《群落的动态》PPT课件.ppt
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1、第九章第九章 群落的动态群落的动态Community Dynamics群落的内部动态群落的内部动态群落的演替群落的演替地球上生物群落的进化地球上生物群落的进化Glacier Bay,Alaska群落的内部动态群落的内部动态包括季节变化和年际变化波动(fluctuation):在不同年度之间生物群落常有的明显变动,只限于群落内部的变化,不产生群落的更替现象波动多数是由群落所在地区气候条件的不规则变动引起的其特点是群落区系成分的相对稳定性,群落数量特征变化的不定性以及变化的可逆性在波动中,群落在生产量、各成分的数量比例、优势种的重要值以及物质和能量的平衡方面会发生相应的变化群落波动的类型群落波动的
2、类型不明显波动:群落各成员的数量关系变化很小,群落外貌和结构基本保持不变摆动性波动:群落成分在个体数量和生产量方面短期波动,与优势种的逐年交替有关偏途性波动:是气候和水分条件的长期偏离而引起一个或几个优势种明显变更的结果不同的生物群落具有不同的波动性特点。一般说来,木本植物占优势的群落较草本植物稳定一些;常绿木本群落要比夏绿木本群落稳定一些。在一个群落内部,许多定性特征(如种类组成、种间关系、分层现象等)较定量特征(如密度、盖度、生物量等)稳定一些;成熟的群落较之发育中的群落稳定群落的形成条件群落的形成条件迁移(migration):繁殖体的传播过程,是形成群落的首要条件,也是群落变化和演替的
3、主要基础定居(ecesis):植物繁殖体到达新地点后,开始发芽、生长和繁殖的过程竞争(competition):随着裸地上定居种类和个体数量的增加,个体间以及物种间对光、水、营养和空气等空间和营养物质的竞争In 1794,Captain George Vancouver visited the inlet to what is today called Glacier Bay,Alaska,he could not pass beyond the inlet to the bay,however,because his way was blocker by a mountain of iceI
4、n 1879,John Muir explored the coast of Alaska,he did not find the“mountains of ice”described by Vancouver,but found open water.He eventually found the glaciers,which had retreated to 30 to 40 km up the glacial valley since Vancouvers visit 85 years earlierIn 1916,William S.Cooper visited Glacier Bay
5、,and saw the place as the ideal laboratory for the study of ecological succession 群落演替的概念群落演替的概念演替(succession):群落变化过程中,由低级到高级,由简单到复杂,一个阶段接着一个阶段,一个群落代替另一个群落的自然演变现象。The gradual change in plant and animal communities in an area following disturbance or the creation of new substrate裸地:没有植物生长的地段原生裸地(prim
6、ary bare area):从来没有植物覆盖的地面,或者原来存在过植被,但被彻底消灭了的地段次生裸地(secondary bare area):原有植被已不存在,但原有植被下的土壤条件基本保留,甚至还有曾经生长在此的种子或其他繁殖体的地段原生演替(primary succession):发生在原生裸地上的演替。Succession occurs on newly exposed geological substrates,not significantly modified by organisms次生演替(secondary succession):发生在次生裸地上的演替。Successi
7、on occurs in areas where disturbance destroys a community without destroying the soilPrimary succession地衣苔藓Primary succession at Glacier Bay,AlaskSpecies richness increased rapidly in the early years of succession and then more slowly during the later stages,approaching a possible plateau in species
8、 richnessNot all groups of plants increased in diversity throughout successionChange in plant species richness during primary succession at Glacier Bay,Alaska(data from Reiners,Worley,and Lawrence 1971)Secondary succession on an abandoned field in North Carolina 幼苗Change in woody plant species richn
9、ess during secondary forest succession in eastern North America(data from Oosting 1942)Change in number of breeding bird species during secondary forest succession(data from Johnston and Odum 1956)演替的类型演替的类型按发生的时间进程快速演替:几年内发生的演替,如:草原撂荒地上的演替长期演替:几十年或几百年的演替,如:森林采伐后的恢复演替世纪演替:以地质年代计算的演替Primary forest su
10、ccession around Glacier Bay may require about 1500 years,and secondary forest succession on the Piedmont Plateau takes about 150 years,the successional change in rock intertidal communities occurred within about 1.5 years,and ecological succession within a desert stream occurs in less than 2 months演
11、替的类型演替的类型按引起演替的主导因素群落发生演替:在原生和次生裸地上发生内因生态演替:演替是环境变化所决定,但环境变化是群落种类成分生命活动的结果,群落改变了生态环境外因生态演替:由环境条件的变化造成,但不是群落成分生活活动的结果演替的类型演替的类型按基质的性质水生基质演替系列旱生基质演替系列按群落代谢特征自养性演替异养性演替我国刘慎谔教授的划分:时间演替空间演替植被类型发生演替演替系列演替系列生物群落的演替过程,从植物的定居开始,到形成稳定的植物群落为止的过程演替系列中的每一个明显的步骤,称为演替阶段或演替时期水生演替系列旱生演替系列Did you ever see this?Did yo
12、u ever see this as well?1.Submersed aquatic plants in the deeper water.2.Emergent cattails(香蒲)and bulrushes(芦苇)rooted in the mud of shallow water.3.Willow thickets(柳树灌丛)along the banks of distant shoreline.4.Conifer forest(针叶林)in drier,well drained soil above the willow thickets.湿草甸灌丛沼泽沼泽水生演替系列水生演替系
13、列 Hydrosere裸裸底底阶阶段段浮浮 叶叶 根根 生生 植植 物物 阶阶 段段挺挺水水植植物物和和沼沼泽泽植植物物阶阶段段沉沉水水植植物物阶阶段段水生演替系列水生演替系列 Hydrosere自由漂浮植物阶段:湖底为原生裸地,植物漂浮生长,死亡残体沉入湖底,湖岸雨水冲刷物也沉积湖底,逐渐提高湖底沉水植物阶段:湖底出现轮藻等,湖底有机质积累加快,抬升加快,其余一些高等植物大量出现,如金鱼藻、眼子菜等浮叶根生植物阶段:湖底日益变浅,浮叶根生植物出现,如莲等,残体进一步促进湖底抬升直立水生阶段:湖底大大变浅,挺水植物如芦苇等取代浮叶根生植物,使湖底迅速抬高湿生草本植物阶段:喜湿生的沼泽植物出现,
14、如莎草科和禾本科中的湿生种类木本植物阶段:木本灌木出现,然后乔木出现,形成森林Succession in stream communitiesRapid succession has been well documented in Sycamore Creek,Arizona,which has been studied for nearly two decades by Stuart Fisher and his colleagues(1982)The creek is a tributary of the Verde River,lies approximately 32 km north
15、east of Phoenix,Arizona,where it drains approximately 500 km2 of mountainous desert terrain.Evaporation(蒸发)nearly equals precipitation(降雨量)within the Sycamore Creek catchment,so flows are generally low and often intermittent.However,the creek is subject to frequent flash floods with sufficient power
16、 to completely disrupt the community and initiate successionSuccession in Sycamore Creek after floodsTwo days after floods,the majority of the stream bottom consisted of bare sand with some patches of diatomsFive days after floods,diatoms covered about half the streambedWithin 13 to 22 days,diatoms
17、almost completely covered the stream bottom,other algae,especially blue-green algae and mats consisting of a mixture of the green alga Cladophora and blue-green algae,appeared in significant quantities by day 35By day 63,the bottom of Sycamore Creek consisted of a patchwork of areas dominated by dia
18、toms,blue-green algae,and mats of Cladophora and blue-green algaeThe diversity of diatoms and other algae,as measured by H,leveled off after only 5 days,and then began to decline after about 50 daysMost macroinvertebrate species survived the flood,because the invertebrate community of the creek is d
19、ominated by insects whose adults are terrestrial,during the floods of August,many adult insects were in the aerial stage and the flood passed under them,these adults were the source of most invertebrate recolonization of the flood-devastated creekAlgal species diversity during succession in Sycamore
20、 Creek,Arizona(data from Fisher et al.1982)旱生演替系列旱生演替系列 Xerosere地衣植物群落阶段:岩石表面无土壤,光照强,温度变化大,贫瘠而干燥,最先出现地衣,分泌的有机酸腐蚀岩石,加上自然的风化,岩石表面出现含有机质的小颗粒,并逐渐增多苔藓植物群落阶段:地衣群落后期开始出现苔藓植物,能忍受极端干旱环境,生长可以积累更多的腐殖质,对岩石表面的改造作用更强烈,岩石颗粒变细小,松软层更厚,为土壤的发育和形成创造条件草本植物群落阶段:一些耐旱的高等植物侵入,对环境改造更强烈,小气候和土壤条件更有利于植物的生长灌木群落阶段:一些喜阳的灌木开始出现,常与高
21、草混生乔木群落阶段:喜阳的树木增加,逐渐形成森林,最后形成与当地气候相适应的乔木群落,形成顶级群落群群落落初初生生演演替替经经历历 的的 地地 衣衣 阶阶 段段、苔苔藓藓阶阶段段、草草本本植植物物阶阶段段、灌灌木木阶阶段段和和森森林林阶阶段段Secondary succession in temperate forestsSuccession of plant species on abandoned fields in North Carolina.Pioneer species consist of a variety of annual plants.This successional
22、stage is then followed by communities of perennials and grasses,shrubs,softwood trees and shrubs,and finally hardwood trees and shrubs.This succession takes about 120 years to go from the pioneer stage to the climax community Succession in rock intertidal communitiesThe first species to colonize ope
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