|
- 积分
- 17983
- 威望
- 17983
- 包包
- 26159
|
本帖最后由 细胞海洋 于 2013-2-8 21:28 编辑 - J8 U" ^1 E) q9 U% ~
# P! d6 J8 L4 x0 E. }; d' m
 7 O" z. @! T G6 i6 M- R3 [$ Z
About the 1 @9 v" b9 [( m
Cover9 i% |: y# l' `& y' G$ g9 C
Stretches of oak savanna
( E# D/ h, u0 D. h" zin the Pacific Northwest of North America have been subject to fire-prevention
' j2 G% T- c# q, ?6 @; t y- emeasures since the mid-nineteenth century. The resulting grassland has lost # t0 t# J% B# m) R, t; u. b3 A
plant species but achieves stable high-yield annual production — rather like a / e/ v: Y$ P ^3 E4 Y% f2 }
high-yield agricultural system — and remains resilient to invasive species and
1 y$ J" z! b$ Jclimate fluctuation. A long-term study in which
/ W9 c1 K, o* Y, Uselected grassland plots were periodically burned and allowed to recover now
N4 l& P' O; ?/ u! Xdemonstrates the critical value of biodiversity when ecosystems experience 6 K/ Z/ a/ [! q7 `
disturbance. Grasslands were able to recover from burning only in areas that had " x8 K R3 ]$ ?
a relatively high diversity of native plants. This work demonstrates how
2 S+ a; d/ N/ d) Npersistent human activity can homogenize both structure and function of an
& K: ^, v9 D' J/ Recological system, while weakening the diversity-related mechanisms needed to
4 V6 h5 S) F9 lcompensate for sudden disturbance. There are many terrestrial systems today that ( _. X5 e3 F3 x5 N% }3 w# _
have become homogenized by persistent human activity that may be similarly # W+ d6 p/ Z9 M- I' a
vulnerable to sudden environmental change that will be only evident after the " Q( q, ]) }/ {/ r2 i
collapse occurs. On the cover 'grass fire' (Dariush
7 ]& o! D9 o9 k3 JM/Shutterstock).
' C5 U: o# e C* W: V' t& b
E# A! P" V" }7 S8 Q9 H
$ J, d+ J$ y8 d0 N' U3 l& K, a; P0 w; s' |5 k) z7 H
3 e$ I5 d% r+ [. O
|
附件: 你需要登录才可以下载或查看附件。没有帐号？注册
-
总评分: 威望 + 20
包包 + 20
查看全部评分
|
发表于 2013-2-8 19:38
发表于 2013-2-15 22:45
