Experimental Evidence for the Desynchronization of Ecosystem Dynamics by Global Change

Ecosystem coupling: A unifying framework to understand the functioning and recovery of ecosystems

Prokaryotic and eukaryotic periphyton responses to warming, nutrient enrichment and small omnivorous fish: A shallow lake mesocosms experiment.

Ecological indicators for aquatic biodiversity, ecosystem functions, human activities and climate change

Reduced herbivory and enhanced nutrient concentrations have both been suggested as probable mechanisms driving phase shifts from coral to algal dominance on tropical reefs. While there is considerable information regarding the effects of herbivores on reefs, there is little experimental evidence of nutrient effects or the interactive effects of both of these factors. This study experimentally tested the role of these factors on benthic community structure on a coral-dominated reef in Hawaii. A randomized factorial block design was used to simultaneously investigate the effects of nutrient enrichment and herbivore exclusion on the development of benthic algal communities on artificial surfaces over a 6-month time period. Total algal biomass was greatest on settlement surfaces exposed to both nutrient enrichment and herbivore exclusion simultaneously. Fleshy algal biomass was greatest on surfaces removed from grazing whereas calcareous biomass was greatest on surfaces exposed to nutrient enrichment. Control surfaces exhibited consistently less total, fleshy and calcareous algal biomass than that on any of the experimental surfaces. Microinvertebrates were most abundant on surfaces within herbivore exclusion treatments but increased in number on all settlement surfaces over time. Sediment accumulation was positively correlated with fleshy algal biomass and was most abundant on surfaces within herbivore exclusion treatments; there was no pattern in sediment accumulation over time. This research demonstrates that on short time scales (less than 6 months), nutrient enrichment and herbivore exclusion can independently and interactively support shifts in benthic algal community structure on a Hawaiian reef.

Critical Zone Science (CZS) represents a powerful confluence of research agendas, tools, and techniques for examining the complex interactions between biotic and abiotic factors located at the interface of the Earth’s surface and shallow subsurface. Earth’s Critical Zone houses and sustains terrestrial life, and its interacting subsystems drive macroecological patterns and processes at a variety of spatial scales. Despite the analytical power of CZS to understand and characterize complicated rate-dependent processes, CZS has done less to capture the effects of disturbance and anthropogenic influences on Critical Zone processes, although some Critical Zone Observatories focus on disturbance and regeneration. Methodological approaches from biogeography and ecology show promise for providing Critical Zone researchers with tools for incorporating the effects of ecological and anthropogenic disturbance into fine-grained studies of important Earth processes. Similarly, mechanistic insights from CZS can inform biogeographical and ecological interpretations of pattern and process that operate over extensive spatial and temporal scales. In this paper, we illustrate the potential for productive nexus opportunities between CZS, biogeography, and ecology through use of an integrated model of energy and mass flow through various subsystems of the Earth’s Critical Zone. As human-induced effects on biotic and abiotic components of global ecosystems accelerate in the Anthropocene, we argue that the long temporal and broad spatial scales traditionally studied in biogeography can be constructively combined with the quantifiable processes of energy and mass transfer through the Critical Zone to answer pressing questions about future trajectories of land cover change, post-disturbance recovery, climate change impacts, and urban hydrology and ecology.

Aims Anthropogenic activities have drastically increased nutrient availability, resulting in declines in species richness in many plant communities. However, most previous studies have explored only species-loss patterns and mechanisms over small sampling areas, so their results might overestimate species loss at larger spatial scales. The aim of this research was to explore species diversity change patterns and speciesloss rates at multiple scales in alpine meadow communities following nutrient enrichment. Specifically, we asked two closely related questions: (i) do changes in species diversity and species-loss patterns differ among spatial scales? and (ii) how does community compositional dissimilarity and species turnover change among spatial scale? Methods This study was implemented in an alpine meadow community, which is regarded as one of the most sensitive and vulnerable terrestrial ecosystems to anthropogenic nutrient enrichment. We conducted a fertilization experiment that involved the addition of nitrogen (N), phosphorus (P) and a mixture of both to a series of quadrats ranging from 1 to 16 m~2 over 5 years to study the variations in the patterns of species diversity in response to nutrient additions at different spatial scales. Important Findings Our results showed that the changes in species diversity and species loss were dependent on the type of fertilization and the spatial scale. After N and NP fertilization, species diversity significantly decreased at the small scale but not at the large scale, and the rate of species loss decreased as the spatial scale increased. In contrast, the differences between the P addition and control communities were negligible at both the small and large spatial scales. N fertilization caused species to be lost from the small sampling scale, but because different species were lost from different samples, there was an increase in compositional dissimilarity at larger spatial scales, which reduced the total number of species lost when measured at larger scales. These findings highlight spatial scale in evaluating the biodiversity loss after fertilization and suggest that the compositional dissimilarity might play an important role in mediating species loss after fertilization. Our study significantly improved our understanding of changes in species diversity and species loss at different spatial scales under nutrient-enrichment scenarios.

Quantifying the degradation of organic matter in marine sediments: A review and synthesis

<p>The United Nations Sustainable Development Goals (SDGs) promote sustainable development and aim to address multiple challenges including those related to poverty, hunger, inequality, climate change and environmental degradation. Interlinkages between SDGS means there is potential for interactions, synergies and trade-offs between individual goals across multiple temporal and spatial scales. We aim to develop an Integrated Assessment Model (IAM) of a complex deltaic socio-ecological system where opportunities and trade-offs between the SDGs can be analysed. This is designed to inform local/regional policy. We focus on the Sundarban Biosphere Reserve (SBR) within the Indian Ganga Delta. This is home to 5.6 million often poor people with a strong dependence on rural livelihoods and also includes the Indian portion of the world’s largest mangrove forest – the Sundarbans. The area is subject to multiple drivers of environmental change operating at multiple scales (e.g. global climate change and sea-level rise, deltaic subsidence, extensive land use conversion and widespread migration). Here we discuss the challenges of linking models of human and natural systems to each other in the context of local policy decisions and SDG indicators. Challenges include linking processes derived at multiple spatial and temporal scales and data limitations. We present a framework for an IAM, based on the Delta Dynamic Emulator Model (ΔDIEM), to investigate the affects of current and future trends in environmental change and policy decisions within the SBR across a broad range of sub-thematic SDG indicators. This work brings together a wealth of experience in understanding and modelling changes in complex human and natural systems within deltas from previous projects (ESPA Deltas and DECCMA), along with local government and stakeholder expert knowledge within the Indian Ganga Delta.</p>

Bacterioplankton communities are made up of a small set of abundant taxa and a large number of low-abundant organisms (i.e. 'rare biosphere'). Despite the critical role played by bacteria in marine ecosystems, it remains unknown how this large diversity of organisms are affected by human-induced perturbations, or what controls the responsiveness of rare compared to abundant bacteria. We studied the response of a Mediterranean bacterioplankton community to two anthropogenic perturbations (i.e. nutrient enrichment and/or acidification) in two mesocosm experiments (in winter and summer). Nutrient enrichment increased the relative abundance of some operational taxonomic units (OTUs), e.g. Polaribacter, Tenacibaculum, Rhodobacteraceae and caused a relative decrease in others (e.g. Croceibacter). Interestingly, a synergistic effect of acidification and nutrient enrichment was observed on specific OTUs (e.g. SAR86). We analyzed the OTUs that became abundant at the end of the experiments and whether they belonged to the rare (<0.1% of relative abundance), the common (0.1-1.0% of relative abundance) or the abundant (>1% relative abundance) fractions. Most of the abundant OTUs at the end of the experiments were abundant, or at least common, in the original community of both experiments, suggesting that ecosystem alterations do not necessarily call for rare members to grow.

Global change has already had observable effects on ecosystems worldwide, and the accelerated rate of global change is predicted in the future. However, the impacts of global change on the stability of biodiversity have not been systematically studied in terms of both large spatial (continental drift) and temporal (from the last inter-glacial period to the next century) scales. Therefore, we analyzed the current geographical distribution pattern of Plecoptera, a thermally sensitive insect group, and evaluated its stability when coping with global change across both space and time throughout the Mediterranean region—one of the first 25 global biodiversity hotspots. Regional biodiversity of Plecoptera reflected the geography in both the historical movements of continents and the current environmental conditions in the western Mediterranean region. The similarity of Plecoptera assemblages between areas in this region indicated that the uplift of new land and continental drift were the primary determinants of the stability of regional biodiversity. Our results revealed that climate change caused the biodiversity of Plecoptera to slowly diminish in the past and will cause remarkably accelerated biodiversity loss in the future. These findings support the theory that climate change has had its greatest impact on biodiversity over a long temporal scale.

The Australian Great Artesian Basin (GAB) supports a unique and diverse range of ecologically significant groundwater-fed wetland ecosystems termed GAB springs. The springs are of great national and international importance for their ecological, scientific and economic values, and are culturally significant to indigenous Australians. The ecological sustainability of the springs has become uncertain in recent times due to increased mining operations and associated groundwater extractions from the GAB. The impacts of existing water extractions from the time of European settlement, pastoral activities and more recently mining are largely unknown. This situation is compounded by the likelihood of future increasing demand of water extractions for mining operations. The GAB springs are spatially disparate ecosystems located within the arid interior of South Australia, akin to islands in their ecological setting. The springs exhibit a diverse range of geomorphology, hydrogeology, surface expressions and vegetation community composition over a wide range of spatial scales. A suite of remote sensing technologies were used to capture the range of scales of the spring wetlands and their surface expressions. This multi-sensor approach enabled definition of the spatial and temporal responses of dominant plant species, communities and entire wetlands. To validate the suite of satellite and airborne imagery several comprehensive field campaigns were conducted, capturing the variation in spring vegetation communities and surface expressions. This paper provides a review highlighting the sensor synergies that can be drawn from research conducted from the Australian National Water Commission flagship research program, Allocating Water and Maintaining Springs in the Great Artesian Basin, which has developed new spatial and temporal tools for monitoring indicators of GAB spring response to water allocations and land use (Lewis et al., 2013). The main objectives of this study included: mapping the location and elevation of western GAB springs using high-precision DGPS; development of protocols for ground-based image validation data; develop techniques for detection and monitoring of the surface characteristics of spring-fed wetlands and surrounding environments using fine spatial and spectral resolution imagery; define the short and long-term temporal dynamics of the springs of indicative vegetation types and entire wetlands; use these remote sensing techniques to provide objective and quantitative information about the spring environments and ecological processes. The sensors and image analyses employed to address these objectives included: MODIS NDVI time series (annual and seasonal traces of entire wetlands and dominant vegetation types); very high resolution multispectral satellite (detailed delineation of wetland extents using NDVI thresholds) and airborne hyperspectral imagery (detailed discrimination of spring plant communities and surrounding substrate using spectral matching algorithms); supported by concurrent colour digital aerial photography and collection of near-concurrent in-situ ecological and spectral data for image calibration and validation purposes. The main focus of this review paper is to draw synergies from the image analyses and research findings that can uniquely be provided using this suite of image data in combination, over differing temporal and spatial scales, to provide new understanding of the drivers and ecological processes underpinning the springs. The multi-sensor approach revealed for the first time the spatial and temporal responses of these unique ecosystems to changing climatic conditions, land use change and groundwater extractions. Our results reveal that long-term variation is an inherent signature of the wetlands, with distinct phenological responses for differing vegetation species being driven by seasonal temperature and rainfall. In addition the springs were found to change over short time periods (2-3 years) in response to rainfall and land use change, expressed as changing trajectories of outflow channels and inter-connectivity between springs. This research provides a baseline definition of the long-term natural variation within these groundwater-fed ecosystems as well as their short-term responses to land use changes and water extractions. These outcomes provide an ideal platform for developing models to predict responses of these ecosystems to present local anthropogenic changes in the region and to global climate change.

近年来国内森林生态系统服务功能研究较多,但应用价值不高,其科学性受到诸多质疑。从森林水源涵养功能的多尺度内涵、过程以及其计量方法出发,对国内外研究动态和发展趋势进行了总结分析,重新审视森林水源涵养功能的研究意义,探讨森林水源涵养功能的多尺度特征。从森林水源涵养功能作用的空间尺度上看,其拦蓄洪水削减洪峰的功能仅在较小尺度上有效,而调节径流的功能只有当森林土壤的入渗量超过蒸散量时,才可能有更多地下水补给河道径流,进而增加旱季河道流量。同时森林水源涵养功能也具有明显的时间尺度特征,具体表现为在次降水事件中,由于蒸散发量较小,森林水源涵养功能的物质量等于森林不同层次的截留量,在功能上表现为拦蓄降水;在长时间尺度上,由于林地蒸散要耗去大量水分,森林水源涵养功能的物质量等于森林不同层次的截留量减去林地蒸散发量,在功能上表现为净化水质和调节径流。大多数研究仅对单一林分的个别层次蓄水功能进行研究,缺乏流域尺度或者更大空间尺度的森林水源涵养功能研究。建议从区域降尺度到流域或将坡面尺度上推到流域,集中在流域尺度解决森林水源涵养空间异质性将是解决森林水源涵养功能尺度外推的有效办法。就目前国内流行的森林水源涵养功能计量方法而言,其与尺度及研究目的有较大相关性,在研究中应根据研究目的、研究尺度和可获取的数据情况选择合适的计量方法。研究突出了不同尺度作用下森林水文过程的复杂性及重要性,并结合森林与水关系的争论问题,分析目前国内对森林水源涵养功能研究的一些误区,提出森林水源涵养功能研究的一些关键科学问题及未来可能的发展方向,主要包括:1)明确界定森林水源涵养功能的边界,探索森林水源涵养功能计量的新方法;2)加强不同时空尺度关联的森林水源涵养功能研究,包括正确评价森林水源涵养功能的时空变异规律,森林生态系统水源涵养功能的尺度效应,森林水源涵养与下游水生态安全,森林水源涵养研究范式转变等核心问题。;Forest water conservation as an important ecosystem function has caused a rising interests in the scientific community in recent years. However, there remain some arguments in several aspects regarding the forest water conservation function. For the concept of the forest water conservation, there is no clear definition about its connotation. Another concern is the scaling issue. It is a challenge to scale up the estimation for the forest water conservation from the plot scale to larger scale, e.g., watershed scale or regional scale. Many quantification methods have been developed, but their suitability, performance, advantages and disadvantages are unknown. Many of such argument issues are significant limits of the forest water conservation in science and management. On the basis of the literature review, we clarify the important role of the water conservation in forest ecosystem function. We also summarize and analyze the concepts of the forest water conservation and its multi-scale connotation, processes and quantification methods. On the spatial scale, function of the forest in mitigating peak flow is effective at a smaller scale but not necessarily at a larger scale. More groundwater recharges into stream flow when forest soil infiltration exceeds evapotranspiration, thus increasing stream flow in the dry season. During a rainfall event, forest water conservation has different features at different temporal scales. For example, the amount of the forest conservation during a rainfall event dominates by the forest canopy interception and most water is stored in the forest due to less evapotranspiration in the rainfall event scale. At the longer temporal scale, the forest water conservation can be determined by the forest canopy interception subtracting evapotranspiration. The functional roles of the forest water conservation at longer temporal scale dominate by purifying water from natural rainfall and mitigating seasonal flow peaks of the river discharges. Most previous studies of the forest water conservation focused on water storage function at the plot scale, but lack better understanding in the forest water conservation function at the watershed or regional scales. We suggest the approach that combines downscaling from the regional to watershed scales and upscaling from the hillside to the watershed scales can an effective way of the scale extrapolation. This idea can be used to address the heterogeneity issue of the forest water conservation function at different spatio-temporal scales. Among the existing quantification approaches of the forest water conservation function, each one highly relies on the temporal and spatial scales and its application goal. An appropriate calculation method should be carefully evaluated and considered based on the objectives, data availability, temporal and spatial scales of each study case. The suitability difference in different calculation methods of the forest water conservation demonstrates the complexity and importance of the multi-scale consideration in forest hydrological processes. In the context of the long-term debates about the relationship between the forest and water, we figure out a few confusing points in the current studies of the forest water conservation function. We also propose the critical scientific questions that should be addressed and a few directions in future studies of forest water conservation function including: 1) to clearly define the connotation and boundary of the forest water conservation function, and develop innovatory methods for determining the forest water conservation function; 2) to pay more attentions on the forest water conservation function studies associated with the different spatial and temporal scales, including evaluation of the spatio-temporal variations in forest water conservation function, the scaling effects on estimation of the water conservation function, the trade-off relationship between the upstream forest water conservation and the downstream ecological water need, and the development of the innovatory ways of forest water conservation practices.

This study focused on the structure of the aquatic insect community in spatial and temporal scales in the Esparza River. The river was sampled for one full year throughout 2007. During the dry season low flow months, five sampling points were selected in two different habitats (currents and pools), with five replicates per sample site. During the wet season with peak rain, only the data in the "current habitat" were sampled at each site. Specimens present in the different substrates were collected and preserved in situ. A nested ANOVA was then applied to the data to determine richness and density as the response variables. The variations in temporal and spatial scales were analyzed using width, depth and discharge of the river, and then analyzed using a nested ANOVA. Only a correlation of 51% similarity in richness was found, while in spatial scale, richness showed significant variation between sampling sites, but not between habitats. However, the temporal scale showed significant differences between habitats. Density showed differences between sites and habitats during the dry season in the spatial scale, while in the temporal scale significant variation was found between sampling sites. Width varied between habitats during the dry season, but not between sampling points. Depth showed differences between sampling sites and season. This work studies the importance of community structure of aquatic insects in rivers, and its relevance for the quality of water in rivers and streams.

The mechanisms by which variability in sea ice cover and its effects on the demography of the Antarctic krill Euphausia superba cascade to other ecosystem components such as apex preda- tors remain poorly understood at all spatial and temporal scales, yet these interactions are essential for understanding causal links between climate change, ecosystem response and resource monitor- ing and management in the Southern Ocean. To address some of these issues, we examined the long- term foraging responses of Adelie penguins Pygoscelis adeliae near Palmer Station, western Antarc- tic Peninsula, in relation to ice-induced changes in krill recruitment and availability. Our results suggest that (1) there is a direct, causal relationship between variability in ice cover, krill recruitment, prey availability and predator foraging ecology, (2) regional patterns and trends detected in this study are consistent with similar observations in areas as far north as South Georgia, and (3) large- scale forcing associated with the Antarctic Circumpolar Wave may be governing ecological inter- actions between ice, krill and their predators in the western Antarctic Peninsula and Scotia Sea regions. Another implication of our analyses is that during the last 2 decades in particular, krill pop- ulations have been sustained by strong age classes that emerge episodically every 4 to 5 yr. This raises the possibility that cohort senescence has become an additional ecosystem stressor in an envi- ronment where ice conditions conducive to good krill recruitment are deteriorating due to climate warming. In exploring these interactions, our results suggest that at least 1 'senescence event' has already occurred in the western Antarctic Peninsula region, and it accounts for significant coherent decreases in krill abundance, predator populations and predator foraging and breeding perfor- mance. We propose that krill longevity should be incorporated into models that seek to identify and understand causal links between climate change, physical forcing and ecosystem response in the western Antarctic Peninsula region.

1. Coastal ecology is mostly regulated by hydro-meteorological factors and human disturbances. The spatial and temporal scales of variation of the processes associated with these factors may not correlate. 2. Monitoring of water and ecosystem quality in the coastal zone must be performed at spatial and temporal scales that adequately address the objectives. They range between two extreme states, i.e. high water turnover due to surface water exchanges and evaporation driven turnover, and can cover a range of ecological situations depending on hydrological variables. 3. The spatial scale for monitoring coastal aquatic ecosystems may be better related to water masses circulation than to physiographic features. Biologically mediated processes require monitoring taking account of meteorological, seasonal and interannual time scales. 4. Variables to be monitored must be in accordance with objectives. They may range from intra-compartment variables (e.g. demography of a biological population) to inter-zone relationships (e.g. budgets of nutrient exchange with the sea). Larger and longer scales, such as including buffer zones around lagoons and the continental and sea basins, and the consideration of interdecadal and secular time scales are required for wider monitoring perspectives. 5. Monitoring the impacts of global changes (both direct, such as urbanization and eutrophication of the coastal zone, and indirect, through relative sea-level rise due to climate change) requires a wider conceptual scale of approach to coastal zone ecology and even longer monitoring programmes. Copyright © 2004 John Wiley & Sons, Ltd.