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In the East Asian monsoon region, eolian deposits widely distributed in the middle-lower reaches of the Yantgze River are among the best materials available for studies on Quaternary climate change in the subtropical zone of Southern China. Typical eolian deposits in this region include upper Xiashu Loess (XL) and underlying Vermiculated Red Soil (VRS) layers. In this paper, chronological and paleoclimatic studies are conducted on an eolian deposit sequence near Jiujiang (JJ) city in northern Jiangxi province. A magnetostratigraphic study, combined with optically stimulated luminescence (OSL) dating, is conducted on the JJ section and provides further evidence that eolian deposits in the middle-lower reaches of the Yangtze River have been formed since the late Early Pleistocene, and that the boundary age between the XL and VRS layers is about 300-400 kaBP. In grain-size records of the JJ section, the median grain-size and content of the >30 μm size fraction increase sharply after 300-400 kaBP, representing an East Asian winter monsoon intensification event. Further pollen analysis reveals differing pollen assemblages before and after 300-400 kaBP: there is an evident increase in plants adapted to grow in a warm humid environment after 300-400 kaBP, implying an increase in precipitation caused by intensification of the East Asian summer monsoon. Global ice volume and uplift of the Tibet Plateau (TP) are regarded as crucial factors influencing variations of the East Asian monsoon on a long-term scale. The deep-sea δ18O record, which reflects variations in global ice volume, shows no obvious change after 300-400 kaBP. Moreover, the influence of global ice volume changes on the East Asian summer and winter monsoons is inverse; the global ice volume increase (decrease) implies a strengthened (weakened) winter monsoon and weakened (strengthened) summer monsoon. We therefore interpret the coupled intensifications of the East Asian summer and winter monsoons at about 300-400 kaBP to the uplift of the TP in the Middle Pleistocene. This climate event is also documented in eolian deposits from the southern margin of the Chinese Loess Plateau (CLP) and from the desert-loess transitional belt. However, it is not recorded in the loess-paleosol sequences from the central part of the CLP, thereby indicating differing climate responses to TP uplift in different regions, which requires further study. [ABSTRACT FROM AUTHOR]

Fire size and fire frequency are important indicators of fire characteristics. Characterizing fire size and fire frequency and understanding its environmental controls are indispensable to fire prediction and sustainable forest landscape management. In this paper, we determined the mean number of fires and the mean forest area burned by province to define five distinct patterns of fires across China by cluster analysis for the period 1987–2007. Then, we performed Redundancy Analysis (RDA) to explore factors influencing the spatial variation in the mean number of fires and the mean forest area burned, and to determine their relative contributions to this variation. Results showed that the north part of China generally had low mean number of fires. Percentage of the total number of fires in northeastern, northern and northwestern region to the total number of fires in whole country is 3.49%, 3.18% and 2.19% respectively. Neimenggu and Heilongjiang had larger mean burned forest area with 208,786 and 103,018 ha respectively. RDA analysis showed that the percentage of forest land and de Martonne aridity had significant impacts on the spatial variation in forest fire characteristics over China ( p < 0.05). These two variables and their interactions explained 44.9% of the total variance of the mean number of forest fires and mean forest area burned (63%), out of which 8.2% was explained by percentage of forest land, 11.7% by de Martonne aridity and 25.0% by their interactions. [ABSTRACT FROM AUTHOR]

Larch caterpillar ( Dendrolimus superans) is very common in the Da Hinggan Mountains, Northeast China, affecting fire regime and forest ecosystem change at large spatio-temporal scales. In this study, we used a spatially explicit landscape model, LANDIS, to simulate the changes of fire regime and forest landscape under four larch caterpillar disturbance intensity levels scenarios in Huzhong forest area, northern of Da Hinggan Mountains. The results indicate that larch caterpillar disturbances would decrease fine fuel load and increase coarse fuel load in the 300 simulation years. Larch caterpillar disturbances would decrease fire frequency in the first 200 years, and the disturbances also decrease fire intensity and fire risk in the early and late stage of simulation. Larch caterpillar disturbances would decrease the area percent of larch cohorts and increase the proportion of white birch, and increase the degree of aggregation of white birch as a result of its strong seed dispersal and colonization ability. Disturbances would also decrease the mature and over-mature larch cohorts and increase all cohorts of white birch, especially the mature and over-mature cohorts. Larch caterpillar disturbances will decrease the stability of forest landscape, therefore, some measures preventing insect outbreak and ensuring the sustainable management of forest ecosystem should been taken in the study area. [ABSTRACT FROM AUTHOR]

Wetlands, as the most essential ecosystem, are degraded throughout the world. Wetlands in Zhenlai county, with the Momoge National Nature Reserve, which was included on the Ramsar list, have degraded by nearly 30%. Wetland degradation is a long-term continuous process with annual or interannual changes in water area, water level, or vegetation presence and growth. Therefore, it requires sufficiently frequent and high-spatial-resolution data to represent its dynamics. This study mapped yearly land-use maps with 30-m resolution from 1985 to 2018 using Landsat data in Google Earth Engine (GEE) to explore the wetland degradation process and mapped 12-day interval land-use maps with 15-m resolution using the Sentinel-1B and Sentinel-2 data in GEE and other assistant platforms to study the characteristics of wetland dynamics in 2018. Four sets of maps were generated using Sentinel-1B (S1), Sentinel-2 (S2), the combination of Sentinel-1B and Sentinel-2 (S12), and S12 with multitemporal remote sensing (S12'). All of the classifications were performed in the Random Forest Classification (RFC) method using remote sensing indicators. The results indicate that S12' was the most accurate. Then, the impact of the historic land-use degradation process on current wetland change dynamics was discussed. Stable, degradation, and restoration periods were identified according to the annual changes in wetlands. The degraded, stable, restored, and vulnerable zones were assessed based on the transformation characteristics among wetlands and other land-use types. The impact of historical land-use trajectories on wetland change characteristics nowadays is diverse in land-use types and distributions, and the ecological environment quality is the comprehensive result of the effect of historical land-use trajectories and the amount of rainfall and receding water from paddy fields. This study offers a new method to map high-spatiotemporal-resolution land-use (S12') and addresses the relationship between historic wetland change characteristics and its status quo. The findings are also applicable to wetland research in other regions. This study could provide more detailed scientific guidance for wetland managers by quickly detecting wetland changes at a finer spatiotemporal resolution. [ABSTRACT FROM AUTHOR]

Simple Summary: Estimation of population abundance or density is necessary for managing deer populations. However, there is no estimation of Siberian roe deer (Capreolus pygargus) in the Lesser Xing'an Mountains, northeast China where the density of roe deer is much lower than that of European or North American populations. We used fecal-DNA capture-mark-recapture to estimate the abundance and density in Liangshui National Nature Reserve. We collected 422 fecal pellet groups during two sampling periods in 2016, identified them to be 77 individuals by the DNA microsatellite technique and estimated the abundance of roe deer to be 87 deer (80–112, 95% CI) using the Program CAPTURE. Density was estimated to be 2.9 deer/km2 (2.7–3.7, 95% CI). Our study estimated the roe deer population abundance by a feces-based capture-mark-recapture approach in northeast China, successfully demonstrating the applicability of this feces sampling method in monitoring deer populations in this area. It also contributes to the development of low-density deer population ecology and management. It is necessary to estimate the population abundance of deer for managing their populations. However, most estimates are from high-density populations inhabiting the forests of North America or Europe; there is currently a lack of necessary knowledge regarding low-density deer populations in different forest habitats. In this article, we used fecal DNA based on the capture-mark-recapture method to estimate the population abundance of Siberian roe deer (Capreolus pygargus) in Liangshui National Nature Reserve in the Lesser Xing'an Mountains, northeast China, where the deer population was found to be of a low density by limited studies. We used a robust survey design to collect 422 fecal pellet groups in 2016 and extracted DNA from those samples, generating 265 different genotypes; we thus identified 77 deer individuals based on six microsatellite markers (Roe1, Roe8, Roe9, BM757, MB25 and OarFCB304). With capture and recapture records of these 77 individuals, the abundance of roe deer was estimated to be 87 deer (80–112, 95% CI) using the Program CAPTURE. Using an effective sampling area which resulted from the mean maximum recapture distance (MMRD), we converted the population abundance to a density of 2.9 deer/km2 (2.7–3.7, 95% CI). Our study estimated the roe deer population abundance by a feces-based capture-mark-recapture approach in northeast China, successfully demonstrating the applicability of non-invasive genetic sampling in monitoring populations of deer in this area, which contributes to the development of low-density deer population ecology and management. [ABSTRACT FROM AUTHOR]

Black carbon (BC) from incomplete combustion of biomass and fossil fuel is widespread in sediments and soils because of its high stability in nature and is considered an important component of the global carbon sink. However, knowledge of BC stocks and influencing factors in forest ecosystems is currently limited. We investigated soil BC contents in burned boreal forests of the Great Khingan Mountains, northeast China. We collected soil samples from 14 sites with different fire severities, slope positions and aspects. The samples were analyzed by the chemo-thermal oxidation method to obtain their BC concentrations. The BC concentrations of the studied soils ranged from 0.03 to 36.91 mg C g−1, with a mean of 1.44 ± 0.11 mg C g−1. BC concentrations gradually decline with depth, and that was significantly less in the 20–30 cm layer compared to all shallower layers. Forests burned by moderate-severity fires had the highest soil BC, the shady aspect had higher soil BC than the sunny aspect. Our results provide some basic data for evaluating the soil BC sink in boreal forests, which is a useful amendment to current carbon budget and carbon cycle in boreal forest ecosystems. [ABSTRACT FROM AUTHOR]

The Sanjiang Plain has the largest marsh wetland area in China. Since the 1950s its size has declined due to land development, between 1986 and 2016 nearly 6072 km 2 (57.5% of the area) was lost due to farm land expansion. Since the "Wetland for Grain" project in 2003, efforts have been made to improve marsh area for animal habitat and ecological protection. A key management concern is prioritizing areas for wetland restoration in scientific planning and polices making. In this study, the natural wetland restoration potentials were evaluated based on land-use change trajectory, seed bank viability and watershed sustainability and restorability. The annual land use maps from 1986 to 2016 were reconstructed using CLUE-S model with land use maps in 1995, 2000, 2005, 2010 and 2016, which were interpreted from Landsat TM/ETM images. Seed bank viability was determined by field sampling in wetland and farm land with different reclamation years and germination in lab. Sub-catchment was chosen as sustainability analysis unit, which was quantified by the impacts of wetland on peak flow reduction. The watershed restorability was performed with the factors of wetland degradation degree, seed bank viability, and the percentage of wetland to watershed area (PWW) with different restoration years. The results indicated that reclaimed wetland with a time since last development (TLD) of <15 years had a higher recovery potential and accounted for 39.2% of the lost wetland. Seventeen sub-catchments with a total area of 2177 km 2 of farmland could be planned for restoration, which could support more than half of the sub-catchments in the study area. Priority areas were identified for short-, mid- and long-term restoration planning. The results can support the scientific planning demands of various restoration goals in the study area, and provide a new method for wetland restoration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The upper reaches of Minjiang River is an ecological sensitive and vulnerable area in southwest of China. It is of great significance to the ecological pattern safety in China. In this study, we analyzed the landscape pattern change through the interpretation of TM imageries in 1986, 1995 and 2000. The results showed that the matrix landscape in this area was grass landscape. Forest landscape patches were embedded in the grass landscape. The forest landscape area increased from 1986 to 1995 and decreased from 1995 to 2000. However, the number of patches of forest landscape was increasing during all the time. This suggested that the intensity of anthropogenic disturbances including harvesting, forest landscape reclaiming and excessive grazing were persistently increasing from 1986 to 2000. The ecological driving forces of the landscape change in this area were the intensified anthropogenic disturbances as a result of the population boom including the predacious harvesting of forest and excessive grazing. The natural disturbances such as the global climatic change also partly influenced the landscape change in this area.

Investigations were made in the sampling plots covering 243 km2 of the Shenyang urban area, and the results were used as the input for the Urban Forest Management Information System (UFMIS), which was developed based on the model of CITY green. With this system, and using tree species, tree density, tree height grade distribution, tree DBH (diameter at beast height) grade distribution, and tree health condition as parameters, the land use and forest structure in Shenyang City were analyzed. It was found that there were 1,914,500 trees in Shenyang, belonging to 136 species. The 25 dominant species accounted for 84.78% of the total number of trees, and the forest coverage was 9.765%. Trees with DBH < 0.25 m and > 0.5 m accounted for 82.8% of the total, and the young, middle-aged and old trees occupied 27%, 58% and 15% of the total, respectively. The healthy status of 84% of the trees was above middle level. Therefore, the forest in Shenyang urban is at a stable stage. According to the statistical results from UFMIS, the ecological value of forest in Shenyang urban is as high as 26,526,955. 1 USD in terms of economy.