Reciprocal facilitation between annual plants and burrowing crabs:Implications for the restoration of degraded saltmarshes

Increasing evidence shows that facilitative interactions between species play an essential role in coastal wetland ecosystems. However, there is a lack of understanding of how such interactions can be used for restoration purposes in saltmarsh ecosystems. We therefore studied the mechanisms of reciprocal facilitative interactions between native annual plants, Suaeda salsa, and burrowing crabs, Helice tientsinensis, in a middle-elevation saltmarsh (with generally high plant density and moderate tides) in the Yellow River Delta of China. We investigated the relationship between the densities of the plants and crab burrows in different seasons. Then, we tested whether and how saltmarsh plants and crabs indeed facilitate each other in a series of field and laboratory experiments. Finally, we applied the results by creating a field-scale artificial approach for microtopographic modification to restore a degraded saltmarsh. We found that the density of plant seedlings in spring was positively correlated with the density of crab burrows in the previous autumn; moreover, the density of crab burrows was correlated with the density of plants in summer. The concave-convex surface microtopography created by crabs promoted seed retention and seedling establishment of saltmarsh plants in winter and spring. These plants in turn facilitated crabs by inhibiting predators, providing food and reducing physical stresses for crabs in summer and autumn. The experimental removal of saltmarsh plants decreased crab burrow density, while both transplanting and simulating plants in bare patches promoted crabs. The microtopographic modification, inspired by our new understanding of the interactions between saltmarsh plants and crabs, showed that these degraded saltmarsh ecosystems can be restored by a single ploughing intervention. Synthesis. Our results suggest a reciprocal facilitation between annual plants and burrowing crabs in a middle-elevation saltmarsh ecosystem. This knowledge yielded new restoration options for degraded coastal saltmarshes through the one-time ploughing initiation of microtopographic variation, which could promote the re-establishment of ecosystem engineers and lead to the efficient recovery of pioneer coastal vegetation and associated fauna

Identifying priority areas of Four Major Chinese carps’ species in the Pearl River basin based on the MaxEnt model

The Pearl River basin (PRB) is an important producing area and the gene pool of wild resources of Four Major Chinese carps (FMCC). However human activities and climate changes causes the area shrink of the river network in PRB, the pollution aggregation, the serious habitat destroy of aquatic organisms, and the threat of biological resources and their living environment. Based on the accurate location and distribution data of FMCC from the literature and the field survey report of 2015–2016, this study used the MaxEnt model to predict the hot spot distribution area of FMCC in PRB. The simulation results show that the distribution of FMCC in the PRB gradually increases from the upper reaches to the middle and lower reaches. According to the MaxEnt model, the hot spots of FMCC in the PRB are mainly distributed in the south reaches and the lower reaches of the southeast. The model simulation also demonstrates that the hottest spots for the distribution of FMCC species in the PRB are the Yujiang basin, the Qianjiang basin and the lower reaches of the Xijiang basin. This study can provide the scientific guidance for the protection and the restoration of FMCC species in the PRB

Analysis Method of Agricultural Total Factor Productivity Based on Stochastic Block Model (SBM) and Machine Learning

When analyzing agriculture’s total factor productivity, traditional measurement approaches do not take into account the inefficiency value. The production functions are assumed to be analyzed on basis of the random boundaries, which makes the analysis results inaccurate and unreliable. As a result, this paper proposes an analytical approach for agricultural total factor productivity based on the stochastic block model (SBM), which combines the benefits of statistics and machine learning. It uses the SBM direction distance function and the Luenberger productivity index to measure the agricultural efficiency, total factor productivity, and their components. The research study considers the data from 31 provinces from 2006 to 2018 years. First, one output indicator and six input indicators are established. The time-varying variations of the national agricultural inefficiency value and its source decomposition under variable scale returns are then determined using the SBM-based algorithm of agricultural total factor productivity and the obtained sample data. The changes of the agricultural total factor productivity and its components are comprehensively analyzed. Following an examination of the elements impacting agricultural efficiency and productivity, the socioeconomic development of the agricultural total factor productivity is examined in order to achieve efficient growth

Rapid urbanization and global warming significantly impact tidal dynamics in the Pearl River Estuary, China

Due to the dual impacts of anthropogenic disturbances and climate change, tidal hydrodynamics of estuaries have been intensively investigated for their potential to increase flood risk and devastate coastal habitats and human communities. Climate change leads to rises in sea levels, which can amplify regional tides and increase tidal ranges. This study takes the estuarine area of the Pearl River (PRE), one of the fastest-developed estuaries in China, as an example to explore the effects of land cover changes and sea level rise on tidal dynamics. Annual mean tidal levels were collected at 26 major hydrological stations from five major rivers/waterways. To better understand the temporal changes in tidal levels, we analyzed the trends and periodic patterns through linear regression and Complex Morlet wavelet analyses. For the main Pearl River outlet, where conversion of agricultural land to urban use had been primarily taking place, the tidal level changes were significantly affected by increased built-up areas and decreased cultivated land areas. On the other hand, in the middle to upper reaches of the Xi River and Shunde-Hengmen Waterway, we observed decreased tidal levels with decreases in the agricultural lands. No significant correlations were found between annual mean tidal levels and land cover changes downstream of the main rivers. Instead, the tidal level changes at locations close to the coastline were more related to sea level rise, with an average of 0.002 m per year increase. This study highlighted the importance of human activity and sea level rise impacts on tidal dynamics. A systematic understanding of the tidal changes in the estuary is expected to help enhance mechanisms of estuarine hydrology, which could serve as the basis for improving the management and practice of coastal regions in coping with climate change and estuary protection

Body mass index had different effects on premenopausal and postmenopausal breast cancer risks: a dose-response meta-analysis with 3,318,796 subjects from 31 cohort studies

Abstract Background There is sufficient evidence supporting a relationship between increased body mass index (BMI) and an increased risk for breast cancer among postmenopausal women. However, most studies have found a decreased risk for premenopausal breast cancer. This study was conducted to find out the different effects of BMI on the risk of breast cancer among premenopausal and postmenopausal women, and explore the potential factors that influence the associations. Methods A dose-response meta-analysis with 3,318,796 participants from 31 articles was conducted. Cohort studies that included BMI and corresponding breast cancer risk were selected through various databases including PubMed, Medline, Web of Science, the China National Knowledge Infrastructure (CNKI) and Chinese Scientific Journals (VIP). Random effects models were used for analyzing the data. Results The summary relative risks (RRs) were 1.33 (95%CI: 1.20–1.48) and 0.94(95%CI: 0.80–1.11) among postmenopausal and premenopausal women, respectively. The dose-response meta-analysis indicated a positive non-linear association between BMI and breast cancer risk among postmenopausal women, and compared to the mean level of the normal BMI category (21.5 kg/m2) the RR in total postmenopausal women were1.03 (95% CI: 1.02–1.05) per 1 kg/m2 increment. However, no statistically significant association among total premenopausal women was detected. In subgroup analysis among European premenopausal women, the summary RR was 0.79(95%CI: 0.70–0.88). The non-linear relationship showed a negative non-linear association between BMI and breast cancer risk among European premenopausal women. When compared to the mean level of the normal BMI category, the RRs were 0.98 (95%CI: 0.96–1.00) per 1 kg/m2 increment, respectively. Conclusions In line with previous studies BMI had different effects on pre-menopausal and postmenopausal breast cancer risk. However, contrary to previous studies, a high BMI was not associated with decreased risk in total pre-menopausal women. More research is needed to better understand these differences

Additional file 1: of Body mass index had different effects on premenopausal and postmenopausal breast cancer risks: a dose-response meta-analysis with 3,318,796 subjects from 31 cohort studies

Study characteristics of published cohort studies on body mass index(BMI) and breast cancer risk. (DOC 725 kb

Additional file 2: of Body mass index had different effects on premenopausal and postmenopausal breast cancer risks: a dose-response meta-analysis with 3,318,796 subjects from 31 cohort studies

The related data and materials in this study. (ZIP 1785 kb