查看更多>>摘要：The expansion of constructed land is one of the important factors leading to the degradation of ecosystems, and it seriously threatens the sustainable development of regional social economies. However, existing studies classify constructed land into one category, and there is a relative lack of research on the impact of different types of constructed land expansion patterns on ecosystem health (EH). In this study, the evaluation of ecosystem resilience was revised based on the spatial neighbourhood effect and human interference. Then the revised vigour-organization-resilience-services (VORS) framework was applied to assess the spatiotemporal patterns of EH in the coastal region of the East China Sea. Constructed land was divided into urban constructed land, rural residential areas, and other constructed lands. And geographically and temporally weighted regression (GTWR) model was used to link the ecosystem health index (EHI) to the expansion of various types of constructed land. The following conclusions were obtained: From 1990 to 2015, the area of constructed land increased by 2.24 times. Urban constructed land displayed a high-density and concentrated expansion pattern. Rural residential areas exhibited a low-density and dispersed expansion pattern. The EH of the study area deteriorated after 1990 and improved after 2000. A healthy ecosystem tends to be healthier, and a poor ecosystem tends to deteriorate. EH showed a high degree of spatial heterogeneity. Shanghai and Jiaxing regions were almost in the very unhealthy range, and this low-value region tended to expand, while the area with an EHI above ordinary accounted for over 90% on the south of Ningbo. The expansion pattern of urban constructed land impacted the regional EH slightly, but the impact was serious in the local EH. However, although the expansion pattern of rural residential areas had a slight impact on the local EH, it had a serious impact on the regional EH. The impact of the expansion of rural residential areas on EH should be given priority consideration in future control policies.
查看更多>>摘要：Coral reefs harbour rich biodiversity by increasing heterogeneous habitat and providing numerous ecosystem services and goods. However, they are highly threatened due to ongoing climate change and various anthropogenic activities. Therefore, the protection of corals is enforced by laws and legislative machinery around the globe. The present work is a case study in the highly urbanized Mumbai city, where a coastal road project required dredging and reclamation that overlapped with a coral habitat. A detailed environmental mitigation plan was undertaken to preserve the fragile corals at the proposed project site. A total of 329 colonies of Pseudosiderastrea tayamai Yabe & Sugiyama, 1935, were relocated from the project site to a recipient site after verifying the habitat suitability. Monthly coral health monitoring was conducted for one year after their relocation to the new habitat. After one year of translocation, 92.1% (n = 303) colonies survived and were in healthy state. Coral bleaching is a well-known phenomenon that occurs due to extreme variability in temperature, salinity and siltation etc. In the present study, coral bleaching was observed during monsoon (July - September 21) wherein maximum (94.83%) occurred in August 21 and minimum (4.86%) was in November 21. Algal overgrowth on coral colonies (maximum 38.9%), and sediment smothering (maximum 44.8%) were observed, but no colony mortality was noted (Jan - May 21). Whereas, 3.4% mortality was recorded during monsoon season only. The gross new recruitment (n = 22) of corals was also recorded collectively during the months of April, May and November 21. Therefore, the current study suggests that relocating corals from coastal development sites, where habitat loss is unavoidable, could be considered a tool that will aid in conservation of urban reefs. This study proves that only committed involvement of stakeholders and project proponents who have developmental perspective with environmental accountability can achieve the sustainability of rare and fragile ecosystems.
Philiphi de RozariAli El HanandehMargaret Greenway
10页
查看更多>>摘要：In constructed wetlands for wastewater treatment, plants contribute to nutrient removal. However, plant species differ in their ability to tolerate high nutrient loads and accumulate nutrients in biomass. Growth and nutrient accumulation were investigated in two subtropical/tropical plants: melaleuca trees (Melaleuca quinquenervia.) and lemongrass (Cymbopogon citratus). These were planted in 240 L mesocosms containing sand media and biochar (0 to 25% by volume). The mesocosms were loaded with tertiary effluent for 4 months, secondary clarified wastewater (SCW) for 8 months and finally septage for 9 months, a total cumulative load of 1060gN m ~(-2) and 320gP m ~(-2). Plant growth, including stem height and girth for melaleuca and leaf regrowth for lemongrass were monitored. Growth rates were higher (0.48 cm/day stem height; 2.22 cm/day leaf regrowth) when irrigated with septage, compared to SCW (0.32 cm/day stem height; 1.14 cm/day leaf regrowth). Plants were harvested at the end of the experiment and the biomass and nutrient content in each part determined. Both melaleuca and lemongrass had very high N and P tissue content: melaleuca leaves 23 mg/gN, 2 mg/gP; rootsl5mg/gN, 2.1 mg/ gP; lemongrass leaves 18 mg/gN,2.2gP; roots 9.5 mg/gN, 2 mg/gP. Annual biomass and nutrient accumulation per plant was 486 g; 5.72 gN; 0.89 gP for melaleuca trees and 180 g; 2.54 gN; 0.39gP for lemongrass, a total nutrient accumulation of 33 g m ~(-2) N and 5 g m ~(-2) P/annum. Plant uptake accounted for 8.6%TN and 4.5%TP of load retained. Biochar amendments did not enhance growth rate nor increase N and P biomass. We postulate that effluent nutrient loads provided adequate nutrients for plant growth even in pure sand media.
查看更多>>摘要：Background and aim: Nature-based solutions to engineering challenges are essential to limit climate change impacts on the urban environment. Quantitative understanding of multiple ''engineering functions'' provided by soil-plant interactions of different species is needed for species selection and re-establishing natural processes affected by urbanisation.Methods: Contrasting herbaceous species (legumes, grasses, and forbs) were selected and grown as monoculture or species mix in soil columns for a five-month growing season. Saturated hydraulic conductivity was initially tested for each column, and then the columns were monitored for three-weeks of evapotranspiration. Water loss, matric suction, and penetrometer resistance were measured. Finally, soil was tested for aggregate stability and water retention.Results: Saturated hydraulic conductivity of vegetated soil was generally larger than that of fallow soil (6.9e-6 ± 1.4e~6 m/s in fallow soil). Saturated hydraulic conductivity was significantly different between species (e.g., from 9.9e-6 ± 1.3e~6 m/s in Festuca ovina to 3.9e~5 ± 1.2e''6 m/s in Lotus corniculatus) and was negatively correlated with specific root length. The water stored in the soil was efficiently removed by plant transpiration (> 60% of evapotranspiration). Large changes in soil structure were observed in vegetated soil, with significant increases in soil strength, aggregate stability, and alteration of water retention properties. Conclusions: Multiple soil-plant interactions influence species selection for optimising nature-based solutions (e. g., bioretention barriers). Substantial scope exists to choose species mixes to manipulate soil hydro-mechanical properties. Enhanced biodiversity did not compromise the engineering services of nature-based solutions (e.g., water removal), and may have multiple benefits.
查看更多>>摘要：Soil water storage (SWS) can effectively be used as an important indicator to manage soil water resources in water-limited ecosystems, being strongly linked to land-use and land management changes. The Government of China launched the Gully Land Consolidation (GLC) project in 2011 to reclaim landforms and resolve land scarcity and food shortages in the Chinese Loess Plateau (CLP) without endangering the environment. Corollary effects of this project were alterations to original landscapes and associated hydrological processes. However, temporal dynamics in available soil water of the newly formed land for cultivation purposes remain unclear. Accordingly, this study measured SWS to a 5 m soil depth over a 5-year period at two gully sites, one newly formed under the GLC project (i.e., the experimental site) and the other left untreated (i.e., the control). SWS exhibited similarly weak temporal variation at both gully sites (coefficient of variation [CV] = 6% at the experimental site; CV = 11% at the control site). Although SWS always negatively correlated to mean temperature and wind speed (p < 0.05) with no observable hysteresis, SWS responded to precipitation at both sites with obvious hysteresis (experimental site = two month hysteresis; control site = three months hysteresis). Seasonal SWS characteristics confirmed the lag response to precipitation. Moreover, spatial SWS patterns differed distinctly at both sites. The mean proportion of available SWS to the available water holding capacity was 69% at the experimental site, indicating that stored soil water was available for crop cultivation without the threat of water shortages. Our results provide new insight into spatial and temporal SWS variation in newly formed land engineered by restoration projects. Furthermore, clarifying SWS temporal dynamics and spatial distributions based on long-term monitoring is essential to evaluate, model, and manage water resources in areas affected by anthropic activities.
查看更多>>摘要：The aggravation of climate change and human activities have challenged the fragile ecology of the arid and semi-arid Xinjiang in Northwest China. The concept of ecological carrying capacity (ECC) refers to the ability of an ecosystem to support the healthy development of the human social system and provide adequate resources and enabling environmental conditions. A comprehensive evaluation of ECC could rationalize ecological restoration and sustainable development. This study evaluates the ECC of Xinjiang's unique landscape structure of mountain-oasis-desert ecosystems from 1982 to 2017, using remote sensing data such as vegetation and evapotranspiration and geographic information system technology, and index evaluation method. The ECC patterns and change trends were explained from multidisciplinary perspectives, and the internal drivers of ECC spatio-temporal variations were evaluated by partial correlation analysis and residual analysis. The results showed an average ECC value at the median level of 0.29. For spatial distribution, ECC value decreased from west to east, the median ECC area was the most widespread, and the poorest ECC area was concentrated mainly in Southern Xinjiang's deserts. From the analysis of the significance of the change, ECC in Xinjiang had generally declined, with the decreasing areas exceeding the increasing areas. The driver analysis found temperature exerting a greater impact than precipitation on ECC improvement, and human activities positively impacted ECC. Altitude was closely associated with ECC distribution with better ECC in high elevation areas. The positive correlation between urbanization and ECC level was significant. The findings provide a relatively comprehensive and synoptic framework for ecological assessment in arid and semi-arid areas to inform sustainable development and ecological restoration in Xinjiang.
查看更多>>摘要：The United Nation decade on ecosystem restoration has been recognized in global and regional policy commitments that play a crucial role towards restoring degraded areas with the continued provision of ecosystem services. Climate-sensitive alpine meadows are vital in this regard as they are facing a continuous threat of degradation governed by both natural and anthropogenic drivers. The present work aims at the investigation of the ecological status and restoration strategies for alpine and sub-alpine areas of the Darma-Byans landscape in the Central Himalayan region of India. It is one of the important conservation landscapes identified under the SECURE Himalaya project of the United Nation Development Programme (UNDP). Under the present work, studies conducted regarding assessment strategies included: Land Use Land Cover (LULC) mapping, Normalized Difference Vegetation Index (NDVI) analysis, grazing capacity estimation, and final validation with secondary data collection followed by the investigation of suitable eco-system based adaptation and mitigation strategies for the area. Results showed the natural regeneration of biodiversity in the alpine meadows of the landscape. Clear indications analyzed from the results depict that grazing pressure was below its capacity (20,897 cow units per year); there was a decreasing trend in human population (in 15 villages) and livestock population (from 1987 by ~50% of the total population), tourists' influx, and an increasing trend in NDVI in the area. However, the sub-alpine areas are still facing the threat of extreme land degradation due to harsh climatic conditions, especially extreme rainfall events. Therefore, sustainable site-specific eco-restoration strategies, viz., grazing, under-grazing capacity, eco-tourism practice, soil erosion control by check dams and geo-coir matting followed by plantation, sustainable resource utilization management practices, shepherd's night staying sites, integrated agricultural practices, etc. are also recommended for the region.
查看更多>>摘要：As part of the effort to improve design and operation schemes of decentralized wastewater systems, the Danish EPA funded a research initiative, to re-evaluate the Danish guidelines for VFCW with an aim to improve its design. Therefore, the aim of this study is to assess the effect of recycling water from the effluent of the VFCW to the pump chamber at several recycle ratios and to compare the effects of recycle to the sedimentation tank in lieu of the pump chamber. In addition, water quality changes within the depth of the bed were assessed in order to make recommendations on an appropriate depth for effective treatment. The results showed overall the system performed very well regardless of the recycle ratio with removal rates of TSS, TOC, BOD5, NH4-N and TP around 99% and thus easily exceeding the national discharge requirements. Despite that, the better results for TN effluent concentrations, below 45 mg/L, were achieved for recycling water from the effluent of VFCW to pump chamber at recirculation rates of 50% to 100%. The changes in concentrations of measured parameters with depth suggest that almost all transformations occurred with the top 20 cm of the 1.0 m thick effective bed depth, thus, the results show that the VFCW dimensions given in the Danish guidelines may be overdesigned from the perspective of meeting current discharge limits.
查看更多>>摘要：In silvopastoral environments, landslide erosion results in loss of productive soils and pasture. Sediment delivered to streams from landslides contributes to the degradation of freshwater and marine receiving environments by smothering benthic habitats and increasing turbidity, light attenuation, and sediment-bound contaminants. Biological mitigation is an important strategy in pastoral environments to combat landslide erosion and improve the health of downstream aquatic ecosystems. Using lasso logistic regression, we investigate determinants of sediment connectivity for a landslide-triggering storm event in 1977 in the Wairarapa, New Zealand. Furthermore, we develop the first morphometric connectivity model to predict the likelihood of sediment delivery to streams following landslide initiation. We explore a range of connectivity scenarios by defining a set of sinks and simulating varying rates of sediment generation during flood events of increasing magnitude. The likelihood of sediment delivery is greatly enhanced where landslide deposits coalesce. Besides scar size variables, overland flow distance and vertical distance to sink were the most important morphometric predictors of connectivity. When scar size variables were removed from the connectivity model, median AUROC was reduced from 0.88 to 0.75.By coupling landslide susceptibility and connectivity predictions in a modular form, we quantify the cost effectiveness of targeted versus non-targeted approaches to shallow landslide mitigation. Sediment delivery ratios range from 0.21 to 0.29, equating to an event sediment yield of 3548 t km-2 to 9033 t km-2. Targeted mitigation of landslide-derived sediment is approximately an order of magnitude more cost-effective than a non-targeted approach. Compared with a pasture-only baseline, a 34% reduction in sediment delivery can be achieved by increasing slope stability through spaced tree planting on 6.5% of the pastoral land. The maximum reduction achievable through comprehensive coverage of widely spaced planting is 56%. The landslide connectivity model provides an objective method to support management decisions relating to mitigation of landslide erosion and sediment delivery to streams.
查看更多>>摘要：The ecological benefits of healthy oyster populations have led to mounting interest in restoration of degraded reef habitats and design of nature-based reef features. However, hydrodynamic studies of restored oyster reef remain sparse, and little is known about changes in mean flow and turbulence as a function of time since restoration. In this study, we investigate hydrodynamic differences between restored (restoration age: <1 y, 2 y, 4 y), degraded, and intact intertidal oyster reefs in a shallow, microtidal estuary. Field experiments conducted at each reef were designed to characterize variability in flow and turbulence associated with differences in reef morphology and restoration age, addressing research questions of whether and when hydrodynamic function is reestablished following restoration. Minor differences in normalized turbulence parameters within the canopies of restored and reference reefs (2 cm above bottom) were associated with variable channel-to-reef velocity attenuation, which was linked to heterogeneity in oyster canopy structure as characterized by high-resolution laser scans. Within-canopy turbulence characteristics and normalized Reynolds stresses were significantly elevated on restored and reference reefs compared to the degraded reef, emphasizing the role of reef restoration in changing near-bed hydrodynamics. Above-canopy (9 cmab) turbulence was hydrodynamically similar across live reference and restored reefs of all restoration ages, with estimated roughness heights that scaled with the canopy height. Comparisons between intact and restored reefs indicate that properly restored reefs can reach hydrodynamic similarity with historically intact reefs within 1 year of restoration, a conclusion that supports the use of reef restoration as a tool to reestablish hydrodynamic functions on degraded reefs.
NSTL