Carbon and corms: Introduced ungulates and saltwater intrusion variably impact coastal floodplain ecosystem services in the Laynhapuy Indigenous Protected Area, northern Australia

Coastal wetlands protect coastlines through efficient storage of organic carbon (OC) that decreases wetland vulnerability to sea level rise (SLR). Accelerated SLR is driving saltwater intrusion and altering vegetation communities and biogeochemical conditions in coastal wetlands with uncertain implications. We quantified changes in OC stocks and fluxes driven by 1) saltwater and phosphorous intrusion on freshwater and brackish marshes, 2) vegetation along an experimental saltmarsh to mangrove gradient, 3) saltwater intrusion and vegetation change across a marsh to mangrove ecotone, and 4) vegetation change and mangrove forest development along a marsh to mangrove ecotone. Increasing salinity in freshwater marshes decreased root biomass and soil elevation within one year. In brackish marshes, increased salinity decreased root productivity and biomass and increased root breakdown rate (k), while added salinity did not increase elevation loss. In our experimental marsh-mangrove ecotone, mangrove vegetation promoted higher organic carbon (OC) storage by increasing above and belowground biomass and reducing organic matter k. However, mangroves also increased belowground k, and decreased allochthonous marine subsidies, indicating the potential for OC storage trade-offs. In the Southeast Everglades, we identified strong interior-coastal gradients in soil stoichiometry and mangrove cover. Interior freshwater soil conditions increased k, while total soil OC stocks decreased toward the coast indicating that saltwater intrusion is driving large scale soil OC loss. In the southeast Everglades, mangrove expansion increased root biomass and root productivity, but did not mitigate the overall loss of OC stocks toward the coast. Similarly, in the southwest Everglades, saltwater intrusion drove a decrease in soil OC. However, mangrove encroachment drove a rapid recovery and increased OC stocks. Mangrove encroachment doubled aboveground biomass within the last ten years, increased it 30 times in the last 30 years, and doubled belowground biomass after 20 years. Our research shows that 1) moderate saltwater intrusion without mangrove encroachment will lead to a loss in OC stocks and potentially lead to wetland elevation loss and submergence, 2) in the absence of a change in saltwater intrusion, mangrove expansion can enhance OC storage 3) mangrove expansion can mitigate OC loss during saltwater intrusion, but this pattern depends on mangrove recruitment and ecosystem productivity.

Saltwater intrusion has been recognized as a major driver of ecological regime shifts in coastal wetlands, but few studies have incorporated long‐term salinity modelling data into the understanding of vegetation dynamics. This study uniquely combined artificial neural network (ANN) modelling and time series of aerial photographs to elucidate saltwater intrusion and mangrove encroachment into the freshwater floodplain of the Loxahatchee River over a period of six decades. Three ANN models were developed to simulate river salinity on a daily time step using freshwater inflow, rainfall and tide as inputs. With 8 years of measured data for training and testing, the ANN models demonstrated comparable or superior model performance for salinity simulation to their hydrodynamic counterparts. Modelling of historical salinity (1948–2011) using the ANNs indicated that the intensity of saltwater intrusion clearly correlated with watershed hydrology, which, in turn, was linked to historical watershed alterations and regional rainfall variability. Interpretation of the 1940, 1953, 1964, 1979, 1985 and 1995 aerial photographs revealed the progressive encroachment of mangroves and displacement of bald cypress and freshwater communities in the floodplain. The spatial extent of mangrove encroachment was related to the increasing mortality of bald cypress under the chronic effect of cumulative salinity exposure. The ecohydrological controls over vegetation changes in the Loxahatchee River support the ongoing ecosystem restoration programme, which aims to achieve incremental freshwater flow targets to protect and restore the floodplain ecosystem. Copyright © 2014 John Wiley & Sons, Ltd.

Salt marsh and mangrove have been recognized as being among the most valuable ecosystem types globally in terms of their supply of ecosystem services and support for human livelihoods. These coastal ecosystems are also susceptible to the impacts of climate change and rising sea levels, with evidence of global shifts in the distribution of mangroves, including encroachment into salt marshes. The encroachment of woody mangrove shrubs and trees into herbaceous salt marshes may represent a substantial change in ecosystem structure, although resulting impacts on ecosystem functions and service provisions are largely unknown. In this review, we assess changes in ecosystem services associated with mangrove encroachment. While there is quantitative evidence to suggest that mangrove encroachment may enhance carbon storage and the capacity of a wetland to increase surface elevation in response to sea-level rise, for most services there has been no direct assessment of encroachment impact. On the basis of current understanding of ecosystem structure and function, we theorize that mangrove encroachment may increase nutrient storage and improve storm protection, but cause declines in habitat availability for fauna requiring open vegetation structure (such as migratory birds and foraging bats) as well as the recreational and cultural activities associated with this fauna (e.g., birdwatching and/or hunting). Changes to provisional services such as fisheries productivity and cultural services are likely to be site specific and dependent on the species involved. We discuss the need for explicit experimental testing of the effects of encroachment on ecosystem services in order to address key knowledge gaps, and present an overview of the options available to coastal resource managers during a time of environmental change.

Groundwater supply systems constructed by gold miners in Victoria during the nineteenth century were highly significant in the historical development of water law and water licensing in Australia. Alluvial gold mining required large volumes of water to separate gold from washdirt, but surface flows often failed in seasonally dry conditions. Drought in the mid-1860s prompted miners on the Ovens goldfield in north-east Victoria to exploit groundwater to increase supplies, despite limited scientific understanding of this resource at the time. Analysis of historical plans held by Public Records Office Victoria has revealed numerous ‘source of supply’ tunnels dug by miners to extract groundwater in the area. By the early 1880s, miners were using up to 31 ML of groundwater per day, with much of the water transferred between creek and river catchments. These activities represent an early, large-scale and significant intervention in the hydrogeological environment, several decades prior to economic development of the Great Artesian Basin in northern Australia. Understanding the nature and scale of groundwater use in this period provides vital social and historical context for modern debates about groundwater modelling, extraction and management.

Culturally diverse expert teams have yet to bring comprehensive linguistic diversity to intergovernmental ecosystem assessments

Saltwater intrusion history shapes the response of bacterial communities upon rehydration

Coastal wetland ecosystems play critical roles in mitigating climate change by sequestering substantial amounts of carbon in vegetation and sediments. The Laynhapuy Indigenous Protected Area, northern Australia, includes culturally significant floodplains that support diverse coastal wetlands. The Yirralka Rangers and Yolŋu Traditional Owners who manage this region have identified invasive ungulates as a key threat to wetlands. Paperbark forests, with species known to Yolŋu as raŋan (Melaleuca viridiflora) and nämbarra (Melaleuca cajuputi), have experienced ungulate damage combined with dieback due to saltwater intrusion. Sedgelands, dominated by culturally significant räkay (Eleocharis dulcis), suffer annual soil and vegetation damage caused by invasive pigs (Sus scrofa) and buffalo (Bubalus bubalis). The Rangers and Macquarie University scientists established an ungulate exclusion fenced plot array in 2018 across a supratidal paperbark forest and sedgeland on the Gurrumuru floodplain. To assess carbon cycle impacts, belowground carbon stocks in sediments and biomass were quantified, along with greenhouse gas (GHG) emissions across the plot array. Our findings revealed fourfold higher GHG emissions (combined CO2 and CH4) in locations damaged by invasive ungulates compared to undamaged sites in the early dry season. Belowground biomass increased by 21%–104% within exclusion plots compared with damaged plots. No significant differences in soil organic carbon (SOC) and total nitrogen (TN) stocks or rates of litter decomposition were found between damaged and undamaged plots. This study contributes to potential carbon crediting methods focused on reducing feral ungulate impacts to wetlands, that could help fund coastal floodplain wetland management.

Litterfall from a Melaleuca forest was investigated as part of chemical cycling studies on the Magela Creek floodplain in tropical, northern Australia. The forest contained two species of tree, Melaleuca cajaputi and Melaleuca viridiflora, with a combined average density of 294 trees ha−1. The M. viridiflora trees had diameter breast height measurements ranging from 11.8 to 62.0 cm, median class 25.1–30.0cm and a mean value of 29.2±1.0 cm, compared to 13.0 to 66.3 cm, 30.1−35.0cm and 33.5±1.0cm for M. cajaputi trees. A regression model between tree height, diameter breast height and fresh weight was determined and used to calculate average tree weights of 775±1.6kg for M. viridiflora and 1009±1.6kg for M. cajaputi, and a total above-ground fresh weight of 263±0.3t ha−1. The weight of litter recorded each month on the ground beneath the tree canopy ranged from 582±103 to 2176±376 g m−2 with a monthly mean value of 1105±51 g m−2. The coefficient of variation of 52% on this mean indicates the large spatial and temporal variability in litter distribution over the study site. This variability was greatly affected by the pattern of water flow and litter transport during the Wet season. Litterfall from the trees was evaluated using two techniques - nets and trays. The results from these techniques were not significantly different with annual litterfall collected in the nets being 705 ± 25 g m−2 and in the trays 716±49 g m−2. The maximum monthly amount of litterfall, 108 ±55g m−2, occurred during the Dry season months of June–July. Leaf material comprised 70% of the total annual weight of litter, 480±29 g m−2 in the nets and 495 ± 21 g m−2 in the trays. The tree density and weight of litter suggest that the Melaleuca forests are highly productive and contribute a large amount of material to the detrital/debris turnover cycle on the floodplain.

Understanding sub-surface solute distributions and salinization mechanisms in a tropical coastal floodplain groundwater system

In addition to the habitat they provide to microbiological fauna (Griebler and Avramov 2015), groundwaters contribute to numerous ecosystem services, including the production and distribution of high-quality water and the feeding of groundwater-dependent aquatic ecosystems such as rivers, lakes and wetlands. This role is particularly important during dry periods, when the water stored in aquifers supplies significant quantities to surface waters that are at low flow. Springs are the interface between aquifers and surface water, making them ideal sites for monitoring groundwater and its ability to provide services to downstream ecosystems. Among these, karst springs are particularly noteworthy for the quantity of water they convey to a specific point. Karst accounts for 21.6% of Europe's surface area (Chen et al. 2017) and some of the ecosystem services it provides have been already described by Goldsheider (2012). However, the supply of water to aquatic ecosystems remains a largely undervalued and understudied feature. In this presentation, we highlight the role of karstic springs in various ecohydrological contexts of France (Fig. 1) and the risks that dependant ecosystems will face in a context of global changes. The Argens is a river that flows through the Triassic limestones of Provence Verte. With a constant temperature throughout the year, the bouillidoux karst springs help to regulate the river's temperature by decreasing it in summer and increasing it in winter. The section of river downstream from the spring is a thermal refugee that is home to significant biodiversity, like other thermal refugees in the south of France. However, these are vulnerable to climate change, which will alter the way they function, as well as the respective inflows of groundwater and surface water, and the temperatures of these waters. The Vise Spring is a submarine karst spring located in the Thau Lagoon in southern France, on the Mediterranean coast. Its karst hydrosystem regularly supplies freshwater to the lagoon, contributing to its quality and ecological balance. Shellfish farming is a major activity here, but other uses of the groundwater also coexist: thermal water for the Balaruc Spa and drinking water supply for neighbouring villages. This spring is the site of regular flow reversals, which cause salt water intrusion from the lagoon into the karst aquifer, disrupting the hydro-ecological balance of the lagoon (Ladouche et al. 2023). The chronic drop in the water level in the aquifer, linked to repeated droughts and the increasing use of groundwater, is leading to an acceleration in the number of flow reversal phenomena. In addition, the particular geometry of the site makes it vulnerable to long-term or even permanent flow reversal and salt water intrusion. The karst springs of the Loue and Lison Rivers are among the largest in France in terms of flow. They emerge in the Jura Mountains and feed the Loue River, which draws most of its flow from the surrounding limestone plateaux. For more than a decade, numerous contaminations of the rivers have led to fish kills, linked in particular to major inputs of nutrients flowing through the karst aquifers. Farming practices linked to cattle rearing for cheese production need to be improved to reduce inputs in the upstream basins. These karst springs, which are highly sensitive to climate change and modifications in land use in their catchment areas, constitute sentinels of global change. As vectors of groundwater, they link upstream and downstream ecosystems and guarantee major ecosystem services. Monitoring them is vital for gaining a better understanding of their ecological functions, which depend on their hydrogeological functions. In this context, a new research project called SentinelSpringS is starting within the Water4All program, with colleagues from Portugal, Italy, Poland, Denmark and Malta, in order to propose a better framework for managing groundwater resources and associated springs.

Increases in temperature are expected to facilitate encroachment of tropical mangrove forests into temperate salt marshes, yet the effects on ecosystem services are understudied. Our work was conducted along a mangrove expansion front in Louisiana (USA), an area where coastal wetlands are in rapid decline due to compounding factors, including reduced sediment supply, rising sea level, and subsidence. Marsh and mangrove ecosystems are each known for their ability to adjust to sea-level rise and support numerous ecosystem services, but there are some differences in the societal benefits they provide. Here, we compare carbon and nitrogen stocks and relate these findings to the expected effects of mangrove encroachment on nitrogen filtration and carbon sequestration in coastal wetlands. We specifically evaluate the implications of black mangrove (Avicennia germinans) encroachment into Spartina alterniflora-dominated salt marsh. Our results indicate that black mangrove encroachment will lead to increased aboveground carbon and nitrogen stocks. However, we found no differences in belowground (that is, root and sediment) nitrogen or carbon stocks between marshes and mangroves. Thus, the shift from marsh to mangrove may provide decadal-scale increases in aboveground nitrogen and carbon sequestration, but belowground nitrogen and carbon sequestration (that is, carbon burial) may not be affected. We measured lower pore water nitrogen content beneath growing mangroves, which we postulate may be due to greater nitrogen uptake and storage in mangrove aboveground compartments compared to marshes. However, further studies are needed to better characterize the implications of mangrove encroachment on nitrogen cycling, storage, and export to the coastal ocean.

Escape from natural enemies is a widely held generalization for the success of exotic plants. We conducted a large-scale experiment in Hawaii (USA) to quantify impacts of ungulate removal on plant growth and performance, and to test whether elimination of an exotic generalist herbivore facilitated exotic success. Assessment of impacted and control sites before and after ungulate exclusion using airborne imaging spectroscopy and LiDAR, time series satellite observations, and ground-based field studies over nine years indicated that removal of generalist herbivores facilitated exotic success, but the abundance of native species was unchanged. Vegetation cover <1 m in height increased in ungulate-free areas from 48.7% +/- 1.5% to 74.3% +/- 1.8% over 8.4 years, corresponding to an annualized growth rate of lambda = 1.05 +/- 0.01 yr(-1) (median +/- SD). Most of the change was attributable to exotic plant species, which increased from 24.4% +/- 1.4% to 49.1% +/- 2.0%, (lambda = 1.08 +/- 0.01 yr(-1)). Native plants experienced no significant change in cover (23.0% +/- 1.3% to 24.2% +/- 1.8%, lambda = 1.01 +/- 0.01 yr(-1)). Time series of satellite phenology were indistinguishable between the treatment and a 3.0-km2 control site for four years prior to ungulate removal, but they diverged immediately following exclusion of ungulates. Comparison of monthly EVI means before and after ungulate exclusion and between the managed and control areas indicates that EVI strongly increased in the managed area after ungulate exclusion. Field studies and airborne analyses show that the dominant invader was Senecio madagascariensis, an invasive annual forb that increased from < 0.01% to 14.7% fractional cover in ungulate-free areas (lambda = 1.89 +/- 0.34 yr(-1)), but which was nearly absent from the control site. A combination of canopy LAI, water, and fractional cover were expressed in satellite EVI time series and indicate that the invaded region maintained greenness during drought conditions. These findings demonstrate that enemy release from generalist herbivores can facilitate exotic success and suggest a plausible mechanism by which invasion occurred. They also show how novel remote-sensing technology can be integrated with conservation and management to help address exotic plant invasions.

PDF HTML阅读 XML下载 导出引用 引用提醒 广西北部湾沿岸地区生态系统服务价值变化及其驱动力 DOI: 10.5846/stxb201704050578 作者: 作者单位: 中南林业科技大学生命科学与技术学院;桂林理工大学旅游学院,中南林业科技大学生命科学与技术学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业公益性行业科研专项（201404316）；林业科技创新平台运行补助项目（2016-LYPT-DW-069）；国家旅游局旅游业青年专家培养计划（TYETP201548） Evolution and driving force analysis of ecosystem service values in Guangxi Beibu Gulf coastal areas, China Author: Affiliation: Central South University of Forestry and Technology, School of Life Science and technology,Changsha; Guilin University of Technology,School of Tourism,Guilin,Central South University of Forestry and Technology,School of Life Science and technology, Changsha Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:掌握生态系统结构及其功能的时空变化规律是开展科学生态系统管理的重要前提，如何衡量人类在满足自我需求的同时对自然资源和生态系统的改变程度是当前研究值得关注的一个问题。伴随北部湾经济区的崛起，区域经济发展与生态保护的矛盾日益凸显，海水倒灌、植被退化和土地沙化等现象加剧，生态系统服务可持续供给受到严重威胁。以时序遥感数据为基础，分析北部湾沿岸地区生态系统时空演变，评估生态系统服务价值时空变化规律及其驱动因素，为区域生态系统管理提供科学基础。研究显示：1999-2014年，城市点状、离散扩张使城市生态系统面积显著增加，破碎化程度加剧；环境恶化给湿地生态系统带来毁灭性的破坏，红树林不断消失，破碎度增加；林地和果园构成的森林生态系统面积有所增加，而耕地面积急剧缩减。生态系统构成中，森林生态系统服务价值最高，约占研究区总价值的50%，且呈增长趋势；生态系统服务构成中，除食物生产、气体调节和维持养分循环价值有所减少外，其他类型生态系统服务价值均呈增长趋势。驱动力分析表明，综合城镇化率是影响北部湾沿岸地区生态系统服务价值变化的重要驱动因素，说明区域生态系统服务与社会经济发展极为相关，合理调控经济结构可有效提升区域生态系统服务价值。 Abstract:With the economic development of the Beibu Gulf economic zone, environmental problems, such as seawater intrusion, vegetation degradation, and desertification in the coastal areas have become more important and pose a serious threat to regional ecological security. The low ecosystem services value has become one of the key factors restricting the rapid economic development of the Beibu Gulf area. Evaluating the ecosystem service value of the Beibu Gulf coastal areas, demonstrating its evolution characteristics, and analyzing the main driving factors are of great significance when attempting to promote the ecological construction and sustainable development of this area. Landsat remote sensing images in 1999, 2006, and 2014 of the study area were the main data source. First, we used the supervised classification and thematic mapping approach to interpret the remote sensing images and obtain the land use/cover distribution maps. Then we analyzed the land use/cover dynamics and the landscape pattern evolution characteristics. We used the improved evaluation method for ecosystem service value based on per unit area to calculate the ecosystem service values in the study area for the three periods. We also analyzed the value changes and the spatio-temporal characteristics for each ecosystem service in every county. Finally, the driving mechanism behind the ecosystem evolution in the Beibu Gulf coastal areas was studied by combining population factors, economic factors, and tourism factors. The land use/cover changes showed that the scattered urban expansion caused the built-up land to increase dramatically and its fragmentation became more serious between 1999 and 2014. The destruction of the ecological environment damaged the mangrove forest. However, this damaged patch has disappeared and the degree of fragmentation has improved. The forestland and orchard areas increased between 1999 and 2006, but then decreased from 2006 to 2014, while the area of cultivated land decreased sharply between 1999 and 2014. The results of the ecosystem services assessment showed that the total value of the ecosystem services in the Beibu Gulf coastal areas increased over the whole study period, and reached about 54 million in 2014. The total value of the ecosystem services provided by the forest ecosystem was the highest, and accounted for 50% of the total value of the study area. In addition, 11 ecosystem service values were analyzed. The food production, gas regulation, and nutrient cycling service values decreased from 1999 to 2014, but other ecosystem service types showed an increasing trend. The results of driving mechanism analysis showed that the comprehensive urbanization rate (%) was an important driving factor behind the changes to the ecosystem service values in the Beibu Gulf coastal areas. However, the comprehensive urbanization rate in our study, which is equal to the proportion of the urban population to the total population, is a population structure index. Therefore, the regression models and comprehensive urbanization could reflect the regional economic structure, and that ecosystem services are closely related to social and economic development. This means that the reasonable regulation of economic structure can effectively enhance the value of regional ecosystem services. 参考文献 相似文献 引证文献

By 2100, it is predicted that streams in the Kakadu region in Northern Australia will be transforming in their coastal floodplains to saline environments because of sea-level rise. Potential impacts need to be assessed, together with existing threats, to manage future change. The fish and macroinvertebrate assemblages of the streams in the region are well researched and were used as indicators to assess centennial-scale changes to freshwaters. Spatial and temporal patterns in assemblage dynamics were described using data from different habitat types, and used as a framework to review current knowledge and assemblage vulnerability for likely conditions ≥100 years from present-day. Twenty threats within three broad classes were identified (climate change, invasive species, decommissioning and rehabilitation of Ranger uranium mine). Seven threatening processes were ranked as high risk to catchment-scale distributions of fish and macroinvertebrate taxa, with six being associated with climate change and one with mine-site rehabilitation. Habitat connectivities and dependencies were identified as key ecological processes for both groups, with saltwater intrusion to coastal floodplains being identified as the major process that will alter assemblage dynamics and system energy flow. Risks posed by climate change highlighted priority research and monitoring needs for management and protection of upland freshwater-refuge habitats.

Forest restoration is being promoted globally as an action that addresses multiple challenges, including climate change, biodiversity loss and poverty. But restoration projects will only persist over the long term if their goals are aligned with local people's interests and priorities. Few projects, however, assess local interests, or how these might be influenced by factors, such as local landscape condition and need for ecosystem services (ES). We hypothesized that inhabitants in highly degraded, intensifying landscapes, would prefer the restoration of regulating and cultural ES to improve ecological function and relational values, whereas people in fast‐changing frontier landscapes with large areas of remaining intact ecosystems would prefer provisioning ES. We surveyed local community members in both intensifying and frontier landscapes in Ecuador, which has been implementing an ambitious national reforestation programme, to assess local preferences and priorities for restoration. Participants selected and ranked potential restoration sites and explained their selection criteria. We categorized these criteria by ES classes to analyse local intentions, interests (frequency of ES) and priorities (ranking) at local and landscape scales. At a landscape scale, contrary to our expectations, inhabitants in both landscapes showed higher interest and priority for regulating and cultural ES than for provisioning ES. Interest in regulating ES was higher in the intensifying landscape (56%) than in the frontier (46%), whereas interest in provisioning ES was higher in the frontier (26%) than in the intensifying (15%). At a local scale (by site type), interest and priority of ES varied within landscapes. Our results show that local communities are motivated to engage in restoration to recover scarce ES. Moreover, the results invoke a pro‐active precautionary ‘Ecosystem service enhancement‐path’ to enhance and prevent ES scarcity. Framing interest and priorities through the lens of ES can help local communities and stakeholders formulate restoration goals that align with the particular socio‐ecological contexts of their landscapes, thereby improving local well‐being while meeting the ambitious global climate targets for restoration. Read the free Plain Language Summary for this article on the Journal blog.