Ecological Engineering最新文献

Herbivores moderate grazing is a fundamental driver of plant diversity maintenance in grassland ecosystems. However, the effects of grazing with different herbivores on plant community composition and recruitment are still little known. Here, we conducted a field moderate grazing experiment to examine the effects of different grazing modes under moderate intensity in the cold season, including sheep grazing (SG), yak grazing (YG), and mixed grazing by sheep and yak (MG), on plant community composition and recruitment. Results showed that all grazing modes significantly decreased plant cover and average height of standing plant litter. Additionally, herbivores grazing significantly increased species richness but decreased community evenness (P < 0.05), with highest richness and evenness found in YG and SG plots, respectively. The trends of increasing aboveground biomass of common and rare species groups were most pronounced in the SG plots relative to the YG and MG plots. MG promoted the increasing of the common species group. From community recruitment, moderate grazing increased the sexual recruitment and decreased the asexual recruitment, and MG significantly inhibited the recruitment of asexual seedlings. Meanwhile, all grazing modes increased the species of poor palatability. These findings imply that the cold-season grazing with moderate intensity facilitated a rapid divergence succession of alpine meadow community by regulating the relative abundance of common and rare species, as well as the asexual seedlings recruitment induced by the removal of standing plant litter. Consequently, the cold-season grazing with different herbivores under moderate intensity can be used as a management tool to modulate grassland community structure and maintain species diversity in alpine grassland ecosystem.

Small-scale experiments have been conducted to investigate a wide range of factors suspected to influence treatment wetland (TW) functions and efficiency. One crucial advantage microcosms and mesocosms offer over field-scale systems is that they enable reproduction of experimental treatment units that are as similar as possible, only varying the factor(s) of interest. The goal of this paper is to discuss key methodological issues to consider, as well as the overall potential and limitations of using small-scale experiments as applied specifically to TW research. Planning a successful small-scale experiment to address a scientific question in TW science involves several key decisions to reach the project's goal. Due to financial, space or resources constraints, it is fundamental at the planning stage to carefully determine a suitable compromise between unit size, number of units, number of treatments (both in terms of number of variables and number of levels within each variable) and replication. Producing, properly storing and rigorously distributing the same volume or flow rate of wastewater to each unit is often the most challenging and time-consuming aspect of a small-scale TW experiment. Unavoidable sources of bias inherent in small-scale models must be identified, and when possible, minimized. Small-scale experiments for treatment wetlands can only take on full meaning when the insights obtained through them inform full-scale operations.

Due to climate change and rapid urban sprawl, central Mediterranean regions are subjected to short but intensive storm events resulting in a significant increase of flow rates and runoff volumes in low-lying coastal urban areas. Within the framework of green urban infrastructures (GUIs), a suitable combination of Nature-Based Solutions (NBS) with traditional grey infrastructures should be adopted to mitigate flood risk effects in urban and sub-urban areas contributing at the same time to achieve multiple benefits for both the environment and the community. The aim of this study is (i) to evaluate flood hazard maps for identifying the areas within a Sicilian hydrological river basin (Toscano catchment) with a high risk of flooding by implementing the HEC-RAS model at catchment scale; (ii) to quantify the peak flow and floodplain area reduction; (iii) to assess the effectiveness of small-scale NBS (green roofs, porous pavements, rain gardens and rain barrel), in terms of peak flow and runoff volume reductions, at urban block scale by using the EPA SWMM model Model simulations are performed integrating the hydraulic (HEC-RAS) and hydrological (EPA SWMM) models for return periods of 10, 50 and 200 years. The results showed that the estimated peak flow (m³ s⁻¹) obtained from the simulations performed at catchment scale for each T in the current scenario (without NBS) using HEC-RAS and EPA SWMM models are very close to each other (R² = 0.99). In addition, the utopian scenario simulation showed the HEC-RAS model sensitivity to CN calibration achieving a peak flow reduction up to about 60% with the floodplain area decreasing up to about 17%. Finally, the model EPA SWMM shows its sensitivity to NBS implementation at urban block scale with a peak flow reduction up to about 16% and a runoff volume (mm) reduction up to about 24%. These reductions decrease as T increases with a higher NBS mitigation effects for the lowest T. The results highlighted that the integration of NBS in urban areas could have hydrological and hydraulic positive effects, particularly in terms of peak flow and runoff volume reduction. Furthermore, the results suggest that small-scale NBS have a potential to be effective to smaller rainfall events, but a combination with large-scale NBS is necessary to cope with extreme events.

Climate change is currently the most crucial environmental problem, and policies on responses to climate change are actively being promoted worldwide. Particularly, greenhouse gas emissions in the city have been a continuous reminder of the need to reduce the effects of climate change. There has been interest in reducing greenhouse gas emissions using the green wall. Therefore, this research analyzed the temperature reduction characteristics and performance evaluation of the green wall system based on monitored data. The target area selected was public building. The monitoring point of the wall was the front of the wall with the installation point (glass and behind the green wall), and readings were taken for 10 min. The results of the analysis showed that the surface temperature of the building was affected by the performance of the green wall point during working hours (09:00 to 18:00). Finally, the data and greenhouse gas emissions were analyzed the data and greenhouse gas emissions of 45 to 72 %.

Disturbance regimes related to water level fluctuation play an important role in the structuring of aquatic macrophyte communities. In managed systems, winter water level drawdowns have shown promise in controlling populations of nuisance macrophytes, however, drawdowns may have unintended negative consequences on erosion, fauna, and non-target plant species. The Chippewa Flowage, located in Sawyer County, WI, has implemented targeted winter water level drawdowns with the goal of reducing nuisance levels of Myriophyllum spicatum. To evaluate the effects of water level drawdowns on Myriophyllum spicatum and the native macrophyte community, we conducted repeated full lake surveys of aquatic macrophytes at 2018 points under drawdown and normal water level management in 2005/06, 2015, and 2017. We supplemented these efforts with downscaled surveys in 2007, 2010, and 2016. Surveys revealed a statistically significant decline in both Myriophyllum spicatum occurrence and abundance, and average macrophyte abundance during active drawdown management. Kernel distributions of change in point-specific c-value between the two time periods showed a significant increase under drawdown conditions, and a decrease under normal management (D = 0.41, P ≤0.0001). Drawdown management appeared to successfully control Myriophyllum spicatum abundance and allowed for improvements in the floristic quality of the macrophyte community but resulted in reduced macrophyte abundance overall.

Urban landscapes homogenize our world at global scales, contributing to “extinction of experience”, a progressive decline in human interactions with native greenspace that can disconnect people from the services it provides. College age adults report feeling disconnected from nature more than other demographics, making universities a logical place to explore interventions intended to restore a connection with nature. This study surveyed 1088 students and staff across four university campus communities in Southern California, USA and used multicriteria decision analysis to explore their landscape preferences and the implications of those preferences for combatting extinction of experience. Our results suggest that perspectives of, and preferences for, different greenspace forms vary significantly (i.e., they are not perceived as substitutable). Support for native ecosystems, particularly coastal sage scrub (top ranked landscape) was generally high, suggesting that disaffection with wild nature is not particularly widespread. Programs for replacing turf grass lawns (lowest ranked landscape) with native plants were also well supported, but support for stormwater bioswales was more moderate (and variable). This may reflect their relative newness, both on university campuses and in urban spaces more generally. Not all members of campus communities preferred the same landscapes; preferences differed with degree of pro-environmentalism and university status (undergraduate student, graduate student, staff). Even so, all respondents exhibited landscape preferences consistent with at least one approach for combatting extinction of experience, suggesting that ecologists, engineers and urban planners have a viable set of generalizable tools for reconnecting people with nature.

Natural estuarine wetland shorelines play a crucial role in coastal stabilization and preserving ecological security patterns. The effectiveness of estuarine shoreline engineering in reducing coastal erosion and maintaining the stability of ecosystem structures and functions is tightly linked to their types and structures. Although the living estuarine shorelines have received increasing attention, there have been few systematic literature reviews on the development process, research hotspots and future trends in this field. Here we summarized the literatures, and analyzed them in terms of annual publications, subject categories, co-cited journals, countries, institutions, authors, references, and keywords based on OriginPro, VOSviewer, and CiteSpace softwares. Results showed that the studies on living estuarine shorelines have experienced a rapid development phase since 2004, which is mainly categorized into Environmental Sciences and Oceanography, and the research institutions and scholars are mainly from the USA and China. The effects of human activities and climate change on the structures and functions of estuarine ecosystems are the dominant topics. Furthermore, the nature-based management solutions have been proposed to improve the functions and services of estuarine ecosystems. Currently, the habitats of estuarine wetlands worldwide have undergone varying degrees of degradation, therefore, the ecological conservation and restoration of estuarine shorelines urgently require the active participation of the public. It is highly important to integrate multi-disciplinary and multi-technology approaches to construct nature-based, more resilient, multi-service synergistic, and composite living shorelines in coastal zones. The findings of this research can provide scientific guidelines for the adaptive management and conservation of estuarine wetlands.

Plant introduction and hydrological management are essential strategies for near-natural wetland restoration. However, the combined effects of plant species and water depth on soil quality restoration remain poorly understood. The wetland ecosystem is crucial for Earth ecosystem health and sustainable development, but it faces challenges due to environmental change and human activities leading to soil quality degradation. In this study, we conducted a five-year near-natural restoration experiment covering approximately 2071 m² area in the Changbai Mountains region of northeastern China to assess the impact of plant species and water depth combinations on soil quality dynamics in reclaimed wetlands. Through an ecological engineering project, a meticulous controlled experiment was implemented to investigate the impact of different plant species and water depth combinations on soil quality in near-naturally restored wetlands. Over the five-year restoration period, we observed significant improvements in soil quality indicators, including pH, bulk density, soil organic carbon content, and labile organic carbon fractions. Soil pH and bulk density both showed a decreasing trend, with notable variations influenced by the combination of plant species and water depth. Particularly significant drops were observed in wetlands where Lythrum salicaria L. was introduced at 10 cm water depth and Iris wilsonii C. H. Wright was introduced at 30 cm water depth. Meanwhile, soil organic carbon content also appeared optimal restoration effects in the aforementioned combinations, highlighting the regulatory effect of these combinations on soil quality regulation. Linear regression modeling demonstrated a significant positive correlation between soil organic carbon and both above-ground and below-ground biomass, highlighting the interplay between vegetation dynamics and soil quality restoration. Our study provides valuable insights into the complex dynamics of soil quality restoration in reclaimed wetlands and underscores the importance of considering plant species-water depth combinations in restoration planning. By understanding these dynamics, restoration practitioners can make informed decisions to enhance the sustainability of wetland ecosystems and their invaluable ecological services.

Clogging has garnered growing interest as a significant operational and maintenance concern that affects the sustainable development and implementation of sub-surface flow (SSF) wetlands in wastewater treatment. The existing literature on clogging has been found to have limitations, as none of the studies have provided a comprehensive overview of the entire clogging process, starting from its initiation to remediation. In addition, very few works have addressed the models that were utilized to forecast the occurrence of system clogging. This study primarily focuses on the process of clogging, in widely used SSF wetland systems due to its negative impact on the lifespan of these systems. The article seeks to evaluate different forms of clogging and their developmental mechanisms, as well as the influencing factors. The work thoroughly examines the several techniques used to measure and evaluate clogging. The current review also encompasses the examination of several mathematical models used to predict the clogging of the system. Lastly, it also emphasizes the remediation methods required to resolve clogs. The main objective of this review is to bring all pertinent information on the clogging of SSF wetlands to the attention of prolific researchers with the goal of mitigating system clogging and establishing CW technology as a viable and sustainable alternative for wastewater treatment in the near future.

Wetland degradation is a major factor in the decline of biodiversity. Ecological engineering construction efforts, such as water diversion, have been the main method of wetland restoration. To reveal the effects of biodiversity conservation and ecological engineering construction in the semiarid regions of China, waterbird surveys were carried out 2 years before and 8 years after the construction of the ecological engineering project discussed in this study. The relationships among waterbirds and habitat landscape patterns, hydrology and vegetation conditions were analyzed. The impacts of ecological engineering on habitats and waterbird diversity were revealed. The results showed that (1) there were significant changes in land use, hydrological distributions and vegetation cover in the study area before and after the construction of the ecological project. The quality of waterbird habitats after the construction project was better than that before construction. However, there were fluctuating conditions. (2) The areas of water bodies and marshes were positively correlated with the number and diversity of waterbirds. However, increases in arable land, forestland, grassland and saline land can stress rare waterbirds. Changes in water levels, water body areas and vegetation cover in the conservation area all directly affect the availability of waterbird habitats, which can affect waterbird diversity. The wetland water level is the most important impact factor. (3) The annual water diversion volume in the study area is 5.00 × 10⁷ m³. When the water level is maintained at approximately 1.5-2.5m, the number of waterbirds remains stable. This study can provide scientific guidance and a methodological basis for the construction of ecological projects with waterbirds as protected targets.