The impact of physical processes on pollutant transport in Hangzhou Bay

A Lagrangian tracer model is set up for Hangzhou Bay based on Coupled Hydrodynamical Ecological model for Regional Shelf Sea (COHERENS). The study area is divided into eight subdomains to identify the dominant physical processes, and the studied periods are March (the dry season) and July (the wet season). The model performance has been first verified by sea-surface elevation and tidal current observations at several stations. Eight tracer experiments are designed and Lagrangian particle tracking is simulated to examine the impact of physical processes (tide, wind and river runoff) on the transport of passive tracer released within the surface layer. Numerical simulations and analysis indicate that: (1) wind does not change the tracer distribution after 30 days except for those released from the south area of the bay during the wet season; (2) the tide and the Qiantang River runoff are important for particle transport in the head area of the bay; (3) the Changjiang River runoff affects the tracer transport at the mouth of the bay, and its impact is smaller in the dry season than in the wet season. Supported by the Natural Science Foundation of China (No.40576080); National High Technology Research and Development Program of China (863 Program, No. 2007AA12Z182)     

Impact factors on distribution and characteristics of natural plant community in reclamation zones of Changjiang River estuary

To identify impact factors on the distribution and characters of natural plants community in reclamation area, with survey data from 67 plant quadrats in July 2009, soil properties data from 216 sampling points in April 2009, and TM (30 m) data in 2006, the composition and characteristics of natural plants community in different time of the Fengxian area in the Changjiang (Yangtze) River estuary were analyzed with two-way indicator species analysis (TWINSPAN), multivariate analysis of variance (MANOVA), detrended canonical correspondence analysis (DCCA) and canonical correspondence analysis (CCA). The results show that: 1) The plant communities in the reclaimed area are mainly mesophytes and helophytic-mesophytic transitional communities, showing a gradient distribution trend with the change in reclamation years. Species richness (MA), species diversity (H) and above-ground biomass also increase with the increase of reclamation years. Nevertheless, they appear to decline slightly in the middle and late reclamation period (> 30 years). 2) With the rise in land use levels, the changes in species richness and species diversity tend to increase at first and then decrease; species dominance (D), however, tends to decline; and above-ground biomass increases slightly. 3) The distribution of the plant community is mainly influenced by the following factors: land use levels (R = 0.55, p < 0.05), soil moisture (R = 0.53, p < 0.05), soil salinity (R = 0.43, p < 0.05) and reclamation time (R = 0.40, p < 0.05).     

EVALUATION OF ECOLOGICAL SERVICES OF JILIN PROVINCE, NORTHEAST CHINA

1INTRODUCTIONEcosystem services can be divided into two major cat-egories, one is system function, and the other is sys-tem services and goods provision, which provide not only materials such as food and medicine, but also support and maintenance of whole system. Ecological services contribute to the whole economic system, both directly and indirectly, and consequently repre-sent parts of the total value of our economy system (COSTANZA etal., 1997; GUO etal., 2001). Sustainable d…     

Impacts of the Wenchuan Earthquake on the giant panda nature reserves in China

The Wenchuan Earthquake that occurred in May of 2008 caused damages to large areas of Sichuan, Gansu, and Shaanxi provinces in China. Reports from local governments and related management agencies show that the giant panda nature reserves in the earthquake-hit areas were heavily damaged. Our estimates in this paper of the impacts of the earthquake on the giant panda in the earthquake-hit areas were made based on the interpretation of remote sensing images and information collected by field survey. A rapid assessment method was designed to estimate the damages of the earthquake on giant panda habitats. By using visual interpretation methods, we decoded the remote sensing images of the disaster area in the 49 giant panda nature reserves. Research results showed that the Wenchuan Earthquake and the succeeding secondary geological disasters caused great damages to the giant panda nature reserves and disturbed the normal life of the giant pandas there (e.g., landscape fragmentation increased significantly). Undoubtedly, the life of the giant pandas there was affected. However, although the earthquake caused certain impacts on the giant pandas, it did not really threat their survival. Even so, we still strongly advocate for protection of the giant pandas, and have prioritized a couple of measures to be taken to restore the giant panda nature reserves in the earthquake-hit areas.     

A landscape pattern analysis method based on boundaries and nodes: A case study in upper Minjiang River, China

Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This study investigated the possibility of applying boundary-and node-based methods in landscape pattern analysis to the upper reaches of the Minjiang River in the southwestern China.Boundary-based and node-based landscape indices were selected to be used in analyzing changes in landscape patterns,and the results were compared with analysis using traditional pattern indices.We compared the responses of patch-area-based,boundary-length-based and node-number-based indices,and concluded that boundary-based and node-based indices are more sensitive to disturbance than patch-based indices with various patterns,and node-based indices are even more sensitive than boundary-based ones.Thus,the results suggest that boundary-based and node-based pattern analysis methods provide helpful supplementary information to traditional patch-based pattern analysis methods.The results about pattern dynamics of landscapes in the upper reaches of the Minjiang River based on boundaries and nodes showed that with human disturbance,the dominance of forest landscape was weakened by other landscape types; thus the landscape pattern of the study area became more homogeneous and the boundary network became more complex.These changes further augmented disturbance interfaces in the landscape and increased the possibilities of further landscape fragmentation.     

Effect of climate change on seasonal water use efficiency in subalpine <Emphasis Type="Italic">Abies fabri</Emphasis>

Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions, and climate change ratio is also uneven in different seasons. Carbon gain and the response of water use efficiency (WUE) to annual and seasonal increases in temperature with or without CO₂ fertilization were simulated in Abies fabri using the atmospheric-vegetation interaction model (AVIM2). Four future climate scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) were selectively investigated. The results showed that warmer temperatures have negative effects on gross primary production (GPP) and net primary production (NPP) in growing seasons and positive effects in dormant seasons due to the variation in the leaf area index. Warmer temperatures tend to generate lower canopy WUE and higher ecosystem WUE in Abies fabri. However, warmer temperature together with rising CO₂ concentrations significantly increase the GPP and NPP in both growing and dormant seasons and enhance WUE in annual and dormant seasons because of the higher leaf area index (LAI) and soil temperature. The comparison of the simulated results with and without CO₂ fertilization shows that CO₂ has the potential to partially alleviate the adverse effects of climate warming on carbon gain and WUE in subalpine coniferous forests.     

Estimating aboveground biomass using Pléiades satellite image in a karst watershed of Guizhou Province,Southwestern China

Biomass in karst terrain has rarely been measured because the steep mountainous limestone terrain has limited the ability to sample woody plants.Satellite observation, especially at high spatial resolution, is an important surrogate for the quantification of the biomass of karst forests and shrublands. In this study, an artificial neural network(ANN) model was built using Pléiades satellite imagery and field biomass measurements to estimate the aboveground biomass(AGB) in the Houzhai River Watershed, which is a typical plateau karst basin in Central Guizhou Province, Southwestern China. A back-propagation ANN model was also developed.Seven vegetation indices, two spectral bands of Pléiades imagery, one geomorphological parameter,and land use/land cover were selected as model inputs. AGB was chosen as an output. The AGB estimated by the allometric functions in 78 quadrats was utilized as training data(54 quadrats, 70%),validation data(12 quadrats, 15%), and testing data(12 quadrats, 15%). Data-model comparison showed that the ANN model performed well with an absolute root mean square error of 11.85 t/ha, which was 9.88%of the average AGB. Based on the newly developed ANN model, an AGB map of the Houzhai River Watershed was produced. The average predicted AGB of the secondary evergreen and deciduous broadleaved mixed forest, which is the dominant forest type in the watershed, was 120.57 t/ha. The average AGBs of the large distributed shrubland,tussock, and farmland were 38.27, 9.76, and 11.69 t/ha, respectively. The spatial distribution pattern ofthe AGB estimated by the new ANN model in the karst basin was consistent with that of the field investigation. The model can be used to estimate the regional AGB of karst landscapes that are distributed widely over the Yun-Gui Plateau.     

Taxonomic distinctness of macrofauna as an ecological indicator in Laizhou Bay and adjacent waters

In this paper, we assessed the ecological and biodiversity status in the Bohai Sea through a quantitative survey on mac-rofaunal community at 25 stations in Laizhou Bay and adjacent waters in the autumn of 2006.We tested the robustness and effectiveness of taxonomic distinctness as an ecological indictor by analyzing its correlation with species richness and natural environmental variables and by analyzing other ecological indicators (Shannon-Wiener H' and W statistics from Abundance Biomass Comparison curve).Results so obtained indicated that the benthic environment of the study waters in general is not under major impact of anthropogenic disturbance, but some stations in Laizhou Bay and along the coast of the Shandong Peninsula and even in the central Bohai Sea might be moderately disturbed and showed signs of ecological degradation.The taxonomic distinctness measures △+ and Λ+ were independent of sampling effort and natural environment factors and were compliant to other ecological indicators.Further application of the taxonomic distinctness indicator to assess marine biodiversity and ecosystem health on a larger regional scale with historical data seems promising.     

Transformation of Carbon and Nitrogen by Earthworms in the Decomposition Processes of Broad-leaved Litters

Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.     

ESTIMATE OF METHANE EMISSIONS FROM RICE FIELDS IN CHINA BY CLIMATE-BASED NET PRIMARY PRODUCTIVITY

1INTRODUCTIONIrrigated ricefieldsarecharacterizedbylargespatialandtemporalvariationsin CH4 emissiontotheatmo-sphere.Accordingly,thereisagreatuncertaintyintheestimate ofCH4 emissionsfromricefields.GreateffortshavebeenmadetoestimatetheCH4 emissionsfromricefieldsandseveralapproacheshavebeendeveloped.TherepresentativemethodsincludetheIPCC(Inter-governmentPanelofClimateChange)region-specificemissionfactormethodandthemodelcalculationmethod.Toimprovethecalculationaccuracy,theIPCCmethodreq…