Wetland vegetation biomass estimation and mapping from Landsat ETM data: a case study of Poyang Lake

Poyang Lake is the largest freshwater lake in China. This paper conducted a digital and rapid investigation of the lake’s wetland vegetation biomass using Landsat ETM data acquired on April 16, 2000. First, utilizing the false color composite derived from the ETM data as one of the main references, the authors designed a reasonable sampling route for field measurement of the biomass, and carried it out on April 18–28, 2000. Then after both the sampling data and the ETM data were geometrically corrected to an equal-area projection of Albers, linear relationships among the sampling data and some transformed data derived from the ETM data and the ETM 4 were calculated. The results show that the sampling data is best relative to the band 4 data with a high correlation coefficient of 0.86, followed by the DVI and NDVI data with 0.83 and 0.80 respectively. Therefore, a linear regression model, which was based on the field data and band 4 data, was used to estimate the total biomass of entire Poyang Lake, and then the map of the biomass distribution was compiled.

Effects of Water-table Depth and Soil Moisture on Plant Biomass, Diversity, and Distribution at a Seasonally Flooded Wetland of Poyang Lake, China

Hydrological regime has been widely recognized as one of the major forces determining vegetation distribution in seasonally flooded wetland. Poyang Lake, the largest freshwater lake in China, has been encountering dramatic changes in hydrological conditions in last decade, which greatly influenced the wetland vegetations. To explore the relationships between hydrology and vegetation distribution, water-table depth, soil moisture, species composition, diversity and biomass were measured at a seasonally flooded wetland section at Wucheng National Nature Reserve. Three plant communities, Artemisia capillaris, Phragmites australis and Carex cinerascens communities, were examined which are zonally distributed from upland to lakeshore with decreasing elevation. Canonical correspondence analysis(CCA), spearmen correlation and logistic regression were adopted to analyze the relationships between vegetation characteristics and hydrological variables of water-table depth and soil moisture. Results show that significant hydrological gradient exist along the wetland transect. Water-table demonstrates a seasonal variation and is consistently deepest in A. capillaris community(ranging from –0.5 m above ground to +10.3 m below ground), intermediate in P. australis community(–2.6 m to +7.8 m) and shallowest in C. cinerascens community(–4.5 m to +6.1 m). Soil moisture is lowest and most variable in A. capillaris community, highest and least variable in P. australis community, and intermediate and moderate variable in C. cinerascens community. The CCA ordination indicated that variables of water-table depth and soil moisture are strongly related to community distribution, which explained 81.7% of the vegetation variations. Species diversity indices are significantly positively correlated with soil moisture and negatively correlated with moisture variability, while above- and belowground biomass are positively correlated with moisture. Above- and belowground biomass present Gaussian models along the gradient of average water-table depth in growing season, while species diversity indices show bimodal patterns. The optimal average water-table depths for above- and belowground biomass are 0.8 m and 0.5 m, respectively, and are 2.2 m and 2.4 m for species richness and Shannon-Wiener indices, respectively. Outcomes of this work improved the understandings of the relationship between hydrology and vegetation.

Implications of Papyrus (<i>Cyperus papyrus</i>L.) Biomass Harvesting on Nutrient Regulation in Nyando Floodplain Wetland, Lake Victoria, Kenya

Harvesting of papyrus biomass plays a significant role in regulating ecosystem services of which one of them is nutrient uptake and cycling. Despite Lake Victoria’s wetlands being important, little is understood about its role in nutrient uptake and removal. Although there have been studies done in these wetlands, there is inadequate understanding on the implication of unselective biomass harvesting on the water quality of Lake Vitoria. At the same time, these wetlands are threatened by livelihood-related pressures which are driven by extreme hydrological regimes. This study focused on Nyando floodplain wetland located in the Eastern part of the shores of Lake Victoria which is a lifeline to many rural communities living around the lake. Papyrus biomass harvesting was assessed in two study sites of Nyando wetland and at different seasons in order to determine its implication on nutrient regulating services. Participatory tools, field survey, observation, field measurements and laboratory analysis were used. Harvesting of papyrus removed 530.6 Kg N/g DM/ha/day and 97 Kg P/g DM/ha/day in Ogenya while 771.2 Kg N/g DM/ha/day and 109.2 Kg P/g DM/ha/day were removed in Wasare. However, addition of nutrients to the wetland may lead to the problem of eutrophication especially at the site where interaction of wetland and lake water occurs. Understanding the role of papyrus harvesting patterns is crucial for better planning and management of this complex resource in a changing environment.

Stem and Total Above-Ground Biomass Models for the Tree Species of Freshwater Wetlands Forest, Coastal Areas and Dry Areas of Bangladesh: Using a Non-Destructive Approach

Biomass and carbon stock in a forested areas are now prime important indicators of forest management and climate change mitigation measures. But the accurate estimation of biomass and carbon in trees of forests is now a challenging issue. In most cases, pantropical and regional biomass models are used frequently to estimate biomass and carbon stock in trees, but these estimations have some uncertainty compared to the species-specific allometric biomass model. Acacia nilotica, Casuarina equisetifolia and Melia azedarach have been planted in different areas of Bangladesh considering the species-specific site requirements. While Barringtonia acutangula and Pongamia pinnata are the dominant tree species of the freshwater swamp forest of Bangladesh. This study was aimed to develop species-specific allometric biomass models for estimating stem and above ground biomass (TAGB) of these species using the non-destructive method and to compare the efficiency of the derived biomass models with the frequently used regional and pantropical biomass models. Four Ln-based models with diameter at breast height (DBH) and total height (H) were tested to derive the best fit allometric model. Among the tested models, Ln (biomass) = a + b Ln (D) + c Ln (H) was the best-fit model for A. nilotica, M. azedarach, B. acutangula and P. pinnata and Ln (biomass) = a + b Ln (D2H) was best-fit for C. equisetifolia. Finally, the derived best-fit species-specific TAGB models have shown superiority over the other frequently used pantropical and regional biomass models in relation to model efficiency and model prediction error.

新疆科克苏湿地植被生物量时空分布特征及与水文连通的关系

区域植被生物量及其与水文连通之间的定量关系对于湿地保护和管理具有重要意义。基于多期Landsat-8遥感影像和野外实地调查数据,提取了新疆科克苏湿地生长季不同月份的湿地水体斑块,反演并分析了湿地植被地上生物量及时空分布特征,量化了水文连通与科克苏湿地植被地上生物量和植被碳库的关系。结果表明:6月新疆科克苏湿地水体斑块面积最大,占保护区面积的63.12%,之后湿地水体斑块面积逐渐减少,8月水体斑块面积仅占保护区面积的6.27%,水体斑块分布具有明显的季节性特征。科克苏湿地植被生物量呈现聚集分布的空间分布模式,额尔齐斯河及克兰河河道两侧以及支流两侧湿地为高生物量区域,北部阿热勒齐及阔克苏村和东南部萨尔胡松乡为低生物量区域。7月地上生物量达到生长季最高值,该时段科克苏湿地的植被总生物量为1.09×10^(9)kg,最大总生物量为4832 g/m^(2),地上生物量较高区域分布在西部的阿克铁热克村及东部的巴勒喀木斯村。水文连通与植被地上生物量及植被碳库呈现抛物线关系,水文连通度为0.6左右时,植被地上生物量及植被总碳库最大,植被总碳库达到4.5×10^(11)kg C。研究揭示了科克苏湿地植被生物量的时空分布特征,建立了科克苏湿地水文连通度与植被地上生物量及植被碳库的量化关系,明确了适宜的水文连通度对植被生物量积累存在促进作用,可为湿地水文连通调控和植被碳储存功能提升提供有效参考。

小尺度高寒湿地放牧干扰格局——以纳帕海湿地为例

高寒湿地放牧干扰强烈,是其生态系统退化的主因。湿地植被生物量空间格局不仅能够反映自然因素的作用,也能够体现地域放牧等人类活动的主要特征,因此常作为表征放牧干扰格局的主要度量方法。但尺度效应导致的植被生物量影响要素在不同空间尺度下存在较大差异,尤其是针对面积为几十至几百km^(2)范围的小尺度高寒湿地而言,自然因素和放牧等人为干扰对其植被地上生物量的共同作用特征仍不明确,缺乏针对该类型湿地的合理评估模式。以滇西北国际重要湿地纳帕海为例,在排除其它人为干扰的条件下,通过植被地上生物量的空间异质性特征来表征其放牧干扰格局,并以该案例为基础提出一种小尺度高寒湿地放牧干扰格局评估模式。研究尝试基于详细地面植被调查,获得潜在植被地上生物量,利用调查同时期高分定量遥感方法(法国PLEIADES卫星数据结合实测植被地上生物量建模)获得实际植被地上生物量,并使用潜在与实际植被地上生物量之差的空间异质性特征表示纳帕海湿地放牧干扰格局。该评估模式可以有效减少对于小尺度湿地放牧干扰数据的依赖,同时减少牛羊马等大牲畜散养带来的空间分布随机性。研究结果显示纳帕海湿地放牧干扰对湿地植被地上生物量的影响严重,影响比例约为93.5%。研究发现水文等自然因素和放牧等人为干扰分别决定纳帕海湿地植被地上生物量的上限和下限,并基于此提出四方面干扰调控策略。

Inventory of mangrove wetlands in the Pearl River Estuary of China using remote sensing

Mangrove forests have important ecological functions in protecting the environment. However, the mangrove wetlands have been largely lost because of intensified human activities in the study area. Remote sensing can be conveniently used for the inventory of mangrove forests because field investigation is very difficult. In this study, a knowledge-based system is developed to retrieve spatio-temporal dynamics of mangrove wetlands using multi-temporal remote sensing data. Radar remote sensing data are also used to provide complementary information for the quantitative analysis of mangrove wetlands. Radar remote sensing is able to penetrate mangrove forests and obtain the trunk information about mangrove structures. The integration of radar remote sensing with optical remote sensing can significantly improve the accuracies of classifying mangrove wetland types and estimating wetland biomass.

Land use effects on soil organic carbon, nitrogen and salinity in saline-alkaline wetland

Land-use and soil management affects soil organic carbon （SOC） pools, nitrogen, salinity and the depth distribution. The objective of this study was to estimate land-use effects on the distribution of SOC, labile fractions C, nitrogen （N） and salinity in saline-alkaline wetlands in the middle reaches of the Heihe River Basin. Three land-use types were selected： intact saline-alkaline meadow wetland, artificial shrubbery （planting Tamarix） and farmland （cultivated for 18 years） of soils previously under meadow wetland. SOC, easily oxidized carbon, microbial biomass carbon, total N, NO3--N and salinity concentrations were measured. The results show that SOC and labile fraction carbon contents decreased significantly with increasing soil depth in the three land-use wetlands. The labile fraction carbon contents in the topsoil （0-20cm） in cultivated soils were significantly higher than that in intact meadow wetland and artificial shrubbery soil. The aboveground biomass and soil permeability were the primary influencing factors on the contents of SOC and the labile carbon in the intact meadow wetland and artificial shrubbery soil, however, the farming practice was a factor in cultivated soil. Agricultural measures can effectively reduce the salinity contents; however, it caused a significant increase of NO 3--N concentrations which posed a threat to groundwater quality in the study area.

Extracting Eco-hydrological Information of Inland Wetland from L-band Synthetic Aperture Radar Image in Honghe National Nature Reserve, Northeast China

Taking a typical inland wetland of Honghe National Nature Reserve (HNNR), Northeast China, as the study area, this paper studied the application of L-band Synthetic Aperture Radar (SAR) image in extracting eco-hydrological information of inland wetland. Landsat-5 TM and ALOS PALSAR HH backscatter images were first fused by using the wavelet-IHS method. Based on the fused image data, the classification method of support vector machines was used to map the wetland in the study area. The overall mapping accuracy is 77.5%. Then, the wet and dry aboveground biomass estimation models, including statistical models and a Rice Cloudy model, were established. Optimal parameters for the Rice Cloudy model were calculated in MATLAB by using the least squares method. Based on the validation results, it was found that the Rice Cloudy model produced higher accuracy for both wet and dry aboveground biomass estimation compared to the statistical models. Finally, subcanopy water boundary information was extracted from the HH backscatter image by threshold method. Compared to the actual water borderline result, the extracted result from L-band SAR image is reliable. In this paper, the HH-HV phase difference was proved to be valueless for extracting subcanopy water boundary information.

中国滨海湿地互花米草生物量时空差异的综述

互花米草作为C4植物,具有较强的固碳作用,其生物量大小数据可为评估互花米草的碳汇功能提供重要参数。本文通过收集分析我国互花米草地上和地下生物量研究数据,得到中国滨海湿地互花米草生物量时、空分异特征及相关分析结果:①互花米草的地上生物量7月至10月较高,4、5月最低;地下生物量6月至10月较高,2月至4月最低,即互花米草的地上和地下生物量均在夏秋季较高,春季最低。互花米草生物量的这种季节变化格局可能是由互花米草本身的生命活动规律决定的。②在不同省份、同一省份不同区域和同一区域不同生境,互花米草的生物量均存在差异。互花米草生物量的空间差异可能与潮汐作用、纬度差异、根际土壤微生物作用、种群入侵年限和互花米草种类有关。③江苏的地上生物量低于上海、浙江和福建(上海>浙江>福建>江苏),而地下生物量却最高,此外江苏的地下生物量高于本省的地上生物量。这种生物量分配格局可能是由江苏的生长条件不利造成的,互花米草需要将更多的资源投入到繁殖来适应逆境环境,并且在相同环境条件下,植物可利用的资源是一定的,分配到生殖构件的生物量多,就必然导致分配到营养构件的生物量少。

Bacteriological Quality of a Forage Grass (<i>Pennisetum purpureum Schumach</i>) Used in Constructed Wetland Removing Domestic Wastewater Pathogenic Microorganism

Constructed Wetlands (CWs) are an adequate wastewater treatment system with possibility to generate income, in particular by the use of plants of economic interest. However, very few studies deal with the bacteriological quality of plants after wastewater treatment. Thermotolerant coliforms and Sulfite-reducing bacteria were investigated on the above-ground biomass of a species of forage plant (Pennisetum purpureum) as well as their removal in an experimental pilot consisting of four beds, for three months. Two beds were planted and two unplanted beds were used as control. Germs in the wastewater were significantly reduced in both filtrates, with higher removal efficiency of 97.4% for Thermotolerant coliforms and 87.5% for Sulfite-reducing bacteria, in the planted bed. Wastewater treatment resulted in bacteriological contamination of the above-ground plant biomass with a significant decreases in number of germs from 660 to 28 CFU/g (Thermotolerant coliforms) and from 15 to 0 CFU/g (Sulfite-reducing bacteria), when the harvest height increased from the base to the upper end of the plants. However, averages of 305 CFU/g of Thermotolerant coliforms and 5 CFU/g of Sulfite-reducing bacteria were obtained in the above-ground plant biomass which would not present any potential risks for a possible use of the plant biomass as fodder. Thus, the use of forage plant suggests good prospects for upgrading said plants for animal feed.

三江平原湿地小叶章功能性状对氮添加的响应

小叶章(Deyeuxiaangustifolia)为三江平原典型沼泽化湿地优势植物,通过野外原位控制试验,研究该物种对氮添加水平和氮素形态的适应性及响应规律,为预测大气氮沉降通量增加及氮素形态变化后湿地植被变化提供科学依据。试验设置3种氮素形态(硝态氮、铵态氮、有机态氮)、3种氮添加水平[4、8、12 g·(m^(2)·a)^(-1)],以及1个对照(不添加氮素),共10个处理,分析各处理间小叶章功能性状的差异。结果表明:在硝态氮与铵态氮作用下,小叶章的基径、节间长、叶片数、地上生物量及茎、叶生物量均随施氮量的增加而增大,中、高氮水平下,铵态氮更侧重于促进小叶章的茎生长,硝态氮对小叶章的叶生长影响显著,有机态氮显著影响小叶章分枝数、叶片数量(P<0.05)。节间数、分枝数、叶片数和生物量随无机态氮添加量增加而增大,有机态氮则趋势相反。施氮后,小叶章叶生物量占比升高。研究结果表明:小叶章对有机态氮的耐受范围小,对无机态氮的耐受范围大。施氮能促进三江平原小叶章的生长和生物量积累,增加叶生物量比重,降低茎和穗生物量比重。

退耕还湿后土壤细菌群落结构和生物量变化过程

土壤细菌对湿地生态系统功能和健康维持起着重要作用。以菜子湖原始湿地、不同退耕年限湿地(3a、7a、11a和21a)和仍耕作油菜地土壤为研究对象,应用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)、高通量测序和磷脂脂肪酸(PLFAs)方法分析土壤细菌群落组成和生物量,探讨它们在退耕还湿后的变化过程及其影响因素。结果表明,退耕还湿后土壤变形菌门(α-变形菌纲、β-变形菌纲和δ-变形菌纲)、酸杆菌门(酸杆菌纲和全噬菌纲)、Nitrospinae(Nitrospinia纲)和硝化螺旋菌门(硝化螺旋菌纲)相对丰度先增高后降低;这些参与氮循环的土壤细菌对退耕后湿地生态恢复过程中土壤氮素提升起着重要作用。与农业生产活动密切关联的厚壁菌门(芽孢杆菌纲和梭菌纲)和放线菌门(放线菌纲)相对丰度逐渐降低。湿地土壤细菌多样性在退耕初期(3—7a)上升达到最大,退耕中后期逐渐降低。表层土壤各类群细菌生物量逐渐升高,亚表层土壤各类群细菌生物量则先降后升再降。水分条件和容重是与研究区土壤细菌群落结构和多样性密切相关的土壤因子,而全氮是与土壤细菌生物量密切相关的土壤因子。研究从生态过程视角解析了土壤细菌群落较详细的演变信息及其生态意义,有助于丰富退化湿地生态系统恢复过程的认识。

模拟降雨量变化对高寒湖滨湿地土壤呼吸的影响

[目的]探究降水变化对青海湖高寒湖滨湿地土壤呼吸速率的影响,阐明驱动土壤呼吸变化的主控因素,为高寒湿地生态系统碳库变化及区域碳预算提供技术支撑。[方法]以地处青海湖西岸的鸟岛高寒湖滨湿地为研究对象,建立9个投影面积为3 m×3 m的小区,通过原位减水50%、自然对照、增水50%试验处理,解析降雨量变化对湿地土壤呼吸速率的影响强度及过程。[结果]模拟减雨和增雨处理促使土壤温度分别增加0.79,0.68℃。减雨显著提高湿地植被地下根系生物量,增雨显著提高土壤含水量,增幅分别为10.3%和13.2%(p<0.05)。增雨和减雨处理均降低土壤呼吸速率,且增雨处理抑制效果更明显。2020年不同处理下降水量变化对土壤呼吸速率影响不显著。减雨处理土壤呼吸速率与0—10 cm土壤温度、湿度、pH、土壤全氮以及地下生物量呈二次项正相关关系,与土壤全碳呈二次项负相关关系;增雨处理下土壤呼吸与0—10 cm土壤湿度、pH、地下生物量二次项负相关,与0—10 cm土壤温度、土壤全碳、全氮二次项正相关。[结论]降水格局改变降低青海湖鸟岛湿地土壤呼吸速率,且其速率受多重因素影响,其中土壤温度贡献最大。

大兴安岭北部4种沼泽湿地土壤活性氮质量分数变化特征

选择大兴安岭北部4种沼泽湿地(毛赤杨沼泽、苔草沼泽、落叶松-苔草沼泽、落叶松-苔藓沼泽),研究不同沼泽类型、月份、土层土壤活性氮质量分数的变化规律及影响因子。结果表明:6—10月,大兴安岭北部4种沼泽类型土壤铵态氮质量分数呈波动式下降,波动范围在0.71~15.03 mg·kg^(-1);土壤硝态氮质量分数在观测期内均呈波动式下降,波动范围为0.35~3.30 mg·kg^(-1)。毛赤杨沼泽、苔草沼泽各土层微生物量氮质量分数均表现为6月、10月相对较低;2种落叶松沼泽表层(0<h≤10 cm)土壤微生物量氮质量分数则表现为9月最低,分别为15.86、22.58 mg·kg^(-1)。4种沼泽湿地土壤可溶性有机氮质量分数在6-10月波动性较大,且规律性不强,波动范围为5.15~38.66 mg·kg^(-1)。除苔草沼泽8月表层土壤铵态氮质量分数低于10 cm<h≤20 cm土层外,其他沼泽类型均表现为0<h≤10 cm土层土壤铵态氮质量分数高于10 cm<h≤30 cm土层土壤。相关分析表明,4种沼泽湿地土壤活性氮除与土壤温度相关性较差外,与其他因子多呈显著或极显著正相关。大兴安岭北部4种沼泽土壤活性氮质量分数差异较大,土壤有机碳和微生物量碳是影响沼泽湿地土壤活性氮的主要因子。

东寨港红树林湿地土壤因子与酶活性的关系

[目的]红树林是热带、亚热带典型的海岸带湿地生态系统。分析不同植物群落条件下红树林湿地的土壤活性有机碳组成、土壤酶活性现状以及两者间的相互作用,进而预测东寨港红树林片区的生态结构和功能发展趋势,为东寨港红树林湿地的生态恢复与保护提供科学依据。[方法]通过实地采样,对9种红树植物群落类型[红海榄(Type 1)、白骨壤(Type 2)、角果木(Type 3)、海莲+角果木(Type 4)、桐花树+海莲+秋茄(Type 5)、海莲+榄李+桐花树(Type 6)、秋茄+海莲+榄李(Type 7)、海莲+无瓣海桑+桐花树+秋茄(Type 8)、海莲+无瓣海桑(Type 9)]的土壤酶活性、土壤活性有机碳组分含量和理化性质进行化验分析。[结果](1)该区表层土壤有机碳介于6.57~74.87 g/kg之间,在不同群落类型间以Type 7群落显著最高,Type 1群落低至6.57 g/kg。(2)各群落类型湿地表层土壤酶活性变化规律为:脲酶>磷酸酶>过氧化氢酶>蔗糖酶,其中脲酶以Type 8群落最高,显著高于Type 1—6群落;磷酸酶以Type 8群落最高,显著高于Type 1—3群落;过氧化氢酶以Type 5最高,显著高于其余群落(Type 6和Type 7除外);蔗糖酶以Type 9群落最高,显著高于Type 2,Type 5和Type 8群落。(3)土壤脲酶、磷酸酶和过氧化氢酶与土壤活性有机碳各组分含量呈显著及极显著正相关;土壤脲酶、磷酸酶与土壤pH值呈极显著负相关,与全氮、全磷呈极显著正相关;土壤过氧化氢酶与全氮、全磷呈极显著正相关;土壤蔗糖酶与全氮、全磷呈显著正相关。(4)冗余分析结果显示:土壤轻组有机碳、土壤总有机碳、土壤颗粒有机碳和土壤微生物生物量碳是影响东寨港红树林植物群落土壤酶活性的主要因子。[结论]土壤酶活性与多种土壤活性有机碳组分呈紧密正相关,因此可用土壤酶活来表征东寨港红树林湿地土壤碳库活跃程度。

南门峡湿地公园不同区域草本植物多样性研究

以南门峡湿地公园生态保育区和合理利用区中草本植物为研究对象,采取典型样方法和随机取样方法对南门峡湿地公园5块样地20个样方展开调查,对其物种组成及多样性进行分析研究。结果表明:样地中草本植物共有24科64属90种,单物种科属数最多;各区域植物的Margalef指数岔巴峡最高,卷槽最低,Pielou指数都比较低,卷槽样点最低,Shannon-Wiener指数在卷槽样点最低,岔巴峡最高;公园内生物量随时间推移呈现先增后减的趋势,八月份该研究区域草本植物体内有机质储存最高。各样点中生物量岔巴峡最高,水库最低;Shannon-Wiener指数与Margalef指数、Pielou指数间存在着显著的正相关关系,Shannon-Wiener指数与生物量和海拔间存在正相关关系;影响南门峡湿地公园草本植物多样性的主要原因是区域生境的不同.

大气CO_(2)浓度升高和海平面上升对滨海湿地植物地下生物量的影响

大气CO_(2)浓度升高和海平面上升会通过影响植物的分布和生长状况,继而影响湿地的稳定性。地下生物量是调节潮汐湿地生态系统功能的关键因素,包括土壤有机质的积累和湿地海拔高程的维持。本文通过设置开顶式生长箱(OTC:open top chamber)试验探究不同海拔的3个典型植物群落(SC群落:C_(3)植物为主的群落;MX群落:C_(3)、C_(4)植物混合群落;SP群落:C_(4)植物为主的群落)对CO_(2)浓度升高和海平面上升的响应差异。研究结果显示:CO_(2)浓度升高能够显著增加SC、MX和SP群落的根茎、根和总地下生物量,但年际差异较大。海平面上升显著降低了3个群落植物的根生物量和SC群落高CO_(2)浓度处理下及SP群落对照处理下的总地下生物量,但对根茎却无显著影响。在高盐的条件下,高CO_(2)浓度一定程度上能够缓解高盐分对植物的胁迫,但高CO_(2)浓度的施肥作用下降。对照条件下的SC和MX群落总地下生物量随试验年份延长呈下降趋势,其下降主要是由于海平面的快速上升导致的,而高CO_(2)浓度能减缓其下降趋势,一定程度上抵消胁迫。因此,海平面上升正严重威胁未来湿地的稳定性,而CO_(2)浓度升高能一定程度上缓解海平面上升的危害。

天津滨海湿地不同生境芦苇种群生长动态变化对比研究

目的:探究不同生境条件下芦苇种群生长动态变化规律。方法:对天津滨海湿地三个不同生境条件(S1、S2、S3)的芦苇分株密度、分株生物量、土壤的理化指标进行监测,并对芦苇分株密度、分株生物量与土壤理化性质之间相关性进行分析。结果:(1)各月份土壤含水率、土壤pH和土壤可溶性盐含量的变化规律一致:S1<S2<S3;各月份土壤有机质含量、土壤速效氮含量、土壤速效磷含量、土壤速效钾含量的变化规律一致:S1>S2>S3。(2)各月份芦苇分株密度和分株生物量变化规律一致:S1>S2>S3;并且三个不同生境下芦苇分株密度和分株生物量的变化规律表现为在生长初期的5月份最低,随着月份的增加而增加,9月份达到最大值,10月各指标开始呈现下降趋势。(3)不同月份影响芦苇分株密度和分株生物量的土壤因素不一致。结论:滨海地区土壤含盐量和pH以及养分是影响芦苇种群生长的关键因素。

青海都兰湖湿地典型植物碳汇价值评价

植物生物量与碳蓄积测算对湿地研究具有重要意义。为了探明青海省都兰湖湿地的碳汇功能,本试验于2022年1—10月在都兰湖湿地进行了实地调查和资料收集。选择湿地中分布较广的7种典型植物(红砂、柽柳、白刺、盐爪爪、梭梭、西北枸杞和柠条),分别设置标准样地,调查其地上部、地下部及凋落物的生物量,得出其生物量分别为0.326、16.955、0.394、10.912、16.370、1.384、2.995 t/hm^(2);对其碳储量和碳汇价值进行估算,得出都兰湖湿地7种典型植物的总碳储量为140.7086 Tg,相应的总经济价值为44.46亿~223.30亿元。