2024年4月3日发(作者：)
托福考试
复习
托福阅读TPO3(试题+答案+译文)第3篇:The Long-Term Stability of
Ecosystems
托福阅读原文
Plant communities assemble themselvesflexibly, and their particular
structure depends on the specific history of thearea. Ecologists use the
term “succession” to refer to the changes that happenin plant
communities and ecosystems over time. The first community in
asuccession is called a pioneer community, while the long-lived
community at theend of succession is called a climax community. Pioneer
and successional plantcommunities are said to change over periods from
1 to 500 years. Thesechanges—in plant numbers and the mix of species—
are cumulative. Climaxcommunities themselves change but over periods
of time greater than about 500years.
An ecologist who studies a pond today maywell find it relatively
unchanged in a year’s time. Individual fish may bereplaced, but the
number of fish will tend to be the same from one year to thenext. We can
say that the properties of an ecosystem are more stable than
theindividual organisms that compose the ecosystem.
发布者：admin，转转请注明出处：http://www.yc00.com/news/1712090189a2003464.html
评论列表（0条）