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1、第九章 群落的动态 Community Dynamics,群落的内部动态 群落的演替 地球上生物群落的进化,Glacier Bay, Alaska,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,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
2、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,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主要基础 定居(ecesis)：植物繁殖体到达新地点后，开始发芽
3、、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 ice In 1879, John Muir explo
4、red 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 earlier In 1916, William S. Cooper visited Glacier Bay, and saw the
5、 place as the ideal laboratory for the study of ecological succession,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(primary bare area)：从
6、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。Succession occurs in
7、 areas where disturbance destroys a community without destroying the soil,Primary succession,地衣苔藓,Primary succession at Glacier Bay, Alask,Species richness increased rapidly in the early years of succession and then more slowly during the later stages, approaching a possible plateau in species richn
8、ess Not all groups of plants increased in diversity throughout succession,Change 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 ric
9、hness 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,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 for
10、est succession 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
11、2 months,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,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,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 eve
12、r see this?,Did you 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 willo
13、w thickets.,湿草甸,灌丛沼泽,沼泽,水生演替系列 Hydrosere,裸底阶段,浮叶根生植物阶段,挺水植物和沼泽植物阶段,沉水植物阶段,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，如莎草
14、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 communities,Rapid 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
15、northeast 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 suf
16、ficient power to completely disrupt the community and initiate succession,Succession in Sycamore Creek after floods,Two days after floods, the majority of the stream bottom consisted of bare sand with some patches of diatoms Five days after floods, diatoms covered about half the streambed Within 13 to 22 days, diatoms 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
