甜槠凋落叶分解中土壤节肢动物群落结构动态及其对森林片段化的响应

选取浙、闽、赣交界山地5个不同的常绿阔叶林群落(1处连续森林和4处片段化森林),对优势种甜槠凋落叶分解过程中土壤节肢动物动态进行了研究.5个研究样地共获得土壤节肢动物899头,分属9纲25目,其中鳞翅目占个体总数的10%以上,为优势类群;膜翅目、弹尾目、双翅目、前气门亚目和地蜈蚣目为常见类群.凋落叶分解速率与土壤节肢动物的类群数、个体数随季节动态呈现相一致的变化趋势.8月凋落物分解最快,土壤节肢动物类群和个体数最多;而4至6月和12月情况与之相反.片段化森林和连续森林在土壤节肢动物的类群数、个体数和物种多样性方面均显示出差异,面积效应和边缘效应在其中都起了一定的作用.     

不同演替阶段热带森林地表凋落物和土壤节肢动物群落特征

为了解不同演替阶段热带森林土壤节肢动物群落结构特征及其与地表凋落物的关系, 2001年9月采用样线调查法对西双版纳23年次生林、35年次生林、季节雨林地表凋落物及其中的土壤节肢动物进行了调查。所获数据表明, 地表凋落物数量(现存量干重)和质量(N和C/N)总体上表现为35年次生林最好, 23年次生林次之; 蜱螨目和弹尾目为3林地地表凋落物土壤节肢动物群落优势类群, 膜翅目蚂蚁、马陆目、鞘翅目、双翅目和半翅目为常见类群。土壤节肢动物个体密度和个体相对密度均表现为35年次生林>季节雨林>23年次生林。群落的丰富度指数以季节雨林最高, 多样性和均匀度指数显示为23年次生林最高, 35年次生林的优势度指数最高, 3林地土壤节肢动物群落类群组成相似性达到较好水平。相关分析表明, 3种不同演替阶段热带森林土壤节肢动物个体密度与林地地表凋落物现存量呈正相关, 而现存凋落物N元素储量与土壤节肢动物的相关性仅表现在23年次生林和季节雨林。研究认为, 热带森林土壤节肢动物群落的发展与森林植被演替密切相关, 其群落个体数量和多样性受森林地表凋落物数量、质量的调控, 但其他环境因素如捕食效应、人为干扰等影响亦不可忽视。     

亚热带森林凋落叶分解过程土壤节肢动物群落的变化特征

土壤动物群落结构和多样性可能随凋落物分解进程和基质质量的变化不断改变。为了解亚热带森林凋落叶分解过程中土壤节肢动物群落变化特征,以四川盆地亚热带森林麻栎（Quercus acutissima）和柳杉（Cryptomeria fortunei）凋落叶为对象,于2011-2015年采用分解袋法研究了2种凋落叶分解过程中土壤节肢动物组成、结构和多样性动态变化。整个研究期间,柳杉和麻栎凋落叶分解袋中共捕获土壤节肢动物3855只,分属于16目51科,且均以等节跳科和棘跳科为优势类群;麻栎凋落叶中土壤节肢动物的个体密度随分解进程呈现增加趋势,在分解的1079天达最高值后降低,而柳杉凋落叶则在分解的156天急剧增加后快速降低,2种凋落叶中土壤节肢动物类群数量具有相似的动态变化过程;2种凋落叶中土壤节肢动物总体以菌食性数量比例最高,腐食性最低,且随凋落叶分解进程,植食性土壤节肢动物占比明显下降,菌食性则上升;非度量多维尺度（NMDS）分析显示,2种凋落叶中土壤节肢动物群落组成具有显著差异,聚类分析表明,2种凋落叶土壤节肢动物群落结构相似性随分解进程不断降低。亚热带森林凋落叶分解过程中土壤节肢动物群落组成、结构和多样性受凋落叶类型影响。     

砂仁种植对季节雨林土壤节肢动物群落结构影响的初步研究

为了探讨砂仁种植对热带季节雨林土壤节肢动物群落的影响,采用样地调查法对西双版纳勐仑自然保护区热带季节雨林及林下砂仁种植地土壤节肢动物群落进行了调查,2种生境、不同季节3次取样共获得土壤节肢动物3772个,隶属6纲23目,其中砂仁地中膜翅目(蚂蚁)、蜱螨目、半翅目为优势类群,占全捕获量的73．329％,而季节雨林中膜翅目(蚁类)、蜱螨目、鞘趔目和弹尾目为优势类群,占全捕量89．778％。2样地土壤节肢动物类群数、个体数和多样性指数的水平分布差异显示为季节雨林高于砂仁地,垂直分布显示季节雨林为土壤表层多于下层,表聚现象明显,砂仁地因受人为活动影响,其土壤节肢动物的垂直分布具有较大变化,出现下层高于表层的逆向分布;2样地土壤节肢动物群落季节变化趋势相近,均表现为干季高于雨季,其中砂仁地土壤节肢动物个体数在干热季最多,季节雨林个体数则在雾凉季最高。     

西双版纳不同演替状态热带次生林土壤节肢动物群落特征

采用样地调查法,对西双版纳4种不同演替状况热带次生林：中平树(Macavanga denticulate)、崖豆藤(Millettia laptobotrya)、野芭蕉(Musa acuminata)与黄竹(Dendrocalamus membranaceae)林的土壤节肢动物群落结构与季节变化进行了研究．结果表明,4类不同演替状况次生林土壤节肢动物群落在数量优势类群组成上无较大差异,蜱螨目为所有4类林地的突出优势类群,膜翅目、弹尾目和鞘翅目在不同林地中分别为不同数量等级的次优势类群,而在常见和稀有类群的组成上,各林地表现出较大的差异．土壤节肢动物类群数、个体数和DG多样性指数以正向演替的崖豆藤林最高,偏途演替的黄竹林最低,但中平树、崖豆藤和野芭蕉林的差异不大．4类林地土壤节肢动物类群数和个体数的垂直分布分别以凋落物层和土壤表层(0～5cm)最高,其它各层分布因林地不同各异,并存在明显的季节差异．各林地土壤节肢动物个体数和类群数的季节消长总体表现出干季和雨季初期与末期高于雨量最大的雨季中期,由于不同林地植被结构、凋落物数量和质量以及土壤水热状况不同,其季节变化显现样地差异,除了受林地降水量和温度变化影响外,食物的丰欠和栖息场所的干扰状况也有重要的影响作用．     

西双版纳热带季节雨林凋落叶分解与土壤动物群落：两种网孔分解袋的分解实验比较

 以西双版纳热带湿性季节沟谷雨林混合凋落叶作为分解基质,在不同位置季节雨林样地,采用不同网孔（ 2和0.15 mm）分解袋,开展大中型土壤动物对雨林凋落叶分解影响的实验,测定了不同网孔分解袋土壤动 物多样性、凋落叶分解速率和主要养分元素释放状况。结果显示：2 mm网孔分解袋土壤动物类群相对密度 年均值为2.67～2.83目•g－1凋落物干重,个体相对密度年均值为22.3～21.77个•g－1凋落物干重,显著 高于0.15 mm网孔分解袋的类群相对密度0.27～0.28目•g－1凋落物干重和个体相对密度2.88～2.77个•g－ 1凋落物干重（p<0.01）,并且0.15 mm网孔分解袋中极少量的动物个体主要为小型类群弹尾目和蜱螨目（ 原生动物、湿生土壤动物线虫不计）,由此我们视2 mm网孔分解袋凋落叶分解由绝大多数土壤动物和其它 土壤生物共同作用,而0.15 mm网孔分解袋基本排除了大中型土壤动物对袋内凋落叶分解的影响。2 mm网 孔分解袋凋落叶物质失重率（71%左右）、分解率指数（1.88～2.44）和主要养分元素释放率明显高于 0.15 mm分解袋（34%～35%,0.48～0.58）。通过比较两种不同网孔分解袋凋落叶失重率和元素释放率的 差异,显示出季节雨林大中型土壤动物群落对凋落叶物质损失的贡献率为年均值46%左右,并使凋落叶C/N 和C/P明显降低,而对不同元素释放率的影响不同,其中对N、S和Ca元素释放率的影响较大,而对K素释放 的影响作用最小。相关分析显示,2 mm网孔分解袋内土壤动物群落类群和个体的相对密度与凋落叶物质残 留率有较好的负相关关系,而群落香农多样性指数与凋落叶分解率指数表现出一定的正相关关系。     

哀牢山不同类型亚热带森林地表凋落物及土壤节肢动物群落特征

分别于2005年4月（干热季）、6月（雨季）和12月（干热季）,采用样线法对哀牢山中山湿性常绿阔叶林、山顶苔藓矮林和滇山杨次生林地表凋落物及其中的土壤节肢动物群落进行了调查.结果表明： 凋落物现存总量、C储量和C/N在干、湿季均表现为苔藓矮林＞滇山杨林＞常绿阔叶林,N储量差异不大.蜱螨目和弹尾目是3林地凋落物层节肢动物群落的优势类群,双翅目幼虫、鞘翅目、蚁类和同翅目为常见类群,3林地凋落物层土壤节肢动物群落相似性系数极高.3林地凋落物层土壤节肢动物群落密度(ind·m^-2)没有显著差异,但相对密度(ind·g^-1)呈现出常绿阔叶林和滇山杨林显著高于苔藓矮林;土壤节肢动物密度季节变化呈现干季（4月和12月）显著高于雨季（6月）,群落香农多样性指数差异不显著.干热季(4月)3林地枯枝落叶现存量与其土壤节肢动物群落和主要类群密度呈显著正相关关系,而在干冷季(12月)凋落物总现存量与其土壤节肢动物群落及蜱螨目相对密度则呈显著负相关关系;弹尾目和鞘翅目密度与地表凋落物层的N储量也有显著的正相关关系.哀牢山亚热带森林凋落物及其土壤节肢动物群落的发展与森林植被结构密切相关, 其群落个体数量和多样性受森林地表凋落物的调控, 但林内其他环境因素如温湿度对森林凋落物层土壤动物个体数的季节变动也有明显影响.     

热带次生林、旱稻种植地和火烧迹地土壤节肢动物群落结构特征及季节变化

通过模拟刀耕火种过程 ,对刀耕火种前后的次生林、旱稻地 (第 2年 )和火烧迹地 (火烧后直接撂荒地第 2年 )土壤节肢动物群落结构特征及季节变化进行了调查研究。结果显示 :3块样地土壤节肢动物群落的优势类群组成相同 ,均为蜱螨目、膜翅目和弹尾目 ,但不同生境样地中各优势类群所占群落总数的比例不同 ,并且 3样地常见和稀有类群的组成差异较大 ;土壤节肢动物类群数、个体数和 DG多样性指数表现为次生林高于其它 2块样地 ,而旱稻地和火烧迹地则无较大差异 ,但一些类群在旱稻地、火烧迹地的数量分布与次生林具有差异 ,且在土壤层的表现较为突出 ;3块样地土壤节肢动物群落具有较好相似性 ,其中旱稻地与火烧迹地达到极相似水平 (D、DS>0 .9)。3种不同类型生境土壤节肢动物群落在类群数、个体数和多样性指数的季节变化总体呈现出雨量少的干季或雨季初末期高于雨量最大的雨季中期 ,与当地降雨量和气温变化有密切关系 ,同时各样地土壤节肢动物群落因生境条件不同及人为活动干扰强弱而形成各自的季节消长特点。研究表明刀耕火种后的旱稻种植对土壤节肢动物群落的恢复和发展在一定限制条件 (面积、周围次生林和坡度 )下无破坏性影响 ,但植被改变、农事活动等对直接撂荒地和旱稻地土壤节肢动物群落的季节消长产生     

土壤节肢动物对箭竹凋落叶分解过程中酶活性的影响

为了解凋落物分解过程中土壤节肢动物与土壤酶活性的相互联系,以川西亚高山森林箭竹(Fargesia spathacea)凋落叶为对象,通过原位控制实验,于2016年4月至2018年4月研究了土壤节肢动物对凋落叶分解过程中碳、氮和磷转化相关酶活性的影响。结果表明:生物抑制剂施用降低了分解袋中土壤节肢动物49.7%~66.8%的个体密度和19.2%~46.3%的类群数量;对照和处理分解袋中凋落叶碳、氮和磷转化相关酶活性随分解过程呈现相似的动态;与处理相比,土壤节肢动物参与(对照)显著提高了凋落叶分解过程中蔗糖酶、β-葡聚糖苷酶、纤维素酶、多酚氧化酶、过氧化物酶、N-乙酰-β-D-氨基葡萄糖苷酶和酸性磷酸酶活性;土壤节肢动物对凋落叶分解过程中酶活性的贡献率在达到一个明显的峰值后快速降低;土壤温度和土壤节肢动物类群数量与蔗糖酶活性呈显著正相关,与β-葡聚糖苷酶、纤维素酶、多酚氧化酶、过氧化物酶、N-乙酰-β-D-氨基葡萄糖苷酶和酸性磷酸酶活性呈显著负相关。土壤节肢动物对凋落叶分解过程中酶活性促进效应随酶类型和分解时间变化存在差异,与土壤节肢动物群落结构和分解环境密切相关。     

土壤节肢动物对箭竹凋落叶分解过程中酶活性的影响

为了解凋落物分解过程中土壤节肢动物与土壤酶活性的相互联系,以川西亚高山森林箭竹(Fargesia spathacea)凋落叶为对象,通过原位控制实验,于2016年4月至2018年4月研究了土壤节肢动物对凋落叶分解过程中碳、氮和磷转化相关酶活性的影响。结果表明:生物抑制剂施用降低了分解袋中土壤节肢动物49.7%～66.8%的个体密度和19.2%～46.3%的类群数量;对照和处理分解袋中凋落叶碳、氮和磷转化相关酶活性随分解过程呈现相似的动态;与处理相比,土壤节肢动物参与(对照)显著提高了凋落叶分解过程中蔗糖酶、β-葡聚糖苷酶、纤维素酶、多酚氧化酶、过氧化物酶、N-乙酰-β-D-氨基葡萄糖苷酶和酸性磷酸酶活性;土壤节肢动物对凋落叶分解过程中酶活性的贡献率在达到一个明显的峰值后快速降低;土壤温度和土壤节肢动物类群数量与蔗糖酶活性呈显著正相关,与β-葡聚糖苷酶、纤维素酶、多酚氧化酶、过氧化物酶、N-乙酰-β-D-氨基葡萄糖苷酶和酸性磷酸酶活性呈显著负相关。土壤节肢动物对凋落叶分解过程中酶活性促进效应随酶类型和分解时间变化存在差异,与土壤节肢动物群落结构和分解环境密切相关。     

鼎湖山季风常绿阔叶林凋落叶分解与土壤动物群落动态和多样性

2001年12月~2002年12月,采用不同孔径分解凋落叶样袋法,对鼎湖山季风常绿阔叶林3类凋落叶的分解进行了研究,并对落叶分解过程中凋落叶袋内和袋下土样中的土壤动物群落和多样性进行了调查。结果表明,3种孔径袋内凋落叶的分解速率为大孔>中孔>微孔;混合凋落叶的分解速率大于单种凋落叶;蜱螨目在凋落叶分解的整个过程中相对数量都较高,弹尾目在凋落叶的分解过程中在凋落叶袋和土壤间移动,数量变化较大。凋落叶袋内大、中型土壤动物的个体数量在分解前期较多,中、小型土壤动物在分解的中期数量剧增;凋落叶袋内土壤动物的个体数量、密度以及多样性指数都随着落叶的分解而增加,9月最高;土壤样内则在分解的前期较高,以后逐渐降低。凋落叶的分解和土壤动物群落动态及多样性受凋落叶基质质量以及样地温度、降雨量等综合因素的影响。     

川西亚高山森林凋落物分解初期土壤动物对红桦凋落叶质量损失的贡献

2010年10月26日-2011年4月18日在川西亚高山地区季节性冻融期间,选择典型的红桦-岷江冷杉林,采用凋落物分解袋法调查了不同网孔(0.02、0.125、1和3 mm)凋落物分解袋内的凋落物质量损失,分析微型、中型和大型土壤动物对红桦凋落叶分解的贡献.结果表明:在季节性冻融期间,0.02、0.125、1和3 mm分解袋内的红桦凋落叶质量损失率分别为11.8％、13.2％、15.4％和19.5％,不同体径土壤动物对红桦凋落叶质量损失的贡献率为39.5％;不同孔径凋落物袋内土壤动物的类群和个体相对密度与凋落叶的质量损失率的变化趋势相对一致.在季节性冻融的初期、深冻期和融化期,不同土壤动物对红桦凋落叶质量损失的贡献率为大型土壤动物(22.7％)＞中型土壤动物(11.9％)＞微型土壤动物(7.9％).季节性冻融期间土壤动物活动是影响川西亚高山森林凋落物分解的重要因素之一.     

Tree functional diversity affects litter decomposition and arthropod community composition in a tropical forest

Disturbance can alter tree species and functional diversity in tropical forests, which in turn could affect carbon and nutrient cycling via the decomposition of plant litter. However, the influence of tropical tree diversity on forest floor organisms and the processes they mediate are far from clear. We investigated the influence of different litter mixtures on arthropod communities and decomposition processes in a 60‐year‐old lowland tropical forest in Panama, Central America. We used litter mixtures representing pioneer and old growth tree species in experimental mesocosms to assess the links between litter types, decomposition rates, and litter arthropod communities. Overall, pioneer species litter decomposed most rapidly and old growth species litter decomposed the slowest but there were clear non‐additive effects of litter mixtures containing both functional groups. We observed distinct arthropod communities in different litter mixtures at 6 mo, with greater arthropod diversity and abundance in litter from old growth forest species. By comparing the decay of different litter mixtures in mesocosms and conventional litterbags, we demonstrated that our mesocosms represent an effective approach to link studies of litter decomposition and arthropod communities. Our results indicate that changes in the functional diversity of litter could have wider implications for arthropod communities and ecosystem functioning in tropical forests.     

No bottom-up effects of food addition on predators in a tropical forest

Several studies in temperate forests have demonstrated effects of litter addition on decomposers and predators. However, adding litter does not allow separating the effects of food availability and habitat space. We investigated the response of decomposers and predators to increased food resources and space in forests of the southern Mata Atlântica of Brazil. In two forest ecosystems representing an early successional stage of secondary forests and old-growth forest, we added nutrient-rich organic material, artificial litter of no nutritional value, or a combination of both to the soil surface of 120 plots to separate the effects of habitat space and food on soil food webs. We sampled litter- and soil-dwelling arthropods after three months using pitfall traps, soil sample extraction, and sticky traps just above the soil. Adding artificial litter had no positive effect on any of the 17 analyzed arthropod groups. Combining all sampled arthropods the effect was even significantly negative. Adding food had a positive effect on the abundance of decomposers, but not predators. We found no interactions between added artificial litter and added organic material. Our results suggest that the soil fauna in tropical forests is food limited. The lack of a bottom-up effect on predators suggests that they are not predominantly regulated by the abundance of epigeic prey but rather by competition or predation.     

四川盆地亚热带常绿阔叶林不同物候期凋落物分解与土壤动物群落结构的关系

为了解植物生长不同物候时期凋落物分解过程中土壤动物群落结构动态及其与凋落物分解的关系,以四川盆地亚热带常绿阔叶林典型人工林树种马尾松和柳杉,次生林树种香樟和麻栎凋落物为研究对象,采用凋落物分解袋试验研究,凋落物分解过程中土壤动物的群落特征。4种凋落物分解袋共获得土壤动物8047只,其中,柳杉(2341只)>香樟(2105只)>马尾松(2046只)>麻栎(1555只)。其中,秋末落叶期、萌动期和展叶期,马尾松凋落物袋中主要以捕食性土壤动物为优势类群,而后以菌食性土壤动物为主;香樟凋落物袋中除秋末落叶期和叶衰期以菌食性土壤动物为主要优势类群外,其他各时期均以捕食性土壤动物为主要优势类群;柳杉凋落物分解各时期均以菌食性土壤动物为主要优势类群;麻栎凋落物分解在前3个时期以菌食性为主,而后以植食性土壤动物为主要优势类群。相关分析表明,在秋末落叶期和萌动期土壤动物的个体密度主要和氮、磷含量及其格局密切相关,叶衰期主要和难分解组分木质素显著相关。除在秋末落叶期土壤动物对凋落物分解的贡献率与土壤动物的个体密度显著相关外,其余主要物候关键时期均与土壤动物的类群密度及其食性显著相关。     

How does litter quality affect the community of soil protists (testate amoebae) of tropical montane rainforests?

Litter quality and diversity are major factors structuring decomposer communities. However, little is known on the relationship between litter quality and the community structure of soil protists in tropical forests. We analyzed the diversity, density, and community structure of a major group of soil protists of tropical montane rainforests, that is, testate amoebae. Litterbags containing pure and mixed litter of two abundant tree species at the study sites (Graffenrieda emarginata and Purdiaea nutans) differing in nitrogen concentrations were exposed in the field for 12?months. The density and diversity of testate amoebae were higher in the nitrogen-rich Graffenrieda litter suggesting that nitrogen functions as an important driving factor for soil protist communities. No additive effects of litter mixing were found, rather density of testate amoebae was reduced in litter mixtures as compared to litterbags with Graffenrieda litter only. However, adding of high-quality litter to low-quality litter markedly improved habitat quality, as evaluated by the increase in diversity and density of testate amoebae. The results suggest that local factors, such as litter quality, function as major forces shaping the structure and density of decomposer microfauna that likely feed back to decomposition processes.     

Drought and presence of ants can influence hemiptera in tropical leaf litter

Climate change is predicted to impact tropical rain forests, with droughts becoming more frequent and more severe in some regions. We currently have a poor understanding of how increased drought will change the functioning of tropical rain forest. In particular, tropical rain forest invertebrates, which are numerous and biologically important, may respond to drought in different ways across trophic levels. Ants are a diverse group that carry out important ecosystem processes, shaping ecosystem structure and function through predation and competition, which can influence multiple trophic levels. Hemiptera are a mega-diverse order, abundant in tropical rain forests and are ecologically important. To understand the roles of ants in exerting predation and competition pressure on invertebrates in tropical rain forests during drought and a post-drought period, we established a large-scale ecosystem manipulation experiment in Maliau Basin Conservation Area in Malaysian Borneo, suppressing the activity of ants on four 0.25 ha plots over a two-year period. We sampled hemipterans found in the leaf litter during a drought (July 2015) and a post-drought period (September 2016) period. We found significant shifts in the assemblage of hemipterans sampled from the leaf litter following ant suppression. Specifically, for ant-suppression plots, the species richness and abundance of herbivorous hemipterans increased only during the post-drought period. For predatory hemipterans, abundance increased with ant-suppression regardless of drought conditions, and we found marginal evidence for a species richness increase during the post-drought period with little or no change in the drought period. These results illustrate how ants in tropical forests structure invertebrate communities and how these effects may vary with climatic variation.     

Litter Decomposition and Nutrient Release in a Tropical Seasonal Rain Forest of Xishuangbanna,Southwest China1

We studied litter decomposition and nutrient release in a tropical seasonal rain forest of Xishuangbanna, Southwest China. The monthly decay rates (k) of leaf litter ranged from 0.02 to 0.21/mo, and correlated with rainfall and soil moisture. Annual k values for leaf litter (1.79/yr) averaged 4.2 times of those for coarse wood (2.5–3.5 cm in diameter). The turnover coefficients of forest floor mass (annual litterfall input/mean floor mass) were: 4.11/yr for flowers and fruits, 2.07/yr for leaves, and 1.17/yr for fine wood (≤2 cm in diameter), with resident time decreasing from fine woods (0.85 yr) to leaves (0.48 yr) and to flower and fruits (0.24 yr). Nutrient residence times in the forest floor mass were ranked as: Ca (1.0 yr) > P (0.92 yr) > Mg (0.64 yr) > N (0.36 yr) > K (0.31 yr). Our data suggest that rates of litter decomposition and nutrient release in the seasonal rain forest of Xishuangbanna are slower than those in typical lowland rain forests, but similar to those in tropical semideciduous forests.