生态化学计量学特征及其应用研究进展

生态化学计量学已成为生态学研究的热点问题。作为一门新兴学科,综观国内外最新研究进展,相关研究目前尚存在着许多不足。基于此,从全球与区域尺度、功能群尺度及个体水平3个方面阐述生态化学计量学特征,从空间、时间、生境和植物类型等生物与非生物因素综述生态化学计量学特征的驱动因素。并讨论生态化学计量学特征在限制性养分判断、生态系统稳定性、生长率与C:N:P关系中的应用。     

黄土丘陵区刺槐叶片-土壤-微生物碳氮磷化学计量学及其稳态性特征

明确植物和微生物在植被恢复过程中的内稳态特性,对反映生物随恢复环境变化的适应性和阐明生态系统养分循环规律有重要意义。以黄土丘陵区恢复5年、10年、20年、30年和45年的刺槐(Robinia pseudoacacia)人工林为研究对象,测定刺槐叶片、土壤和微生物生物量C、N、P含量及其化学计量学指标,重点揭示了叶片和微生物生物量养分在恢复过程中随土壤养分变化的稳态性特征。结果表明:(1)随着恢复年限的增加,土壤、叶片和微生物生物量C、N、P含量表现为增加趋势;(2)不同恢复年限叶片、土壤、微生物生物量C∶N分别为17.03—26.03、9.55—16.94、5.57—10.76、C∶P分别为465.04—634.48、19.89—65.81和39.64—110.53、N∶P分别为17.89—37.03、1.24—4.68和7.15—10.26,除叶片C∶N随恢复年限增加而降低外,其他指标均表现为随恢复年限增加而增加或先增加后降低;刺槐林生长后期可能面临P限制;(3)叶片和微生物生物量C、N、P及其计量比大部分指标与土壤指标的关系能够被内稳态模型很好地模拟(P0.01);其中叶片N∶P、微生物C、N对土壤养分变化较为敏感;其他指标比较稳定。研究表明植物和微生物在面对土壤养分变化时均会通过自我调节呈现内稳态性,说明刺槐在黄土丘陵区有较好的适应性;微生物对土壤养分的变化比植物更加敏感,其养分和计量比指标能较好地指示土壤恢复状况。     

不同林龄樟子松人工林土壤-针叶-微生物生态化学计量及稳态性特征

为明确樟子松人工林生态系统的养分特征和稳定机制,在辽西北章古台地区选取幼龄林、中龄林、成熟林和过熟林阶段的樟子松人工林为研究对象,探讨其土壤-针叶-微生物C、N、P含量及生态化学计量比特征,分析各组分的耦合关系和内稳态特性。结果表明：辽西北樟子松人工林土壤C、N、P养分贫瘠;与全球尺度相比,针叶具有较高C、P和较低N的特征;不同林龄相比,土壤C含量峰值12.93 g·kg^-1出现在过熟林,土壤N、P含量峰值0.41、0.25 g·kg^-1,针叶C、N、P含量峰值641.38、10.18、1.81 g·kg^-1,微生物C含量峰值165.68 mg·kg^-1,均出现在成熟林,微生物N、P峰值9.29、2.92 mg·kg^-1出现在中龄林;各林龄樟子松人工林土壤C∶N均高于全国平均水平,表现为N限制;仅过熟林土壤C∶P高于全国平均水平,表现为P限制;樟子松土壤、针叶、微生物C∶N、C∶P均在过熟林达到峰值,此阶段N、P限制最为强烈。樟子松人工林土壤、植物、微生物3个组分间的生态化学计...     

三沙湾浮游动物生态类群演替特征

根据2010年6月-2011年5月三沙湾海域5个航次海洋综合调查资料,对三沙湾浮游动物种群特征进行分析,并与我国不同纬度海湾生态类群结构进行比较.探讨三沙湾海域浮游动物生态类群季节变化特征及其受水团季节变化的影响.研究结果表明:4月和5月三沙湾海域主要受到浙闽沿岸流影响,生物多样性H'指数分别为2.03和2.02;种类数分别仅为17种和19种,明显低于6月、8月和10月;浮游动物生态类群以暖温带近海种为主;优势种种类数少,单一优势种优势性明显,4月中华哲水蚤丰度占浮游动物总丰度的65.03％;群落结构特征与同期我国长江口浮游动物区系特征相似.6月三沙湾海域受到浙闽沿岸流和台湾暖流共同影响,同时因闽北雨季导致大量大陆径流汇入,使得该月浮游动物种群结构复杂,生物多样性指数和种类数全年最高,为3.12和45种,与5月相比,种类更替明显,物种更替率为69.39％;亚热带近海种丰度百分比最高(73.03％),亚热带外海种种类数百分比次之(48.89％),是海域浮游动物生态类群由以暖温带近海种为主向以亚热带外海种为主的过渡时期.8月和10月浙闽沿岸流消失,三沙湾海域受台湾暖流控制,海水温度和盐度升高,生物多样性指数和种类数均略低于6月;生态类群结构以亚热带外海种为主;优势种特征表现为种类数多而各个优势种丰度较低;浮游动物群落结构特征与南海北部海域浮游动物组成极为相似.     

生态系统碳氮磷元素的生态化学计量学特征

生态系统元素平衡是当前全球变化生态学和生物地球化学循环的研究热点和焦点.在系统介绍生态化学计量学与碳氮磷元素循环研究进展的基础上,重点从土壤C:N:P化学计量比的分布特征、指示作用、对碳固定的影响,以及人类活动对C:N:P比的影响等方面探讨了C:N:P比在养分限制、生物地球化学循环、森林演替与退化等领域中的应用等问题,并展望了生态系统碳氮磷平衡的元素化学计量学未来研究的发展方向.通过对生态化学计量学理论和方法的研究,可以深入认识植物-凋落物-土壤相互作用的养分调控因素,对于揭示碳氮磷元素之间的相互作用及平衡制约关系,为减缓温室效应提供新思路和理论依据,具有重要的现实意义.     

不同林龄木荷叶片-细根-土壤碳氮磷化学计量及稳态性特征

为了解不同林龄木荷人工林生态系统的养分特征及稳定机制,本研究以福建省尤溪县8、13、27、36和54年生5个年龄木荷人工纯林为对象,探讨其叶片-细根-土壤碳(C)、氮(N)、磷(P)及化学计量变化特征,分析木荷叶片和细根两构件与土壤的耦合关系和稳态性特征。结果表明: 随着林龄增加,木荷叶片和细根C、N、P含量总体呈先降后升的变化趋势,叶片和细根的N、P含量最小值均出现在13年生,N含量分别为10.38和3.45 g·kg^-1,P含量为0.44和0.21 g·kg^-1。两构件C:N、C:P随林龄增加呈先增后减变化,均在13年生达到最大值。随着林龄的增加,林地土壤 C、N和P含量均呈下降-上升-下降的变化特征,且均以13年生为最低,分别为34.27、1.82和0.11 g·kg^-1;土壤C:N、C:P和N:P最大值均出现在13年生,分别为19.2、315.8和17.0。木荷叶片和细根的N、P含量及其计量比与土壤P含量有显著的相关关系,与土壤C、N含量的相关性不显著。叶片与细根C、N及N:P的稳态性模型回归结果均不显著,具有绝对稳态,且叶片N、P及其计量比的稳态性均小于细根,但叶片和细根P及C:P对土壤P含量变化较为敏感。综上,13年为木荷的速生期;在木荷生长过程中,土壤P含量显著影响木荷叶片与细根N、P含量,叶片对土壤中P含量变化更敏感,建议适时添加P肥以改善土壤质量,并重点关注叶片N、P含量的变化状况。     

生态化学计量学研究进展

生态化学计量学结合生物学、化学和物理学等基本原理,研究能量和碳、氮、磷等化学元素在生态系统中,特别是各种生态系统过程(如竞争、捕食、寄生、共生等)参与者中的变化,以及它们之间的动态平衡,并分析这种平衡对生态系统的影响。目前,C∶N∶P化学计量学研究已深入到生态学的各个层次(细胞、个体、种群、群落、生态系统)及区域等不同尺度。近年来,由于认识到化学计量学研究可以把生态实体的各个层次在元素水平上统一起来,因此生态化学计量学已成为许多生态系统的新兴研究工具。其中,C∶N∶P化学计量学是各种生态过程研究中的核心内容。论述了生态化学计量学在物种、群落、生态系统等各层次的应用现状,并指出了C∶N∶P化学计量学研究的应用前景和发展趋势,以期引起同行的重视并推动该领域的进一步发展。     

黄海南部大型水母暴发区中小型浮游动物生态特征

根据2007年5-9月黄海南部(121°15'E-122°09'E、31°53'N-32°53'N)大型水母暴发区调查数据,对该区6个站点中小型浮游动物的种类组成、数量分布、群落特征及优势种等进行了分析.共鉴定出调查区浮游动物58种(不含鱼卵和仔鱼),隶属于5门11大类58种,其中桡足类为优势种,占80.86%;浮游动物总丰度均值为783.17 ind·m-3(452.23～1241.86 ind·m-3),最高密集区位于St.4;多样性指数(H')均值为2.76(2.44～2.95),调查区南部(St.4～St.6)比北部(St.1～St.3)的物种更为丰富;小拟哲水蚤(Para-calanus parvus)为最主要优势种,丰度为263.76 ind·m-3(152.23～451.89 ind·m-3),集中分布在St.4,浮游动物总丰度和总生物量大小取决于优势种小拟哲水蚤的丰度.线性回归分析揭示,浮游动物总生物量,总单位捕捞努力量渔获量(CPUE)正相关性显著,而水母CPUE-总CPUE、水母CPUE-小黄鱼CPUE均存在极显著的负相关关系.     

陆地生态系统植被氮磷化学计量研究进展

因化学功能的耦合和元素的不可替代性, 植物对N、P的需求和利用存在严格的比例。植物N、P化学计量在不同功能群、生长地区、生长季、器官之间以及环境梯度下存在明显的变化规律。多数研究从N、P浓度、N:P及N、P间异速指数等角度分析了植物化学计量变化规律, 并探讨其在全球范围内的具体数值。为增进对植物响应全球变化的理解, 该文综述了N、P化学计量的影响因素及其机理的最新研究进展, 并指出未来拟重点研究的方向。     

全球变化背景下陆地植物N/P生态化学计量学研究进展

生态化学计量学理论最早应用在水生生态系统的研究中,但最近20年来在陆地生态系统中也开展了大量的相关研究,特别是关于全球变化背景下陆地植物N/P生态化学计量学方面的研究得到很大的发展,极大地丰富和提升了我们对陆地植物包括生态系统生态过程的认识。就全球变化背景下陆地植物生态化学计量学的研究现状进行了综述,同时以中国科学院华南植物园90周庆为契机,总结我们关于南亚热带森林植物生态化学计量学的研究工作,进而分析当前存在的一些问题并提出今后研究的发展重点,以期促进和推动我园和我国生态化学计量学相关领域的研究。     

Temperature driven changes in the diet preference of omnivorous copepods: no more meat when it's hot?

Herbivory is more prevalent in the tropics than at higher latitudes. If differences in ambient temperature are the direct cause for this phenomenon, then the same pattern should be visible in a seasonal gradient, as well as in experiments manipulating temperature. Using ¹⁵N stable isotope analyses of natural populations of the copepod Temora longicornis we indeed observed seasonal differences in the trophic level of the copepod and a decrease in trophic level with increasing temperature. In a grazing experiment, with a mixed diet of the cryptophyte Rhodomonas salina and the heterotrophic dinoflagellate Oxyrrhis marina, T. longicornis preferred the cryptophyte at higher temperatures, whereas at lower temperatures it preferred the non‐autotrophic prey. We explain these results by the higher relative carbon content of primary producers compared to consumers, in combination with the higher demand for metabolic carbon at higher temperatures. Thus, currently increasing temperatures may cause changes in dietary preferences of many consumers.     

Temperature and the effects of elemental food quality on Daphnia

1. We examined the responses of two species of Daphnia to changes in food phosphorus (P) content, with animals reared at three different water temperatures. Specifically, we measured mass‐specific growth rate (MSGR), body P content and respiration rate of Daphnia magna and Daphnia pulex acclimatised to 10, 17.5 and 25 °C and fed food carbon : phosphorus (C : P) ratios of either 150 or 500. 2. The responses of these three physiological variables to temperature–food quality interactions were species‐specific. There was a significant interactive effect of temperature and food quality on D. magna, as the greatest proportional effect of food quality on growth was observed at 10 °C and reductions in body P because of low food P content were relatively greater at 25 °C. These effects may reflect the temperature dependence of mechanisms that reduce elemental constraints associated with food quality in D. magna. By contrast, there were no interactive effects between food quality and temperature on MSGR, body P or mass‐specific respiration of D. pulex. 3. It thus appears that temperature can alter food quality effects on Daphnia but the nature of these alterations depends upon the daphniid species and its thermal adaptability. Significant temperature–food quality interactions will complicate efforts to understand zooplankton nutrition in nature and warrant future consideration.     

植物生态化学计量内稳性特征

化学计量内稳性是生态化学计量学研究的核心概念之一,是指生物在面对外界变化的时候保持自身化学组成相对稳定的能力,其反映了生物对周围环境变化作出的生理和生化响应与适应。通过研究植物生态化学计量内稳性,有助于深入了解植物对环境的适应策略和生态适应性,以及植物化学计量内稳性与生态系统功能的关系,但目前关于植物生态化学计量内稳性的研究较少。已有的研究结果表明:不同物种或功能群由于其生长策略不同而具有不同的生态化学计量内稳性特征;同一物种的不同器官、不同生长阶段以及不同元素的内稳性存在较大的差异。该文对植物生态化学计量内稳性概念、内稳性指数的测算方法,不同植物物种或功能群、不同器官、不同生长阶段内稳性特征,以及植物内稳性与生态系统结构、功能和稳定性的关系等方面进行了综述,并结合现已开展的工作,对有待进一步拓展的相关植物生态化学计量内稳性研究领域进行了展望,以期为促进国内相关研究工作的开展提供参考。     

Essential fatty acids and phosphorus in seston from lakes with contrasting terrestrial dissolved organic carbon content

1. It is often assumed that lakes highly influenced by terrestrial organic matter (TOM) have low zooplankton food quality because of elemental and/or biochemical deficiencies of the major particulate organic carbon pools. We used the biochemical [polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) – 20:5ω3] and elemental (C : P ratio) composition of particulate matter (PM) as qualitative measures of potential zooplankton food in two categories of lakes of similar primary productivity, but with contrasting TOM influence (clear water versus humic lakes). 2. C : P ratios (atomic ratio) in PM were similar between lake categories and were above 400. The concentration (μg L⁻¹) and relative content (μg mg C⁻¹) of EPA, as well as the particulate organic carbon concentration, were higher in the humic lakes than in the clear‐water lakes. 3. Our results show high fatty acid quality of PM in the humic lakes. The differences in the biochemical quality of the potential zooplankton food between lake categories can be attributed to the differences in their phytoplankton communities. 4. High biochemical quality of the food can result in high efficiency of energy transfer in the food chain and stimulate production at higher trophic levels, assuming that zooplankton are able to ingest and digest the resource available.     

Seasonal correlations of elemental and ω3 PUFA composition of seston and dominant phytoplankton species in a eutrophic Siberian Reservoir

The elemental and fatty acid composition of seston was studied for 3 years, from May to October, in a small Reservoir. Under comparatively low C:P ratio, multivariate canonical analysis revealed no straightforward simple correlations between phosphorus and single ω3 PUFA species, but complex significant interaction between elemental composition (stoichiometry) of seston and total sestonic ω3 PUFA as a whole. Since sestonic C, P and N were found to originate mostly from phytoplankton, the contents of particulate elements and PUFA were attributed to single species in periods of their pronounced dominance. Phytoplankton species of genera of Stephanodiscus, Peridinium, Gomphosphaeria, Planktothrix and Anabaena in periods of their pronounced dominance had relatively constant species-specific elemental and PUFA composition. Phytoplankton species significantly differed in their elemental and PUFA composition, as well as in ratios of C:N, N:P, PUFA:P and partly C:P that indicate food quality for zooplankton. Hence, there were no phytoplankton species of clearly high or low nutritional value. All of phytoplankters, or at least detritus, that originated from them, may meet specific elemental and biochemical requirements of specific groups of zooplankton. Dividing phytoplankton on basis of their elemental and biochemical composition, i.e., nutrition quality, into large taxa (cyanobacteria, diatoms, etc.) appeared to be too coarse for assessing nutritional value for zooplankton.     

Experimental dietary manipulations for determining the relative importance of allochthonous and autochthonous food resources in tropical streams

1. Autochthonous sources of organic matter appear to make a minor contribution to food webs in temperate forest streams, but their roles in supporting consumer biomass in tropical lotic environments have received little attention. We investigated the importance of autochthonous and allochthonous food sources to Brotia hainanensis (Pachychilidae), a detritivorous and algivorous snail common in Hong Kong hillstreams, using experimental dietary manipulations and assimilation-based analyses, including stoichiometry, carbon (C) and nitrogen (N) stable isotopes and fatty acid (FA) profiles.
2. Juvenile B. hainanensis collected in Pak Ngau Shek Stream were cultured under controlled laboratory conditions and fed for 2 months with either conditioned Liquidambar formosana (Hamamelidaceae) leaf litter or periphyton. Samples of B. hainanensis were also collected from the stream at the end of the experiment for comparison with snails reared in the laboratory.
3. Periphyton and leaf litter exhibited marked differences in C/N ratios, δ ¹³C and δ ¹⁵N values and FA profiles. Stable isotope analysis and FA profiling of laboratory-reared and field-collected B. hainanensis both confirmed that snails relied primarily on autochthonous foods, especially periphytic diatoms and cyanobacteria. Stoichiometry results indicated that periphyton was a more nutritious food (with lower C/N ratio) than leaf litter.
4. This is the first study demonstrating that the combined use of stable isotopes and FA profiles is an effective diagnostic tool to trace the basal food sources of consumers in natural stream habitats. Our findings further support the hypothesis that primary production in tropical streams is generally more important to aquatic consumers than inputs of terrestrial detritus.