Search

Exploring the spatio-temporal variations of farmland landscape patterns in a traditional agricultural region can provide scientific support for decision-making on sustainable rural land use and rural vitalization development. This study established a comprehensive evaluation index for farmland fragmentation with multiple aspects (dominance, integrity, aggregation, regularity, and connectivity) at the county scale. The goal was to identify the evolution of farmland fragmentation in the traditional agricultural region of the Huang-Huai-Hai Plain during 2000–2015 and investigate underlying drivers using panel data of 359 counties. Results showed an accelerating but fluctuating fragmentation pattern of the farmland landscape. The indexes of dominance, integrity, and aggregation of farmland decreased most sharply, while the index of connectivity increased. Furthermore, the evolution of the farmland fragmentation pattern showed significant spatio-temporal heterogeneity, which is similar to the trajectory of urbanization and land use transition. Farmland fragmentation in municipal districts also emerged earlier and was more severe than in county-level cities and counties. Factors influenced by advancing urbanization include the proportion of artificial land, population density, and proportion of primary industry; these factors drove the evolution of farmland fragmentation. In contrast, the increase in income of rural residents and production efficiency of farmland were the key factors contributing to the improvement in farmland connectivity. [ABSTRACT FROM AUTHOR]

Mangrove ecosystems play an important role in global carbon budget, however, the quantitative relationships between environmental drivers and productivity in these forests remain poorly understood. This study presented a remote sensing (RS)-based productivity model to estimate the light use efficiency (LUE) and gross primary production (GPP) of mangrove forests in China. Firstly, LUE model considered the effects of tidal inundation and therefore involved sea surface temperature (SST) and salinity as environmental scalars. Secondly, the downscaling effect of photosynthetic active radiation (PAR) on the mangrove LUE was quantified according to different PAR values. Thirdly, the maximum LUE varied with temperature and was therefore determined based on the response of daytime net ecosystem exchange and PAR at different temperatures. Lastly, GPP was estimated by combining the LUE model with the fraction of absorbed photosynthetically active radiation from Sentinel-2 images. The results showed that the LUE model developed for mangrove forests has higher overall accuracy (RMSE = 0.0051, R2 = 0.64) than the terrestrial model (RMSE = 0.0220, R2 = 0.24). The main environmental stressor for the photosynthesis of mangrove forests in China was PAR. The estimated GPP was, in general, in agreement with the in-situ measurement from the two carbon flux towers. Compared to the MODIS GPP product, the derived GPP had higher accuracy, with RMSE improving from 39.09 to 19.05 g C/m2/8 days in 2012, and from 33.76 to 19.51 g C/m2/8 days in 2015. The spatiotemporal distributions of the mangrove GPP revealed that GPP was most strongly controlled by environmental conditions, especially temperature and PAR, as well as the distribution of mangroves. These results demonstrate the potential of the RS-based productivity model for scaling up GPP in mangrove forests, a key to explore the carbon cycle of mangrove ecosystems at national and global scales. [ABSTRACT FROM AUTHOR]

Being a key ecological security barrier and production base for grassland animal husbandry in China, the balance between grassland forage supply and livestock-carrying pressure in North China directly affects grassland degradation and restoration, thereby impacting grassland ecosystem services. This paper analyzes the spatiotemporal variation in grassland vegetation coverage, forage supply, and the balance between grassland forage supply and livestock-carrying pressure from 2000 to 2015 in North China. We then discuss the spatial pattern of grassland ecological conservation under the impacts of grassland degradation and restoration, and livestock-carrying pressure. Over the last 16 years, the total grassland area in North China decreased by about 16,000 km2, with vegetation coverage degraded by 6.7% of the grasslands but significantly restored by another 5.4% of grasslands. The provisioning of forage by natural grassland mainly increased over time, with an annual growth rate of approximately 0.3 kg/ha, but livestock-carrying pressure also increased continuously. The livestock-carrying pressure index without any supplementary feeding reached as high as 3.8. Apart from the potential livestock-carrying capacity in northeastern Inner Mongolia and the central Tibetan Plateau, most regions in North China are currently overloaded. Considering the actual supplementary feeding during the cold season, the livestock-carrying pressure index is about 3.1, with the livestock-carrying pressure mitigated in central and eastern Inner Mongolia. Assuming full supplementary feeding in the cold season, livestock-carrying pressure index will fall to 1.9, with the livestock-carrying pressure alleviated significantly in Inner Mongolia and on the Tibetan Plateau. Finally, we propose different conservation and development strategies to balance grassland ecological conservation and animal husbandry production in different regions of protected areas, pastoral areas, farming-pastoral ecotone, and farming areas, according to the grassland ecological protection patterns. [ABSTRACT FROM AUTHOR]

Coastal water eutrophication and resource depletion have become serious issues in many coastal regions of the world. Seaweed aquaculture in Chinese coastal waters is a very important industry. This work assessed the major environmental benefits of seaweed cultivation, mapped the spatial distributions of various species and analyzed their environmental impacts during 2015 in China. This study found that seaweed aquaculture had brought in considerable environmental benefits, including the removal of about 75,563 t of nitrogen and 9592 t of phosphate from coastal waters, the sequestration of about 539,555 t of carbon, the absorption of 1,980,167 t of CO2, the release of 1,440,612 t of O2 into coastal waters, and the production of 5809 t of Iodine. In addition, seaweed cultivation saved approximately 29,313 t of chemical fertilizers, 1873 t of pesticide and 62,492 ha of farmland compared with terrestrial vegetable cultivation. These results demonstrate that Chinese seaweed aquaculture has turned the pollutants that cause eutrophication into nutrients, which generates considerable environmental benefits as well as socio-economic values. However, seaweed species, as well as coastal water qualities, vary by regions, spatial management of seaweed farms related to the coastal water quality is necessary. In the eutrophic coastal waters, more seaweed species that are highly capable of removing nitrogen and phosphate should be cultivated. Besides, the potentially negative effects of seaweed farming should also be considered before performing spatial management to ensure the healthy development of seaweed industry. As Chinese seaweed production continues to boom, it is a unique opportunity to strengthen the seaweed industry and to reach a win–win situation that both gains considerable environmental benefits and generates substantial socio-economic returns. This is also a promising way for other coastal developing nations/regions to follow. [ABSTRACT FROM AUTHOR]

China's investments, financial incentives and deductions in terms of ecological conservation are based at the county level. Therefore, the monitoring and assessment of the effects of ecological conservation at the county level is important to provide a scientific basis for the assessment of the ecological and environmental quality at the county scale. This paper quantitatively estimated the dynamics of high-quality ecosystems and vegetation coverage over the past 15 years, and their relationships with the number of ecological conservation programs at the county level were analyzed. Then, the effects of ecological conservation measures on ecological changes at the county level and their regional suitability were assessed and discussed. The results showed that counties with a percentage of high-quality ecosystems greater than 50% were primarily distributed in northeastern China, southern subtropical China and the southeastern Qinghai-Tibet Plateau, and those with a percentage lower than 20% were mostly distributed in northwestern China, the southwestern karst region and the North China Plain. In recent decades, ecological conservation has focused on ecologically fragile regions; more than five ecological conservation programs have been implemented in most counties of the Three River Source Region in Qinghai Province, southeastern Tibet, western Sichuan, the Qilian Mountains, southern Xinjiang and other western regions, while only one or zero have been implemented in the eastern coastal area of China. Over the past 15 years, the proportional area of high-quality ecosystems has increased in approximately 53% of counties. The vegetation coverage of counties in the Loess Plateau, Huang-Huai-Hai Plain, Beijing-Tianjin-Hebei (Jing-Jin-Ji), Sichuan-Guizhou-Chongqing, and Guangdong-Guangxi provincial-level areas has increased significantly. However, it decreased in northern Xinjiang, central Tibet, central and eastern Inner Mongolia, the Yangtze River Delta and other regions. The relationships between the numbers of ecological conservation programs and the indicators of ecosystem restoration response, such as high-quality ecosystem and vegetation coverage, do not show positive correlations. These results suggest that ecological conservation programs should be planned and implemented according to the distribution patterns of high-quality ecosystems and that restoration measures such as afforestation should follow natural principles and regional differentiation under the background of climate change. [ABSTRACT FROM AUTHOR]

In this paper, we study the controllability of the semi-discrete internally controlled 1-D wave equation by using the finite difference method. In the discrete setting of the finite difference method, we derive the observability inequality and get the exact controllability for the semi-discrete internally controlled wave equation in the one-dimensional case. Then we also analyze whether the uniform observability inequality holds for the adjoint system as $h\rightarrow0$ . [ABSTRACT FROM AUTHOR]

Type 2 helper T cells (TH2) are critically involved in allergies and asthma. Here we demonstrate that extracellular matrix protein-1 (ECM1) is highly and selectively expressed in TH2 cells. ECM1 deficiency caused impaired TH2 responses and reduced allergic airway inflammation in vivo. Functional analysis demonstrated that although the TH2 polarization of ECM1-deficient cells was unimpaired, these cells had a defect in migration and were retained in peripheral lymphoid organs. This was associated with reduced expression of KLF2 and S1P1. We also found that ECM1 could directly bind the interleukin-2 (IL-2) receptor to inhibit IL-2 signaling and activate S1P1 expression. Our data identify a previously unknown function of ECM1 in regulating TH2 cell migration through control of KLF2 and S1P1 expression. [ABSTRACT FROM AUTHOR]

China is facing intense coastal eutrophication. Large-scale seaweed aquaculture in China is popular, now accounting for over 2/3's of global production. Here, we estimate the nutrient removal capability of large-scale Chinese seaweed farms to determine its significance in mitigating eutrophication. We combined estimates of yield and nutrient concentration of Chinese seaweed aquaculture to quantify that one hectare of seaweed aquaculture removes the equivalent nutrient inputs entering 17.8 ha for nitrogen and 126.7 ha for phosphorus of Chinese coastal waters, respectively. Chinese seaweed aquaculture annually removes approximately 75,000 t nitrogen and 9,500 t phosphorus. Whereas removal of the total N inputs to Chinese coastal waters requires a seaweed farming area 17 times larger than the extant area, one and a half times more of the seaweed area would be able to remove close to 100% of the P inputs. With the current growth rate of seaweed aquaculture, we project this industry will remove 100% of the current phosphorus inputs to Chinese coastal waters by 2026. Hence, seaweed aquaculture already plays a hitherto unrealized role in mitigating coastal eutrophication, a role that may be greatly expanded with future growth of seaweed aquaculture. [ABSTRACT FROM AUTHOR]

Type 2 helper T cells (TH2) are critically involved in allergies and asthma. Here we demonstrate that extracellular matrix protein-1 (ECM1) is highly and selectively expressed in TH2 cells. ECM1 deficiency caused impaired TH2 responses and reduced allergic airway inflammation in vivo. Functional analysis demonstrated that although the TH2 polarization of ECM1-deficient cells was unimpaired, these cells had a defect in migration and were retained in peripheral lymphoid organs. This was associated with reduced expression of KLF2 and S1P1. We also found that ECM1 could directly bind the interleukin-2 (IL-2) receptor to inhibit IL-2 signaling and activate S1P1 expression. Our data identify a previously unknown function of ECM1 in regulating TH2 cell migration through control of KLF2 and S1P1 expression. [ABSTRACT FROM AUTHOR]