|
 
- 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 9 g! Z: A; V# ~4 g r+ m" q! M5 a
8 A5 d* z- e+ r1 h
9 Y% i- f! S4 V; l% AAbout the ' M1 O$ z' b2 h! o( }
Cover! ^( N, _, M- m& e5 d! q% ?
Stretches of oak savanna
4 C; }$ L! p M! j+ S6 B5 H6 Ain the Pacific Northwest of North America have been subject to fire-prevention 5 U5 V2 ~7 g/ e8 I* a
measures since the mid-nineteenth century. The resulting grassland has lost + \' t* x8 L- L5 n
plant species but achieves stable high-yield annual production — rather like a
8 R5 P, e4 C2 Whigh-yield agricultural system — and remains resilient to invasive species and 5 }' Y' ^# q+ ]8 T
climate fluctuation. A long-term study in which
% E+ r+ j9 ^9 C" h2 uselected grassland plots were periodically burned and allowed to recover now . b0 e: X0 [ ]/ p7 x
demonstrates the critical value of biodiversity when ecosystems experience
( l; o, t1 V9 |2 b3 wdisturbance. Grasslands were able to recover from burning only in areas that had + ?4 I/ A( ]( d7 U7 u
a relatively high diversity of native plants. This work demonstrates how
% ]) E5 C, @4 M7 ~, `' cpersistent human activity can homogenize both structure and function of an
# r' s% |, a* Y/ ]& s2 T uecological system, while weakening the diversity-related mechanisms needed to 6 F) o/ _) k: e" ?1 K( m
compensate for sudden disturbance. There are many terrestrial systems today that 4 |( G3 {. M. W$ D, D) v: V
have become homogenized by persistent human activity that may be similarly
0 i0 I; l0 [% _! l0 ^4 j* |vulnerable to sudden environmental change that will be only evident after the
4 X! H/ Q9 A) E, O( Lcollapse occurs. On the cover 'grass fire' (Dariush }& |' `# @% B/ W5 J
M/Shutterstock).
6 V& d0 g( z3 T& E! q+ g
7 [5 }1 W7 W4 Q6 C/ } u& ?4 a6 @
3 N6 K% u8 i; B0 j2 {+ d! v2 q$ v
& K* L2 g* M) L7 m# D. Y. S1 T
" J+ V! A/ S: W1 C |
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
|