Integration of Multiple Spectral Data via a Logistic Regression Algorithm for Detection of Crop Residue Burned Areas:A Case Study of Songnen Plain,Northeast China

The burning of crop residues in fields is a significant global biomass burning activity which is a key element of the terrestrial carbon cycle,and an important source of atmospheric trace gasses and aerosols.Accurate estimation of cropland burned area is both crucial and challenging,especially for the small and fragmented burned scars in China.Here we developed an automated burned area mapping algorithm that was implemented using Sentinel-2 Multi Spectral Instrument(MSI)data and its effectiveness was tested taking Songnen Plain,Northeast China as a case using satellite image of 2020.We employed a logistic regression method for integrating multiple spectral data into a synthetic indicator,and compared the results with manually interpreted burned area reference maps and the Moderate-Resolution Imaging Spectroradiometer(MODIS)MCD64A1 burned area product.The overall accuracy of the single variable logistic regression was 77.38%to 86.90%and 73.47%to 97.14%for the 52TCQ and 51TYM cases,respectively.In comparison,the accuracy of the burned area map was improved to 87.14%and 98.33%for the 52TCQ and 51TYM cases,respectively by multiple variable logistic regression of Sentind-2 images.The balance of omission error and commission error was also improved.The integration of multiple spectral data combined with a logistic regression method proves to be effective for burned area detection,offering a highly automated process with an automatic threshold determination mechanism.This method exhibits excellent extensibility and flexibility taking the image tile as the operating unit.It is suitable for burned area detection at a regional scale and can also be implemented with other satellite data.

COUPLING ANALYSES OF FRAGILE ECO-ENVIRONMENT IN THE WEST OF THE SONGNEN PLAIN

The fragile eco-environment is a special type of ecosystem,its response to the change of environmental condi -tions is very susceptive.So it is rather prone to be disturbed under unfav orable conditions.Human activity h as greatly changed the geo-chemical process in the ecosystem,thus caused a series o f positive and negative effects.In t he ecosys-tem,especially in the fragile eco-e nvironment,different systems and r egimes are interconnected and interdetermined.For the suntainable development of ecosystem and the protection and rational utilization of resources,it is of great impor-tance to study these internal relati onships and seek rational regulatio n and control measure.This paper tak es the fragile eco-environment in the west of the Songnen Plain as an example.Based on th e study of the topograph,physiognom y,soil,vegetation and their geographic distribution in the landscape,th e paper explains the structure of the ecologic land-scape and quantifies the ecologic ge o-chemical processes under differe nt landscape conditions.In additio n,the paper al-so tries making coupling analyses of the ecologic succession and the landscape geochemical environment.And in the pa-per,some research results are given.

Analysis of the Groundwater System Change and Driving Factors in Songnen Plain in Jilin Province

[Objective] The aim was to provide theoretical basis for the study of underground water dynamic changes in Songnen Plain in Jilin Province.[Method] The dynamic changes and driving factors for the underground water in Songnen Plain in Jilin Province was expounded.[Result] Since 1960s,the temperature in the Songnen Plain in Jilin Province increased gradually.The average temperature increased 2℃;precipitation reduced gradually.Especially,the trend of precipitation reduction in west area was more distinct;in the meantime,the development of underground water augmented gradually and reached 2 800 million m3 in 2008.Driven by many factors,regional underground water level had distinct changes.Potential water position reduced greatly in northwest fan-shaped area.The one in other places were stable and even increased in certain parts;confined water position decreased quickly in general and it increased in certain parts.[Conclusion] The general deterioration trend of underground water environment was inevitable.But,the deterioration process can be eased through scientific planning and regional underground water resources so as to realize sustainable utilization of regional underground water resources.

Survey of breeding populations of the Red-Crowned Crane (Grus japonensis) in the Songnen Plain,northeastern China

With the support of the UNEP/GEF Siberian Crane Wetland Project,a five-year field survey of breeding waterbirds was conducted in four nature reserves - Zhalong,Keerqin,Xianghai and Momoge National Nature Reserves in the Songnen Plain for the period from May 2004 to August 2008.The purpose of the survey was to improve our understanding of the distribution and populations of breeding waterbirds in this area.The Red-crowned Crane (Grus japonensis) was the most important target species.Our survey results confirm that the Zhalong wetland is the largest breeding ground for the Red-crowned cranes in the Songnen Plain.Over 90％ of the breeding birds were found in Zhalong,with numbers fluctuating from 112 to 275 over the years.Reed (Phragmites australis) is the most important plant species associated with breeding locations of this bird species.Water supply to the wetland can relieve pressure from deterioration of wetland habitats for the breeding of Red-crowned cranes.However,a sound scientific basis for the water supply mechanism is the key to better management of their habitat and a prerequisite for ensuring the breeding success of the Red-crowned Crane.

Dynamics of Saline-alkali Land and Its Ecological Regionalization in Western Songnen Plain, China

As the important reserve land resources for food production,saline-alkali land should play a significant role to ensure the national food security in the context of global food crisis. The western Songnen Plain is one of main distribution regions of saline-alkali land in China,with great potential in agricultural development. In this study,the extent,transformation,spatial distribution and temporal change of saline-alkali land in the western Songnen Plain during 1954–2005 were investigated by using remote sensing and GIS spatial analysis methods. Saline-alkali land change was detected from a temporal series of topographic maps in 1954,satellite images of Landsat MSS in 1976,Landsat TM/ETM in 1988,2000 and 2005 through artificial visual interpretation. The results indicated a significant expansion in saline-alkali land area and aggravation in salinization. The area of saline-alkali land had increased from 401.48×103 ha in 1954 to 1 097.45×103 ha in 2005. While the ratio of light,moderate and serious salinized land areas changed from 6.72︰2.92︰1.00 to 1.25︰1.06︰1.00 in the study period. Grassland,cropland,swampland and water body were the major land use and land cover types from which saline-alkali land transformed. And the secondary salinization occured mainly in Da′an City,Tongyu County,Changling County,Daqing City,Dorbod Mongolian Autonomous County and Zhaoyuan County. Finally,seven large ecoregions and 14 corresponding sub-ecoregions were delineated out based on spatio-temopral dynamic characteristics of saline-alkali land and geo-relational environmental attributes. According to the results,measures of amelioration and ways of development of saline-alkali land in the western Songnen Plain were put forward.

SUSTAINABLE AGRICULTURE DEVELOPMENT IN SALINE-ALKALI SOIL AREA OF SONGNEN PLAIN,NORTHEAST CHINA

There is great potential for agriculture in saline-alkali soil area in Songnen Plain, Northeast China. But the sustainable crop production in this area has been restricted by a few of main factors, such as less precipitation, h igher evaporation and frequent drought, high salinity and alkalinity, high excha ngeable sodium content and poor infiltration of the soil, and insufficiency and low availability in nutrition. It is also considered that there are a few of fav orable conditions for agricultural development in this region, such as sufficien t light and heat resources, rich ground water resources, plenty of manure produc ed by livestock, and so on. At the same time, scientific management and measurem ents have been employed; rational irrigation and drainage system has been establ ished; reclamation, amendment and fertilization of soil, and suitable strategies of cropping practices have been made for the sustainable development of agricul ture. Great progress has been made during 1996-2000.

CATASTROPHIC ECO-ENVIRONMENTAL CHANGE IN THE SONGNEN PLAIN,NORTHEASTERN CHINA SINCE 1900S

Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thom Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.

Land Use/Cover Changes and Environmental Consequences in Songnen Plain,Northeast China

The Songnen Plain in Northeast China,one of the key national bases of agricultural production,went through remarkable land use/cover changes in recent years.This study aimed to explore the long-term land use/cover changes and the effects of these changes on the environment.The Landsat-based analysis showed that,during 1986-2000,cropland,built-up land and barren land had increased,among which cropland had the largest increase of 9,198km2 with an increase rate of 7.5%.Woodland,grassland,water body and swampland had decreased correspondingly,among which grassland had the most dramatic decrease of 6,127km2 with a decrease rate of 25.6%.The transition matrix results revealed that grassland,woodland and swampland were the three main land use types converted to cropland.Climate warming created the potential environment for the conversion of grassland and swampland into cropland.Land resources policy made by central and provincial governments of China affected the pattern and intensity of land use.Land use/cover changes accompanied by climatic variation brought out a series of environmental consequences,such as sand desertification of land,land salinization and alkalinization,grassland degradation,and more frequent floods.Under this circumstance,optimized land use structure and restoration measures are needed.

The renewability and quality of shallow groundwater in Sanjiang and Songnen Plain, Northeast China

Groundwater is a key component for water resources in Sanjiang and Songnen Plain, an important agriculture basement in China. The quality and the renewability of irrigation groundwater are essential for the stock raising and agricultural production. Shallow groundwater was sampled and analyzed for various variables. The salinity sodium concentration and bicarbonate hazard, were examined with regard to the United States Department of Agriculture （USDA） irrigation water standards. The concentration of chlorofluorocarbons （CFCs） was determined to analyze the age of groundwater. Most groundwater samples labeled as excellent to good for irrigation with low salinity hazard or medium salinity hazard. Four groundwater samples were good and suspected for irrigation with high salinity hazard. Generally groundwater in Sanjiang Plain was younger than the groundwater in Songnen Plain. Meanwhile, groundwater nearby river is younger than the groundwater further away inside the watershed. The mean age of groundwater in Sanjiang Plain is in average of 44.1,47.9 and 32.8 years by CFC-11 （CCI3F）, CFC-12 （CCI2F2） and CFC-113 （C2CI3F3）, respectively. The mean ages of groundwater in Songnen Plain is in average of 46.1, 53.4, and 40.7 years by CFC-11, CFC-12 and CFC-113, respectively. Thus, groundwater nearby rivers could be directly exploited as irrigation water. Partial groundwater has to be processed to lower the salt concentration rather than directly utilized as irrigation water in Songnen Plain. Both water quality and renewability should be put in mind for sustainable agricultural development and water resources management.

Hydrochemical characteristics of salt marsh wetlands in western Songnen Plain

In western Songnen Plain of China, the saline-alkaline degree of water bodies is high in salt marsh wetlands. Generally, pH is above 8.0, and the hydrochemical types belong to HCO3 2?-Na+. Through analysis on the basic saline variables such as CO3 2?, HCO3 2?, Cl?, Ca2+, Mg2+, SO4 2?, Na+, and the derivative variables such as SAR, SDR, RSC, SSP, the relationships between different variables are found, and the discriminant equations are established to identify different saline-alkaline water bodies by using principal component analysis.

Sandy desertification trend in western Northeast China Plain in the past 10 years

The west sandy land of the Northeast China Plain is located in the eastern huge sandy belt of mid-latitude in Eurasia and the eastern fringe of desertified land with best bio-climatic conditions in China. With rapid economic development, the deterioration of eco-environment has occurred and the desertification becomes very obvious. The first part of this paper studies the regional differences of landscape patterns and explores the regional differences of desertification. The second part aims to reveal the dynamics of desertification in the 1990s by using NOAA/AVHRR data and thematic data in GIS database. This work lays a scientific basis for the rehabilitation and development of the sandy lands.

Establishment of a diatom-total phosphorus transfer function for lakes on the Songnen Plain in northeast China

To understand the relationship between planktonic diatoms and environmental variables in the lakes on the Songnen Plain,northeast(NE)China,we investigated water quality and planktonic diatoms from 71 sampling points in 27 lakes,based on which Canonical Correspondence Analysis(CCA)was conducted.The result show that planktonic diatoms displayed certain responses to environment gradients,and the total phosphorus(TP)explained the maximum variation of planktonic diatom species among the 15 environmental variables,suggesting that TP was the most important and significant environmental parameter affecting the distribution of diatom species.In addition,we established a diatom-total phosphorus transfer(DTPT)function,of which component 5 of the weighted averaging partial least squares regression(WAPLS)was chosen to and compared with a series of weighted average regression(WA)models and WA-PLS models.According to the jackknifing statistical test,the component 5 of WA-PLS models provided a lower root-mean-square error prediction(RMSEP=0.202)and a higher correlation coefficient between observation and prediction(R^2_Jack=0.759).After deletion of three outliers,the root-mean-square error prediction of the DTPT function was reduced(RMSEP=0.169)while the correlation coefficient between observation and prediction was increased(R^2_Jack=0.823).Therefore,this DTPT function performed better than other regional TP models in the world.However,it remains demanding for expanding the background dataset to improve the prediction ability of the model.

Changes in groundwater resources and their influencing factors in Songnen Plain, China

The Songnen Plain is a crucial agricultural area in China,and in the past 20 years,a large number of dry fields have been developed into paddy fields in order to improve land output efficiency.As a result,the effective irrigation area of agriculture has increased annually,and the conversion mode and quantity between surface water and groundwater have changed considerably.It is essential to identify the changes in groundwater resources and their influencing factors for the sustainable development of economy and society.This study evaluates groundwater resources in the Songnen Plain using the water balance method based on meteorological,hydrological and groundwater monitoring data from 2000 to 2020.The results 3 show that the groundwater resources in the region amount to 15.945 billion m with precipitation infiltration being the most important component,accounting for 73.09%,which is followed surface water irrigation infiltration and river and ditch infiltration,constituting 14.55%and 10.32%,respectively.Different factors influence groundwater resources in different periods.Compared to 1985,the increase of surface water irrigation infiltration is the primary factor responsible for the increase of groundwater resources,while other recharge sources have decreased during the same period.Compared to 2005,all groundwater resources have increased,with the increase of surface water irrigation infiltration and river channel infiltration being the primary factors.

Effect of maize sowing area changes on agricultural water consumption from 2000 to 2010 in the West Liaohe Plain, China

The West Liaohe Plain is located in the eastern Inner Mongolia, known as the golden maize belt in China, where maize acreage has continued to rise in recent years. Water is the main limiting factor for maize production in the region, therefore, this study calculated the effect of maize sowing area changes on agricultural water consumption in the West Liaohe Plain in 2000, 2005 and 2010, based on remote sensing and meteorological data. Maize remote sensing classification was con- structed based on moderate-resolution imaging spectroradiometer, normalized difference vegatation index （MODIS NDVI） data. Then the maize sown area and water requirement and irrigation water resources were investigated. Finally, the effect of the maize sowing area changes on agricultural water consumption in the West Liaohe Plain was systematically analyzed in 2000, 2005, and 2010. The results showed that maize sown areas rose from 2000 to 2010 and were concentrated in the center of the West Liaohe Plain. Average per unit maize water deficit amount also increased in an uneven distribution, increasing from the south, east and north to the center and west of the West Liaohe Plain. The per unit area maize water deficit increased from 2000 to 2010, and reached 266 mm in 2000, 272 mm in 2005 and 273 mm in 2010, respectively. and the study concluded that water deficit during the whole growth period of maize in the West Liaohe Plain was defined by a single peak curve. The maize water requirements increased with maize sowing area changes from 2000 to 2010, and the maize water requirements increased from 0.89 billion m3 in 2000 to 1.19 billion m3 in 2005, and 1.21 billion m3 in 2010.

Community-Based Approach in the Prevention and Management of Flood Disasters in Babessi Sub-Division (Ndop Plain, North West Cameroon)

Flood is a recurrent natural disaster that has caused enormous human and material damage in many places and continues to hit local committees at an alarming rate. The need to setup permanent committees to prevent and manage flood disasters by local communities is therefore indispensable. In rural areas, the creation of such a structure is always a welcome relief to flood victims but it is often marred by numerous management problems. This study aimed to analyze the community-based approach in the prevention and management of flood disasters in Babessi Subdivision (North West Cameroon), to identify the causes of flood disasters and the preventive strategies used by this local community. A total number of 300 questionnaires as well as structured interviews were used to collect data in the field and the data were analyzed by simple descriptive statistics. The main results revealed that the main cause of flood disasters is heavy and consistent rainfall. Also, poor refuse disposal and drainage system management contribute to floods. The identification of areas likely to be affected by floods and preventing the riparian population from constructing houses along these areas especially beside the main rivers are the flood preventive measures adopted by the local flood management committee. The flood victims are reluctant to relocate to the settlement site earmarked by the Government, meanwhile, the local flood committee do not have the legal tools to forcefully relocate them. The population of Babessi needs to be sensitized on the impending dangers of flood hazard and be encouraged to participate in implementing the adopted strategies to prevent and manage subsequent flood disasters.

Effects of Biochar Application on Soil Organic Carbon in Degraded Saline-sodic Wetlands of Songnen Plain,Northeast China

Biochar amendment is considered as an efficient practice for improving carbon storage in soils.However,to what extent that biochar application promotes organic carbon in saline-sodic soils remains poorly understood.By comparing soil organic carbon(SOC)contents change before and after biochar addition,we deciphered the driving factors or processes that control SOC change in response to biochar application.A limited increase in SOC was observed,about by 1.16%-12.80%,even when biochar was applied at the rate of 10%of bulk soil weight.Biochar application enhanced soil dissolved organic carbon(DOC)significantly by up to 67%.It was estimated that about 50%SOC was allocated to small macroaggregates(250-2000μm,CPOC),and SOC in silt and clay-sized particles(<53μm)decreased obviously after biochar addition.Microbial biomass increased with biochar amendment,of which actinomycetes(ACT),fungus(FUN),protozoon(PRO),and bacteria with straight-chain saturated fatty acids(OB)increased remarkably.Multiple linear regression models implied that DOC was governed by ACT and soil N∶P ratio,while SOC mostly depended on CPOC.The principal component analysis and the partial least square path model(PLS-PM)indicated that biochar addition aggravated nitrogen limitation in saline-sodic soils,and effects of microorganisms on regulating SOC greatly depended on nitrogen bioavailability.Biochar application had vastly changed interactions between environmental factors and SOC in saline-sodic soils.Effects of nutrients on SOC shifted to great inhibition from strong stimulation after biochar addition,meanwhile,aggregation was the only factor presenting positive effects on SOC.How to eliminate nutrient limitation and better soil aggregation process should be considered in priority when biochar was used to improve SOC in saline-sodic soils.

Effects of land use/cover change(LUCC) on the spatiotemporal variability of precipitation and temperature in the Songnen Plain,China

Understanding the effects of land use/cover change(LUCC) on regional climate is critical for achieving land use system sustainability and global climate change mitigation. However, the quantitative analysis of the contribution of LUCC to the changes of climatic factors, such as precipitation & temperature(P&T), is lacking. In this study, we combined statistical methods and the gravity center model simulation to quantify the effects of long-term LUCC on P&T in the Songnen Plain(SNP) of Northeast China from 1980–2018. The results showed the spatiotemporal variability of LUCC. For example, paddy field had the largest increase(15 166.43 km2) in the SNP, followed by dry land, while wetland had the largest decrease(19 977.13 km;) due to the excessive agricultural utilization and development. Annual average precipitation decreased at a rate of –9.89 mm per decade, and the warming trends were statistically significant with an increasing rate of 0.256°C per decade in this region since 1980. The model simulation revealed that paddy field, forestland, and wetland had positive effects on precipitation, which caused their gravity centers to migrate towards the same direction accompanied by the center of precipitation gravity, while different responses were seen for building land, dry land and unused land. These results indicated that forestland had the largest influence on the increase of precipitation compared with the other land use types.The responses in promoting the temperature increase differed significantly, being the highest in building land, and the lowest in forestland. In general, the analysis of regional-scale LUCC showed a significant reduction of wetland, and the increases in building land and cropland contributed to a continuous drying and rapid warming in the SNP.

Intra-specific variations of two Leymus chinensis divergence populations in Songnen Plain, Northeast China

Population demography, seed production, biomass allocation, net photosynthesis and transpiration of two Leymus chinensis divergent populations and between two years in Songnen plain, northeast China were compared. Strong differences between the dry 1997 and moist 1998 occurred in vegetative shoot and sexual shoot densities, sexual differentiation and tiller densities, as well as in the lengths of inflorescence, seed numbers per inflorescence, seed weights and biomass allocation in each population respectively ( P < 0.01). While strong differences between the two populations occurred in vegetative shoot densities, sexual shoot densities, sexual differentiation and seed weights in each year ( P < 0.01). The differences between the two populations in tiller densities and in biomass allocation to sexual shoots were significant ( P <0.05). But there were no significant differences between the two populations in the lengths of inflorescence, seed numbers per inflorescence and biomass allocation to rhizomes and vegetative shoots ( P >0.05). Excepting the transpiration rate in the early June, the differences between the two populations in net photosynthesis and transpiration rate of vegetative shoots and sexual shoots were strongly significant in the early June and July respectively ( P <0.01). Relative stable variations in population demography and physiological traits between the two populations indicated that they are divergently in the Songnen Plain.

THE TYPES OF LAKE IN SONGNEN PLAIN AND THEIR REGIONAL CHARACTER

The lake groups in the Songnen Plain are low plain lake groups, which are located in the temperate semihumid area in China. They are characterized by small area, shallow basin, thick density and various types. In the try for classifying comprehensively the lake groups, a classification system is developed based on three main factors, i.e. forming cause, water quantity and water quality. The most internal character can be concisely grasped through three principal indexes and three auxiliary indexes of three main factors. A sample of complicated changeable path is put forward for further analyzing and outlining these basic types, in the meantime, it’s linking up easily with the classification system of the single factor. According to the regional environment, the regional differences of the type composition and the principal types, the lake groups in the Songnen Plain can be divided into 6 sub-regions.

Effects of Groundwater with Various Salinities on Evaporation and Redistribution of Water and Salt in Saline-sodic Soils in Songnen Plain,Northeast China

Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.