Monitoring spatiotemporal changes of marshes in the Sanjiang Plain, China

Climate Change and Anthropogenic Impacts on Wetland and Agriculture in the Songnen and Sanjiang Plain, Northeast China

“…In short, due to the large-scale anthropogenic activities (e.g., agricultural development), approximately 70-80% of the freshwater wetlands has been reclaimed during the past several decades in these two typical plains [26,34,35]. Intensive anthropogenic activities also resulted enormous changes in ecological environment as increasingly frequent drought, decreased river runoff, decline of groundwater, and so on.…”

“…Trajectory analysis can recover the history of LULCC and relate the spatiotemporal pattern of such changes to natural and anthropogenic factors [23,26,42], which can also be utilized to effectively analyze the trends of LULCC over time [43,44]. This study referenced this approach and the trajectory codes were adopted to express the change trajectory of time series of LULCC as follows:…”

“…Firstly, with respect to the quantitation of the relative role of human activities from climatic changes in terms of their impacts on marshland conversions derived from this study, further in consideration of the results from [26], indicated that, on the one hand, comparing with natural factors, human activities played a predominate role (89.67%) in the conversion of marshland to the other LULC types during 1954-2013 over the SJP, especially the dramatic marshland degradation taken place in the earlier period from 1954 to 1980. On the other hand, the role human activities played tended to decreasing from 89.67% to 10.30%, while the role of climatic changes predominated the conversion from marshland to the other LULC types, which demonstrated the reliability of the fundamental assumption in predicting the effects of future climate change on LULCC.…”

“…However, characteristic analysis on the long-term LULCC over these two plains suggested the complexity and discrepancies of spatiotemporal variations between these two plains. Based on previous studies in the region [22,23,26,27,78] together with main findings of this study, LULCC in different periods were further analyzed with attempt to explore the primary driving forces for the LULCC over the region. It should be noted firstly that, given the availability of continuous long-term LULC observation with a unified classification system in the study region, we mainly focused on the period after the reform and opening-up policy in 1978.…”

“…In this study, codes 1-8 were used to represent the paddy field, dry farmland, marshland, waterbody, forest land, grassland, settlement and other unused land, respectively. Additionally, following [26], we aggregated LULCC types into three categories according to Y i : human induced changes, naturally induced changes, and unchanged land. The LULCC types were defined as human-induced as long as at least one of the observed LULCC types is recognized as human-induced, as listed in Table 1, no matter when it occurs, can distinguish human induced changes from naturally induced changes.…”