4月5日的愛思唯爾期刊《森林生態(tài)與管理》（Forest Ecology and Management）刊登了美國科學(xué)家的一項(xiàng)最新研究,，他們發(fā)現(xiàn)一種可以使夏威夷相思木生長更快的方法,。大面積的夏威夷相思木林在提供美麗的自然景觀的同時(shí)，還對(duì)水土保持,、維護(hù)生物多樣性及通過碳的儲(chǔ)存和多價(jià)螯合減緩氣候變化等起著積極的作用,。
夏威夷相思木即夏威夷洋槐，是一種非常珍貴的木材,，一直被用來制作高檔的家具和樂器,。隨著農(nóng)業(yè)占地的擴(kuò)張和大面積的砍伐，其覆蓋率越來越低,。早在2002年,，科學(xué)家就開始對(duì)夏威夷相思木進(jìn)行研究,，他們對(duì)于肥料以及疏伐（間伐）對(duì)相思木的影響做了系統(tǒng)的研究，疏伐是為了緩和樹木間的生存競爭和促進(jìn)其生長而采取砍伐一部分樹木的措施,。
經(jīng)過多年的試驗(yàn),，研究人員找到了一種新的適合夏威夷相思木的培育方法。結(jié)果顯示,，用新培育方法的試驗(yàn)林生長很快,，樹木的直徑每年增加1.2倍。此外,，他們還發(fā)現(xiàn)采用該方法并不對(duì)周圍草木以及植被長生不利的影響,，同時(shí)研究表明采取新培育措施對(duì)于鳥類棲息也沒有負(fù)面影響。
研究人員認(rèn)為對(duì)夏威夷相思木幼苗采用新的培育措施不僅可以增加了樹木的成活率,，增加其生長速度,，同時(shí)還兼顧維持了本土健康而完整的生態(tài)環(huán)境。（科學(xué)網(wǎng) 于乃森/編譯）
生物谷推薦原始出處：
（Forest Ecology and Management）,，doi:10.1016/j.foreco.2007.11.019,，Paul G. Scowcroft, Janis E. Haraguchi and David M. Fujii
Understory structure in a 23-year-old Acacia koa forest and 2-year growth responses to silvicultural treatments
Paul G. Scowcroft, a, , Janis E. Haraguchia and David M. Fujiia
Abstract
Restoration of degraded Acacia koa forests in Hawaii often involves mechanical scarification to stimulate germination of seed buried in the soil and to suppress vegetation that competes with shade intolerant A. koa. Resulting even-age stands are gradually colonized by other plant species, but understory structure is poorly quantified, and the effects of management on understory vegetation are unknown. We examined the structure of the dominant understory species 23 years after stand initiation and determined their subsequent 2-year growth responses to silvicultural treatments prescribed to improve growth of koa. Release thinning, chemical control of introduced grasses, and phosphorus fertilization were applied in a split-plot experimental design. Results for DBH and height class distributions indicated that recruitment for most tree species began within a few years of stand initiation. By 23 years understory trees made up only 14% of total stand basal area, but they added greatly to native plant biodiversity. Alien grasses covered 92% of the forest floor and averaged 1.35 Mg ha−1. Of the four most abundant native understory tree species, only shade intolerant Myoporum sandwicense grew faster in response to the treatments. P-fertilizer combined with grass control significantly increased production of the native shrub, Rubus hawaiiensis. Notably, alien grass biomass did not increase in response to thinning, and actually declined in P-fertilized plots. Only, where P-fertilizer was applied were P concentrations of understory leaves elevated. Foliar concentrations of other nutrients were generally unaffected by treatments. Our findings suggest that the conservative silvicultural treatments we used can be applied without adversely impacting the capacity of aggrading A. koa forests to support a diversity of native understory plants. Lack of an increase in alien grass biomass, and in the case of P fertilization, a reduction in grass biomass, indicates that treatments should not increase competition with native species.
