Long-Term Ecological Research Program Research Articles

The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics

We investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:234Th ratios of sinking particles collected by a surface-tethered sediment trap (C:234ThST) varied from 2.3 to 20.5 μmol C dpm−1 over a depth range of 47–150 m. C:234ThST was significantly greater (by a factor of 1.8) than C:234Th ratios of suspended >51-μm particles collected in the same water parcels with in situ pumps. C:234Th ratios of large (>200-μm) sinking particles also exceeded those of smaller sinking particles. C:234ThST decreased with depth from the base of the euphotic zone through the upper twilight zone. C:234ThST was positively correlated with several indices of ecosystem productivity including particulate organic carbon (POC) and chlorophyll (Chl) concentrations, mesozooplankton biomass, and the fraction of Chl >20-μm. Principal component analysis and multiple linear regression suggested that decaying phytoplankton blooms exhibited higher C:234ThST than actively growing blooms at similar biomass levels. C:234ThST was positively correlated with indices of the fractional contribution of fecal pellets in sediment traps when the proportion of fecal pellets was low in the traps, likely because of a correlation between mesozooplankton biomass and other indices of ecosystem productivity. However, when fecal pellets were a more important component of sinking material, C:234ThST decreased with increasing fecal pellet content. C:234ThST was also positively correlated with the Si:C ratio of sinking particles. Across the dataset (and across depths) a strong correlation was found between C:234ThST and the ratio of vertically-integrated POC to vertically-integrated total water column 234Th (vC:234Thtot). A mechanistic one-layer, two-box model of thorium sorption and desorption was invoked to explain this correlation. Two empirical models (one using vC:234Thtot; one using depth and vertically-integrated Chl) were developed to predict C:234Th ratios in this coastal upwelling biome. The former regression (log10(C:234ThST) = 0.43 × log10(vC:234Thtot) + 0.53) was found to also be a reasonable predictor for C:234ThST from diverse regions including the Southern Ocean, Sargasso Sea, Subarctic North Pacific, and Eastern Tropical North Pacific.

Contemporary International Long-Term Ecological Research (ILTER)—from biogeosciences to socio-ecology and biodiversity research

Long-term ecological research (LTER) has a strong foundation in the fields of biogeosciences and ecosystem research with infrastructures established in the nineteenth (e.g., 1891—Plon, Germany; 1840—Rothamsted, England) and twentieth centuries (e.g., 1906—Lunz, Austria; 1925—Trout Lake Station, WI, USA; 1955—Hubbard Brook, NH, USA; 1960—Solling, Germany). Over time, it has been repeatedly shown that the long-term study of processes has the potential to significantly improve ecological understanding at the ecosystem or larger scales. The international network of LTER sites (ILTER) was established in 1993 and included 28 countries by the turn of the millennium. The geographical spread of LTER sites across the globe has significantly increased since then, and by 2016, 44 countries have established formal LTER programs with approximately 800 LTER sites and 70 Long-term Socio-ecological Research (LTSER) platforms as part of the international network. Stimulated by the World Summit on Sustainable Development and the UN Convention on Biodiversity, research topics at ILTER sites have diversified considerably. Scientists started to address societal processes driving environmental change, as well as feedbacks of environmental changes on society. Furthermore, biodiversity research became an intrinsic part of LTER in many countries initializing the establishment of research infrastructures in ecosystems not yet included (e.g., caves, marine habitats). In October 2016, the ILTER Open Science Meeting in the Kruger National Park, South Africa, gave an impressive overview of the diversity of LTER across the globe today. With this special issue, we aim to present the broad range of research currently conducted across the ILTER network with a collection of papers from different continents and with research topics both classical to LTER and emerging fields of contemporary LTER.

Linking permafrost thaw to shifting biogeochemistry and food web resources in an arctic river.

Rapidly, increasing air temperatures across the Arctic are thawing permafrost and exposing vast quantities of organic carbon, nitrogen, and phosphorus to microbial processing. Shifts in the absolute and relative supplies of these elements will likely alter patterns of ecosystem productivity and change the way carbon and nutrients are delivered from upland areas to surface waters such as rivers and lakes. The ultra-oligotrophic nature of surface waters across the Arctic renders these ecosystems particularly susceptible to changes in productivity and food web dynamics as permafrost thaw alters terrestrial-aquatic linkages. The objectives of this study were to evaluate decadal-scale patterns in surface water chemistry and assess potential implications of changing water chemistry to benthic organic matter and aquatic food webs. Data were collected from the upper Kuparuk River on the North Slope of Alaska by the U.S. National Science Foundation's Long-Term Ecological Research program during 1978-2014. Analyses of these data show increases in stream water alkalinity and cation concentrations consistent with signatures of permafrost thaw. Changes are also documented for discharge-corrected nitrate concentrations (+), discharge-corrected dissolved organic carbon concentrations (-), total phosphorus concentrations (-), and δ13 C isotope values of aquatic invertebrate consumers (-). These changes show that warming temperatures and thawing permafrost in the upland environment are leading to shifts in the supply of carbon and nutrients available to surface waters and consequently changing resources that support aquatic food webs. This demonstrates that physical, geochemical, and biological changes associated with warming permafrost are fundamentally altering linkages between upland and aquatic ecosystems in rapidly changing arctic environments.

Engaging Middle School Students in Authentic Scientific Practices Can Enhance Their Understanding of Ecosystem Response to Hurricane Disturbance

Ecosystem response to hurricane disturbance is complex and multi-faceted. The likelihood of increased frequency of severe hurricanes creates a need for the general public to understand how ecosystems respond to hurricanes. Yet, opportunities to study disturbances to complex systems are rare in U.S. K–12 schools. Educators and researchers in the Luquillo Long-Term Ecological Research program used the results of research on ecosystem response to hurricane disturbance in the Luquillo Experimental Forest as a foundation for the development of Journey to El Yunque, a web-based, middle-school curriculum unit. The program engages students in using models as evidence to develop explanations for how particular species respond to hurricane disturbance. Prior research in education has shown that engaging students in a particular role, like that of a scientist, could have detrimental effects on students’ abilities to transfer what is learned from one context to another. In this research, we sought to understand whether having students engage in authentic scientific practices could support transfer of knowledge to the abstract context of a standards-based assessment. Students were randomly assigned to engage in the program in the role of a scientist or in the role of a student learning about an ecosystem. The dependent variables included students’ comprehension of the background readings, their predictions of population changes, and their overall learning of ecology. The results indicate that taking on a scientist role during the learning activities had an indirect effect on general ecology knowledge by increasing the quality of students’ notetaking during background reading. The results also indicate that students struggled to use their knowledge to develop a robust explanation for how species respond to hurricane disturbance. Journey to El Yunque provides a framework for engaging students in authentic investigations of hurricane disturbance. Future research will examine how to improve the quality of students’ final explanations.

Climate-driven declines in arthropod abundance restructure a rainforest food web.

A number of studies indicate that tropical arthropods should be particularly vulnerable to climate warming. If these predictions are realized, climate warming may have a more profound impact on the functioning and diversity of tropical forests than currently anticipated. Although arthropods comprise over two-thirds of terrestrial species, information on their abundance and extinction rates in tropical habitats is severely limited. Here we analyze data on arthropod and insectivore abundances taken between 1976 and 2012 at two midelevation habitats in Puerto Rico's Luquillo rainforest. During this time, mean maximum temperatures have risen by 2.0 °C. Using the same study area and methods employed by Lister in the 1970s, we discovered that the dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps. Analysis of long-term data on canopy arthropods and walking sticks taken as part of the Luquillo Long-Term Ecological Research program revealed sustained declines in abundance over two decades, as well as negative regressions of abundance on mean maximum temperatures. We also document parallel decreases in Luquillo's insectivorous lizards, frogs, and birds. While El Niño/Southern Oscillation influences the abundance of forest arthropods, climate warming is the major driver of reductions in arthropod abundance, indirectly precipitating a bottom-up trophic cascade and consequent collapse of the forest food web.

CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection

Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models.

Forest ethnography: An approach to study the environmental history and political ecology of urban forests

A landscape succession paradigm has shaped much of our understanding about the processes of forest emergence and transformation in the United States. Drawing heavily from theory and method in environmental history, this paradigm has focused attention on the role of landscape-scale shifts in land use and land cover in the production of forests. The geography of cities is patchy, dynamic and heterogeneous, with change and differences occurring at much smaller scales (e.g. Jacobs 1961; Clay 1973) compared to coarse scale of stand replacing successions affecting rural forests (Grove et al. Ecosyst Health and Sustain 2(9):e01239, 2016; Pickett et al. Urban Ecosyst 20(1):1–14, 2017). Therefore, trying to understand how urban forests came to be, as well as what they are, requires a research approach that is specific to the land use dynamics of cities and attentive to the social life of urban forests. In response to this methodological gap, this paper describes a research approach called “forest ethnography,” which we are piloting in Baltimore, Maryland as part of the Baltimore Ecosystem Study (BES), one of the National Science Foundation’s urban Long-term Ecological Research Programs (LTER). As we describe, we propose that an urban forest ethnography approach can contribute to our understanding of both forest environmental history and urban political ecology.

Temporal coherence of physical, chemical and biological variables in four tropical lakes (Minas Gerais, Brazil)

Abstract Aim: The main objective of this study was to evaluate the presence of temporal coherence of limnological variables and pairs of lakes considering four tropical lakes of the Rio Doce State Park, using monthly data from the Long-Term Ecological Research Program (LTER) between the years of 2004 to 2009. Methods Subsurface data (0.5 meters) from the Carioca, Dom Helvécio, Gambazinho, and Jacaré Lakes were used in the analysis. We estimated the temporal coherence from the creation of time series for each of the variables. Through these series, we calculated the Pearson correlation coefficient between all pairs of lakes (N=6) and performed the average. We also analyzed the correlation between the temporal coherence found for the different pairs of lakes and two predictors of spatial patterns: proximity and exposure to climatic factors. The spatial proximity of the lake pairs was calculated in kilometers, and the exposure to climatic factors was estimated using two metrics: surface area and surface area/mean depth ratio. Results The largest temporal coherence levels were recorded for water temperature (0.97), pH (0.78), and dissolved organic carbon (DOC) (0.74). The lowest levels were found for chlorophyll-a (0.25) and phytoplankton richness (-0.02). The average temporal coherence was 0.58. Different from other studies, no significant correlation was found between the synchronicity of the lake pairs and the differences in their exposure to climatic factors. Also, no relation was found with the spatial proximity. Conclusions Our results demonstrate the existence of temporal coherence in tropical lakes to compatible levels with those found in temperate regions. Our work contributes to the knowledge of how synchronicity works at different set of lakes and climatic regions.

Thermal autecology describes the occurrence patterns of four benthic diatoms in McMurdo Dry Valley streams

Benthic microbial mats in the glacial-fed meltwater streams are hotspots of productivity in the McMurdo Dry Valleys (MDV), Antarctica. Benthic diatoms are common in these mats and the >45 primarily endemic taxa represent the most diverse group of eukaryotes in the MDV. In this harsh polar desert, streams are thermally dynamic with daily water temperatures varying 6–9 °C and daily maximum temperatures as high as 15 °C. Stream temperature may play a role in determining growth rates and survival strategies. To understand taxon-specific adaptations to their environment, we measured the growth rates of unialgal cultures of four diatom taxa (Psammothidium papilio, Hantzschia abundans, Hantzschia amphioxys, and Hantzschia amphioxys f. muelleri) under three temperature conditions (7.6, 10, and 15 °C) that were representative of maximum daily stream temperatures. We found that P. papilio exhibited a constant growth rate across the full temperature range; this species is most common in streams that begin to flow early in the summer and with less variable thermal regimes. Growth rates for H. abundans were greatest at 15 °C, but showed a non-linear relationship with temperature. H. amphioxys f. muelleri grew faster than the other taxa studied and thrived at 10 °C. Hantzschia amphioxys grew only at the two lower temperatures. These results aligned with the observed relationships between each taxon’s relative abundance and stream temperatures in the long-term record maintained by the MDV Long-Term Ecological Research program. Overall, our observations suggest that differences in thermal optima may be one factor contributing to and maintaining the diversity of benthic diatom flora in the MDV.

Controls on dissolved and particulate iron distributions in surface waters of the Western Antarctic Peninsula shelf

The Western Antarctic Peninsula (WAP) displays high but variable productivity and is also undergoing rapid change. Long-term studies of phytoplankton communities and primary production have suggested transient limitation by the micronutrient iron (Fe), but to date no data have been available to test this hypothesis. Here, we present the first spatially extensive, multi-year measurements of dissolved and particulate trace metals in surface waters to investigate the key sources and sinks of Fe in the central WAP shelf. Surface samples of dissolved and particulate metals were collected throughout the 700 × 200 km grid of the Palmer Long-Term Ecological Research program in three consecutive austral summers (2010 − 2012). Iron concentrations varied widely. Both dissolved and particulate Fe were high in coastal waters (up to 8 nmol kg− 1 and 42 nmol kg− 1, respectively). In contrast, very low Fe concentrations (< 0.1 nmol kg− 1) were widespread in mid- to outer-shelf surface waters, especially in the northern half of the sampling grid, suggesting possible Fe limitation of primary production on the shelf. Sea ice and dust inputs of Fe were minor, although their relative importance increased with distance from shore due to the larger near-shore sources. Sedimentary inputs were inferred from manganese distributions; these were more significant in the northern portion of the grid, and showed interannual variation in intensity. Overall, the interannual distribution of Fe was most closely correlated to that of meteoric water (glacial melt and precipitation). Although the Fe concentrations and relative contributions of dissolved and particulate Fe attributed to meltwater were variable throughout the sampling region, increasing glacial meltwater flux can be expected to increase the delivery of Fe to surface waters of the coastal WAP in the future.

Seasonality and land cover characteristics drive aphid dynamics in an arid city

Urbanization of arid environments results in biotic communities that differ from the surrounding desert. The growth of cities has lowered biodiversity and increased abundance of generalist species, known as urbanophiles. However, the mechanisms by which specific organisms can dominate urban ecosystems remain unclear. Using an 11-year data set from the Central Arizona-Phoenix Long-Term Ecological Research program, we evaluated how aphids, an arthropod urbanophile, were affected by habitat type and seasonality in Phoenix, Arizona, USA. Twenty-five sites were selected in habitat types varying in land use and land cover characteristics. Aphids varied along a gradient of water availability and vegetation, rather than level of urbanization. Seasonal aphid abundance was the highest in the spring and lowest in the summer, a pattern that did not differ between habitat types. We developed a mathematical model parallel to our empirical study to explain how temperature may affect the temporal patterns. The analysis of our model demonstrated that although seasonal patterns were similar across habitats, slight shifts in microclimate can result in dramatic variation of population dynamics. We conclude that both land cover and climate have huge impacts on aphids and that urbanophiles are able to take advantage of favorable environmental conditions caused by urbanization.

Abiotic/Biological Interactions in Coastal Marine Communities: Insights from an Alaskan Fjord

Interactions among multi-scale coastal marine ecosystem processes can be expected to play large roles in and interact with biological processes as stresses increase, potentially allowing interfering processes (including biological interactions) to become more prevalent. Retrospective analyses of intertidal (1988–1992) and subtidal (1971–2012) species compositions from a long-term ecological research program in Port Valdez, Alaska evaluated associations between benthic community structure and physical conditions to better understand interactions between regional to local processes on flora and fauna. Low salinity, habitat structure (varying from mudflats to rocky shores over a distance of <18 km), and suspended sediments contributed to intertidal community structure via elimination of predators from low-salinity prey refugia. Subtidal communities demonstrate adjustments by macrofauna to sedimentation with smaller, disturbance-tolerant fauna towards the head of the fjord as well as effects from depth-related covariates. Shared ecological processes result in comparable community trends in subtidal and intertidal habitats among subarctic and arctic fjords and similarly among coastal environments of the North Pacific. Control exerted by interactions among climatic, oceanographic, and local processes interacting with biota contributes to the direction and length of recovery from disturbance events and environmental changes. Feedbacks, mediation of recovery by additional processes, and strengths of interactions also play important roles in determining interaction outcomes. Interactions among local, regional, and global-scale processes may become critical sources of change as global ecosystem transitions through new climate states.

Information management at the North Temperate Lakes Long-term Ecological Research site — Successful support of research in a large, diverse, and long running project

Information management has been an integral part of the research process at the North Temperate Lakes Long-term Ecological Research (NTL LTER) program for over 30years. A combination of factors has made the information management system (IMS) at NTL very successful. Significant resources have been invested in the IMS from the beginning, the Information Manager has been part of the leadership team at NTL and later in various roles at the LTER network level; the NTL IMS was a very early adopter of database systems, standardized metadata, and a data delivery system based on those metadata. This approach has made data easily accessible to NTL researchers and the broader scientific community. Data management workflows have become increasingly more automated with adoption of modern technologies as they became available, making the system efficient enough to handle core data as well as all one-time research data generated within NTL and several related projects. More than three decades of core data from eleven lakes are reused extensively as critical background information and as the limnological go-to site for many synthesis projects within and beyond LTER.The NTL IMS continues to implement new technologies for improving data management efficiency, discovery, access, integration, and synthesis. Accordingly, the functionality of the original online data access system programmed in Java and JavaServer Pages (JSP) was ported to the modern content management system, Drupal and integrated into LTER's Drupal Ecological Information Management System (DEIMS). NTL has invested in sensor technology for studying lake conditions over the long term, which necessitated a sophisticated management system tailored to high frequency data streams. Several technologies have been used at different times for automation of management, quality control and archiving of these high volume data. Near real time lake conditions can be accessed on the NTL website and smart phone Apps.Easy access to long-term and sensor data in the NTL IMS has led NTL researchers to develop new analytical methods and the publication of several R statistical packages. Recent graduate students are now employed as data scientists helping define a new career path inspired by the availability of data.The NTL project has amassed one of the world's most comprehensive long-term datasets on lakes and their surrounding landscapes. The NTL IMS facilitates the use of these data by multiple groups for research, education, and communication of science to the public.

Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER). This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR) and chlorophyll-A (CHL)from Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input.

The contribution and reuse of LTER data in the Provenance Aware Synthesis Tracking Architecture (PASTA) data repository

Sites in the Long Term Ecological Research (LTER) Network have now contributed greater than 5000 data packages into the LTER Network Information System (NIS). This corpus of data and metadata allows us to analyze characteristics of data from the LTER program, including temporal coverage, data format, rate of submission, volume of data, and ecological characteristics of the data (e.g., ecosystems, processes, organisms). In addition, data/metadata congruence checks included in the Provenance Aware Synthesis Tracking Architecture (PASTA) underlying the NIS allow us to examine the quality of metadata submitted. Initial records of data use and citation provide the means to evaluate the efficacy of this repository in disseminating data throughout a broader community – 89 citations of data packages found in 52 articles have been documented to date.

HIGHLAND GRASSLANDS AT THE SOUTHERN TIP OF THE ATLANTIC FOREST BIOME: MANAGEMENT OPTIONS AND CONSERVATION CHALLENGES

The natural vegetation in the highlands of the southernmost state of Brazil, Rio Grande do Sul, is characterized by extensive grasslands in mosaics with Araucaria forests, usually under cattle grazing. Plant species diversity and endemism in these grasslands is high, though poorly recognized in conservation policy and the general public, and conversion rates into other land uses are high. In this paper, we give an overview of principal biological features of grassland vegetation in the South Brazilian highland region (plant species richness and diversity) and initiate a debate on conservation possibilities and challenges. We use data from four sites of the Long-Term Ecological Research program (LTER/PELD) Campos Sulinos situated in the highland region of the state, where we explore the effects of different types of grassland management (grazing and grazing exclusion) on vegetation structure and composition. Our data give insight into high species richness on both the plot and site scale. Overall, the results indicate the importance of adequate management for the maintenance of grassland vegetation and its characteristic biological features. In theory, grazing or fire can be employed in grassland management, but specific effects of these two types of management need to be considered, as each type of management has distinct effects. We discuss the question of active nature management in conservation units and highlight the importance of research on restoration of degraded grassland areas. Even though grasslands make up the smaller portion of the South Brazilian Atlantic Forest region, their ecological uniqueness calls for specific conservation policy. Normal 0 false false false EN-US X-NONE X-NONE

Contribución del seguimiento ecológico a largo plazo a la investigación y la gestión en la plataforma LTSER-Doñana

Diaz-Delgado, R., Carro, F., Quiros, F., Osuna, A., Baena, M. 2016. Contribution from Long-Term Ecological Monitoring to research and management of Donana LTSER Platform. Ecosistemas 25(1): 09-18. Doi.: 10.7818/ECOS.2016.25-1.03 Donana, as a whole, has definitely helped to consolidate ecological monitoring and long-term research in Spain. An integrated approach, combining the efforts of managers and researchers has led to scientific contributions improving the understanding of Donana’s biodiversity and ecosystem functioning. This paper reviews the scientific contributions and management improvements provided by the implementation of a long-term ecological monitoring program and the LTER networking activities. Especially, the paper reviews the contribution of landscape-scale monitoring by remote sensing s.l., with its retrospective and multi-scale analysis capacity; the different monitoring protocols of local populations of primary consumers and their role in the Donana ecosystems; the great effort made to incorporate automatic monitoring by deploying sensors and developments adapted to harsh field conditions; the contributions of the socio-ecological approach to assess the state of conservation and environmental services of the Donana LTSER platform; and finally, the perspective from the management of the program's usefulness when it comes to decision making and the incorporation in international networks LTER. In summary, this review aims to show the different benefits achieved by the implementation of a long-term (socio-)ecological monitoring and research program in Donana.

Assessing resilience in long-term ecological data sets

In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.

MacroSystems Biology: stimulating new perspectives on scaling in ecology

MacroSystems Biology, as a programmatic experiment by the Biological Sciences Directorate at NSF, began in 2010 with the objectives to inventory and to stimulate thinking and research in the U.S. that spans physical scales from the local to the continental. The concept itself was not new, but rather an attempt to expand macroecology, an organism-centric sub-field (sensu Brown and Maurer 1989) to the full range of ecological entities. In fact, the motivation went beyond a ‘‘simple’’ conceptual broadening. The Long-Term Ecological Research Program (LTER) was in its 30th year, with well-established local research sites from the Arctic to the Antarctic to build on, while construction of the National Ecological Observation Network (NEON) had just begun, promising a next 35 years of unprecedented availability of synoptic environmental and ecological data at a continental scale. During this period, genomic techniques were transforming the core of community and ecosystem ecology by bringing massive amounts of microbial data to the table. And at the same time, applications of whole ecosystem flux measurements and remote sensing from increasingly diverse platforms—drones to satellites—were maturing and being used to address fundamental questions. The time just seemed ripe. The articles in this special issue all owe something to that experiment. But it would be a mistake, and highly misleading, to view this one program in isolation. Investments by the Department of Energy in AmeriFlux and various experimental infrastructures (e.g., soil warming plots, FACE, rainfall manipulations), NASA in remote sensing, USDA in its intramural programs, other NSF programs (including Ecosystem Studies, Population and Community Ecology, LTER, Critical Zone Observatories), and many more form a more complete and essential context for the projects described here. Since 2010, MacroSystems itself has supported 42 projects, most of them still active and a number of them (9) represented in this special issue. In short, our inventory uncovered a very large pent-up demand for support enabling research that links local ecological processes with global climate changes, reveals continental patterns of microbial dynamics, explores the consequences of biotic homogenization and species introductions, and explains how micro-environmental conditions around tree seedlings influence the structure of mature forests centuries later. We think there is Special issue: Macrosystems ecology: Novel methods and new understanding of multi-scale patterns and processes.

Snakes for lunch: bird predation on reptiles in a tropical floodplain

Based on collaboration between a wildlife photographer and a scientist, this paper provides novel information and images of predation by birds (Black-necked Storks, White-bellied Sea-Eagles, Whistling Kites) on reptiles (Macleay's Water Snakes, Keelback Snakes, Long-necked Turtles). The observations and photographs come from the wall of Fogg Dam, 60 km east of Darwin, the site of a long-term ecological research program on reptiles and amphibians. Professional ecologists rarely witness predation on their study animals, and this has been true at Fogg Dam despite ≯20 years' continuous research on reptiles at the site. The photographs provide the first specific records of predation upon reptiles by birds in this floodplain ecosystem.