|
- 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
5 ^6 H" S/ K, V& y5 m$ ^
+ @- W$ o4 r" t5 p2 Y
1 O, f% u d/ O. f% R! ~7 g, lAbout the 8 d% {" s, w. h8 ^# c( {/ F
Cover
' Z) n A# a' `; _6 P& j: @( pStretches of oak savanna
% [/ V3 M( E1 w0 J# S' \) C$ P0 lin the Pacific Northwest of North America have been subject to fire-prevention
! v( w* s5 i0 c# c) Emeasures since the mid-nineteenth century. The resulting grassland has lost
& k. g8 l* S! _0 g3 j+ c1 y) A4 dplant species but achieves stable high-yield annual production — rather like a % n* D1 ^7 \& t' L
high-yield agricultural system — and remains resilient to invasive species and
$ A4 d1 s/ A4 bclimate fluctuation. A long-term study in which
2 p+ N6 C* S# N- D6 V" @ lselected grassland plots were periodically burned and allowed to recover now
& h/ @3 E0 l. V4 |4 q$ Fdemonstrates the critical value of biodiversity when ecosystems experience 5 m2 M, |" g8 G, h+ _
disturbance. Grasslands were able to recover from burning only in areas that had . O! R' D* R$ ]# A
a relatively high diversity of native plants. This work demonstrates how
+ W3 F$ ^8 ^5 s# V$ }persistent human activity can homogenize both structure and function of an
. [- u/ p0 C; gecological system, while weakening the diversity-related mechanisms needed to
8 `& {3 Y. `6 u" G# kcompensate for sudden disturbance. There are many terrestrial systems today that " e: ^$ c3 l. S, {/ V
have become homogenized by persistent human activity that may be similarly
l# e' N2 }/ ` @/ k) L8 Q% x* Xvulnerable to sudden environmental change that will be only evident after the " }; a3 U/ d4 e
collapse occurs. On the cover 'grass fire' (Dariush
" Y' N: A8 ?0 |* j7 Q2 ]8 ?* `M/Shutterstock).* A; ~& o) A- o' [8 ?. a; z
4 O1 h( ?' N$ u3 O7 V0 Z* l
9 W8 \: a) T) M3 Y X+ ]4 G
" `0 ?6 u4 C8 M: r$ {/ ^
( l, Y( Z% P6 @1 g8 r |
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
