Patterns of Primary Succession of Native and Introduced Plants in Lowland Wet Forests in Eastern Hawai‘i
Patterns of Primary Succession of Native and Introduced Plants in Lowland Wet Forests in Eastern Hawai‘i
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夏威夷东部低地湿森林中本地和引进植物的初级演替模式
DOI：
10.1111/j.1744-7429.2007.00371.x
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发表时间：
2008
期刊：
影响因子：
2.1
通讯作者：
R. Ostertag
中科院分区：
文献类型：
--
作者：
Naupaka B. Zimmerman;R. Flint Hughes;S. Cordell;P. Hart;Heather Kalei Chang;David Perez;Ryan Kaipoalohaakala Like;R. Ostertag
夏威夷的大部分低地湿润森林已不复存在，仅存的几片森林分布在最大岛屿的东侧迎风面。为了更好地了解这些原生系统的演替模式和入侵，我们在夏威夷岛普纳地区的9个地点量化了基础面积（BA）、木本物种密度和林下覆盖度，代表了“a”ā和pāhoehoe熔岩流中原生林分发育的年龄梯度。在两种流量类型上，随着林龄/流龄的增加，本土树种BA增加（从5增加到50 m2/ha），茎密度减少（从3700枝/ha减少到2600枝/ha）。原生物种和引进物种的组成在较老的河流中不同的基质类型之间存在差异。我们发现，在一些地方，低地湿原生森林至少部分保持完整，但它们的功能和组成完整性正日益受到外来物种入侵的损害，如Psidium catleanum和Melastoma candidum，这些物种在300年以上的遗址中更为常见。这段时间可能代表一个阈值，在此之后，非生物环境条件不再限制引进物种的补充。在较老的河流中，非本地物种的茎密度以一个数量级淹没了本地物种的密度，非本地物种的茎（高> 1.3 m）的密度高达18000茎/公顷。此外，所有林分都缺乏林下原生木本物种的补充，这表明如果不进行管理，这些林分的原生成分可能很快就无法自我维持。
The majority of Hawaii's lowland wet forests no longer exist, with many of the last remaining patches found on the eastern, windward sides of the largest islands. To better understand successional patterns and invasion in these native systems, we quantified basal area (BA) and densities of woody species and understory cover at nine sites in the Puna district on the Island of Hawai‘i, representing age gradients of native stand development on both ‘a’ā and pāhoehoe lava flows. On both flow types, BA of native species increased (from 5 to 50 m2/ha) and stem densities decreased (from 3700 to 2600 stems/ha) with increasing stand/flow age. Both native and introduced species compositions diverged between substrate types on older flows. We found that lowland wet native forests remain at least partially intact in several locations, but their functional and compositional integrity is increasingly compromised by invasion of nonnative species, such as Psidium cattleianum and Melastoma candidum, which become more common at sites greater than 300‐yr old. This time period may represent a threshold, after which abiotic environmental conditions no longer constrain recruitment of introduced species. On older flows, nonnative stem densities swamped those of native species by an order of magnitude, with nonnative stems (height > 1.3 m) achieving densities as high as 18,000 stems/ha. In addition, all stands lacked recruitment of native woody species in the understory, suggesting that without management, the native componentsof these forests may soon no longer be self‐sustaining.