互花米草入侵对漳江口红树林湿地土壤有机碳官能团特征的影响

红树林对全球气候变化敏感, 近年来不少区域又受互花米草(Spartina alterniflora)入侵的影响, 土壤碳库组成发生显著变化, 然而鲜有从有机碳官能团特征角度出发的关于两群落的研究。为了解在红树林群落与互花米草群落下土壤碳库及其有机碳官能团的特征差异, 在福建省云霄县漳江口红树林自然保护区湿地内由内陆到海岸方向选取3条样带, 每条样带依次选取3个样地: 红树林群落(MC)、秋茄(Kandelia obovata)-互花米草过渡带(TC)和互花米草群落(SC), 每个样地选取3个呈品字形分布的采样点, 分5层采集0-100 cm土壤样品, 分析土壤中的总有机碳(TOC)、颗粒有机碳(POC)以及可溶性有机碳(DOC)特征, 并利用核磁共振波谱法测定表层0-15 cm与深层75-100 cm土壤总有机碳官能团特征, 以空间换时间法研究入侵前后土壤碳库变化特征。结果表明: (1)从MC群落到SC群落, 土壤有机碳库显著减小, 各样地总有机碳与颗粒有机碳含量表现为MC > TC > SC, 并随着土层深度增加而减少, DOC含量没有表现出明显的变化趋势。(2)各植被类型土壤有机碳以烷基碳与烷氧碳为主, 其次是芳香碳与羰基碳, N-烷氧碳与酚基碳含量最少, 其中表层0-15 cm土壤从红树林群落到互花米草群落, 烷基碳与烷氧碳含量呈现增加趋势但不显著, 芳香碳与酚基碳含量显著减少, 其余有机碳组分含量无显著差异。在深层75-100 cm随着植被类型的改变, 土壤有机碳组成结构均无显著差异。(3)在0-15 cm土层, 烷基碳/烷氧碳含量表现为: SC > MC > TC; 芳香度表现为SC最小, MC与TC无显著差异; 疏水碳/亲水碳无显著差异; 脂族碳/芳香碳表现为SC显著大于其他两种植被类型, MC与TC无显著差异。在75-100 cm土层, 各比值无显著差异。综上所述, 红树林群落碳储量显著高于互花米草群落, 受植被的影响, 互花米草群落表层土壤有机碳分解程度显著高于红树林群落, 而红树林群落的土壤有机碳分子结构要比互花米草群落更复杂, 以维持其土壤有机碳的稳定性。因此, 互花米草入侵红树林后可能会加快有机碳的分解, 最终稳定在相对简单的分子结构, 降低土壤碳储量。     

互花米草生物量变化对盐沼沉积物有机碳的影响

以江苏王港典型互花米草(Spartina alterniflora)盐沼湿地为研究对象,分析光滩及互花米草滩沉积物中有机碳的水平和垂向分布特征,了解互花米草生物量的季节动态变化,探讨二者之间的相互关系,在此基础上研究互花米草生物量分布和季节变化对沉积物中有机碳(TOC)含量的影响。结果表明,互花米草枯落物中的有机碳数量在两个月内衰减了40%,而表层沉积物中TOC含量及其中互花米草来源TOC所占比例的变化,均与互花米草地表枯落物量的季节变化存在两个月的"相位差",这与枯落物快速分解时间大致吻合,说明枯落物是表层沉积物中TOC的重要来源。高达60%的互花米草地下生物量分布在0—20cm深度内,该深度范围内沉积物中TOC含量较高,且TOC主要来源于互花米草。此外,不同深度TOC含量与地下生物量之间存在良好的正相关关系,说明地下生物量是影响沉积物TOC含量的重要因子。研究区互花米草年固碳能力为2274g m-2a-1,盐沼沉积物中TOC埋藏速率达到了470 g m-2a-1,是地表一个重要的碳汇;同时研究区每年向近岸水域输出大量的TOC,是近岸海域生态系统的一个重要碳源。     

北部湾大风江口互花米草湿地有机碳储量的分布特征

互花米草被引入我国滨海地区后,经过多年的生长与演替,改变了潮间带原有生态系统的碳储量,而影响机制仍有待深入研究.为进一步探讨互花米草入侵后潮滩有机碳储量演变特征,该文以广西北部湾大风江口入侵约6 a的互花米草湿地为研究对象,分析了2018年8月、11月及2019年1月、3月采集的样品中有机碳及相关理化指标.结果表示:(...     

长江口九段沙盐沼湿地芦苇和互花米草生物量及碳储量

2010-2012年,采用野外采样和实验室测定相结合的方法,研究了长江口九段沙芦苇、互花米草植被带生物量的季节动态和碳储存能力.结果表明:两种植物生物部分(地上、地下、枯立物生物量之和)的有机碳储量均为秋季最高、春季最低.地上活体互花米草单位面积的平均碳储量(445.81 g·m-2)高于芦苇(285.52 g·m-2),芦苇枯立物的平均碳储量(203.15 g·m-2)低于互花米草(315.28 g· m-2),但芦苇区土壤表层(0 ～30 cm)有机碳储量(1048.62 g·m-2)约为互花米草区(583.33 g· m-2)的2倍.芦苇区的碳储存能力(3212.96g· m-2)总体上高于互花米草区(2730.42 g·m-2).表明保护芦苇群落对于维护盐沼湿地的碳汇功能具有重要意义.     

互花米草入侵对沿海湿地甲烷排放的影响

采集互花米草不同入侵年限(8、11和15年)的原状土壤,采用盆栽试验,研究了土壤有机碳含量对沿海湿地CH4排放的影响。结果表明,土壤有机碳含量随着互花米草入侵年限的增加而增加。在植物生长季,互花米草入侵15年的土壤有机碳含量为12.97g·kg-1,土壤CH4排放通量为2.94mg·m-2·h-1,显著高于入侵年限为8和11a(有机碳含量为8.11和9·16g·kg-1)的土壤,其土壤CH4排放通量分别为1.95和2.34mg·m-2·h-1。这主要是由于随着土壤有机碳含量提高,不仅为产甲烷菌提供了更多底物,同时也促进了产甲烷菌数量增加,从而导致更多CH4排放。因此,在评价互花米草入侵的综合环境效应时,需要兼顾土壤固碳能力和温室气体排放。     

胶州湾典型河口湿地土壤活性有机碳和酶活性对互花米草入侵的响应

以胶州湾洋河口湿地为研究对象,按照互花米草入侵年份(0、1、5、8年)分层采集土壤样品(0—10、10—20、20—40 cm和40—60 cm),研究土壤活性有机碳(LOC)和酶(脲酶、过氧化氢酶、碱性磷酸酶、蔗糖酶)活性的变化,分析土壤活性有机碳和酶活性及两者相关性对互花米草入侵的响应。结果表明:与光滩相比,互花米草入侵增加了表层土壤LOC含量,且随着入侵时间的延长显著增加(P0.05)。同时也改变了土壤LOC垂直分布规律,除光滩和入侵1年样地表现出沿剖面逐渐上升之外,其他样地表现为沿剖面先上升后下降趋势;互花米草入侵提高了河口湿地土壤酶活性,但并未改变酶活性随深度增加而逐渐降低的分布规律。随着入侵时间的延长4种酶活性变化趋势有所差异,过氧化氢酶和蔗糖酶活性变化趋势一致,表现为随入侵时间延长先急剧增加后逐渐减少,而碱性磷酸酶和脲酶活性随着入侵时间的延长逐渐增加。Pearson相关性分析结果显示,土壤LOC和酶活性呈显著负相关且互花米草入侵时间越长两者间相关性越低,8年后无显著相关性。     

农田土壤有机碳库大小及周转

对水稻土、早地潮土和红壤下土壤有机碳库的大小、分解速率和平均驻留时间进行了分析,根据有机碳周转时间的不同,可将土壤有机碳库划分为活性碳库、缓效性碳库和惰效性碳库3个库,其遵循三库一级动力学方程,根据土壤有机碳的分解变化,用此方程在SAS8.2软件上拟合出活性碳库、缓效性碳库的大小及其分解速率.结果表明,农田土壤各剖面的活性碳一般占土壤有机碳的0.6%～3.7%,平均驻留时间为4～45 d;缓效性碳库一般占土壤有机碳的37.7%～81.2%,平均驻留时间为5～24年;利用酸水解测得的惰效性碳一般占土壤有机碳的17.1%～48.1%.不同水型及不同母质下的水稻土中各碳库变化规律分别为：潴育型水稻土＞潜育型水稻土＞淹育型水稻土、第四纪红粘土＞第三纪红砂岩类.不同水稻土和旱地土壤中,活性碳库变化规律为水稻土＞旱地,而缓效性碳为旱地土壤＞水稻土,表明旱地土壤的固碳能力较水田强.     

广州市常绿阔叶林土壤有机碳组分特征分析

选取广州市(龙眼洞、天鹿湖、大夫山、龙头山、滴水岩、王子山、石门)的7个常绿阔叶林为样地,分析城市化对广州森林土壤有机碳组分的影响。研究发现:(1)7个森林土壤总有机碳、易氧化有机碳和不易氧化有机碳含量的差异显著(p<0.05),均呈随样地距市中心距离增加而增加;(2)森林土壤的碳库活度和活度指数距离市中心越近数值越高,碳库指数和碳库管理指数距离市中心越近数值越低;(3)土壤总有机碳与易氧化有机碳、不易氧化有机碳、碳库指数、碳库管理指数、全氮、C:N和样地距城中心距离均呈显著正相关。结果表明城市化改变了常绿阔叶林土壤的有机碳组分,使土壤有机碳的稳定性下降。     

滇南地区桃树种植模式对土壤有机碳组分及碳库管理指数的影响

经果林种植可改变土壤质量、改善生态环境,同时具有较高的经济效益。合理的种植模式可通过物种间的互补性提高资源利用效率,改善土壤碳库质量并提高综合效益。为探讨桃树种植模式对土壤有机碳组分及碳库管理指数的影响,以云南省开远市不同桃树种植模式(桃树单种-SP和桃树南瓜套种-PP)为研究对象,以毗邻的天然林地(CK)为对照,分析不同种植模式下活性碳库,即高锰酸钾氧化有机碳(POXC)、颗粒有机碳(POC),惰性有机碳库即矿物结合态有机碳(MAOC)在0—40 cm土层的分布情况,明确土壤有机碳组分与土壤理化性质的关系;计算碳库活度指数(CPAI)、碳库指数(CPI)以及碳库管理指数(CPMI),明确不同桃树种植模式的碳库变化情况。结果表明：桃树种植模式和对照的土壤有机碳组分的含量均随着土层深度的增加而减少,平均土壤有机碳(SOC)含量为：14.68 g/kg(CK)>9.57 g/kg(PP)>8.58 g/kg(SP)。平均活性有机碳组分所占比例与POC/MAOC均表现为：SP>CK>PP,PP的活性有机碳比例较低,具有较高的有机碳稳定性。两种桃树种植模式的CPMI在1...     

华南典型人工林土壤有机碳库及其稳定性特征研究

研究了华南地区4种25年林龄的典型人工林土壤有机碳库及其稳定性特征。测定了林内0～10 cm和10～20 cm层土壤的有机碳(Total organic carbon,TOC)含量、易分解碳库/稳定性碳库大小以及土壤微生物生物量碳。结果表明,4种林型土壤TOC含量为:马占相思林大叶相思林湿地松林荷木林,其中豆科人工林(马占相思和大叶相思林)的TOC含量显著高于非豆科人工林(湿地松和荷木林)。在表土层(0～10 cm),荷木林易分解碳库最大(7.80 mg g-1),易分解性碳潜在周转时间最短(49 d),马占相思林易分解碳库最小(2.14 mg g-1),占总碳量也最小(8.63%),说明马占相思林土壤有机碳库比其它人工林具有更好的稳定性。4种人工林表土层土壤微生物量碳含量为马占相思林湿地松林大叶相思林荷木林,马占相思林显著高于其它3种人工林,表土层微生物量碳含量格局与土壤有机碳含量相似,较高的微生物量有利于更多的枯枝落叶转化为土壤有机碳。在亚表土层(10～20 cm),大叶相思林土壤微生物量碳最大,马占相思林最小,与表土层的格局相反,但亚表土层微生物碳总含量并不高。因而,人工林土壤有机碳积累水平与土壤有机碳的稳定性及表层土壤微生物量有关。     

Genetic diversity and population genetic structure of saltmarsh Spartina alterniflora from four coastal Louisiana basins

Seventy-two Spartina alterniflora accessions originating from four coastal Louisiana basins (18 accessions per basin) were used to evaluate the genetic structure of this native perennial low-intertidal plant species. The objective of this study was to determine the population genetic structure and diversity of S. alterniflora accessions originating from these four basins using amplified fragment length polymorphism (AFLP) markers. A total of 250 unambiguous and highly repeatable AFLP markers, 186 of which (74.4%) were polymorphic, were obtained using four primer combinations. Overall, pairwise similarity estimates between accessions ranged from 0.70 to 0.93 (average = 0.80) with only a small portion of alleles (0.54–1.08%) unique to each basin. The average H_s (genetic diversity within coastal basins) was 0.20 with an H_s values of 0.19, 0.20, 0.20, and 0.21 for Mermentau, Terrebonne, Calcasieu, and Barataria-Breton basin, respectively. AMOVA analysis showed no genetic structure among basins, with the majority of genetic variation, 96.6%, residing within the basins. There was no indication of isolation by distance. Our results suggest that maintaining high levels of genetic diversity can be accomplished through the use of an adequate number of S. alterniflora samples collected within any large basin. Choosing parental lines from several Louisiana coastal basins for breeding purposes may not significantly increase genetic variability among the progeny lines.     

Adsorptive removal of Pb(II) by activated carbon prepared from Spartina alterniflora: Equilibrium,kinetics and thermodynamics

Low-cost activated carbon was prepared from Spartina alterniflora by phosphoric acid activation for the removal of Pb(II) from dilute aqueous solution. The effect of experimental parameters such as pH, initial concentration, contact time and temperature on the adsorption was studied. The obtained data were fitted with the Langmuir and Freundlich equations to describe the equilibrium isotherms. The kinetic data were fitted with the Lagergren-first-order, pseudo-second-order and Elovich models. It was found that pH played a major role in the adsorption process. The maximum adsorption capacity for Pb(II) on S. alterniflora activated carbon (SAAC) calculated from Langmuir isotherm was more than 99 mg g⁻¹. The optimum pH range for the removal of Pb(II) was 4.8–5.6. The Freundlich isotherm model was found to best describe the experimental data. The kinetic rates were best fitted to the pseudo-second-order model. Thermodynamic study showed the adsorption was a spontaneous exothermic process.     

Clonal integration enhances flood tolerance of Spartina alterniflora daughter ramets

Recently, considerable attention has been paid to the invasion of the clonal plant Spartina alterniflora into coastal wetlands at lower elevations. In this experiment, we tested whether clonal integration improved flood tolerance in S. alterniflora daughter ramets. Daughter ramets at two growth stages (young and old ramets) were flooded to water levels of 0, 9 and 18 cm above the soil surface, and the rhizomes between mother and daughter ramets were either severed or left intact. Biomasses of connected ramets grown in controls or in shallow and deep water treatments were 119%, 108% and 149% higher in the old ramet group than those of severed ramets, respectively, whereas they were 3.0, 3.3 and 11.2 times higher in the young ramet group, respectively. At the end of the experimental period, the shoot height, connected with young ramets, in shallow and deep water treatments increased by 19% and 26%, respectively, over that in the control treatments, whereas the old ramets increased by 11% and 39%, respectively. In contrast, the shoot height of the severed young ramets was 27% and 26% lower in shallow and deep water treatments than in the control treatment, respectively. However, the shoot height of the severed old ramets remained constant with increasing water depth. We conclude that clonal integration enhances the flood tolerance of S. alterniflora daughter ramets, and the trait of clonal integration plays more important roles in severe flooding stress conditions and at early growth stages.     

Seasonal and within-plant gradients in the intramolecular carbon isotopic composition of amino acids of Spartina alterniflora

Autotrophy and heterotrophy create different patterns of carbon flux through the central metabolic pathway. One consequence of these different fluxes is that the α-carboxyl carbon of amino acids is derived from different carbon sources and has a different isotopic composition under autotrophic and heterotrophic conditions. In Spartina alterniflora, a C4 grass and a common and ecologically important component of coastal ecosystems, the isotopic composition of bulk acid hydrolyzable carbon and total amino acid carboxyl carbon were compared over a seasonal cycle. The isotopic composition of plants varied significantly between aboveground and below ground tissues, and the δ¹³C of both hydrolyzable organic carbon and total amino acid carboxyl carbon showed significant variation among seasons. The isotopic heterogeneity within amino acids was used to infer seasonal changes in source/sink relationships for amino acid carbon among plant organs. Comparison of the intramolecular isotope data for Spartina and C3 freshwater marsh plants indicates that the patterns and processes inferred for Spartina are not unique to this taxon.     

崇明东滩湿地不同潮汐带入侵植物互花米草根际细菌的多样性

为了调查崇明东滩湿地入侵植物互花米草(Spartina Alterniflora)在不同潮汐带和季节根际细菌的多样性与丰富度,以本地植物芦苇、海三棱藨草(P. australis和 S.mariqueter)和光滩为对照实验研究,在崇明东滩湿地10样点采集根际土壤和光滩土壤,通过PCR-DGGE分子生物学等技术并结合传统培养方法对土壤细菌进行分析研究。研究表明:东滩湿地不同潮汐带的植物根际细菌群落丰富度和多样性不同,在夏季中潮带的根际细菌丰富度(P=0.021<0.05)较高,各个潮带的植物根际细菌在夏秋季有高多样性,其中中潮带的植物根际细菌平均多样性指数最高(H=4.20)。在中潮带入侵物种互花米草根际细菌的丰富度和多样性要显著高于本地植物芦苇和海三棱藨草,其中海三棱藨草的根际细菌在夏季略高。崇明东滩湿地入侵植物互花米草根际细菌与本地植物相比较具有较高的多样性,而且外来种互花米草对湿地土壤微生物群落结构有着较强影响;入侵种互花米草根际细菌的高丰富度和多样性可能是其成功入侵东滩湿地的一个重要因素。     

Positive interactions of the smooth cordgrass Spartina alterniflora on the mud snail Heleobia australis, in South Western Atlantic salt marshes

The role of positive interactions is often crucial in communities with intense abiotic stress such as intertidal environments. Grasses acting as ecosystem engineers, for example, may ameliorate intertidal harsh physical conditions and modify the community structure. The mud snails Heleobia australis d'Orbigny frequently inhabit the SW Atlantic marshes, mainly associated to intertidal marsh plants (mainly the smooth cordgrass Spartina alterniflora Loisel) probably due to the plant indirect effects. The purpose of this work was to investigate the magnitude of these association and the processes that generate the pattern. Samples of the snail abundance in six SW Atlantic coastal marshes show that H. australis is associated to coastal areas of low energy and low or none freshwater input. This result is important because this species is being used as bioindicator of coastal estuarine systems during the Holocene. Thus the paleontological interpretation based on this species should be revised. Within the studied areas, snails are associated to intertidal marsh plants. However, stable isotope analysis shows that neither plant nor their epiphytes are their main food sources. Field experiments show that snails actively select areas with plants, although tethering experiments show that plants do not provide shelter from predators. However, plants do buffer physical stress factors such as temperature, which generate important mortality outside plants covered areas. These positive interactions have large effects on H. australis distributions in marsh communities; increasing the habitats available for colonization and affecting their local distribution.     

红壤侵蚀地马尾松林恢复后土壤有机碳库动态

运用RothC(version 26.3)模型,并结合“时空代换法”对长汀河田红壤侵蚀退化地马尾松人工恢复后林地表层(0-20cm)土壤有机碳库的动态变化进行了反演和预测,研究结果表明:RothC 26.3模型的模拟结果能够较好地反映红壤侵蚀地植被恢复过程中土壤有机碳的变化趋势;RothC 26.3模型适用于中亚热带季风气候条件下马尾松林地土壤碳库的动态模拟;侵蚀退化地在马尾松林建植后,林地表层土壤碳吸存速率以非线性的形式上升,并在15-25a时间内达到最大,马尾松恢复后前30a林地土壤平均碳吸存速率约为0.385 tC·hm-2· a-1,自马尾松建植后演替至当地顶级群落(次生林)全过程中平均碳吸存速率约0.156 tC·hm-2·a-1;根据模拟结果得到的拟合方程,计算得到研究区红壤侵蚀退化地的碳饱和容量约为36.85 tC/hm2,固碳潜力约为33.26 tC/hm2.