Long-Term Ecological Research Site Research Articles

Do Terrestrial Salamanders Indicate Ecosystem Changes in New England Forests?

Long-term ecological research (LTER) and monitoring programs accrue invaluable ecological data that inform policy and improve decisions that enable adaptation to and mitigation of environmental changes. There is great interest in identifying ecological indicators that can be monitored easily and effectively to yield reliable data about environmental changes in forested ecosystems. However, the selection, use, and validity of ecological indicators to monitor in LTER programs remain challenging tasks for ecologists and conservation biologists. Across the eastern United States of America, the foundation tree species eastern hemlock (Tsuga canadensis (L.) Carrière) is declining and dying from irruptions of a non-native insect, the hemlock woolly adelgid (Adelges tsugae Annand). We use data from the Harvard Forest LTER site’s Hemlock Removal Experiment together with information from other eastern US LTER sites to show that plethodontid salamanders can be reliable indicators of ongoing ecological changes in forested ecosystems in the eastern USA. These salamanders are abundant, they have a history of demographic stability, are both predators and prey, and can be sampled and monitored simply and cost-effectively. At the Harvard Forest LTER, red-backed salamanders (Plethodon cinereus Green) were strong indicators of intact forests dominated by eastern hemlock (Tsuga canadensis); their high site fidelity and habitat specificity yielded an indicator value (robust Dufrêne and Legendre’s “IndVal”) for this species of 0.99. Eastern red-spotted newts (Notopthalmus viridescens viridescens Rafinesque) were better indicators of nearby stands made up of young, mixed hardwood species, such as those which replace hemlock stands following adelgid infestation. At the Hubbard Brook and Coweeta LTER sites, plethodontid salamanders were associated with intact riparian habitats, which may also be dominated by eastern hemlock. We conclude that plethodontid salamanders satisfy most criteria for reliable ecological indicators of environmental changes in eastern US forests.

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.

Species richness and endemism of Reptilian Fauna in four Long-Term Ecological Research sites in Mindanao, Philippines

Species richness and endemism of Reptilian Fauna in four Long-Term Ecological Research sites in Mindanao, Philippines

Monitoring of soil moisture in Long-Term Ecological Research (LTER) sites of Romanian Carpathians

Understanding soil moisture and its relationship with different climatic and soil characteristics is essential for better analysing the interactions between forest and soil water dynamics, allowing us to more precisely predict climatic changes. The present paper investigates the temporal variability of soil moisture in three different forest ecosystems (LTER – long term ecological research site) with the same soil type (Eutric Cambisol). Soil moisture was measured daily from 2011 to 2016 by using three sensors at three different depths (20, 40, 70 cm). We identified the interactions between soil properties, vegetation type, local climatic conditions and soil moisture. In order to establish the temporal variability of the soil moisture content, we have applied two procedures, namely the Fourier series and the neural network fitting. A high variability in time and depth for soil volumetric water content was identified. The highest soil moisture levels were recorded at higher depths (70 cm) for almost all surfaces, with the exception of the Fundata surface because of the occurrence of limestone. In the mountainous areas, with higher precipitation (Fundata and Predeal sites), volumetric soil water content was mainly influenced by soil physical characteristics. Soil moisture levels below the drought level were only recorded for the Stalpeni site from September to October 2012. There was a delay between the precipitation event and soil humidification of 0.4-0.8 time units (days). We also found a significant correlation between soil moisture and soil texture and a weak correlation with vegetation type. Temperature influenced soil moisture levels at almost all depths, while precipitation only had an impact when there was a delay of 1 or 2 days. Our results can serve as a scientific base in the monitoring and analysing of soil moisture against the background of a changing climate.

Rapid Assessment of Ecological Integrity for LTER Wetland Sites by Using UAV Multispectral Mapping

Long-term ecological research (LTER) sites need a periodic assessment of the state of their ecosystems and services in order to monitor trends and prevent irreversible changes. The ecological integrity (EI) framework opens the door to evaluate any ecosystem in a comparable way, by measuring indicators on ecosystem structure and processes. Such an approach also allows to gauge the sustainability of conservation management actions in the case of protected areas. Remote sensing (RS), provided by satellite, airborne, or drone-borne sensors becomes a very synoptic and valuable tool to quickly map isolated and inaccessible areas such as wetlands. However, few RS practical indicators have been proposed to relate to EI indicators for wetlands. In this work, we suggest several RS wetlands indicators to be used for EI assessment in wetlands and specially to be applied with unmanned aerial vehicles (UAVs). We also assess the applicability of multispectral images captured by UAVs over two long-term socio-ecological research (LTSER) wetland sites to provide detailed mapping of inundation levels, water turbidity and depth as well as aquatic plant cover. We followed an empirical approach to find linear relationships between UAVs spectral reflectance and the RS indicators over the Doñana LTSER platform in SW Spain. The method assessment was carried out using ground-truth data collected in transects. The resulting empirical models were implemented for Doñana marshes and can be applied for the Braila LTSER platform in Romania. The resulting maps are a very valuable input to assess habitat diversity, wetlands dynamics, and ecosystem productivity as frequently as desired by managers or scientists. Finally, we also examined the feasibility to upscale the information obtained from the collected ground-truth data to satellite images from Sentinel-2 MSI using segments from the UAV multispectral orthomosaic. We found a close multispectral relationship between Parrot Sequoia and Sentinel-2 bands which made it possible to extend ground-truth to map inundation in satellite images.

Mapping foliar functional traits and their uncertainties across three years in a grassland experiment

Foliar functional traits refer to a range of biochemical and physiognomic characteristics of vegetation that control photosynthesis, nutrient and water cycling, and can be used to describe the functional diversity of ecosystems. In this study, we utilize NASA AVIRIS - Next Generation imaging spectroscopy data to map 15 foliar functional traits in a grassland experiment at the Cedar Creek Ecosystem Science Reserve, a Long-Term Ecological Research site in Central Minnesota, across three years. To estimate traits, we compared the widely used partial least squares regression (PLSR) with Gaussian processes regression (GPR) to assess differences in model performance and uncertainty estimates. PLSR is attractive for its straightforward implementation and interpretation, but requires bootstrapping-based methods to estimate and map prediction uncertainties. On the other hand, GPR is more complex to implement and interpret, but provides explicit estimates of uncertainties. Our results indicated that foliar functional traits can be retrieved in these grasslands with moderate to high accuracies using either method. Highest validation accuracies were obtained for leaf mass per area (LMA), soluble cell contents, hemicellulose and cellulose (all with R2 > 0.8), and lower accuracies for lignin, nitrogen, and some pigments with both techniques. The estimations for the mass-based pigments were more accurate than the area-based pigments (at least 5% improvement in normalized RMSE). Overall, GPR and PLSR performed comparably with respect to both skill of predictions and the selection of most informative spectral regions. Maps of uncertainties corresponded well between the two models, with highest uncertainties related to low vegetation cover, high diversity levels, or under irrigation and nitrogen treatments (not represented in the field sampling). The maps showed that trait values in each plot were relatively stable across three years of managed species richness. Our results provide a template for mapping foliar traits and their uncertainties in grasslands, and point to the need for extensive ground data across time to properly evaluate performance of trait mapping algorithms.

Litterfall Production and Turnover in the Long-Term Ecological Research Sites in Southern Philippines

Mt. Apo, Mt. Hamiguitan, Mt. Musuan, oven-dry weight, tropical forests

Molecular analyses of protists in long-term observation programmes—current status and future perspectives

Protists (microbial eukaryotes) are diverse, major components of marine ecosystems, and are fundamental to ecosystem services. In the last 10 years, molecular studies have highlighted substantial novel diversity in marine systems including sequences with no taxonomic context. At the same time, many known protists remain without a DNA identity. Since the majority of pelagic protists are too small to identify by light microscopy, most are neither comprehensively or regularly taken into account, particularly in Long-term Ecological Research Sites. This potentially undermines the quality of research and the accuracy of predictions about biological species shifts in a changing environment. The ICES Working Group for Phytoplankton and Microbial Ecology conducted a questionnaire survey in 2013–2014 on methods and identification of protists using molecular methods plus a literature review of protist molecular diversity studies. The results revealed an increased use of high-throughput sequencing methods and a recognition that sequence data enhance the overall datasets on protist species composition. However, we found only a few long-term molecular studies and noticed a lack of integration between microscopic and molecular methods. Here, we discuss and put forward recommendations to improve and make molecular methods more accessible to Long-term Ecological Research Site investigators.

Dust, impure calcite, and phytoliths: Modeled alternative sources of chemical weathering solutes in shallow groundwater

In highly reactive, carbonate terrains that constitute more than one-fifth of critical zone landscapes, quantifying bedrock weathering processes may require understanding the realities of carbonate mineral impurity on solubility, biotically-produced minerals as an integral part of leaky biogeochemical cycles, and dust-deposited minerals as important high-surface-area, first-contact solute sources. The potential impact of these processes has not been thoroughly investigated as groundwater solutes are mostly thought to be sourced from chemical reactions with soil and bedrock, although dust is often viewed as an important delivery mechanism of nutrients to other ecosystems, including those in mountain and tropical settings. We present results of computer and hand-calculated (manual) inverse modeling of two years of stream-water chemistry, spanning a dry and a wet year, for a groundwater-fed headwater stream at the Konza Tallgrass Prairie Long-Term Ecological Research Site in northeastern Kansas. Weathering of the limestone and shale bedrock at the site provide a possible source of solutes to the groundwater-fed stream, but our modeling suggests an alternate source considering the pathway of groundwater recharge likely encounters highly reactive phases before encountering bedrock. We used the mineralogy and geochemistry of local dust collected previously, estimates of a possible chemical composition of phytolith containing potassium, and an impure calcite representing measured limestone bedrock chemistry to show that chemical reactions with the current dust flux are adequate to account for the groundwater chemistry. Average annual amounts were about: 1) 380 kg ha−1 yr−1 dust dissolved, 2) 80 kg ha−1 yr−1 bedrock carbonate dissolved, and 3) 320 kg ha−1 yr−1 phytoliths precipitated. Small amounts of cation exchange were also required to balance the models. There were only small differences between the computer and manual inverse models; both methods resulted in up to 4.6 times more mass of dust dissolved than bedrock. We suggest that dust weathering may be a process that occurs widely, considering the ubiquitous dust flux in continental regions. Significance of researchSolutes in groundwater and in streams fed by groundwater are thought to be mostly derived from aquifer bedrock and soil water recharging the aquifer. This paradigm may fail for landscapes that have been subaerially exposed for 10's to 100's of millions of years in terrains where relatively rapid dissolution of minerals dominates, such as carbonate-mineral dominated rocks like limestone. Here we test whether dust, having high surface area and being the first inorganic solid encountered by meteoric precipitation, could provide enough solutes water to reduce the amount of bedrock that dissolves, extending the timeframe of landscape evolution. We found, through inverse modeling with PHREEQC, that dust can provide 4.6 times as much mass to stream water in merokarst than calcite and that the mass of dust dissolved was the same order of magnitude as local dust deposition. These results give permissive evidence that dust is important to understanding groundwater chemistry.

Declines in methane uptake in forest soils

Forest soils are a sink for atmospheric methane (CH4) and play an important role in modulating the global CH4 budget. However, whether CH4 uptake by forest soils is affected by global environmental change is unknown. We measured soil to atmosphere net CH4 fluxes in temperate forests at two long-term ecological research sites in the northeastern United States from the late 1990s to the mid-2010s. We found that annual soil CH4 uptake decreased by 62% and 53% in urban and rural forests in Baltimore, Maryland and by 74% and 89% in calcium-fertilized and reference forests at Hubbard Brook, New Hampshire over this period. This decrease occurred despite marked declines in nitrogen deposition and increases in atmospheric CH4 concentration and temperature, which should lead to increases in CH4 uptake. This decrease in soil CH4 uptake appears to be driven by increases in precipitation and soil hydrological flux. Furthermore, an analysis of CH4 uptake around the globe showed that CH4 uptake in forest soils has decreased by an average of 77% from 1988 to 2015, particularly in forests located from 0 to 60 °N latitude where precipitation has been increasing. We conclude that the soil CH4 sink may be declining and overestimated in several regions across the globe.

Chemical and Physical Properties of Soils in Mt. Apo and Mt. Hamiguitan, Mindanao, the Philippines

Aims: The study was aimed to determine the edaphic qualities of two Long-Term Ecological Research (LTER) sites in Mindanao; Mt Apo in Cotabato and Mt. Hamiguitan in Davao Oriental, the Philippines
 Study Design: Random soil sampling within the plots
 Place and Duration of Study: Analyses of the soil samples collected from each site were performed at Soil and Plant Analysis Laboratory (SPAL), Central Mindanao University, Musuan, Bukidnon, the Philippines from October, 2012 to December 2013.
 Methodology: One hectare permanent plot was established in each site. Soil profile description was done in a pit measuring 1m wide, 1.5m long and 1m deep in each site. Soil samples for physicochemical characterization were collected within the plot. Soil physical properties included bulk density, particle density, soil texture and water holding capacity while the chemical properties included soil pH, organic matter, extractable P and exchangeable K contents using the methods employed at SPAL.
 Results: Results showed that the soils in Mt. Apo were extremely to very strongly acidic, had very high organic matter contents, slightly deficient to very deficient in extractable P, low to very high exchangeable K content, low particle and bulk density values, high porosity, moderate water holding capacity and moderately coarse to moderately fine-textured soils belonging to loamy textural class. On the other hand, the soils in Mt. Hamiguitan were slightly to very strongly acidic, contained adequate organic matter content, low extractable P, low exchangeable K, low particle and bulk density values, high porosity, moderate water holding capacity and are moderately fine to fine-textured belonging to loamy and clay textural classes. Generally, soils in Mt. Apo were more acidic but with relatively higher fertility status and comparable physical make-up with the soils in Mt. Hamiguitan.
 Conclusion: It was found that both sites have some soil constraints, particularly in terms of soil acidity and low nutrient availability to plants. Information obtained on this study revealed that identification of soil constraints are indispensable in formulating proper land use and conservation program.

Dealing with impact. An interdisciplinary, multi-site ethnography of environmental impact assessment in the coastal zone

The SPA (“Savoir, Pouvoir, Avoir”) project (CNRS, 2017-2019) presented in this article focuses on the ways French society deals with the issue of environmental impact – from the vast question of impact in the context of global change and the issue of the measurement of impact in science, to the specific case of the public policy instrument known as “environmental impact assessment”. Impact is considered as a boundary object at the intersection of several fields of inquiry which captures both the architecture and the dynamics of relationships between “savoir” (scientific and lay knowledge), “pouvoir” (power and decision) and “avoir” (economy/appropriation), that aggregate different interests around the sustainable management of coastal socio-ecological systems. Three sites were selected along a north-south gradient of Long-Term Ecological Research sites: the Bay of Brest and the Iroise Sea, the National Nature Reserve of the French islands in the Southern Ocean and the overseas collectivity of Saint Pierre and Miquelon. The approach of the SPA project is to link concretely social sciences, natural sciences and engineering sciences on these study sites, in an interdisciplinary, multi-site and multi-scale methodology that makes it possible to reveal the conditions for the possible – or impossible – implementation of sustainable management of coastal socio-ecological systems.

Modelling study of soil C, N and pH response to air pollution and climate change using European LTER site observations

Current climate warming is expected to continue in coming decades, whereas high N deposition may stabilize, in contrast to the clear decrease in S deposition. These pressures have distinctive regional patterns and their resulting impact on soil conditions is modified by local site characteristics. We have applied the VSD+ soil dynamic model to study impacts of deposition and climate change on soil properties, using MetHyd and GrowUp as pre-processors to provide input to VSD+. The single-layer soil model VSD+ accounts for processes of organic C and N turnover, as well as charge and mass balances of elements, cation exchange and base cation weathering. We calibrated VSD+ at 26 ecosystem study sites throughout Europe using observed conditions, and simulated key soil properties: soil solution pH (pH), soil base saturation (BS) and soil organic carbon and nitrogen ratio (C:N) under projected deposition of N and S, and climate warming until 2100. The sites are forested, located in the Mediterranean, forested alpine, Atlantic, continental and boreal regions. They represent the long-term ecological research (LTER) Europe network, including sites of the ICP Forests and ICP Integrated Monitoring (IM) programmes under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP), providing high quality long-term data on ecosystem response. Simulated future soil conditions improved under projected decrease in deposition and current climate conditions: higher pH, BS and C:N at 21, 16 and 12 of the sites, respectively. When climate change was included in the scenario analysis, the variability of the results increased. Climate warming resulted in higher simulated pH in most cases, and higher BS and C:N in roughly half of the cases. Especially the increase in C:N was more marked with climate warming. The study illustrates the value of LTER sites for applying models to predict soil responses to multiple environmental changes.

Global-change effects on early-stage decomposition processes in tidal wetlands – implications from a global survey using standardized litter

Abstract. Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over the global carbon cycle and at the same time gain elevation to keep pace with sea-level rise (SLR). The present study assessed the effects of temperature and relative sea level on the decomposition rate and stabilization of OM in tidal wetlands worldwide, utilizing commercially available standardized litter. While effects on decomposition rate per se were minor, we show strong negative effects of temperature and relative sea level on stabilization, as based on the fraction of labile, rapidly hydrolyzable OM that becomes stabilized during deployment. Across study sites, OM stabilization was 29 % lower in low, more frequently flooded vs. high, less frequently flooded zones. Stabilization declined by ∼ 75 % over the studied temperature gradient from 10.9 to 28.5 ∘C. Additionally, data from the Plum Island long-term ecological research site in Massachusetts, USA, show a pronounced reduction in OM stabilization by > 70 % in response to simulated coastal eutrophication, confirming the potentially high sensitivity of OM stabilization to global change. We therefore provide evidence that rising temperature, accelerated SLR, and coastal eutrophication may decrease the future capacity of tidal wetlands to sequester carbon by affecting the initial transformations of recent OM inputs to soil OM.

Weather conditions and chlorophyll concentrations determine long-term macrophyte community dynamics of Lake Bohinj (Slovenia)

Lake Bohinj is a Long-term Ecological Research (LTER) site. This contribution discusses the environmental factors that define the macrophyte community of Lake Bohinj and explains the observed long-term trends in the species present and their abundance and depth distributions from 1996 to 2016. These macrophyte parameters are related to water quality parameters (i.e. total nitrogen and phosphorus, chlorophyll a, water transparency) and meteorological parameters (i.e. precipitation rate, monthly temperature, hours of solar radiation and frequency of storm events per month). We determined 10 submerged macrophyte species, with the stonewort Chara aspera and Eurasian watermilfoil Myriophyllum spicatum prevailing. The variability in the chemical parameters of the water in Lake Bohinj over the study period was low, while the regional air temperatures in the peak season were increasing (R2 = 0.56). Cumulative macrophyte abundance revealed a decreasing trend in the studied period, while the maximal depth distribution was less affected. Cumulative macrophyte abundance was positively related to total nitrogen (r = 0.67) and maximal chlorophyll a concentrations (r = 0.59), while negatively to total phosphorus (r = − 0.56) and minimal transparency (r = 0.63). Redundancy correspondence analysis (RDA) run with the water quality parameters revealed the importance of the maximal chlorophyll a concentrations in the lake water, which explained 54% of variability in the species composition and abundance, followed by total nitrogen that explained additional 10%. Regarding their maximum depth distribution, only 22% of its variability was explained by maximal chlorophyll a concentrations. RDA run with the meteorological data showed the importance of temperature in July in explaining the variability of the species present and their abundance and depth distribution. The study revealed differences in macrophyte community structure during the experimental period, even though during the monitoring period, annual averages of water quality parameters had never exceeded the values, indicating oligotrophic conditions according to the criteria of Organisation for Economic Co-operation and Development. This study points out the importance of macrophytes for assessing the ecological status of lakes and a need for detailed survey of direct disturbances into the lake littoral.

Spores and soil from six sides: interdisciplinarity and the environmental biology of anthrax (Bacillus anthracis).

Environmentally transmitted diseases are comparatively poorly understood and managed, and their ecology is particularly understudied. Here we identify challenges of studying environmental transmission and persistence with a six-sided interdisciplinary review of the biology of anthrax (Bacillus anthracis). Anthrax is a zoonotic disease capable of maintaining infectious spore banks in soil for decades (or even potentially centuries), and the mechanisms of its environmental persistence have been the topic of significant research and controversy. Where anthrax is endemic, it plays an important ecological role, shaping the dynamics of entire herbivore communities. The complex eco-epidemiology of anthrax, and the mysterious biology of Bacillus anthracis during its environmental stage, have necessitated an interdisciplinary approach to pathogen research. Here, we illustrate different disciplinary perspectives through key advances made by researchers working in Etosha National Park, a long-term ecological research site in Namibia that has exemplified the complexities of the enzootic process of anthrax over decades of surveillance. In Etosha, the role of scavengers and alternative routes (waterborne transmission and flies) has proved unimportant relative to the long-term persistence of anthrax spores in soil and their infection of herbivore hosts. Carcass deposition facilitates green-ups of vegetation to attract herbivores, potentially facilitated by the role of anthrax spores in the rhizosphere. The underlying seasonal pattern of vegetation, and herbivores' immune and behavioural responses to anthrax risk, interact to produce regular 'anthrax seasons' that appear to be a stable feature of the Etosha ecosystem. Through the lens of microbiologists, geneticists, immunologists, ecologists, epidemiologists, and clinicians, we discuss how anthrax dynamics are shaped at the smallest scale by population genetics and interactions within the bacterial communities up to the broadest scales of ecosystem structure. We illustrate the benefits and challenges of this interdisciplinary approach to disease ecology, and suggest ways anthrax might offer insights into the biology of other important pathogens. Bacillus anthracis, and the more recently emerged Bacillus cereus biovar anthracis, share key features with other environmentally transmitted pathogens, including several zoonoses and panzootics of special interest for global health and conservation efforts. Understanding the dynamics of anthrax, and developing interdisciplinary research programs that explore environmental persistence, is a critical step forward for understanding these emerging threats.

The importance of leaf area index in mapping chlorophyll content of corn under different agricultural treatments using UAV images

ABSTRACTThe impact of structural parameters of agricultural crops on the retrieval of chlorophyll content presents a real challenge for the remote-sensing community. Canopy reflectance can differ between crops of different canopy structure even when they have the same canopy chlorophyll content. Thus, structural properties should be incorporated in chlorophyll mapping to reduce modelling errors. The empirical relationships between vegetation indices and chlorophyll content are well established and commonly used in precision agriculture. Recent advances in using unmanned aerial vehicle (UAV/drone) technology offer successful retrieval of crop structural and biochemical parameters. However, transfer of empirical algorithms derived from satellite to UAV-based analyses introduces new challenges mainly due to fine spatial resolution and details such as crop rows and between- and within-canopy gaps that are more pronounced in UAV images. There are two components of the analysis in this study. The first part is related to heterogeneity of leaf area index (LAI) and chlorophyll content of corn under four agricultural treatments (conventional ploughed, conventional with no tilling, biological with reduced chemical inputs, and certified organic) at the Kellogg Biological Station Long-Term Ecological Research (KBS LTER) site in Michigan, USA. The second part examines the necessity and importance of LAI in chlorophyll mapping using UAV images collected over the heterogeneous KBS LTER parcels at peak growing season. The UAV-derived normalized difference red edge index (NDRE) is found to be highly correlated with canopy chlorophyll, calculated as a product of leaf chlorophyll content and LAI. The coefficient of determination changes from R2 = 0.177 to R2 = 0.774 when LAI is added to the empirical model. NDRE is also found to be highly correlated with LAI (R2 = 0.620). The findings suggest that the conventional corn treatment with no-tilled soil exhibits the highest crop vigour during the peak growing season. The herbicide management applied earlier in the season may have a strong effect on weeds, reducing the crop–weeds competition for nutrients.

Comparative analysis of the ecosystems in the northern Adriatic Sea and the Inland Sea of Japan: Can anthropogenic pressures disclose jellyfish outbreaks?

A prominent increase in the moon jellyfish (genus Aurelia) populations has been observed since 1980 in two semi-enclosed temperate seas: the northern Adriatic Sea and the Inland Sea of Japan. Therefore, we reviewed long-term environmental and biotic data from the two Long-Term Ecological Research (LTER) sites, along with the increase in the moon jellyfish occurrence to elucidate how these coastal seas shifted to the jellyfish-dominated ecosystems. The principal component analysis of atmospheric data revealed a simultaneous occurrence of similar climatic changes in the early 1980s; thereafter, air temperature increased steadily and precipitation decreased but became more extreme. Accordingly, the average seawater temperature from March to October, a period of polyps' asexual reproduction i.e. budding, increased, potentially leading to an increase in the reproductive rates of local polyp populations. Conspicuous eutrophication occurred due to the rise of anthropogenic activities in both areas from the 1960s onwards. This coincided with an increase of the stock size of forage fishes, such as anchovy and sardine, but not the population size of the jellyfish. However, by the end of the 1980s, when the eutrophication lessened due to the regulations of nutrients loads from the land, the productive fishing grounds of both systems turned into a state that may be described as ‘jellyfish-permeated,’ as manifested by a drastic decrease in fish landings and a prominent increase in the intensity and frequency of medusa blooms. A steady increase in artificial marine structures that provide substrate for newly settled polyps might further contribute to the enhancement of jellyfish population size. Elevated fishing pressure and/or predation by jellyfish on ichthyoplankton and zooplankton might jeopardize the recruitment of anchovy, so that the anchovy catch has never recovered fully. These semi-enclosed seas may represent many temperate coastal waters with increased anthropogenic stressors, which have degraded the ecosystem from fish-dominated to jellyfish-dominated.

The potential to characterize ecological data with terrestrial laser scanning in Harvard Forest, MA.

Contemporary terrestrial laser scanning (TLS) is being used widely in forest ecology applications to examine ecosystem properties at increasing spatial and temporal scales. Harvard Forest (HF) in Petersham, MA, USA, is a long-term ecological research (LTER) site, a National Ecological Observatory Network (NEON) location and contains a 35 ha plot which is part of Smithsonian Institution's Forest Global Earth Observatory (ForestGEO). The combination of long-term field plots, eddy flux towers and the detailed past historical records has made HF very appealing for a variety of remote sensing studies. Terrestrial laser scanners, including three pioneering research instruments: the Echidna Validation Instrument, the Dual-Wavelength Echidna Lidar and the Compact Biomass Lidar, have already been used both independently and in conjunction with airborne laser scanning data and forest census data to characterize forest dynamics. TLS approaches include three-dimensional reconstructions of a plot over time, establishing the impact of ice storm damage on forest canopy structure, and characterizing eastern hemlock (Tsuga canadensis) canopy health affected by an invasive insect, the hemlock woolly adelgid (Adelges tsugae). Efforts such as those deployed at HF are demonstrating the power of TLS as a tool for monitoring ecological dynamics, identifying emerging forest health issues, measuring forest biomass and capturing ecological data relevant to other disciplines. This paper highlights various aspects of the ForestGEO plot that are important to current TLS work, the potential for exchange between forest ecology and TLS, and emphasizes the strength of combining TLS data with long-term ecological field data to create emerging opportunities for scientific study.

Long-term environmental monitoring infrastructures in Europe: observations, measurements, scales, and socio-ecological representativeness

The challenges posed by climate and land use change are increasingly complex, with ever-increasing and accelerating impacts on the global environmental system. The establishment of an internationally harmonized, integrated, and long-term operated environmental monitoring infrastructure is one of the major challenges of modern environmental research. Increased efforts are currently being made in Europe to establish such a harmonized pan-European observation infrastructure, and the European network of Long-Term Ecological Research sites – LTER-Europe – is of particular importance. By evaluating 477 formally accredited LTER-Europe sites, this study gives an overview of the current distribution of these infrastructures and the present condition of long-term environmental research in Europe. We compiled information on long-term biotic and abiotic observations and measurements and examined the representativeness in terms of continental biogeographical and socio-ecological gradients. The results were used to identify gaps in both measurements and coverage of the aforementioned gradients. Furthermore, an overview of the current state of the LTER-Europe observation strategies is given. The latter forms the basis for investigating the comparability of existing LTER-Europe monitoring concepts both in terms of observational design as well as in terms of the scope of the environmental compartments, variables and properties covered.