江苏海岸带泊海盐土植被和沙土植被生物量和能量研究

在滩涂生态演替序列中,自海向陆随着土壤和植被的演替,初级生产者的生物量及其固定的能量同步增长,滩涂主要陆生盐生植被和盐沼生植被的初级生产均始于3月,初级生产力和光能利用率峰值,大穗结缕草群落出于出现在5月,盐蒿群落出现在7月,白茅群落,芦苇群落和糙叶苔群落出现在6月,生物量峰值出现在9月或10月。     

莱州湾滨海柽柳林湿地植被碳储量的分布特征及其影响因素

莱州湾南岸的柽柳林湿地是我国北方现存面积最大的柽柳林滨海湿地,也是我国“南红北柳”生态工程的重要组成部分.本文基于2014年8月在昌邑海洋生态特别保护区的调查资料,研究了该湿地植被生物量、碳储量的空间分布特征及其影响因素.结果表明: 该湿地植被生物量为949.0 g·m^-2,植被碳储量为393.1 g·m^-2,基本呈中部高、东西部低的分布特征;植被各部分生物量、碳储量均表现为:地上部>地下部>凋落物.该区域主要有柽柳、碱蓬2个单优群落和4个混生群落,植被碳储量以柽柳群落最高,混生群落居中,碱蓬群落最低.受北部潮间带防潮坝的影响,表层土壤的含水量和电导率均不高,土壤盐分不是植被碳储量的主控因子,植被碳储量主要受土壤的营养盐状况(全氮和全磷)和粒径结构(粉粒含量)的影响.土壤水文条件的改变造成了植被群落的演替,在由耐盐群落(盐地碱蓬群落)向轻耐盐群落(茵陈蒿群落、狗尾草群落等)的演替过程中,植被碳储量增大.     

镜泊湖岩溶台地不同植被类型土壤微生物群落特征

为了探讨不同演替阶段植被类型土壤微生物群落特征,分别选取镜泊湖岩溶台地草本、矮灌木、高灌木、小乔木与灌木混生(简称混生)群落、落叶阔叶林及针阔混交林6种典型植被类型,进行植物群落调查和对土壤微生物生物量、群落结构和多样性指标、土壤物理化学性质的测定。结果表明：从土壤微生物量、土壤微生物群落组成、土壤微生物代谢动力学过程和代谢功能多样性的角度来看,各种植被类型土壤微生物群落具有明显的差异。演替前期的草本群落土壤微生物量碳氮、细菌生物量、真菌生物量,代谢活性及丰富度指数均最低,但Shannon-Wiener多样性指数和均匀度指数显著(P<0.05)高于其他植被类型。矮灌木土壤微生物群落组成显著受植被类型的影响。高灌木群落和混生(小乔木与灌木混生)群落具有极强的相似性, 但在碳源利用类型上两者表现出一定的差异。落叶阔叶林代谢活性最高,碳源利用能力最强,能利用BIOLOG微孔板中的所有31种碳源,这与其具有较高的微生物量碳氮和细菌生物量一致,其代谢功能丰富度最高。演替后期的针阔混交林下的土壤pH最低,真菌比例升高,在碳源丰富的条件下具有极强的竞争优势(仅次于落叶阔叶林),但在碳源贫瘠的条件下其利用碳源能力较弱(仅高于草本)。植被可能主要通过土壤全磷和有机质影响土壤微生物代谢功能多样性。     

崇明东滩围垦堤内植被快速次生演替特征

崇明东滩湿地98大堤内的生态示范区由于人工排水而干涸,芦苇塘成为次生裸地,土壤条件发生变化,呈明显的旱化和盐渍化,植被群落结构呈典型的次生演替,适宜旱地的耐盐植物獐茅和碱蓬等先锋植物出现.文中分别于2003年秋季、冬季和2004年春季沿植被带对塘内各种植物的生物量、高度、密度等指标进行取样分析.结果表明,堤内植被群落已形成明显的带状獐茅草-獐茅草/碱蓬-碱蓬/芦苇-芦苇旱生植被群落.碱蓬在裸地中2003年秋季平均生物量达到415.4 g·m^-2、2004年春季为391.53 g·m^-2,成为裸地的优势种,并向芦苇中扩散,生物量和高度逐渐增加,密度逐渐稳定,表现出良好的生长趋势.     

鄱阳湖滨沙生植被的初步研究

通过样方法和植被踏查初步分析了鄱阳湖滨沙生植被,发现该地典型沙生植被是以单叶蔓荆和狗芽根为建群种,同时从流动沙丘到固定沙丘流生植被的地上部分生物量、生物量枝叶比、种类组成及沙生植的植株高度随生境条件的不同而改变,含水量指标例外;探讨了本区沙生植被与沙生环境的密切生态关系;并从种类组成、叶形特征、叶含水量、地上部分生物量和群落演替顶极方面比较了该地与我国干旱半干旱工     

杭州湾滩涂湿地植被群落演替与物种多样性动态

以杭州湾不同年份形成的滩涂湿地植被群落为研究对象,采用样线法结合样方法进行调查取样,并通过除趋势对应分析排序研究了群落演替的动态和方向,同时采用Pielou均匀度指数、Margalef丰富度指数、Shannon-Wiener多样性指数和Simpson多样性指数分析了物种多样性在群落演替过程中的动态变化.结果表明:该区域植被群落演替序列为海三棱藨草群落→芦苇群落→柽柳 芦苇群落→旱柳 白茅群落;随着演替的进行,群落物种丰富度显著增加,均匀度逐渐降低,物种多样性呈先增加后降低的趋势.     

陕北黄土丘陵区撂荒草地群落生物量及植被土壤养分效应

为了明确植被演替过程中植被与土壤的互动效应,为植被恢复提供依据。根据陕北黄土丘陵区36块不同年限（时间尺度为2—45a）的撂荒样地地上生物量、土壤养分和水分的测定结果,及4块典型撂荒群落样地地上／地下生物量,7种撂荒群落主要植物生长特性的测定,分析了撂荒演替过程中群落生物量与土壤养分的变化过程、趋势及其相互关系,进而探讨了撂荒演替过程中群落生物量对土壤养分的作用效应,并利用多元回归和通径分析法分析了土壤养分对群落生物量的作用。结果表明：（1）除速效磷外,撂荒演替过程中群落地上生物量和土壤有机质、全氮、全磷、全钾、NO3-N、NH4-N和速效钾都呈先减少后增加的趋势,步调基本一致。（2）从撂荒年限与土壤养分的相关性来看,0—20cm土壤有机质含量、速效磷含量和0—20、20—40cm土壤层NO3-N含量与撂荒年限相关显著,说明演替过程中有机质、速效磷和NO3-N有较为明显的植被土壤效应,而其它土壤养分与撂荒年限相关不显著,不能排除演替初始条件和植物暂时固定的影响;从群落生物量与土壤养分的相关性来看,群落生物量对土壤有机质、全氮、磷、钾、NO3-N、速效钾和速效磷含量具有正效应,而对NH4-N具有负效应,但都不显著。（3）通径分析说明撂荒年限、土壤全氮、全钾、速效钾和土壤水分变异量对生物量表现为正的直接作用,其中以撂荒年限和土壤水分波动量作用较大,土壤养分对群落地上生物量的作用以土壤全氮最大,全钾和速效钾影响较小;演替过程中群落地上生物量的变化主要是由于植被盖度和群落组成种的生态学特性造成的（撂荒年限较大的直接作用）,其次是由于撂荒演替过程中土壤水分的波动造成的（撂荒年限通过土壤水分的间接负作用）。（4）随着土层深度的加深植物根系生物量呈幂函数递减过程,演替后期群落根冠比有增加的趋势,演替后期序列种根冠比和根长也有增加的趋势,这些在一定程度上会影响到生物量积累和有机质分解等,进而会影响到植被土壤效应。     

天童国家森林公园废弃采石场植被自然恢复早期阶段的种群动态及生物量的研究

对天童国家森林公园废弃采石场植被自然恢复早期阶段的种群动态及生物量研究表明,采石废弃地植被自然恢复早期阶段的群落种类组成非常简单,只有木荷、马尾松两个种;两种群的密度动态趋势为先升后降,最大密度分别出现在３ 龄、４ 龄;马尾松地上部分生长速度明显高于木荷;群落中马尾松总生物量是木荷的１２ 倍多,木荷分配到叶和根中的生物量比例高于马尾松,而马尾松分配到茎中的比例高于木荷．这说明在采石迹地早期演替阶段马尾松以快速生长方式在竞争中处于优势地位．对采石迹地和砍伐迹地演替早期阶段的群落特性进行了比较,并对植被有效恢复进行了讨论     

江苏海岸沙生植被的研究

 海岸沙生植被系由沙生植物和一些耐沙植物所组成的隐域植被,具旱生性质;种类组成简单,只24种,隶属18科,21属。此外,在砂质海岸听见的一个向森林演替的群落地段,含有19种木本,21种草本植物,概为新发观的耐沙植物,根据组成植物的生活型分析,作了沙生植被的生活型谱。 海岸沙生植被可分为草本与木本两个基本类型、共6个群落。它们的演替规律作了论述。最后讨论了沙生植被的开发、利用及保护问题。     

黄土高原半干旱区退化草地恢复与利用过程研究

草地退化表现为土壤和植被遭到彻底破坏,草地演替过程受到强烈抑制.实验采用长期(30年)封禁措施,定位监测退化草地从次生半裸地演变为近似原生植被(进展演替)的变化过程.结果表明,随着封禁时间的变化,退化草地恢复演替经历了4个阶段,群落盖度、植株密度、物种丰富度和多样性指数、地上生物量和地下生物量在草地群落恢复过程中逐渐增加,其特征变化出现的峰值均在封禁第20年(地下生物量峰值在第15年),其中地上生物量最高达520.5 g/m2;直到封禁的第20~25年,以本氏针茅为建群种的草原群落衰败退化现象明显,而大针茅种群密度剧增;在封禁的第26年以上以大针茅为优势的群落生长较为稳定,从目前群落演替进程看,大针茅有替代本氏针茅的趋势.另外,在草原沟道两侧以斑块状聚集分布有中旱生灌木,群落的演替进入了一个新的阶段.随着封禁时间的延续,退化草地从自然封禁恢复的0~26年,通过侵入-竞争-扩散-定居的几个演替阶段,目前形成以大针茅为建群种相对稳定的"亚顶级".虽然草地生物量有一定下降,但草地质量提高,物种多样性丰富,促进草地的进展演替.草地植物群落主要由禾本科、豆科和菊科组成;多年生植物、C3和旱生物种可以作为草地演替过程和植被恢复的指示物种.长期封育对草地物种更新和生态系统稳定性有负面影响,因此,合理的封育时间是草地生态恢复中非常重要的一个因素.本研究提出,在黄土区退化草地封育10~15年后可以开始进行合理的利用,例如通过两年一次刈割和轻度放牧(2只羊/hm2).本研究可为干旱区、半干旱区相似的退化草地恢复提供理论依据.     

Net primary productivity and spatial distribution of vegetation in an alpine wetland,Qinghai-Tibetan Plateau

To initially describe vegetation structure and spatial variation in plant biomass in a typical alpine wetland of the Qinghai-Tibetan Plateau, net primary productivity and vegetation in relationship to environmental factors were investigated. In 2002, the wetland remained flooded to an average water depth of 25 cm during the growing season, from July to mid-September. We mapped the floodline and vegetation distribution using GPS (global positioning system). Coverage of vegetation in the wetland was 100%, and the vegetation was zonally distributed along a water depth gradient, with three emergent plant zones (Hippuris vulgaris-dominated zone, Scirpus distigmaticus-dominated zone, and Carex allivescers-dominated zone) and one submerged plant zone (Potamogeton pectinatus-dominated zone). Both aboveground and belowground biomass varied temporally within and among the vegetation zones. Further, net primary productivity (NPP) as estimated by peak biomass also differed among the vegetation zones; aboveground NPP was highest in the Carex-dominated zone with shallowest water and lowest in the Potamogeton zone with deepest water. The area occupied by each zone was 73.5% for P. pectinatus, 2.6% for H. vulgaris, 20.5% for S. distigmaticus, and 3.4% for C. allivescers. Morphological features in relationship to gas-transport efficiency of the aerial part differed among the emergent plants. Of the three emergent plants, H. vulgaris, which dominated in the deeper water, showed greater morphological adaptability to deep water than the other two emergent plants.     

Nitrogen and phosphorus in mire plants: variation during 50 years in relation to supply rate and vegetation type

Southern Sweden has long been exposed to an increasing atmospheric nitrogen deposition. We investigated the effects of this supply on the Sphagnum mire vegetation in SW Götaland by comparing above‐ground tissue concentrations of N and P and biomass variables in five vascular plant and two Sphagnum species collected during three periods since 1955 at 81 sites representing three vegetation types, viz. ombrotrophic bog, extremely poor fen and moderately poor fen, within two areas differing in annual N deposition. The N:P ratios in the plants were rarely below 17, suggesting P as the growth‐limiting mineral nutrient. In the vascular plants both growth and concentrations of N and P were highest in the moderately poor fen sites because of a higher mineralization rate, the differences between the extremely poor fen and bog sites being smaller in these respects. In the extremely poor fen and bog sites the N concentrations were slightly higher in the area with the highest N deposition. From 1955 to 2002 the concentration of N in the Sphagnum spp. increased proportionally to the supply rate while P remained constant. In the vascular plants the concentrations of P remained constant while N showed slightly decreasing trends in the bog and extremely poor fen sites, but since the size of the plants increased the biomass content of N and P increased, too. The increased N deposition has had its greatest effects on the site types with the highest Sphagnum biomass and peat accumulation rate. The high N concentration in the Sphagnum mosses probably reduced their competitiveness and facilitated the observed expansion of vascular plants. However, the increased N deposition might also have triggered an increased mineralization in the acrotelm increasing the supply of P to the vascular plants and thus also their productivity. This may also explain the slightly higher productivity among the vascular plants in the area with the highest N deposition rate. In conclusion, it seems as the increased N deposition has directly influenced only the growth of the Sphagnum mosses and that the effects on the growth of the vascular plants are indirect.     

The response of Arctic vegetation and soils following an unusually severe tundra fire

Fire causes dramatic short-term changes in vegetation and ecosystem function, and may promote rapid vegetation change by creating recruitment opportunities. Climate warming likely will increase the frequency of wildfire in the Arctic, where it is not common now. In 2007, the unusually severe Anaktuvuk River fire burned 1039 km² of tundra on Alaska''s North Slope. Four years later, we harvested plant biomass and soils across a gradient of burn severity, to assess recovery. In burned areas, above-ground net primary productivity of vascular plants equalled that in unburned areas, though total live biomass was less. Graminoid biomass had recovered to unburned levels, but shrubs had not. Virtually all vascular plant biomass had resprouted from surviving underground parts; no non-native species were seen. However, bryophytes were mostly disturbance-adapted species, and non-vascular biomass had recovered less than vascular plant biomass. Soil nitrogen availability did not differ between burned and unburned sites. Graminoids showed allocation changes consistent with nitrogen stress. These patterns are similar to those seen following other, smaller tundra fires. Soil nitrogen limitation and the persistence of resprouters will likely lead to recovery of mixed shrub–sedge tussock tundra, unless permafrost thaws, as climate warms, more extensively than has yet occurred.     

西双版纳热带人工雨林生物量及净第一性生产力的研究

通过标准木法和收获法研究分析了西双版纳热带人工模拟雨林的生物量及净第一性生产力。结果表明,林分总生物量约为390.4t·hm^-2,其中乔木层生物量达362.5t·hm^-2,占总生物量的92.8%,灌木层生物量为19.3t·hm^-2,占4.9%,层间植物9包括附生植物）的生物量为3.6t·hm^-2,草本层生物量为5.0t·hm^-2,分别占1.3%和0.9%。林分净第一性生产力为2227.3g.m^-2.年^-1,其中乔木层的净生产力为1553.5g·m^-2.年^-1,占整个林分净生产力的69.7%,灌木层、草本层及层间植物分别仅占26.9%、2.4%和1.0%,其器官分配比例以茎最高,0达42.0%;其次为叶,占30.2%;枝占13.5%。叶面积指数为7.061。同时建立了林分优势种及乔木层各器官生物量的优化回归模型。     

The distribution of deer biomass in North America supports the hypothesis of exploitation ecosystems

The hypothesis of exploitation ecosystems (EEH) predicts that, along a productivity gradient in terrestrial environments, predators will regulate herbivores at a relatively constant density whenever primary productivity exceeds 700 g m⁻² y⁻¹; under this threshold, or if predators are absent, forage production determines herbivore density. I tested EEH using the pattern of deer biomass distribution over North America, the dominant family of large herbivores. Deer biomass increased from the High Arctic to the north of the boreal forest and remained in the same range southward within the gray wolf range; for the same latitude, deer biomass increased by a factor of 5 in the absence of wolves. South of the wolf range, there existed a clear relationship between actual evapotranspiration, a proxy of primary productivity, and deer biomass. Highest deer densities occurred in the south-east of the continent where only white-tailed deer are present. The observed pattern lends support to EEH and suggests that the removal of large predators in southern North America may have imposed an unprecedented pressure on plants eaten by deer.     

基于CASA模型的长江口崇明东滩湿地植被净初级生产力与固碳潜力

湿地生态系统具有很强的储碳、固碳能力,在全球碳循环中占有重要地位.为了解盐沼的固碳能力,以崇明东滩南部典型盐沼潮沟体系为对象,结合实验观测与遥感影像解译,估算了盐沼湿地的净初级生产力,并探讨了环境变化下盐沼湿地固碳潜力的变化.结果 表明:盐沼植物净初级生产力表现出显著的时空差异,时间差异体现在年际和季节差异,即2013...     

Plant size metrics and organic carbon content of Florida salt marsh vegetation

Carbon stored in soil and vegetative biomass in mangrove swamps, salt marshes, and seagrass flats (“coastal blue carbon”) is a significant component of the coastal carbon budget due to the ability of these ecosystems to sequester atmospheric carbon dioxide as plant biomass and peat. Growing interest in the protection of these essential yet vulnerable coastal ecosystems, as well as recognition of their capacity to sequester atmospheric carbon dioxide, has led to the need for rapid and accurate quantification of location-specific coastal blue carbon stocks. This study provides allometric equations for the calculation of aboveground dry biomass based on plant height for 18 salt marsh species from Tampa Bay, Florida, USA. The 18 plant species were also analyzed for carbon and nitrogen content to determine the appropriate carbon conversion factor to use for blue carbon calculations. The salt marsh plants had an average of 1.2 ± 0.4% nitrogen and 41.1 ± 5.5% carbon. With the exception of Batis maritima, which had a carbon content of only 23.4%, carbon content for all other species ranged from 33.4–47.1%. The four most succulent plant species in this study contained an average of 33.3 ± 7.0% carbon, while the nine graminoid species contained 44.4 ± 2.0% carbon. These species-specific equations and carbon data provide non-destructive methods to rapidly quantify vegetative biomass and carbon stocks for monitoring efforts and blue carbon stock assessments.     

青藏高原多年冻土区不同草地生态系统恢复能力评价

草地生态系统恢复能力是评价人类工程活动对青藏高原多年冻土生态系统影响的重要组分.分析了不同草地生态系统干扰带和非干扰带群落特征、植物多样性、草地初级生产力和经济类群,综合评价了青藏高原多年冻土区地上植被在受工程活动干扰后的综合恢复能力.结果表明:经过近20多年的自然恢复,青藏苔草草原、紫花针茅草原、扇穗茅草原、高山嵩草草甸、矮蒿草草甸和藏蒿草沼泽化草甸6种草地的盖度和物种组成均有一定程度的恢复,且草原群落的恢复程度好于草甸群落,但干扰群落仍低于未干扰群落;紫花针茅草原分布区物种多样性恢复好于其他草地类型分布区;干扰带由最初的地上植物生物量全部为0恢复到148.8～489.6 g·m^-2,其中藏嵩草沼泽化草甸干扰带恢复最好,生物量达489.6 g·m^-2;除藏嵩草恢复群落的饲用植物类群组成相对稳定外,干扰后的其他5种草地类型饲用价值降低.高寒草原生态系统的植被综合恢复能力显著高于草甸生态系统.     

Study of docosahexaenoic acid production by the heterotrophic microalga <Emphasis Type="Italic">Crypthecodinium cohnii</Emphasis> CCMP 316 using carob pulp as a promising carbon source

In this work, carob pulp syrup was used as carbon source in C. cohnii fermentations for docosahexaenoic acid production. In preliminary experiments different carob pulp dilutions supplemented with sea salt were tested. The highest biomass productivity (4 mg/lh) and specific growth rate (0.04/h) were observed at the highest carob pulp dilution (1:10.5 (v/v), corresponding to 8.8 g/l glucose). Ammonium chloride and yeast extract were tested as nitrogen sources using different carob pulp syrup dilutions, supplemented with sea salt as growth medium. The best results were observed for yeast extract as nitrogen source. A C. cohnii fed-batch fermentation was carried out using diluted carob pulp syrup (1:10.5 v/v) supplemented with yeast extract and sea salt. The biomass productivity was 420 mg/lh, and the specific growth rate 0.05/h. Under these conditions the DHA concentration and DHA production volumetric rate attained 1.9 g/l and 18.5 mg/lh respectively after 100.4 h. The easy, clean and safe handling of carob pulp syrup makes this feedstock a promising carbon source for large-scale DHA production from C. cohnii. In this way, this carob industry by-product could be usefully disposed of through microbial production of a high value fermentation product.     

Abiotic stress mediates top-down and bottom-up control in a Southwestern Atlantic salt marsh

Increasing evidence has shown that nutrients and consumers interact to control primary productivity in natural systems, but how abiotic stress affects this interaction is unclear. Moreover, while herbivores can strongly impact zonation patterns in a variety of systems, there are few examples of this in salt marshes. We evaluated the effect of nutrients and herbivores on the productivity and distribution of the cordgrass Spartina densiflora along an intertidal stress gradient, in a Southwestern Atlantic salt marsh. We characterized abiotic stresses (salinity, ammonium concentration, and anoxia) and manipulated nutrients and the presence of the herbivorous crab Neohelice (Chasmagnathus) granulata, at different tidal heights with a factorial experiment. Abiotic stress increased at both ends of the tidal gradient. Salinity and anoxia were highest at the upper and lower edge of the intertidal, respectively. Nutrients and herbivory interacted to control cordgrass biomass, but their relative importance varied with environmental context. Herbivory increased at lower tidal heights to the point that cordgrass transplants onto bare mud substrate were entirely consumed unless crabs were excluded, while nutrients were most important where abiotic stress was reduced. Our results show how the impact of herbivores and nutrients on plant productivity can be dependent on environmental conditions and that the lower intertidal limits of marsh plants can be controlled by herbivory.