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1.
During the period of May to October in 1999, systematical studies were given to the rate of decomposition of Calamagrostis angustifolia litter, the phosphorus content and weight in decomposed residua of litter, and phosphorus content in the corresponding soil in the Sanjiang Plain. At the same time, the simulation models were listed in the paper. The results showed that the rate of weight lost of decomposition of Calamagrostis angustifolia litter is 29.80% and the maximum of daily rate of weight lost is 0.25%, which appeared in July. The change trend of phosphorus content and weight in the decomposed residua of litter is to reduce with the decomposing process, when it comes to the day of 157, the decrement amount of the both were respectively 57.69mg/kg and 1.6199mg, which were 72.80% and 76.30% of its previous amount. In addition, there is a polynomial minus correlationship of phosphorus content between the variation in corresponding soil and the decomposed residua of litter at the corresponding period. The study will be helpful to further understand the process and mechanism of biochemical cycling of nutrient elements in wetland ecosystems, in addition, it will also be helpful to the restoration and rebuilding of retrogressive wetlands and reasonable development and utilization of wetlands in the Sanjiang Plain. Foundation item: Under the auspices of the National Natural Science Fundation of China (No. 49771002), the Key B Items of Chinese Academy of Sciences (KZ951-B1-201-3) and the Innovative Project of the Chinese Academy of Sciences (KZCX2-302). Boigraphy: WANG Shi-yan (1974 -), male, a native of Jinan City, Shandong Province, Ph. D. candidate of Changchun Institute of Geography, the Chinese Academy of Sciences. His research interests include ecology of wetland environment and application of remote sensing and GIS.  相似文献   

2.
In the Sanjiang Plain,Northeast China,the natural wetland is undergoing a rapid conversion into agricultural land,which has resulted in drastic ecological changes in the region. To investigate the effects of different land uses on soil labile organic carbon,soils of Calamagrostis angustifolia wetland,Carex lasiocarpa wetland,dry farmland,paddy field,forest land and abandoned cultivated land were collected for measuring the contents of soil microbial biomass carbon (MBC),dissolved organic carbon (DOC),readil...  相似文献   

3.
Deyeuxia angustifolia wetlands were widely distributed in the Sanjiang Plain in Northeast China. Due to strong demand for food production, large-area wetlands were reclaimed to farmlands, which threatened regional ecological security greatly. Since the 21 th century, returning farmlands to wetlands was widely adopted for natural restoration in the Sangjiang Plain. As the first reflection of wetland restoration, vegetation succession of restored D. angustifolia wetlands should be fully assessed. In this study, vegetation investigation was carried out in three restored D. angustifolia wetlands with 5, 8 and 12 yr restoration, respectively. Meanwhile, a natural D. angustifolia wetland was selected as reference wetland. Results showed that community composition changed greatly and there was visible community succession. Community dominant species changed from composite to gramineae as restoration time increasing.At first, weeds community appeared in the restored wetlands, especially the xerophytes developed to the pioneer species rapidly. And then, mesophytes and wetland species became the dominant species in the restored wetlands. Finally, wetland species, especially D. angustifolia, occupied the dominant position of restored community. Shannon-wiener index(H) and Simpson index(D) both decreased to close to natural D. angustifolia wetlands. Compared with natural D. angustifolia wetland, species composition and diversity in restored wetlands were more complex and higher. As restoration time increasing, there were not significant differences between community characteristics of restored wetlands and natural wetland. All these suggested that vegetation in reclaimed D. angustifolia wetland could be restored naturally, but its restored period is 10 yr at least. From another angle, it is important to protect current natural wetlands.  相似文献   

4.
The purification law of nitrogen in Deyeuxia angustifolia,Carex lasiocarpa and Deyeuxia angustifo-lia-Carex lasiocarpa combined wetland systems in the Sanjiang Plain,China was studied by field simulation experi-ment.The results indicate that the removal rates of TN,NH4+-N and NO3--N in above three types of wetlands present an obvious logarithm growth trend along with the time.There are evident removal effects for NH4+-N and NO3--N in water bodies of wetlands after the 30th day of experiment,with the removal rates over 80.0%,but the removal rate of TN is slightly low,being 63.1%-74.3%.NO3--N is most quickly removed by the combined wetland,and NH4+-N by Deyeuxia angustifolia wetland.The removal speeds of TN by the three wetland systems are comparatively slow,of which the Deyeuxia angustifolia wetland is the fastest.In consideration of plant growth season,Deyeuxia angustifolia wetland has much more practical application value in purifying nitrogen.These results can provide references for the study on the purification function of wetlands and the control of non-point source pollution in Northeast China.  相似文献   

5.
Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3–4.1 times that in 0.058mm ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% (Carex lasiocapa) to 32.94% (Carex meyeriana), then increased to 38.16% (Calamagrostics angustifolia). The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon (TC), total nitrogen (TN) and total phosphorus (TP) contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of influencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation. Foundation item: Under the auspices of State Key Development Program for Basic Research of China (No. 2009CB421103), Key Program of National Natural Science Foundation of China (No. 40830535/D0101), Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-BR-16, KSCX2-YW-N-46-06)  相似文献   

6.
I INTRODUCTIONWetland has very important effect on retainingwater and against drought, regUlating climate, controlling soil erosion and so on ac. Today men often attachimportance to economic effect of wetland reclamation,but neglect and destroy other functions and effectswhich result in blind wetland development, a lot ofwetland degeneration. The area of freshwater wetland inthe 1950s was 134 x 10'ha, but in the 1970s 70% hadchanged into farmland (MITSCH, 1993). The area ofwetland in d…  相似文献   

7.
Northeast China is the region with the largest area of wetlands in China. The Sanjiang Plain and the Songnen Plain are large freshwater marsh distribution regions that are affected by climate warming and by the increasing frequency and density of extreme weather and are the regions most subject to disturbances by human activities in Northeast China. The wetlands of the Sanjiang Plain and the Songnen Plain have shrunk severely in the past 60 years, and wetland functions have been reduced substantially because of climate change, unreasonable land use, fire episodes, engineering and construction works and urbanization. Large-scale agricultural development started in the 1950s has been the most important driving factor for wetland loss and degradation in the Sanjiang Plain. Water shortage has been the most important factor for degradation and fragmentation of wetlands in the Songnen Plain. To mitigate wetland degradation and better protect wetlands, special regulations, long-term mechanisms and technical support of wetland protection should be established. A wetland compensation program should be implemented, and technologies for increasing the adaptive capacity of wetlands should be developed. Moreover, it is most important to find the balanced threshold between agricultural development and wetland protection.  相似文献   

8.
１ＩＮＴＲＯＤＵＣＴＩＯＮＦｏｒｅｓｔｌｉｔｔｅｒｗｈｉｃｈｉｓｔｈｅｐｈｙｓｉｃａｌｍａｋｅｕｐｐａｒｔｏｆｆｏｒｅｓｔｅｃｏｓｙｓｔｅｍｐｒｅｓｅｎｔｓｍａｎｙｉｍｐｏｒｔａｎｔａｃｔｉｏｎｓｕｐｏｎｅｃｏｓｙｓｔｅｍ．Ｈｏｗｅｖｅｒｉｆｆｏｒｅｓｔｌｉｔｔｅｒｉｓａｃｃｕｍｕｌａｔｅｄｔｏｅｘｃｅｓｓｉｔｗｉｌｌｐｒｏｄｕｃｅｓｏｍｅｎｏｎｎｅｇｌｉｇｉｂｌｅｎｅｇａｔｉｖｅｉｎ-ｆｌｕｅｎｃｅｗｈｉｃｈｃｏｕｌｄｂｅｔｈｅｃａｕｓｅｏｆａｆｏｒｅｓｔｆｉｒｅｏｒｔｈｅｉｍｐｏｒ…  相似文献   

9.
Adjacent intensive agriculture disturbs the natural condition of wetlands.However, to assess the effect of this agriculture on wetlands, few studies have used indices based on aquatic invertebrates.Multi-metric indices(MMIs) have been successfully used to assess freshwater ecosystems worldwide and are an important management tool, but little is known about their applicability in the Sanjiang Plain, Northeast China.In this study, we developed a MMIs for aquatic invertebrates to assess freshwater wetlands in this region.The aquatic invertebrate assemblages were sampled in 27 wetlands in the Sanjiang Plain that included those in natural reserves and those affected by adjacent, intensive agriculture.Twenty-four candidate metrics were initially reviewed and screened before four core metrics were selected: total number of taxa, number of Hemiptera taxa, proportion of Gastropoda, and proportion of predators.Mann-Whitney U tests, Box and Whisker plots, correlation analyses, and redundant metric tests were used to assess the ability of metrics to distinguish among reference and impaired wetlands.Four ordinal rating categories for wetland were defined: poor, fair, good, and excellent.Of the impaired freshwater wetlands, 76.2% were in poor or fair categories.The MMIs was robust in discriminating reference wetlands from impaired wetlands and therefore have potential as a biomonitoring tool to assess the condition and to guide the restoration efforts of freshwater wetlands in Northeast China.  相似文献   

10.
The multi-level ditch system developed in the Sanjiang Plain,Northeast China has sped up water drainage process hence transferred more pollutants from farmlands into the rivers of this region.Understanding the seasonal dynamics of nitrogen (N) and phosphorus (P) transportation in the ditch system and the role of different ditch size is thus crucial for water pollution control of the rivers in the Sanjiang Plain.In this study,an investigation was conducted in the Nongjiang watershed of the Sanjiang Plain to ...  相似文献   

11.
As a key parameter for indicating the fraction of surface-reflected solar incident radiation, land surface albedo plays an important role in the Earth's surface energy budget(SEB). Since the Sanjiang Plain has been severely affected by human activities(e.g., reclamation and shrinking of wetlands), it is important to assess the spatiotemporal variations of surface albedo in this region using a long-term remote sensing dataset. In order to investigate the surface albedo climatology, trends, and mechanisms of change, we evaluated the surface albedo variations in the Sanjiang Plain, China from 1982 to 2015 using the Global LAnd Surface Satellite(GLASS) broadband surface albedo product. The results showed that: 1) an increasing annual trend(+0.000 58/yr) of surface albedo was discovered in the Sanjiang Plain based on the GLASS albedo dataset, with a much stronger increasing trend(+0.001 26/yr) occurring during the winter. Most of the increasing trends occurred over the cultivated land, unused land, and land use conversion types located in the northeastern Sanjiang Plain. 2) The increasing trend of land surface albedo in Sanjiang Plain can be largely explained by the changes of both snow cover extent and land use. The surface albedo in winter is highly correlated with the snow cover extent in the Sanjiang Plain, and the increasing trend of surface albedo can be further enhanced by the land use changes.  相似文献   

12.
The decomposition of plant litter is a key process in the flows of energy and nutrients in ecosystems. However, the response of litter decomposition to global climate warming in plateau wetlands remains largely unknown. In this study, we conducted a one-year litter decomposition experiment along an elevation gradient from 1891 m to 3260 m on the Yunnan Plateau of Southwest China, using different litter types to determine the influences of climate change, litter quality and microenvironment on the decomposition rate. The results showed that the average decomposition rate(K) increased from 0.608 to 1.152, and the temperature sensitivity of litter mass losses was approximately 4.98%/℃ along the declining elevation gradient. Based on a correlation analysis, N concentrations and C︰N ratios in the litter were the best predictors of the decomposition rate, with significantly positive and negative correlations, respectively. Additionally, the cumulative effects of decomposition were clearly observed in the mixtures of Scirpus tabernaemontani and Zizania caduciflora. Moreover, the litter decomposition rate in the water was higher than that in the sediment, especially in high-elevation areas where the microenvironment was significantly affected by temperature. These results suggest that future climate warming will have significant impacts on plateau wetlands, which have important functions in biogeochemical cycling in cold highland ecosystems.  相似文献   

13.
Large oilfields are often coincidentally located in major river deltas and wetlands, and potentially damage the structure, function and ecosystem service values of wetlands during oil exploration. In the present study, the effects of crude oil contamination during oil exploration on soil physical and chemical properties were investigated in marshes of the Momoge National Nature Reserve in Jilin Province, China. The concentrations of total petroleum hydrocarbons in the marsh soil near the oil wells are significantly higher than those in the adjacent control marsh. Soil water contents in oil-contaminated marshes are negatively correlated with soil temperature and are significantly lower than those in the control area, especially in fall. Crude oil contamination significantly increases the soil pH up to 8.0, and reduces available phosphorus concentrations in the soil. The concentrations of total organic carbon are significantly different among sampling sites. Therefore, crude oil contamination could potentially alkalinize marsh soils, adversely affect soil fertility and physical properties, and cause deterioration of the marshes in the Momoge National Nature Reserve. Phyto-remediation by planting Calamagrostis angustifolia has the potential to simultaneously restore and remediate the petroleum hydrocarbon-contaminated wetlands. Crude oil contamination affects the soil physical and chemical properties, so developing an effective restoration program in the Momoge wetland is neccesary.  相似文献   

14.
Microorganisms are nutritious resources for various soil fauna.Although soil fauna grazing affects microorganism composition and decomposition rate,the responses of soil fauna and leaf litter decomposition to added microorganism is little understood.In this study,in the coniferous and broad-leaved mixed forest of Tahe County in the northern Da Hinggan Mountains,China,three sampling sites(each has an area of 10 m2) were selected.The first two sites were sprinkled with 250 times(EM1) and 1000 times(EM2) diluted effective microorganism(EM) preparations evenly,and the third site was sprinkled with the same volume of water as a control site.The responses of soil fauna structure and leaf litter decomposition to EM treatment were conducted during three years.The results revealed that EM treatment resulted in significant increase of soil organic matter.The number of soil fauna in the EM1 and EM2 sites increased by 12.88% and 2.23% compared to the control site,and among them springtails and mites showed the highest increase.However,the groups of soil fauna in the EM1 and EM2 sites decreased by 6 and 9,respectively.And the changes in the diversity and evenness index were relatively complicated.EM treatment slowed the decomposition of broad-leaved litter,but accelerated the decomposition of coniferous litter.However,the decomposition rate of broad-leaved litter was still higher than that of coniferous litter.The results of this study suggested that the added microorganisms could help individual growth of soil fauna,and this method led to a change in the process of leaf litter decomposition.This paper did not analyze the activity of soil microorganisms,thus it is difficult to clearly explain the complex relationships among litter type,soil fauna and soil microorganisms.Further research on this subject is needed.  相似文献   

15.
In this study,the Surface Energy Balance Algorithms for Land(SEBAL) model and Moderate Resolution Imaging Spectroradiometer(MODIS) products from Terra satellite were combined with meteorological data to estimate evapotranspiration(ET) over the Sanjiang Plain,Northeast China.Land cover/land use was classified by using a recursive partitioning and regression tree with MODIS Normalized Difference Vegetation Index(NDVI) time series data,which were reconstructed based on the Savitzky-Golay filtering approach.The MODIS product Quality Assessment Science Data Sets(QA-SDS) was analyzed and all scenes with valid data covering more than 75% of the Sanjiang Plain were selected for the SEBAL modeling.This provided 12 overpasses during 184-day growing season from May 1st to October 31st,2006.Daily ET estimated by the SEBAL model was misestimaed at the range of-11.29% to 27.57% compared with that measured by Eddy Covariance system(10.52% on average).The validation results show that seasonal ET from the SEBAL model is comparable to that from ground observation within 8.86% of deviation.Our results reveal that the time series daily ET of different land cover/use increases from vegetation on-going until June or July and then decreases as vegetation senesced.Seasonal ET is lower in dry farmland(average(Ave):491 mm) and paddy field(Ave:522 mm) and increases in wetlands to more than 586 mm.As expected,higher seasonal ET values are observed for the Xingkai Lake in the southeastern part of the Sanjiang Plain(Ave:823 mm),broadleaf forest(Ave:666 mm) and mixed wood(Ave:622 mm) in the southern/western Sanjiang Plain.The ET estimation with SEBAL using MODIS products can provide decision support for operational water management issues.  相似文献   

16.
Due to its rapid growth and high rate of spread, Phyllostachys pubescens can suppress other species, eventually leading to pure P. pubescens forests. Research on the patterns of litter decomposition and nutrient release from P. pubescens across stand mixtures are helpful to understand the decomposition and nutrient dynamics during the invasion process. However, little is known for unmanaged conditions at high elevations. Therefore, we studied the decomposition of four litter compositions comprised of different combinations of P. pubescens and Cunninghamia lanceolata foliage for one year to explore the pattern of litter decomposition and nutrient release at the Daiyun Mountain National Nature Reserve. The results show that:(1) the litter decomposed faster with a higher proportion of P. pubescens based on Olson's decay model;(2) the remaining litter compositions followed a trigonometric function model better than Olson'sdecay model and fluctuated periodically in tandem with changing temperature and precipitation;(3) the litter mixture decompositions did not support the biomass-ratio hypothesis test; and(4) there were significant binomial, power and exponential relationships between initial concentration and final amounts remaining after 1 year decomposition for C, N and P. The correlations between litter decomposition and nutrient releases were significant. The results may be used to explain the rapid spread of P. pubescens and to guide the natural management of plantations.  相似文献   

17.
CARBON CYCLE OF MARSH IN THE SANJIANG PLAIN   总被引：1，自引：0，他引：1  
Peat~hisaprocessofbeinghelpfulfordecreasingtheincrementofopcontentintheair,whichiscausedbycombustionofdineralfuelsandhumanactivitiesinterrestrialecosystem.But,exploitingrnaxsh,eSPeCiallyPeatedtObefuels,impliesthatorgbocsubstanceaccUInulatedfroma~hereduringthepastthousandsofyearsisrapidlyOxidized.aamthemarShplaysanimPOrtantroleinthecycleofbiogaxhdristry.TheSanjiangPlainisalowplainformedbythecommonreactionoftheHeilongRiver,SonghuaherandWUSuliabover.Thetotalareais10.89X104klnZandmarsharea…  相似文献   

18.
Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human disturbances such as collection of wood for fuel purpose and livestock grazing. Removal of vegetation of rangelands has a significant negative impact on soil organic matter(SOM). This research evaluates litter decomposition in three sites of Hazarganji Chiltan mountain with varying history of human disturbances(unprotected site, young protected site and old protected site). Twigs of Pistacia khinjuk with approximately equal weight and length were placed in litter bags of mesh size 2 mm and were buried in 0-5 cm depth in three sites in January. Half of the twigs of each site received rain simulation in April, August, October, November and January while the other half of the twigs were subjected under natural conditions for 15 months. Twigs from each plot of each treatment of each site were collected from soil after every rain simulation in the previous month of experiment and were processed for weight loss assessment. Results showed that weight loss of twigs by decomposition was significantly higher in the soil of unprotected site as compared to other two sites and there was no difference between rain simulation and control treatments except that loss of weight of twigs of unprotected site was higher under control than rain simulation condition. To confirm that SOM was the major controlling factor for the decomposition of litter decay, soils of each site were collected and burned to remove SOM;thereafter, burned soil samples were mixed with homogenous powder of oven-dried native plants, incubated for 6 months and were provided with dissolved organic matter of the soils of each site. Results showed that there was no difference in the decomposition of litter between soils under controlled laboratory condition, which confirmed that SOM was a major controlling factor for the litter decay in soil under field conditions. The pyrosequencing analysis of the DNA of soils collected from three sites revealed the presence of bacterial species Thermovum composti.  相似文献   

19.
Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, 10-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, China. Optimal nonlinear equations were applied to model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and 20-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, respectively. Also, it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages (p < 0.05) but not soil temperature (p > 0.05). Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at 10-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity (Q 10) increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets.  相似文献   

20.
The regularity of CH4 emission from marshland in the Sanjiang Plain was studied by sampling in the open field and analyzing under laboratory condition, the annual emission amount is also estimated. By Grey Relatively Analysis we know that the soil temperature in the 10-cm depth of grass-root layer is close related with CH4 emission. CH4 emission has different kinds of diurnal emission modes:before-dawn maximum mode, night maximum mode and irregular fluctuation mode. The seasonal variation trend of CH4 emission rates is going up steadily from May to August and dropping down from September, the maximum lies behind the maximum of temperature. CH4 emission rates of different marshland types are different, the CH4 emission rate of Glyceriaspiculosa — Carex marshland is always higher than that of Carex lasiocarpa marshland. The paper also studies the difference of CH4 emission rates in different managing modes and analyzes the emission rates between China and U. S. A. The result shows: the average value of CH4 emission rate is 17.26mg/(m2·h), the annual amount of CH4 emission is about 0.75Tg. Supported by National Natural Sciences Foundation of China, and thank the Ecological Test Station of Mires and Wetlands in the Sanjiang Plain, the Chinese Academy of Sciences.  相似文献   

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