peninsula in February 2020 when he first saw news of the increasingly rapid spread of the novel coronavirus. Field research in Antarctica always requires months of planning. Everyone has to go through a rigorous medical evaluation and researchers have to package up their equipment and ship it to designated ports for transport arranged by the National Science Foundation (NSF). The logistics are so complicated that Schofield says he is typically home from the field no more than 3 weeks before it is time to start planning the next season. But in March 2020, with the virus raging, Antarctic researchers knew they were in for more uncertainty and surprises than usual. Program officers at the NSF, which funds most US Antarctic research, were working with international partners to assess fieldwork prospects on the continent during the pandemic. Eventually, they created a three tiered system, says Karla Heidelberg, program director for the NSF's Antarctic Organisms and Ecosystems Program in the Office of Polar Programs. While recognizing that sending no one would jeopardize the infrastructure at the various stations, she says that the NSF determined early on that the 2020 to 2021 summer season would be greatly scaled back. The LTER sites and other American research projects in Antarctica look at everything from penguins and seals to phytoplankton and nematodes to atmospheric conditions and glaciers. Polar regions are responding faster than other latitudes to global warming, so they are a focus of climate change research across many disciplines. Instead of close to 10 researchers, this year, just three students tagged seals and collected biometric data that will be used to estimate breeding and survival rates. The McMurdo LTER project did not get to send a single researcher. Despite the frustration and the uncertainty, researchers report that the overall scientific integrity of most studies remains intact, and the impacts are not devastating. Funding agencies and scientists expect they will again have delays and last-minute decisions for the 2021 to 2022 Antarctic summer field season. But Cannone sees one benefit the pandemic brought to Antarctic science.

INTEGRATING LONG TERM ECOLOGICAL RESEARCH (LTER) AND MARINE PROTECTED AREA MANAGEMENT: CHALLENGES AND SOLUTIONS

Long Term Ecological Research (LTER) generates unique data sets that have the potential to identify and quantify trends in ecological processes that may be difficult to detect at lower temporal resolutions. Even though many LTER sites are within protected areas, they do not necessarily produce data that are well aligned with the objectives of the institutions and individuals who manage and govern these sites. There are several potential reasons for this, including: i) insufficient information provided by the LTER on socio-ecological variables of relevance to management; ii) a mismatch between the spatial scale of the data collected by the LTER and the scale of data needed to inform management decisions; iii) a lack of inclusion of policy-makers in crucial steps of LTER project implementation, including experimental design and analysis, and; iv) an absence or insufficiency of formal or informal mechanisms for incorporating LTER data into environmental decision-making and protected area governance. Using examples from recently implemented LTER in the Costa dos Corais Environmental Protected Area (known as the PELD-CCAL), we reflect on how some of these challenges can be addressed and provide general recommendations for increasing the conservation management and policy relevance of LTER projects in Brazil.

The Impact of Targeted Data Management Training for Field Research Projects – A Case Study

We present a joint effort at Virginia Tech between a research group in the Department of Fish and Wildlife Conservation and Data Services in the University Libraries to improve data management for long-term ecological field research projects in the Florida Panhandle. Consultative research data management support from Data Services in the University Libraries played an integral role in the development of the training curriculum. Emphasizing the importance of data quality to the field workers at the beginning of this training curriculum was a vital part of its success. Also critical for success was the research group’s investment of time and effort to work with field workers and improve data management systems. We compare this case study to three others in the literature to compare and contrast data management processes and procedures. This case study serves as one example of how targeted training and efforts in data and project management for a research project can lead to substantial improvements in research data quality.

Benthic Macroinvertebrate Diversity in the Middle Doce River Basin, Brazil

This resource contains a checklist of the benthic macroinvertebrate community sampled biannually from 1999 to 2010 in eight natural lakes from the middle Rio Doce Valley lake system and eight river segments in the Piracicaba River basin (sub-basin of Doce river), Minas Gerais State, Brazil. Three of the lakes are located inside a protected state park and are surrounded by preserved vegetation (Atlantic Forest). The other five lakes are in private properties, surrounded by Eucalyptus plantations. The seven stretches of rivers have a distinct degree of anthropogenic impacts. Samples were collected with a kick net and fixed with formaldehyde solution. Four phyla were represented: Mollusca, Annelida, Arthropoda, and Platyhelminthes. For Insecta, 76 families were identified, one family was identified for Crustacea, and nine families were identified for Mollusca. This subproject belongs to the International Long-Term Ecological Research Project (ILTER—Programa de Pesquisas Ecológicas de Longa Duração—PELD) site 4.

Recurrent seascape units identify key ecological processes along the western Antarctic Peninsula.

The western Antarctic Peninsula (WAP) is a bellwether of global climate change and natural laboratory for identifying interactions between climate and ecosystems. The Palmer Long-Term Ecological Research (LTER) project has collected data on key ecological and environmental processes along the WAP since 1993. To better understand how key ecological parameters are changing across space and time, we developed a novel seascape classification approach based on insitu temperature, salinity, chlorophyll a, nitrate+nitrite, phosphate, and silicate. We anticipate that this approach will be broadly applicable to other geographical areas. Through the application of self-organizing maps (SOMs), we identified eight recurrent seascape units (SUs) in these data. These SUs have strong fidelity to known regional water masses but with an additional layer of biogeochemical detail, allowing us to identify multiple distinct nutrient profiles in several water masses. To identify the temporal and spatial distribution of these SUs, we mapped them across the Palmer LTER sampling grid via objective mapping of the original parameters. Analysis of the abundance and distribution of SUs since 1993 suggests two year types characterized by the partitioning of chlorophyll a into SUs with different spatial characteristics. By developing generalized linear models for correlated, time-lagged external drivers, we conclude that early spring sea ice conditions exert a strong influence on the distribution of chlorophyll a and nutrients along the WAP, but not necessarily the total chlorophyll a inventory. Because the distribution and density of phytoplankton biomass can have an impact on biomass transfer to the upper trophic levels, these results highlight anticipated links between the WAP marine ecosystem and climate.

Influence of infrastructure on water quality and greenhouse gas dynamics in urban streams.

Streams and rivers are significant sources of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) globally, and watershed management can alter greenhouse gas (GHG) emissions from streams. We hypothesized that urban infrastructure significantly alters downstream water quality and contributes to variability in GHG saturation and emissions. We measured gas saturation and estimated emission rates in headwaters of two urban stream networks (Red Run and Dead Run) of the Baltimore Ecosystem Study Long-Term Ecological Research project. We identified four combinations of stormwater and sanitary infrastructure present in these watersheds, including: (1) stream burial, (2) inline stormwater wetlands, (3) riparian/floodplain preservation, and (4) septic systems. We selected two first order catchments in each of these categories and measured GHG concentrations, emissions, and dissolved inorganic and organic carbon (DIC and DOC) and nutrient concentrations biweekly for 1 year. From a water quality perspective, the DOC : NO3 - ratio of streamwater was significantly different across infrastructure categories. Multiple linear regressions including DOC : NO3 - and other variables (dissolved oxygen, DO; total dissolved nitrogen, TDN; and temperature) explained much of the statistical variation in nitrous oxide (N2O, r2 = 0.78), carbon dioxide (CO2, r2 = 0.78) and methane (CH4, r 2 = 0.50) saturation in stream water. We measured N2O saturation ratios, which were among the highest reported in the literature for streams, ranging from 1.1 to 47 across all sites and dates. N2O saturation ratios were highest in streams draining watersheds with septic systems and strongly correlated with TDN. The CO2 saturation ratio was highly correlated with the N2O saturation ratio across all sites and dates, and the CO2 saturation ratio ranged from 1.1 to 73. CH4 was always supersaturated, with saturation ratios ranging from 3.0 to 2157. Longitudinal surveys extending form headwaters to third-order outlets of Red Run and Dead Run took place in spring and fall. Linear regressions of these data yielded significant negative relationships between each gas with increasing watershed size as well as consistent relationships between solutes (TDN or DOC, and DOC : TDN ratio) and gas saturation. Despite a decline in gas saturation between the headwaters and stream outlet, streams remained saturated with GHGs throughout the drainage network, suggesting that urban streams are continuous sources of CO2, CH4, and N2O. Our results suggest that infrastructure decisions can have significant effects on downstream water quality and greenhouse gases, and watershed management strategies may need to consider coupled impacts on urban water and air quality.

Variability of Mya arenaria growth along an environmental gradient in the Plum Island Sound estuary, Massachusetts, USA

An understanding of the environmental factors that determine how clam growth varies in space and time improves effective mariculture and shellfish management. We examined the importance of temperature, salinity and chlorophyll-a in controlling the spatial pattern of Mya arenaria growth, the commercially important soft-shell clam, in the Plum Island Sound estuary in northeastern Massachusetts, USA. We collected clams (>5.08 cm) monthly during the April to November growing season from which we determined growth rate, maximum size (L-infinity), and time to reach a harvestable size. We also surveyed selected sites along the estuary to estimate the relationship between clam size and weight. We collected environmental data along the estuary, and our data were complemented with data collected and maintained by the Plum Island ecosystems long-term ecological research project. Clams reached harvestable size fastest and had the greatest L-infinity at the most oceanic site (Yacht Club) in the estuary. Clams had the smallest L-infinity and were slowest to reach the harvestable size at the least oceanic site (Railroad Meander). The spatial patterns of clam growth were best explained by a positive distribution of salinity. Salinity significantly accounted for 95 % of the spatial variation of clam growth in the estuary. Snow melt in spring increases freshwater input to the estuary and results in the lowest spring salinity during a year, and this explained the upper estuary limit of clam distribution. IPCC-projected climate change will cause sea-level rise and increasing precipitation in the northeastern USA, which will modify the spatial pattern of salinity in the region’s estuaries. Our research therefore suggests that future management of M. arenaria, an important economic resource for the local economy, should be concerned with the changes of salinity distribution under climate and land-use change.

Program Profile: The Georgia Coastal Ecosystems Long Term Ecological Research Project (GCE‐LTER)

Program Profile: The <scp>G</scp>eorgia Coastal Ecosystems Long Term Ecological Research Project (GCE‐LTER)

The value of a broad temporal and spatial perspective in understanding dynamics of kelp forest ecosystems

Many ecological processes play out over longer time scales and larger spatial scales than can be studied in a traditional 2–4-year grant cycle. Uncertainties in future funding hinder efforts to implement comprehensive research programs that integrate coupled time series observations of physical variables and ecological responses, manipulative experiments and synthetic analyses over the long term. Such research is essential for advancing our understanding of ecological responses associated with climate change, and the physical and biological processes that control them. This need is perhaps greatest for ecosystems that display highly dynamic and spatially complex patterns that are difficult to explain with short-term, small-scale studies. Such is the case for kelp forest ecosystems, which often show tremendous spatial and temporal variability in resource supply, consumer control and physical disturbance across spatial scales of metres to hundreds of kilometres and temporal scales of hours to decades. Here we present four examples from the Santa Barbara Coastal Long-term Ecological Research project that demonstrate the value of a broad temporal and spatial perspective in understanding the causes and ecological consequences of short-term local dynamics of giant kelp forests of California, USA.

Spatial and temporal variability in spectral-based surface energy evapotranspiration measured from Landsat 5TM across two mangrove ecotones

Coastal mangroves lose large amounts of water through evapotranspiration (ET) that can be equivalent to the amount of annual rainfall in certain years. Satellite remote sensing can play a crucial role in identifying regional ET trends and surface energy changes after disturbances in isolated and inaccessible areas of coastal mangrove wetlands, like those found in Everglades National Park in southern Florida. Using a combination of long-term datasets acquired from the NASA Landsat 5TM satellite database and the Florida Coastal Everglades Long-Term Ecological Research project, the present study investigates how ET as well as radiation and other energy balance parameters in the Everglades mangrove ecotone have responded to multiple hurricane events and restoration projects over the past two decades. An energy balance model using satellite data was used to estimate latent heat (λE) in tall and scrub mangrove environments. An eddy-covariance tower and weather tower supplied long-term data of multiple environmental and meteorological parameters that were used in calibrating and testing the modeled results from the Landsat images. Results identified significant differences in λE and soil heat flux measurements between the tall and scrub, and fringe and basin mangrove environments. The scrub mangrove site had the lowest λE rates, highest soil heat flux and lowest biophysical index (i.e., Fractional Vegetation Cover (FVC), Normalized Difference Vegetation Index (NDVI), and Soil-Adjusted Vegetation Index (SAVI) values. Mangrove damage and mortality associated with two strong hurricanes decreased FVC, NDVI, and SAVI, and increased soil heat flux at the tall mangrove site located in a basin-type environment. Recovery of the spectral characteristics, energy balance parameters and λE following hurricane disturbance was quicker in fringe mangroves than in basin mangroves. Latent heat fluxes (λE) were also relatively high after each storm and may have increased as a result of increasing vapor pressure deficits. Remote sensing of the surface energy balance and λE of mangrove forests can help our understanding of how these environments respond to disturbances to the landscape and the effect that these changes can have on the energy and water budget. Moreover, relationships between energy and water balance components developed for the coastal mangroves of southern Florida could be extrapolated to other mangrove systems in the Caribbean to measure changes caused by natural events and human modifications.

Tree Health in Phoenix, Arizona, U.S.

Two studies of tree diversity, visual health, and mortality in the Phoenix, Arizona, U.S. metropolitan basin were conducted as part of the Central Arizona Long-Term Ecological Research project. For one study, tree diversity, mortality, and visual health were determined in 2010 at 204 sites, encompassing both the Phoenix metropolitan basin and in the surrounding Sonoran Desert. In another study, records of tree visual health and mortality were taken during the winter months (2003–2007) at 65 non-residential sites across an urban to rural gradient. Average tree mortality rates were 4.2% per annum. Crown condition was rated as very good or good for the majority of trees. Poor pruning practices and abiotic injuries, such as trunk sunscald, were observed on 70% and 23%, respectively, of trees in non-residential areas. Disease and pest problems were detected in 41% of urban trees, including wood decay, Verticillium wilt, sooty canker, and ash decline. Based on these data, researchers suggest that urban forest health in Phoenix is being negatively impacted by extensive wounding of trees, particularly in non-residential settings, possibly caused by excessive crown manipulation through pruning.

Microzooplankton community composition along the Western Antarctic Peninsula

Microzooplankton are an integral part of aquatic food webs, yet compared to macrozooplankton, are understudied in the Southern Ocean. The region along the Western Antarctic Peninsula (WAP) is experiencing rapid climate warming, resulting in declines in sea ice extent and duration, and affecting the marine food web. Microzooplankton community structure along the WAP was analyzed in January 2010 and 2011 as part of the Palmer Antarctica Long-Term Ecological Research project. Whole seawater samples were collected within the top 100m of the water column along both north-south and coastal-offshore gradients, and major taxa of microzooplankton were quantified using microscopy. Average chlorophyll-a concentrations and microzooplankton biomass were higher in 2011 compared to 2010. Athecate dinoflagellates and aloricate ciliates dominated microzooplankton biomass, and the biomass of most taxonomic groups was higher in the south compared to the north. Specifically, aloricate ciliate and tintinnid biomass increased with increasing latitude, and biomass peaked at several southern, inshore stations – including Marguerite Bay, which was an area of high biomass for some microzooplankton taxa. Biomass was higher in surface waters compared to 100m, and variability in microzooplankton biomass between years and with distance from shore was most likely due to sea ice dynamics. Microzooplankton biomass was positively correlated with chlorophyll-a and particulate organic carbon. These results are used to consider how microzooplankton populations may be adjusting to environmental changes along the WAP.

Variation in monsoon precipitation drives spatial and temporal patterns of Larrea tridentata growth in the Sonoran Desert

Summary 1. Broad-scale patterns of above-ground net primary production (ANPP) are closely coupled to climate features, particularly the distribution and magnitude of rainfall. In arid and semi-arid regions, however, the precipitation regime, together with local geomorphology and plant life history traits, combine to regulate soil water availability and patterns of growth, complicating simple correlations with climatic variables. 2. To better understand the drivers of plant growth in desert ecosystems, we characterized the rates and spatial heterogeneity of stem elongation by the dominant perennial shrub, creosote bush (Larrea tridentata) in the northern Sonoran Desert of Arizona (USA). Estimates of stem growth were made over a 5-year period (2006–2010) from 60 plots at 15 sites spanning c. 120 km across the Central Arizona–Phoenix (CAP) Long-term Ecological Research (LTER) area. 3. We observed both the highest and lowest rates of stem growth during summer, and these patterns were related to the amount of monsoon rainfall and local rates of water infiltration. The relationship between growth and precipitation in the summer was nonlinear, with rates increasing more than eightfold at plots receiving more than 100 mm of seasonal rainfall. Conversely, growth during the winter/spring was intermediate in magnitude, similar among years and poorly correlated with seasonal precipitation. 4. The spatial heterogeneity of stem growth also differed markedly between seasons and was greater both within and among sites during summer compared to winter/spring growing periods. At broad scales, spatial heterogeneity of shrub growth was correlated with seasonal changes in the spatial variability of rainfall across the study area. At small spatial scales, greater heterogeneity during the summer appears linked to local soil properties that influence infiltration and water availability following monsoon storms. 5. Overall, the strong, nonlinear growth response by L. tridentata to monsoon rainfall suggests that the recurrence interval of wet summer seasons is an important driver of ANPP for this long-lived shrub. More generally, our results illustrate how regional climate variability and local soil properties can interact to influence the rates and heterogeneity of desert plant growth at multiple scales.

Introduction to the Baltimore Ecosystem Study, Long-Term Ecological Research Project, Phase III

AbstractThe Baltimore Ecosystem Study (BES) is one of two urban Long-Term Ecological Research (LTER) projects in the United States. It began its third funding cycle in 2011. Although the project continues key measurements that were started in 1997 at the inception of the research, the third phase is characterized by a new conceptual framework. Phase III of BES focuses on metropolitan Baltimore, Maryland, as a system poised for transition from a "sanitary city" -- characterized by engineered environmental solutions, management via discrete disciplines, and government control to a "sustainable city" -- which would be characterized by additional biological solutions, collaborative management, and polycentric and multi-level governance. In such a situation, the guiding research question becomes, "What are the effects of adaptive processes aimed at sustainability in the Baltimore socio-ecological system?" Adaptive processes are those social and biophysical features and actions which allow a complex system to adjust to changing internal and external drivers. The full proposal and other details of BES can be discovered on the project website: www.beslter.org