Reduction Of Ecosystem Services Research Articles

Elucidating the Consequences of a Warming Climate for Common Bat Species in North-Western Europe

Climate change presents a serious threat to global biodiversity. In the extreme north of Europe, for example, some boreal bat species have been predicted to become extinct by the end of the century. We have used bat activity data derived from car-based surveys across Ireland to examine the effects of weather and climate using an approach that teases apart their spatial and temporal effects. This allows more accurate modelling of the impacts of weather than has heretofore been possible. Our results also support previous work that suggests the standard approach for combining the spatio-temporal variation in weather covariates is unsound. We used the results of this modelling exercise to forecast the effects of predicted climate change on three widespread Irish species for the years 2046–2059. Nyctalus leisleri, in its international stronghold, is predicted to undergo a decline in the north-west with increases likely in the south-east. Pipistrellus pipistrellus is predicted to undergo similar changes to N. leisleri, with declines in the north. Pipistrellus pygmaeus may increase in coastal locations. Predicted declines in the north of Ireland run somewhat contrary to expectations since increased ambient temperature there may have been anticipated to favour bat population growth. This work is a promising step towards disentangling the spatial and temporal impacts of weather and, from there, assessing the effects of climate change on bats in Europe. Pipistrelle species, in particular, are likely to be north-western Europe's most abundant consumers of aerial nocturnal insects and future conservation plans must consider potential losses of these species from agricultural areas and how any resulting reduction in ecosystem services can be mitigated.

Synergistic potential of dual-polarized synthetic aperture radar and multispectral optical imagery for invasive alien species detection and mapping

Invasive alien species are a major threat to global biodiversity and result in adverse environmental and socioeconomic implications, such as reduced ecosystem services, landscape productivity, and costly eradication initiatives. The ability to monitor the extent and spread of alien species invasions provides valuable insight for the mitigation of these adverse implications. The generation of Earth Observation (EO) Sentinel sensor provides unprecedented freely available imagery, which is suitable for both local and regional invasive species monitoring. Specifically, its radar (S1) and optical (S2) sensors offer unique tandem datasets valuable for landscape analysis. Hence, we sought to determine the synergistic potential of fused S1 dual-polarized synthetic aperture radar (SAR) imagery with S2 optical imagery for invasive alien species detection and mapping. S1 and S2 imageries were fused at the feature level, and the support vector machine algorithm used for the multiclass image classification. Results indicated that the fusion of the S1 dual-polarized imagery with S2 optical imagery produced the highest classification accuracy (85%), whereas stand-alone S2 optical bands produced the lowest classification accuracy (79%). Findings from this study underline the significant synergistic potential and complementarity of new-age S2 optical imagery and dual-polarized S1 SAR imagery for invasive alien species detection and mapping. Due to large swath, higher pixel resolution, free availability, and possible tandem complementarity between optical and SAR sensors, we recommend Sentinel EO imagery as an economically viable option for the invasive alien species detection and mapping.

Quantifying the social and economic benefits of the biological control of invasive alien plants in natural ecosystems.

Invasive alien plants reduce ecosystem service delivery, resulting in environmental, economic and social costs. Here we review the returns on investment from biological control of alien plants that invade natural ecosystems. Quantifying the economic benefits of biological control requires estimates of the reductions in ecosystem goods and services arising from invasion. It also requires post-release monitoring to assess whether biological control can restore them, and conversion of these estimates to monetary values, which has seldom been done. Past studies, mainly from Australia and South Africa, indicate that biological control delivers positive and substantial returns on investment, with benefit:cost ratios ranging from 8:1 to over 3000:1. Recent studies are rare, but they confirm that successful biological control delivers attractive returns on investment, which increase over time as the value of avoided impacts accumulates.

Water quality simulation for rehabilitation of a eutrophic lake in Selangor, Malaysia

More than 50 % of lakes worldwide, including 60 % in Malaysia, are contaminated by eutrophication due to excessive nutrient inputs. These nutrients include phosphorus and nitrogen derived from agriculture, industry and domestic wastes. Eutrophication is an undesirable lake condition characterized by turbid water and dominated by abundant growth of algae, resulting in suppressed macrophytes and in reduced ecosystem services. Healthy lakes provide ecosystem services that have been valued to be worth billions to the Malaysian Gross Domestic Production annually. Rehabilitation of eutrophic lakes located in urban areas is therefore urgently needed. A recreational lake located in Selangor Malaysia has shown persistent signs of eutrophication with chlorophyll-a level fluctuating between 10 and 25 µg/L. Left untreated, the lake water quality will deteriorate further, potentially inducing a regime shift to hypereutrophic condition, caused by intense interaction between water column phosphorus and sediment phosphorus. Based upon water and sediment quality data compiled over the last eight years, this paper presents analysis and model simulations for implementation of a sustainable program for controlling eutrophication using low cost technology.

Non‐random loss of phylogenetically distinct rare species degrades phylogenetic diversity in semi‐natural grasslands

Abstract Although biodiversity loss is a critically important topic, our understanding of how both land abandonment and land‐use intensification in semi‐natural grasslands alters the community diversity and assembly mechanisms is very limited. Large‐scale economic drivers of land‐use change might inadvertently result in the loss of vulnerable species and reduce ecosystem service provisioning. In this study, we assessed non‐random community change by examining patterns of low‐abundance species loss, and community assembly in semi‐natural grasslands due to land abandonment and intensification in southwest Japan. We analysed relationships between evolutionary distinctiveness and abundance for each species. In addition, we used metrics of species and phylogenetic diversity and phylogenetic structure to assess patterns of non‐random biodiversity loss due to both abandoned and intensified land‐use. We demonstrated that low‐abundance species were more evolutionarily distinct compared to high‐abundance (i.e. dominant) species. Furthermore, land‐use intensification resulted in further declines in low‐abundance species, whereas land abandonment resulted in declines in all species, regardless of their initial abundance. We found that both forms of land‐use change (abandonment and intensification) resulted in non‐random patterns of community change, with traditional land‐use maintaining the highest biodiversity and land‐use change coinciding with decreased species and phylogenetic diversity measures. Intensified land‐use caused phylogenetic community structure to be more closely related than expected by chance, whereas the metrics of how distant species are from one another on average based on phylogenetic tree (i.e. mean pairwise phylogenetic distance) did not change from land abandonment. Synthesis and applications. We show that the loss of phylogenetic diversity, and especially of low‐abundance species with high value of phylogenetic distinctiveness, resulted in non‐random community disassembly. Our results argue that in order to maintain biodiversity in these semi‐natural grasslands, traditional management practices should be encouraged over intensification and simple abandonment. Government agencies should adopt policies or provide incentives that encourage the maintenance of traditional practices in rural Japan, and elsewhere where the combination of land consolidation and abandonment are important conservation issues.

HESS Opinions: Socio-economic and ecological trade-offs of flood management – benefits of a transdisciplinary approach

Abstract. In light of climate change and growing numbers of people inhabiting riverine floodplains, worldwide demand for flood protection is increasing, typically through engineering approaches such as more and bigger levees. However, the well-documented “levee effect” of increased floodplain use following levee construction or enhancement often results in increased problems, especially when levees fail or are compromised by big flood events. Herein, we argue that there are also unintended socio-economic and ecological consequences of traditional engineering solutions that need to be better considered, communicated and weighed against alternative solutions. Socio-economic consequences include reduced aesthetic and recreational values as well as increased downstream flooding risk and reduced ecosystem services. Ecological consequences include hydraulic decoupling, loss of biodiversity and increased risk of contamination during flooding. In addition, beyond river losses of connectivity and natural riparian vegetation created by levees, changes in groundwater levels and increased greenhouse gas emissions are likely. Because flood protection requires huge financial investments and results in major and persistent changes to the landscape, more balanced decisions that involve all stakeholders and policymakers should be made in the future. This requires a transdisciplinary approach that considers alternative solutions such as green infrastructure and places emphasis on integrated flood management rather than on reliance on technical protection measures.

The burn severity and plant recovery relationship affect the biological and chemical soil properties of Pinus halepensis Mill. stands in the short and mid-terms after wildfire

In the Mediterranean Basin, changes in climate and fire regime (increased recurrence and severity) reduce ecosystem services after wildfires by increasing soil degradation and losses in plant diversity. Our study was a biological approach to relate soil properties to vegetation recovery and burn severity. We focused our study on the natural recovery of the soil-plant interphase in Pinus halepensis Mill. forests located in the SE of Iberian Peninsula, a semiarid climate. We included some chemical properties 3 years after fire (available phosphorus (P) and soil organic carbon (Corg), among others), and biological soil indicators 3 and 5 years after fire (i.e. basal soil respiration (BSR), microbial biomass carbon (Cmic), carbon mineralization coefficient (Cmineral), metabolic quotient (qCO2) and microbial quotient (Cmic:Corg)). We analyzed the activity of three different enzymes: urease (UR), phosphatase (PHP) and β-glucosidase (GLU).The changes in most chemical properties were ephemeral, but P and Corg showed higher values in burned areas, and the highest were found for low-moderate severity. Plant recovery was the triggering factor for the recovery of Corg and biological soil function. Burn severity and time after fire influenced Cmic and the Cmic:Corg, which were higher for moderate-high severity 3 years later, but were below the unburned values 5 years after fire. The microbial activities of GLU and UR were recovered in burned areas 5 years after fire. The PHP values lowered according to higher burn severity and time after fire. The soil ecological trends obtained by a principal component analysis revealed a relationship linking GLU, BSR and qCO2 that explained soil response to burn severity. PHP, Cmic and Cmic:Corg explained most of the variability related to time after fire.Our results provide insights into how burn severity, in Mediterranean fire-prone Aleppo pine stands, modulated the natural plant recovery linked to soil biochemical and microbiological response to fire. High burn severity limited natural vegetation recovery, and both reduced biological soil functionality. This knowledge can be implemented in post-fire planning to apply post-fire management (for mitigation and restoration) in which the “no intervention” tool should be contemplated. These findings provide information to be applied in adaptive forest management to improve the resilience of vulnerable ecosystems and to reduce burn severity in future fire events.

Common mycorrhizal networks influence the distribution of mineral nutrients between an invasive plant, Solidago canadensis, and a native plant, Kummerowa striata.

Invasive species often reduce ecosystem services and lead to a serious threat to native biodiversity. Roots of invasive plants are often linked to roots of native plants by common mycorrhizal networks (CMNs) of arbuscular mycorrhizal (AM) fungi, but whether and how CMNs mediate interactions between invasive and native plant species remains largely uninvestigated. We conducted two microcosm experiments, one in which we amended the soil with mineral N and another in which we amended the soil with mineral P. In each experiment, we grew a pair of test plants consisting of Kummerowia striata (native to our research site) and Solidago canadensis (an invasive species). CMNs were established between the plants, and these were either left intact or severed. Intact CMNs increased growth and nutrient acquisition by S. canadensis while they decreased nutrient acquisition by K. striata in comparison with severed CMNs. 15N and P analyses indicated that compared to severed CMNs, intact CMNs preferentially transferred mineral nutrients to S. canadensis. CMNs produced by different species of AM fungi had slightly different effects on the interaction between these two plant species. These results highlight the role of CMNs in the understanding of interactions between the invasive species S. canadensis and its native neighbor.

Willingness to produce perennial bioenergy crops: A contingent supply approach

In order to reduce economic and national security risks, U.S. energy policy, in 2005 and 2007, mandated production of renewable biofuels. By 2010, the renewable biofuel industry was consuming approximately one-third of domestic corn and soybean production. To meet this growing demand, conservation and pastureland has been cultivated with corn and soybean, resulting in a reduction in ecosystem services. Perennial bioenergy crops (e.g., switchgrass) offer a more sustainable alternative. However, unlike annual crops, farmers and landowners have little experience with perennial bioenergy crop production. Uncertainty in production and prices may impact the supply of these novel crops into an emerging market. Using a contingent supply method, we show that agricultural landowners are willing to produce perennial bioenergy crops, given competitive returns, but only on a portion of their land.

Anthropogenic global defaunation and its consequences for planetary health

The Convention on Biological Diversity has set the 20 Aichi targets for biodiversity by 2020. However, almost all indicators of the Aichi targets show negative trends. Anthropogenic pressure (human appropriation of biological productivity), biodiversity (Living Planet Index), biodiversity benefits (domesticated breeds, Red List of pollinators) show decline with negative consequences on resources and ecosystem services. Many academic studies and reports conducted by international organizations stressed that biodiversity loss is affecting ecosystem resilience but also health and well-being. However, we still lack a framework that could link socio-economics, ecosystems, biodiversity and health. The social-ecology approach links ecological and biological metabolism with social metabolism, where social systems are seen as hybrid systems between cultures, socio-economics (exchanges and flows) and environments (metabolic exchanges). Human societies can then be characterized by stocks and flows that involve: population and its demography, biophysical stocks and trade/production, land and its biological productivity. An important parameter is HANPP (Human Appropriation of the Net Primary Productivity). HANPP has doubled in the 20th century and scenarios suggest that this appropriation will continue to increase considerably in the coming decades. HANPP is an appropriate indicator for research into the impact of human intervention on biodiversity and can link human appropriation of environmental metabolism with ecological theories on biodiversity, like the species-energy hypothesis. We used the conceptual framework of social-ecology that links “drivers” (food consumption, energy), “pressures” (land use, HANPP), “states” (biodiversity change), “impacts” (reduction of the quality of ecosystem services) and “responses” (governance, land planning, conservation). This conceptual framework makes it possible to address the link between biodiversity and health. We tested this social-ecology framework using several databases at the nation level. We confirmed the species-energy hypothesis by showing a positive correlation between HANPP and declining biodiversity. The hypothesis of a reduction in ecosystem services for the regulation of infectious diseases appears also to be confirmed with an increase in zoonotic disease epidemics with the increase in HANPP at the world nation level. The incorporation of health components in social-ecology might provide governance tools for global biodiversity conservation and planetary health.

Landscape complexity perception and representation in a wine-growing region with the designation of origin in the Loire Valley (France): a cultural ecosystem service?

AbstractEcosystem services related to biodiversity, including cultural services, are essential for agricultural production such as viticulture. In agricultural landscapes, pesticides and mechanization threaten biodiversity, lead to landscape simplification and may reduce ecosystem services. On the other hand, consumers are more and more aware of environmental issues in food production. We investigated if landscape complexity, including soil management practices, was (i) appreciated by visitors and (ii) presented by winegrowers and tourism professionals in the French vineyards with the designation of geographical origin (DGO) ‘Coteaux du Layon’. Our goal was to determine if landscape complexity provides cultural ecosystem services such as aesthetics beneficial for the wine trade and the DGO region's attractiveness. We analyzed the iconographic content and the composition of landscape photographs on 50 websites to investigate if local winegrowers and tourism professionals associate biodiversity in the landscape and soil management practices with wine promotion. A questionnaire was realized to study the perception of local landscapes by interviewing 192 visitors of the region. The benefits of landscape complexity and soil management practices favoring biodiversity in viticulture were known and appreciated by many visitors, even if photographs of wine and traditional practices appeared to encourage wine purchasing. Local winegrowers’ representation of the DGO region only partially served these preferences; instead they mainly presented the wine-growing region by photographs focusing on wine bottles and vineyards. Consumer's preferences showed that complex landscapes could provide cultural ecosystem services that winegrowers are still less aware of. Therefore, complexity-targeted landscape planning including vegetation cover in soil management should be included in policy recommendations as agroecological measures for sustainable DGO production.

Mechanisms regulating the productivity and stability of artificial grasslands in China: Issues, progress, and prospects

China has 400 million hectares of grasslands, occupying 41.7% of the country’s total land area. Due to the overexploitation of grassland’s production functions and the neglect of its ecological functions, intensive livestock grazing in recent decades has resulted in widespread grassland degradation, reduction in ecosystem services, and imbalance between forage production and livestock demands in China. Compared to natural grasslands, artificial grasslands can increase forage yield up to 10–20 times. The development of high-quality artificial grasslands could fundamentally ease the severe shortage of forage supply, break the bottleneck in meat and milk production, curb grassland degradation caused by overgrazing, and thereby restore grassland ecological functions. Therefore, understanding the mechanisms that regulate the productivity and stability of artificial grasslands is a major national strategic need in order to transform the practices of sustainable livestock production based on the scientific and technological advancements, and to promote national ecological security, food security, and the development of ecological civilization. In this study, we examined theoretical basis underlying the regulations of artificial grassland productivity and stability, including theories of ecological stoichiometry, niche differentiation, compensation, mutualism, grazing optimization, and intermediate disturbance. Then, we reviewed current research status and the latest progress that has made in this field. Finally, we proposed fundamental research questions that need to be fully addressed in future studies, regarding the effects of stoichiometry of key nutrient elements, coupled water and nutrient availability, mutualism between forage species and soil microbes, and complementarity of functional traits and multiple forage species on plant carbon assimilation, growth, reproduction, forage quality, biomass allocation, primary productivity, and ecosystem stability. We also highlighted several key biological and ecological mechanisms regulating the productivity and stability of artificial grasslands.

Plant-Soil Microbiome Feedback Impacts on Native and Non-native Grasses Throughout Kansas

Beginning in 1917, a group of perennial warm-season bunchgrasses collectively called Old World Bluestems (OWBs) were introduced from the countries of Europe, Asia, Russia, and Australia. These grasses were brought in to reduce soil erosion and increase hay and forage production, as they can produce up to four times more biomass than native grasses. However, the forage quality of OWBs is reduced as the plant matures and must therefore be harvested prior to maturation. Furthermore, OWBs have become problematic in the southern and central Great Plains, invading and then dominating native warm-season rangelands causing a reduction in ecosystem services.

A watershed decision support tool for managing invasive species on Hawai‘i Island, USA

Non-native species invasions, growing human populations, and climate change are central ecological concerns in tropical island communities. The combination of these threats have led to losses of native biota, altered hydrological and ecosystem processes, and reduced ecosystem services. These threats pose complex problems to often underfunded management entities. We developed a watershed decision support tool (WDST) for the windward coast of Hawai‘i Island aimed at prioritizing catchments for invasive species removal and native forest protection from non-native species invasions. Using the Ecosystem Management Decision Support (EMDS) system, we integrated spatial data from four sources: (i) native and invasive species coverage; (ii) modeled water yield; (iii) treatment cost and efficacy; and (iv) native species conservation value. We used a distributed hydrology model (DHSVM) to estimate catchment-level (∼90ha) water yield under six climate and non-native species invasion scenarios to identify where (1) invasive species removal and (2) protection from invasion would have the greatest benefit to increasing or maintaining native biodiversity and hydrologic functioning. The hydrology model predicted a 30% decline (386Glyr−1) in total water yield under a drier future climate (20% reduction in rainfall), with an additional 2% reduction when catchments were fully invaded by non-native species. Increased temperatures had a small compensatory effect on water yield. The WDST identified 6.3% of the study area as high priority for invasive species removal, based on characteristics of large hydrological response to the removal treatment (concentrated in high rainfall areas), high quality road or trail access, and high conservation value. High protection priority from invasive species (5.9% by area) occurred in higher elevation catchments, near the upper range of strawberry guava (the main invasive species), where water yield was most sensitive to invasion. Climate change scenarios had little influence on the spatial distribution of priority scores despite large changes in overall water yield. In contrast, priority scores were sensitive to very high variation in treatment costs, which were influenced largely by travel times to catchments via road and trail networks. This last finding suggests that future management feasibility will hinge on improvements to road and trail networks, or development of alternative management strategies that reduce travel costs and time.

Forest fragmentation reduced carbon storage in a moist tropical forest in Bangladesh: Implications for policy development

Forest fragmentation is continued to be widespread in the tropics resulting in reduced ecosystem services including carbon storage. However, the effect of forest fragmentation is not considered in the current carbon policy. We investigated the effect of forest fragmentation on tree biomass carbon and soil organic carbon (SOC) storage in a moist tropical forest in Bangladesh. Above and below-ground tree biomass carbon were calculated by using widely accepted allometric equations and SOC was measured by sampling soils up to 10cm depth and analyzing them in a soil laboratory. Results showed that carbon storage in tree biomass was significantly lower in fragmented forests (16.3±1.37tCha−1) than in contiguous forests (31.21±2.75tCha−1) (p<0.001). Likewise, a significantly lower SOC was contained in the soils of fragmented forests (17.26±0.83tCha−1) than in contiguous forests (21.62±0.78tCha−1) (p<0.001). Thus a total of 36% less carbon retained in tree biomass and soils in fragmented forests than in contiguous forests. Backward multiple linear regression analysis revealed tree density, tree height, tree DBH, height-diameter ratio (H/D) and tree species richness as influential factors of carbon variation in fragmented forests. All these structural parameters except tree species richness were significantly lower in fragmented forests, were positively associated with carbon storage and explained together 69% of the carbon storage variation. These findings suggest that the altered stand structure and tree allometry likely caused reduced carbon storage in fragmented forests and highlight the importance of landscape scale management intervention in the tropics. Here, we provided with the evidence of strong negative impact of forest fragmentation on carbon storage and argue that this effect should be in consideration which is currently overlooked in existing carbon accounting systems for tropical forests.

Interlinking climate change with water-energy-food nexus and related ecosystem processes in California case studies

Global climate change creates critical challenges with increasing temperature, reducing snowpack, and changing precipitation for water, energy, and food, as well as ecosystem processes at regional scales. Ecosystem services provide life support, goods, and natural resources from water, energy, and food, as well as the environments. There are knowledge gaps from the lack of conceptual framework and practices to interlink major climate change drivers of water resources with water-energy-food nexus and related ecosystem processes. This paper provided an overview of research background, developed a conceptual framework to bridge these knowledge gaps, summarized California case studies for practices in cross sector ecosystem services, and identified future research needs. In this conceptual framework, climate change drivers of changing temperature, snowpack, and precipitation are interlinked with life cycles in water, energy, food, and related key elements in ecosystem processes. Case studies in California indicated climate change affected variation in increasing temperature and changing hydrology at the regional scales. A large variation in average energy intensity values was also estimated from ground water and federal, state, and local water supplies both within each hydrological region and among the ten hydrological regions in California. The increased regional temperature, changes in snowpack and precipitation, and increased water stresses from drought can reduce ecosystem services and affect the water and energy nexus and agricultural food production, as well as fish and wildlife habitats in the Sacramento-San Joaquin Delta (Delta) and Central Valley watersheds. Regional decisions and practices in integrated management of water, energy, food, and related ecosystem processes are essential to adapt and mitigate global climate change impacts at the regional scales. Science and policy support for interdisciplinary research are critical to develop the database and tools for comprehensive analysis to fill knowledge gaps and address ecosystem service complexity, the related natural resource investment, and integrated planning needs.

Ecological Consequences of Shoreline Hardening: A Meta-Analysis.

Protecting coastal communities has become increasingly important as their populations grow, resulting in increased demand for engineered shore protection and hardening of over 50% of many urban shorelines. Shoreline hardening is recognized to reduce ecosystem services that coastal populations rely on, but the amount of hardened coastline continues to grow in many ecologically important coastal regions. Therefore, to inform future management decisions, we conducted a meta-analysis of studies comparing the ecosystem services of biodiversity (richness or diversity) and habitat provisioning (organism abundance) along shorelines with versus without engineered-shore structures. Seawalls supported 23% lower biodiversity and 45% fewer organisms than natural shorelines. In contrast, biodiversity and abundance supported by riprap or breakwater shorelines were not different from natural shorelines; however, effect sizes were highly heterogeneous across organism groups and studies. As coastal development increases, the type and location of shoreline hardening could greatly affect the habitat value and functioning of nearshore ecosystems.

Designing agricultural landscapes for biodiversity-based ecosystem services

Sustainable and resilient agricultural systems are needed to feed and fuel a growing human population. However, the current model of agricultural intensification which produces high yields has also resulted in a loss of biodiversity, ecological function, and critical ecosystem services in agricultural landscapes. A key consequence of agricultural intensification is landscape simplification, where once heterogeneous landscapes contain increasingly fewer crop and non-crop habitats. Landscape simplification exacerbates biodiversity losses which leads to reductions in ecosystem services on which agriculture depends. In recent decades, considerable research has focused on mitigating these negative impacts, primarily via management of habitats to promote biodiversity and enhance services at the local scale. While it is well known that local and landscape factors interact, modifying overall landscape structure is seldom considered due to logistical constraints. I propose that the loss of ecosystem services due to landscape simplification can only be addressed by a concerted effort to fundamentally redesign agricultural landscapes. Designing agricultural landscapes will require that scientists work with stakeholders to determine the mix of desired ecosystem services, evaluate current landscape structure in light of those goals, and implement targeted modifications to achieve them. I evaluate the current status of landscape design, ranging from fundamental ecological principles to resulting guidelines and socioeconomic tools. While research gaps remain, the time is right for ecologists to engage with other disciplines, stakeholders, and policymakers in education and advocacy to foster agricultural landscape design for sustainable and resilient biodiversity services.

A century-scale, human-induced ecohydrological evolution of wetlands of two large river basins in Australia (Murray) and China (Yangtze)

Abstract. Recently, the provision of food and water resources of two of the world's largest river basins, the Murray and the Yangtze, has been significantly altered through widespread landscape modification. Long-term sedimentary archives, dating back for some centuries from wetlands of these river basins, reveal that rapid, basin-wide development has reduced the resilience of biological communities, resulting in considerable decline in ecosystem services, including water quality. Large-scale human disturbance to river systems, due to river regulation during the mid-20th century, has transformed the hydrology of rivers and wetlands, causing widespread modification of aquatic biological communities. Changes to cladoceran zooplankton (water fleas) were used to assess the historical hydrology and ecology of three Murray and Yangtze river wetlands over the past century. Subfossil assemblages of cladocerans retrieved from sediment cores (94, 45, and 65 cm) of three wetlands: Kings Billabong (Murray), Zhangdu, and Liangzi lakes (Yangtze), showed strong responses to hydrological changes in the river after the mid-20th century. In particular, river regulation caused by construction of dams and weirs together with river channel modifications, has led to significant hydrological alterations. These hydrological disturbances were either (1) a prolonged inundation of wetlands or (2) reduced river flow, both of which caused variability in wetland depth. Inevitably, these phenomena have subsequently transformed the natural wetland habitats, leading to a switch in cladoceran assemblages to species preferring poor water quality, and in some cases to eutrophication. The quantitative and qualitative decline of wetland water conditions is indicative of reduced ecosystem services, and requires effective restoration measures for both river basins which have been impacted by recent socioeconomic development and climate change.

Floodplain fish communities in river systems in Bolivia: Current knowledge and addressing future research challenges

Tropical freshwater fish communities are increasingly under threat from anthropogenic pressures, particularly alteration to the hydrological regime (e.g. via deforestation and mining within the watershed and in-stream impoundments) which defines the extent and characteristics of in-channel and floodplain habitats for fishes. The ecological consequences of altered hydrology for tropical floodplain ecosystems are likely to be major declines in fish abundance and diversity, lower food web connectivity, reduced microhabitat availability for reproduction and refuge, modified migration patterns and consequently reduced ecosystem services, e.g. fishery resource. Evidence of change is lacking and the current species inventory approaches of collecting fish-related data do not consider spatial (i.e. river-floodplain distances) and temporal (i.e. flood water levels) gradients that are known to largely influence fish communities present in floodplain waterbodies. In the context of increasing threats, fish diversity and community declines are real and require suitable methodological approaches to combine available information and an informed analysis of likely change before actions are irreversible. Bolivian rivers are relatively undisturbed compared to other tropical rivers, however, plans for hydropower and increased deforestation and mining in the region could have devastating effects on the hydrological patterns and the dependent biodiversity. This review aims to summarize the current knowledge of floodplain freshwater fishes using Bolivian rivers as the example, identify the gaps that exist in the science and to propose a landscape ecology approach to integrate pattern and process understanding of the river-floodplain mosaic to fill knowledge gaps in an appropriate way towards the conservation of fish resources.