scholarly journals Impacts of Intensified Agriculture Developments on Marsh Wetlands

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Zhaoqing Luan ◽  
Demin Zhou
Keyword(s):  
Agricultural Development ◽  
Agricultural Landscape ◽  
Nature Reserve ◽  
Spatiotemporal Analysis ◽  
Sanjiang Plain ◽  
Natural Marsh ◽  
The Sanjiang Plain ◽  
Wetland Ecosystems ◽  
The Past ◽  
Remote Sensing Techniques

A spatiotemporal analysis on the changes in the marsh landscape in the Honghe National Nature Reserve, a Ramsar reserve, and the surrounding farms in the core area of the Sanjiang Plain during the past 30 years was conducted by integrating field survey work with remote sensing techniques. The results indicated that intensified agricultural development had transformed a unique natural marsh landscape into an agricultural landscape during the past 30 years. Ninety percent of the natural marsh wetlands have been lost, and the areas of the other natural landscapes have decreased very rapidly. Most dry farmland had been replaced by paddy fields during the progressive change of the natural landscape to a farm landscape. Attempts of current Chinese institutions in preserving natural wetlands have achieved limited success. Few marsh wetlands have remained healthy, even after the establishment of the nature reserve. Their ecological qualities have been declining in response to the increasing threats to the remaining wetland habitats. Irrigation projects play a key role in such threats. Therefore, the sustainability of the natural wetland ecosystems is being threatened by increased regional agricultural development which reduced the number of wetland ecotypes and damaged the ecological quality.

scholarly journals DOC concentrations and spectroscopic characteristics in surface runoff from contrasting wetland ecosystems: a case study in the Sanjiang Plain, Northeast China

2012 ◽  
Vol 9 (6) ◽  
pp. 7919-7945
Author(s):  
L. L. Wang ◽  
C. C. Song ◽  
G. S. Yang
Keyword(s):  
Land Use ◽  
Surface Runoff ◽  
Rice Paddy ◽  
Sanjiang Plain ◽  
Natural Wetland ◽  
Artificial Wetland ◽  
The Sanjiang Plain ◽  
Wetland Ecosystems ◽  
Wetland Site ◽  
Spectroscopic Characteristics

Abstract. Dissolved organic carbon (DOC) is a significant component of carbon and nutrient cycling in fluvial ecosystems. Natural wetlands, as important DOC sources for river and ocean ecosystems, have experienced extensive natural and anthropogenic disturbances such as climate change, hydrological variations and land use change in recent years. In this study, we examined the concentrations and spectroscopic characteristics of DOC in surface runoff from contrasting wetlands along the lower Amur River Basin in the Sanjiang Plain, Northeastern China. Surface runoff from seven sites (two natural phialiform wetlands, three natural riparian wetland, one degraded wetland, and one artificial wetland i.e. rice paddy) were monitored during the growing seasons of 2009 and 2010. Surface runoff from the natural wetland sites exhibited a wide range of DOC concentrations (10.06–48.73 mg l−1) during the two-year sampling period. The specific ultraviolet absorbance (SUVA) and color values of DOC in surface runoff were also highly variable at different natural wetland sites. Our analysis also found that DOC values were significantly lower in the surface runoff at the artificial wetland site compared with those from surface runoff at the five natural wetland sites and one degraded wetland site (P < 0.01). The colour per carbon unit (C / C) ratio in surface runoff at the artificial wetland site was one to three times lower, while the E4 / E6 ratio (Abs465 / Abs665) was reduced by 42.07% to 55.36%, compared to those from runoff water at the five natural wetland sites. The C / C ratios in surface runoff at the natural wetland sites were higher than that from surface runoff at the degraded wetland, which in turn has greater values than that from surface runoff at the artificial wetland site. Meanwhile, the E4 / E6 ratio in the surface runoff from the artificial wetland was lower compared to that in surface runoff at the degraded wetland site (P < 0.05). This implies that disturbance to DOC concentrations and spectroscopic characteristics in surface runoff is stronger from natural wetland conversion to rice paddy land than that from wetland degradation. The dataset from this study can provide insightful points for understanding the underlying mechanisms of aquatic DOC dynamics from wetland ecosystems, and improve land use policy and management strategies in the future.

scholarly journals Crop Structure Changes Altered the Cropland Nitrogen Balance between 2005 and 2015 on the Sanjiang Plain, China

2018 ◽  
Vol 10 (11) ◽  
pp. 4011 ◽  
Author(s):  
Chunxia Yang ◽  
Hua Zheng ◽  
Binbin Huang ◽  
Ruonan Li ◽  
Zhiyun Ouyang ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Nitrogen Balance ◽  
Agricultural Development ◽  
Driving Forces ◽  
Sanjiang Plain ◽  
N Balance ◽  
The Sanjiang Plain ◽  
Use Efficiency ◽  
The Impact ◽  
N Use

Nitrogen (N) budgets have been computed in many countries at various scales to improve understanding of N-balance characteristics and to assess the environmental pollution risks of applying chemical fertilizer N. However, dynamic characteristics, driving forces, and potential soil fertility consequences related to cropland N balance have seldom been discussed, especially in regions with highly fertile soils and low N-use intensities. This study investigated the temporal and spatial characteristics of N balance, and the impact of agricultural development on the agro-ecosystems of the Sanjiang Plain, one of the largest producers of commodity food grains in China. County-level agricultural statistics at five-year intervals were used to calculate agricultural N balances, N surplus intensity, and N-use efficiency between 2005 and 2015. Agricultural development has brought about continual increases in cultivated land area, consumption of chemical fertilizers, and nitrogen use efficiency (NUE). Nitrogen surplus intensity decreased from 65.0 kg/ha in 2005 to 43.5 kg/ha in 2010, and to 22.2 kg/ha in 2015. However, NUE was >90% in 13 counties in 2015, and in 11 counties in 2010. In contrast, only 5 counties had NUE above 90% in 2005, which indicates that N from the soil was used by crops and soil fertility was gradually decreasing. The percentage change of crop area, namely, the increase in maize area percentage, contributed significantly to the increases in NUE. A judicious management of fertilizers that meets the nutrient needs of the crops and ensures agricultural sustainability on the Sanjiang Plain is therefore essential. The findings of this study emphasize the importance of assessing the impact of crop structure adjustment on soil fertility and nitrogen balance during agricultural development.

scholarly journals Optimizing Feature Selection of Individual Crop Types for Improved Crop Mapping

2020 ◽  
Vol 12 (1) ◽  
pp. 162 ◽  
Author(s):  
Leikun Yin ◽  
Nanshan You ◽  
Geli Zhang ◽  
Jianxi Huang ◽  
Jinwei Dong
Keyword(s):  
Feature Selection ◽  
Agricultural Development ◽  
Development Planning ◽  
Sanjiang Plain ◽  
The Sanjiang Plain ◽  
Regional Food ◽  
Probability Maps ◽  
Medium Resolution ◽  
Crop Mapping ◽  
Crop Types

Accurate crop planting area information is of significance for understanding regional food security and agricultural development planning. While increasing numbers of medium resolution satellite imagery and improved classification algorithms have been used for crop mapping, limited efforts have been made in feature selection, despite its vital impacts on crop classification. Furthermore, different crop types have their unique spectral and phenology characteristics; however, the different features of individual crop types have not been well understood and considered in previous studies of crop mapping. Here, we examined an optimized strategy to integrate specific features of individual crop types for mapping an improved crop type layer in the Sanjiang Plain, a new food bowl in China, by using all Sentinel-2 time series images in 2018. First, an automatic spectro-temporal feature selection (ASTFS) method was used to obtain optimal features for individual crops (rice, corn, and soybean), including sorting all features by the global separability indices for each crop and removing redundant features by accuracy changes when adding new features. Second, the ASTFS-based optimized feature sets for individual crops were used to produce three crop probability maps with the Random Forest classifier. Third, the probability maps were then composited into the final crop layer by considering the probability of each crop at every pixel. The resultant crop layer showed an improved accuracy (overall accuracy = 93.94%, Kappa coefficient = 0.92) than the other classifications without such a feature optimizing process. Our results indicate the potential of the ASTFS method for improving regional crop mapping.

scholarly journals Human Activities Introduced Degenerations of Wetlands (1975–2013) across the Sanjiang Plain North of the Wandashan Mountain, China

Land ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1361
Author(s):  
Jing Xie ◽  
Yeran Sun ◽  
Xiao Liu ◽  
Zhi Ding ◽  
Ming Lu
Keyword(s):  
Land Use ◽  
Agricultural Development ◽  
Arable Land ◽  
Wetland Loss ◽  
Sanjiang Plain ◽  
Rapid Expansion ◽  
Wetland Protection ◽  
Landsat Images ◽  
The Sanjiang Plain ◽  
Backtracking Analysis

Human-induced dramatic loss and fragmentation of wetlands need further understanding through historical backtracking analysis at a geographical landscape scale. In this study, we investigated time-series wetlands maps from 1975, 1983, 1989, 2000, 2006, and 2013 derived from Landsat images based on the object-oriented classification of wetlands across the Sanjiang Plain north of the Wandashan Mountains. The spatial and temporal changes in the wetlands that occurred at different time periods and the Euclidean distances between artificial land-use types and natural land-cover areas were evaluated for their impact. Our results showed that wetland was the dominant landscape in 1975; however, arable land became the main land coverage in 2013 owing to severe changes in agricultural development over the past decades. The closer to arable land, the greater the wetland loss during the entire investigated period; agriculture activities were the dominant driving force for the degradation of wetlands based on landscape changes; secondary was the rapid expansion in building land use (i.e., human settlement, transportation, and establishment of irrigation canals). More specifically, the rapid loss of wetland areas over 1975–2000 was mainly owing to extensive agricultural reclamation. The mitigated loss of wetland areas over 2000–2013 was because of the protection and restored implementation of wetlands under governmental policies. The wetlands of the study area suffered severe human disturbance, and our analysis may help explain the loss process of wetlands, but more effective management and administration is still needed to address the issues around the balance between agricultural production and wetland protection for further sustainable development.

scholarly journals Quantitative Assessment of the Influences of Snow Drought on Forest and Grass Growth in Mid-High Latitude Regions by Using Remote Sensing

2021 ◽  
Vol 13 (4) ◽  
pp. 668
Author(s):  
Hezhen Lou ◽  
Xijin Wu ◽  
Xiaoyu Ren ◽  
Shengtian Yang ◽  
Mingyong Cai ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Latitude ◽  
Global Climate ◽  
Meteorological Data ◽  
Sanjiang Plain ◽  
Snow Accumulation ◽  
Extreme Weather Events ◽  
The Sanjiang Plain ◽  
The Past ◽  
Grass Growth

Global climate change, especially the snow drought events, is causing extreme weather events influencing regional vegetation growth and terrestrial ecosystem stability in a long-term and persistent way. In this study, the Sanjiang Plain was selected, as this area has been experiencing snow drought in the past two decades. Logistic models, combined with multisource remote sensing and unmanned aerial vehicle (UAV) data, as well as the meteorological data over the past 20 years, were used to calculate sixteen phenological periods and biomass. The results show that (1) over the past two decades, snow drought has been based on the snow accumulation and has been occurring more frequently, wider-ranging and more severely; (2) snow drought has advanced the forest start of season (SOS)/end of season (EOS) by 6/5 days, respectively; (3) if the snowfall is greater than 80% of a normal year, the SOS/EOS of grass is postponed by 8/6 days; conversely, if it is less than 80%, the SOS/EOS are advanced by 7/5 days; and (4) biomass decreased approximately 0.61%, compared with an abundant snowfall year. Overall, this study is the first to explore how snow drought impacts the phenological period in a mid-high latitude area, and more attention should be paid to these unknown risks to the ecosystem.

scholarly journals Dissolved organic carbon characteristics in surface ponds from contrasting wetland ecosystems: a case study in the Sanjiang Plain, Northeast China

2013 ◽  
Vol 17 (1) ◽  
pp. 371-378 ◽  
Author(s):  
L. L. Wang ◽  
C. C. Song ◽  
G. S. Yang
Keyword(s):  
Organic Carbon ◽  
Rice Paddy ◽  
Sanjiang Plain ◽  
Riparian Wetlands ◽  
Natural Wetland ◽  
The Sanjiang Plain ◽  
Wetland Ecosystems ◽  
Wetland Site ◽  
Doc Concentration ◽  
Natural Wetlands

Abstract. Dissolved organic carbon (DOC) is a significant component of carbon and nutrient cycling in fluvial ecosystems. Natural wetlands, as important DOC sources for river and ocean ecosystems, have experienced extensive natural and anthropogenic disturbances such as climate change, hydrological variations and land use change in recent years. The DOC characteristics in surface ponds from contrasting wetlands in the Sanjiang Plain, Northeastern China were investigated. Surface ponds at seven sites (two natural phialiform wetlands, three natural riparian wetlands, one degraded wetland and one artificial wetland, i.e., rice paddy) were monitored during the growing seasons of 2009 and 2010. The results show that the surface ponds at the five natural wetland sites exhibited a wide range of DOC concentrations (10.06–48.73 mg L−1) during the study period. The DOC concentrations showed no annual differences (P > 0.05) at all the wetland sites, except one of the phialiform wetland sites. The two phialiform wetlands exhibited higher DOC concentrations than the three riparian wetlands (P < 0.05). The DOC concentration in the surface pond at the artificial wetland site was relatively low (P < 0.05) compared to that at the degraded wetland site. The C/C ratios (the color per carbon unit ratio, Abs400/DOC concentration) showed inconsistent variations among these seven wetland sites, while the E4/E6 ratio (Abs465/Abs665, fulvic acid/humic acid) from the surface pond in the rice paddy land exerted 42.07–55.36% reductions (P < 0.05), compared to those at the five natural wetland sites. Furthermore, the E4/E6 ratio in the surface pond at the rice paddy site was significantly lower compared to that at the degraded wetland site (P < 0.05), which indicated that disturbance to wetland DOC in surface ponds might be stronger when natural wetlands were converted to rice paddies in comparison with wetland degradation. This study could not only provide insightful points for understanding the aquatic DOC dynamics from different wetland ecosystems, but also support data information for incorporating the aquatic DOC into the model for regional carbon budgets in the future.

The impacts of land reclamation on the accumulation of key elements in wetland ecosystems in the Sanjiang Plain, northeast China

2018 ◽  
Vol 237 ◽  
pp. 487-498 ◽  
Author(s):  
Chuanyu Gao ◽  
Shaoqing Zhang ◽  
Hanxiang Liu ◽  
Jinxin Cong ◽  
Yunhui Li ◽  
...  
Keyword(s):  
Northeast China ◽  
Land Reclamation ◽  
Sanjiang Plain ◽  
The Sanjiang Plain ◽  
Wetland Ecosystems
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