Hughes Flint, Vitousek Peter M
Department of Biological Sciences, Stanford University, 94305, Stanford, CA, USA.
Oecologia. 1993 Apr;93(4):557-563. doi: 10.1007/BF00328965.
Introduced grass species have invaded extensive areas of Hawaii Volcanoes National Park and increased the size and frequency of fire. Following fire, grass cover is enhanced while native shrub cover is reduced; the reduction in most shrubs persists for at least 20 years even in the absence of fire. Shrub seedlings were planted in burned and unburned plots with and without grass cover. Biomass of 14 month old shrub seedlings was generally highest in recently burned/grass removed plots, intermediate in old burn/grass removed plots, and lowest in unburned/grass removed plots. In contrast, shrub biomass in plots with grass cover was low and did not differ significantly among burn treatments. Light competition is likely to be responsible for differences in shrub growth rates; grass cover reduced light to 1-10% of background levels. In addition, pool sizes of available soil N were highest in recently burned, intermediate in old burn, and lowest in unburned areas.
外来草种已侵入夏威夷火山国家公园的大片区域，并增加了火灾的规模和频率。火灾后，草地覆盖度增加，而本地灌木覆盖度降低；即使在没有火灾的情况下，大多数灌木的覆盖度降低也会持续至少20年。在有草覆盖和无草覆盖的已烧毁和未烧毁地块中种植灌木幼苗。14个月大的灌木幼苗生物量通常在最近烧毁/除草地块中最高，在旧烧毁/除草地块中居中，在未烧毁/除草地块中最低。相比之下，有草覆盖地块中的灌木生物量较低，且在不同火烧处理之间没有显著差异。光照竞争可能是灌木生长速率差异的原因；草覆盖将光照降低到背景水平的1%至10%。此外，有效土壤氮的库容量在最近烧毁区域最高，在旧烧毁区域居中，在未烧毁区域最低。
