Shift from soil chemical to physical filters in assembling riparian floristic communities along a flooding stress gradient.

Understanding community assembly is a key issue in recognizing community succession and guiding the restoration of degraded ecosystems. Based on the stress-dominance hypothesis (SDH), along a gradient of increasing environmental stress, the relative importance of environmental filtering is supposed to be dominant but species interaction could be a minor process in assembling communities. However, this hypothesized model of the assembly-rule shift was equivocally supported by various studies. In this study, by examining riparian plant communities with the zonation distribution of species composition along a markedly contrast flooding-stress gradient, a general aim was to clarify whether assembly rules of the communities would be also sorted into the zonation pattern as expected by the SDH. Another aim was to identify how edaphic factors associate with the assembly processes. Firstly, we found that even under the distinct stress gradient, community assembly was not stratified into different rules as the SDH expected, but environmental filtering appeared as a dominant assembly process across the stress gradient. Secondly, although filtering holds as a dominant assembly rule, environmental filters were found different along the gradient. By disentangling the filters of edaphic attributes, we found that the filters significantly shifted from soil physical properties to chemical nutrients governing the filtering process along the gradient. This result revealed that, across the contrast gradient, the environmental deterministic process on assembly is so strong that the other assembly processes became weaker. By synthesizing our results, the SDH may not be applied even under the context of a contrast stress gradient, which suggests that environmental context may be a key in testing and applying the SDH. Finally, in guiding riparian restoration under strong stress, we suggest that soil physical structure rather than chemical nutrients shall be given a priority for consideration in rebuilding the degraded riparian communities.

Decomposition and Decoupling Analysis of CO2 Emissions Based on LMDI and Two-Dimensional Decoupling Model in Gansu Province, China.

Currently, little attention has been paid to reducing carbon dioxide (CO2) emissions of Gansu, and the two-dimensional decoupling model has been rarely used to study the relationship between the economic development and CO2 emissions, especially in western China (e.g., Gansu). Thus, here, we first used the Logarithmic Mean Divisia Index (LMDI) to decompose the driving factors of Gansu's CO2 emissions between 2000-2017 and then analyzed the decoupling relationship by using the two-dimensional model. Results showed: (1) Gansu's CO2 emissions increased from 7805.70 × 104 t in 2000 to 19,896.05 × 104 t in 2017. The secondary industry accounted for the largest proportion in Gansu's CO2 emissions, followed by the tertiary industry and the primary industry. (2) The economic output showed the dominant driving effect on Gansu's CO2 emissions growth with the cumulative contribution rate of 201.94%, followed by the effects of industrial structure, population size, and energy structure, and their cumulative contribution rates were 9.68%, 7.81%, and 3.05%, respectively. In contrast, the energy intensity effect presented the most obvious mitigating effect with the cumulative contribution rate of -122.49%. (3) The Environmental Kuznets Curve (EKC) between CO2 emissions and economic growth was demonstrated the inverted U-shape in Gansu. The two-dimensional decoupling status was the low level-weak decoupling (WD-LE) during 2000-2017. Thus, dropping the proportion of the secondary industry, reducing the use of carbon-intensive fuel like coal, introducing advanced technologies, and increasing the investment of new energy might effectively restrain the growth of Gansu's CO2 emissions.

Walls offer potential to improve urban biodiversity.

Within urban environment with high-rise buildings and structures, walls represent the most common vertical spaces. Conventionally, such spaces are viewed as abiotic areas, where spontaneous flora is neglected. Through investigations in a typical mountainous city Chongqing, this study concerns the spontaneous species diversity on walls and the influences of wall factors and the adjacent environment. A total of 239 vascular plant species belonging to 172 genera and 75 families were found; 90% of the species are indigenous. More fern species inhabit walls, compared with xerophytes that dominate general urban environment. Variation partitioning indicated that wall attributes played a more important role in explaining the total variation in wall vegetation composition and structure than did the adjacent environment. Given that there are limited possibilities to extend more green space in urban land environment, we support a "let Nature take its course" approach to improve urban biodiversity, where vertical urban space with spontaneous flora can act as a valuable complement to biodiversity and ecosystem services in dense urban environment. This study should raise urban designers' and ecosystem managers' awareness of the possibilities of this type of informal, unconventional habitat as a "supplement" for urban greening and landscaping.

Backcasting approach with multi-scenario simulation for assessing effects of land use policy using GeoSOS-FLUS software.

The method presented is helpful for assessing effects of land use policy and unfolding the action mechanism and implementation effect of policies on land use changes. The backcasting method is based on the re-simulation of the historical real changes of land use. By observing the error between the real and simulated states, adjust the parameters for many times, and a variety of land use scenarios are obtained, and the scenario with the minimum and acceptable error is selected to assess the effects of land use policy represented by its parameters. The method is structured in four sequential stages, including expressing the policy action mechanism as the parameter combinations to control land use changes, and then translating the parameter combination that can reflect the effect of land use policies into the policy effectiveness. This process is realized by ArcGIS and GeoSOS-FLUS software developed based on Cellular Automata (CA) model. The method was successfully tested in the peri-urban region near Shanghai metropolitan area. The raw material is Land-Use/Cover (LULC) data of study area in 2000 and 2015. This method assessed the effects of land use policies during fifteen years, and analyzed the mechanism of effective policies, as well as the types and reasons of failure policies. This presented method is useful in land governance and the formulation and implementation of land use policy. •This article developed a backcasting approach to evaluate the effectiveness of land use policies on land use changes in a certain period of time.•The policy action mechanism was transformed into controllable, visible, and adjustable parameter combinations.•The method built an analytical framework for the assessment of land use policy effectiveness in any regions.

The resilience research of the plant and soil optimization design base on the habitat-site design in semiarid green space.

As the northwest region's advancement in urbanization has improved, the contradiction between urbanization and the fragile ecological environment has been gradually resolved. Facing the constraint of regional fragile ecological pressures, northwestern cities must create new ecological processes by using resilient designs. It is necessary to promote an organic ease construction mode, which is proper for the ecological matrix space in ecological construction of the northwestern landscape. In this research, which aims to solve problems and conflicts between the plant landscape design and site habitat conditions, we used the experimental method for plant landscape construction and soil optimization based on the previous theory and foundation of habitat-site design. We established the research framework as "natural plant community investigation experimental base simulation database construction." First, based on natural plant community research, the ecological prototype of the near natural plant community was quantized and evaluated, and the database was established; second, the plant community fabric was constructed, and the soil optimization technique was tested by using a "habitat island," the purpose of which was to create a stably structured, low-maintenance, drought-adaptive, water-resistant, and beautiful plant community model to screen the suitable soil medium ratio and mulching type for plant growth. Finally, following the "artificial intervention, natural formation" design idea, the practice of habitat unit construction and established database of the plant community structure model was carried out to provide theoretical and technical support for the plant landscape construction and soil optimization of habitat construction in the northwestern green space.

Use it or not: An agro-ecological perspective to flooded riparian land along the Three Gorges Reservoir.

The extensive flooded land associated with the Three Gorges Reservoir, poses a great social and environmental challenge, yet it is a potential valuable land and sociological resource for resolving human-land conflicts in the surrounding communities. Controversies arose over use or non-use of such land among local communities and authorities; and different management strategies were adopted. We compared two representative ecosystems, Wuyang Bay in small-scale agricultural use through opportunistic farming, and Baijiaxi Bay in a state of natural succession, and learned the challenges-cum-opportunities regarding sustainability through an agro-ecological perspective. We integrated the plant diversity, water quality improvement, market production services and people's attitudes to obtain a holistic evaluation of the socio-ecological and economic benefits delivered by two bays. Significant differences were found: Wuyang Bay performed much better than Baijiaxi Bay in terms of plant diversity maintenance and people's acceptance. Regarding the concerns about impacts on reservoir water, Wuyang Bay has lower TN, and NH4-N concentrations than Baijiaxi Bay. This may be because of the decomposition of a large amount of naturally grown-drowned vegetation in Baijiaxi Bay. Emergy analysis showed that the economic efficiency of Wuyang Bay is better than other similar systems given its limited growing season. However, this is at the expense of the environment through chemical fertilisers and pesticides seeping into the reservoir waters. Strictly speaking, Wuyang Bay cannot be counted as a sustainable agro-ecosystem although it hints at many practical merits, such as integrating natural landscape elements in fields, and employing multiple crops in spatial and temporal patterns. Our study offers new insights into the impacts of world's largest reservoir construction on the livelihoods of nearby communities on a small scale and the possible solutions. With the use-or-not contradiction, the government should offer appropriate policies and technical support to incentivise farmers to a more sustainable, multi-functional living landscape.

Functions of traditional ponds in altering sediment budgets in the hilly area of the Three Gorges Reservoir, China.

The landscape pattern will affect the sediment transport process. The cluster of ponds is a common landscape, which has traditionally been used for irrigation in the hilly area of the Three Gorges Reservoir (TGR). However, little is known about how the landscape elements temporally changed over the past decades and if the ponds can be applied to function in balancing watershed sediments against soil erosion. The Jinglingxi watershed, covering 20.5 km2, was selected as the study area. The changes in pond number, surface area, and drainage catchment were analyzed with aid of high-resolution typographical map and unmanned aerial vehicles imagery. The spatial WaTEM/SEDEM model was developed to simulate watershed soil erosion and sediment deposition under the absence and presence of water bodies scenarios. Results from different simulation scenarios were compared and revealed the trapping effects of the multi-pond system. From 1983 to 2016, the number and total area of ponds roughly doubled. The density reached 30 ponds/km2. From 1983 to 2016, the total drainage area of ponds increased from 13.22% to 35.4% of the whole watershed. The sediments deposited at the bottom of ponds can indicate the past specific sediment yield (SSY) in drainage catchments. Our results suggest that the multi-pond system not only reduce watershed sediment export but also alter the sediment deposition in different land uses. The reduced sediments export is expected to prolong the service life of downstream reservoirs at the expectancy of ponds' storage capacities. The ecological compensation from downstream reservoirs' revenues to upstream regions should be established to drive dredging actions for the upstream ponds.

New toxicogenetic insights and ranking of the selected pharmaceuticals belong to the three different classes: A toxicity estimation to confirmation approach.

Tetracycline hydrochloride (TH), indomethacin (IM), and bezafibrate (BF) belong to the three different important classes of pharmaceuticals, which are well known for their toxicity and environmental concerns. However, studies are still elusive to highlight the mechanistic toxicity of these pharmaceuticals and rank them using both, the toxicity prediction and confirmation approaches. Therefore, we employed the next generation toxicity testing in 21st century (TOX21) tools and estimated the in vitro/vivo toxic endpoints of mentioned pharmaceuticals, and then confirmed them using in vitro/vivo assays. We found significant resemblance in the results obtained via both approaches, especially in terms of in vivo LC50 s and developmental toxicity that ranked IM as most toxic among the studied pharmaceuticals. However, TH appeared most toxic with the lowest estimated AC50s, the highest experimental IC50s, and DNA damages in vitro. Contrarily, IM was found as congener with priority concern to activate the Pi3k-Akt-mTOR pathway in vitro at concentrations substantially lower than that of TH and BF. Further, IM exposure at lower doses (2.79-13.97 µM) depressed the pharmaceuticals detoxification phase I (CYP450 s), phase II (UGTs, SULTs), and phase III (TPs) pathways in zebrafish, whereas, at relatively higher doses, TH (2.08-33.27 µM) and BF (55.28-884.41 µM) partially activated these pathways, which ultimately caused the developmental toxicity in the following order: IM > TH > BF. In addition, we also ranked these pharmaceuticals in terms of their particular toxicity to myogenesis, hematopoiesis, and hepatogenesis in zebrafish embryos. Our results revealed that IM significantly affected myogenesis, hematopoiesis, and hepatogenesis, while TH and BF induced prominent effects on hematopoiesis via significant downregulation of associated genetic markers, such as drl, mpx, and gata2a. Overall, our findings confirmed that IM has higher toxicity than that of TH and BF, therefore, the consumption of these pharmaceuticals should be regulated in the same manner to ensure human and environmental safety.

Multi-perspective comparisons and mitigation implications of SO2 and NO x discharges from the industrial sector of China: a decomposition analysis.

This study is the first attempt to investigate the drivers of Chinese industrial SO2 and NO x emissions from both periodic and structural perspectives through a decomposition analysis using the logarithmic mean Divisia index (LMDI). The two pollutants' emissions were decomposed into output effects, structural effects, clean production effects, and pollution abatement effects. The results showed that China's industrial SO2 discharge increased by 1.14 Mt during 2003-2014, and the contributions from the four effects were 23.17, - 1.88, - 3.80, and - 16.36 Mt, respectively. Likewise, NO x discharge changed by - 3.44 Mt over 2011-2014, and the corresponding contributions from the four effects were 2.97, - 0.62, - 1.84, and - 3.95 Mt. Thus, the output effect was mainly responsible for the growth of the two discharges. The average annual contribution rates of SO2 and NO x from output were 14.33 and 5.97%, respectively, but pollution abatement technology presented the most obvious mitigating effects (- 10.11 and - 7.92%), followed by the mitigating effects of clean production technology (- 2.35 and - 3.7%), and the mitigation from the structural effect was the weakest (- 1.16 and - 1.25%, respectively), which meant pollutant reduction policies related to industrial structure adjustment should be a long-term measure for the two discharges. In addition, the sub-sectors of I20 (manufacture of raw chemical materials and chemical products), I24 (manufacture of non-metallic mineral products), and I26 (smelting and pressing of non-ferrous metals) were the major contributors to both discharges. Thus, these sub-sectors should be given priority consideration when designing mitigation-related measures. Last, some particular policy implications were recommended for reducing the two discharges, including that the government should seek a technological discharge reduction route.