地中海灌木丛中两种优势物种在实验性干旱和变暖条件下的生长变化对比
Contrasting growth changes in two dominant species of a Mediterranean shrubland submitted to experimental drought and warming.
作者信息
Llorens Laura, Peñuelas Josep, Estiarte Marc, Bruna Paula
机构信息
Unitat d'Ecofisiologia CSIC-CEAB-CREAF, CREAF (Center for Ecological Research and Forestry Applications), Edifici C, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain.
出版信息
Ann Bot. 2004 Dec;94(6):843-53. doi: 10.1093/aob/mch211. Epub 2004 Oct 5.
BACKGROUND AND AIMS
Climate projections predict drier and warmer conditions in the Mediterranean basin in the next decades. The possibility of such climatic changes modifying the growth of two Mediterranean species, Erica multiflora and Globularia alypum, which are common components of Mediterranean shrublands, was assessed.
METHODS
A field experiment was performed from March 1999 to March 2002 to prolong the drought period and to increase the night-time temperature in a Mediterranean shrubland, where E. multiflora and G. alypum are the dominant species. Annual growth in stem diameter and length of both species was measured and annual stem biomass production was estimated for 1999, 2000 and 2001. Plant seasonal growth was also assessed.
KEY RESULTS
On average, drought treatment reduced soil moisture 22 %, and warming increased temperature by 0.7-1.6 degrees C. Erica multiflora plants in the drought treatment showed a 46 % lower annual stem elongation than controls. The decrease in water availability also reduced by 31 % the annual stem diameter increment and by 43 % the annual stem elongation of G. alypum plants. New shoot growth of G. alypum was also strongly reduced. Allometrically estimated biomass production was decreased by drought in both species. Warming treatment produced contrasting effects on the growth patterns of these species. Warmer conditions increased, on average, the stem basal diameter growth of E. multiflora plants by 35 %, raising also their estimated stem biomass production. On the contrary, plants of G. alypum in the warming treatment showed a 14 % lower annual stem growth in basal diameter and shorter new shoots in spring compared with controls.
CONCLUSIONS
The results indicate changes in the annual productivity of these Mediterranean shrubs under near future drier and warmer conditions. They also point to alterations in their competitive abilities, which could lead to changes in the species composition of these ecosystems in the long term.
背景与目的
气候预测显示，未来几十年地中海盆地将变得更加干燥和温暖。本研究评估了这种气候变化对地中海灌木丛常见组成物种——多花欧石南（Erica multiflora）和沙地金球花（Globularia alypum）生长的影响。
方法
1999年3月至2002年3月，在以多花欧石南和沙地金球花为优势物种的地中海灌木丛中进行了一项田间试验，以延长干旱期并提高夜间温度。测量了这两个物种茎直径和长度的年生长量，并估算了1999年、2000年和2001年的年茎生物量产量。同时评估了植物的季节性生长。
主要结果
平均而言，干旱处理使土壤湿度降低了22%，增温使温度升高了0.7 - 1.6摄氏度。干旱处理下的多花欧石南植株年茎伸长量比对照低46%。水分可利用性的降低还使沙地金球花植株的年茎直径增量减少了31%，年茎伸长量减少了43%。沙地金球花的新梢生长也大幅减少。两个物种的生物量产量经异速生长估算后均因干旱而降低。增温处理对这些物种的生长模式产生了相反的影响。温暖条件下，多花欧石南植株的茎基部直径生长平均增加了35%，其估算的茎生物量产量也有所提高。相反，增温处理下的沙地金球花植株与对照相比，年茎基部直径生长降低了14%，春季新梢更短。
结论
结果表明，在不久的将来，干燥和温暖的条件会改变这些地中海灌木的年生产力。研究还指出其竞争能力会发生改变，从长期来看可能导致这些生态系统的物种组成发生变化。
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