灵石山米槠林优势树种不同年龄叶片养分特征

Nutrient characteristics of uneven-aged leaves for dominant species with a Castanopsis carlesii forest in Lingshishan National Forest Park

植物叶片养分特征能反映植物对环境的适应能力,逐渐成为生态学研究的重点和热点问题之一。对福建省灵石山米槠林Castanopsis carlesii优势树种不同年龄叶片的养分特征进行分析表明:米槠林优势种不同年龄叶片的养分符合对数正态分布。将优势种按养分对数的平均值和标准差分为4类,结果优势种各种养分处于第2分类等级的较多;厚叶冬青Ilex elmerrilliana对磷,青冈栎Cyclobalanopsis glauca对锌有较强的"排斥"效应(处于第1分类等级);鹅掌柴Schefflera octophylla对钾,狗骨柴Diplospora dubia对钠和钾,围涎树Pithecellobium clypearia和石栎Lithocarpus glaber对氮有明显的"累积"效应(处于第4分类等级);不同年龄叶片对同种养分的"累积"效应不尽相同,优势种2年生叶片养分对数大于平均值即处于第3分类等级的比例大于1年生叶片。优势种米槠较低的叶片养分表明它对于贫瘠的立地环境适应性较强。此外,厚叶冬青、青冈栎分别较低的磷、锌表明它们可以耐受这种养分缺乏的生境,可能是贫瘠环境下造林的适合树种。

Reflecting its adaptability to the environment, leaf nutrient characteristics have been a key point in ecological research field. Very few data were available on nutrient characteristics of subtropical evergreen broad-leaved forest species. This research analyzed nutrient characteristics for uneven-aged leaves of a Castanopsis carlesii forest in Lingshishan National Forest Park of Fnjian Province. Based on means and standard deviations of logarithmic concentrations for each nutrient, nutrient concentration of each dominant species were classified into four classes. The different classes are as follows： （1） the logarithmic nutrient concentration falls below the mean value minus 2 standard deviation （X-2SD）o （2） the nutrient concentration falls between （X-2SD） and X; （3） the nutrient concentration lies between X and （X ＋ 2SD） ; （4） the nutrient concentration is above （X ＋ 2SD）. Tree species whose logarithmic concentration of a nutrient falls below the （X-2SD） value is an ＂excluder＂ for that particular nutrient, while if above the （X ＋ 2SD） value, it is an ＂accumulator＂ species for that nutrient. The results showed that leaf nutrient content had a log-normal distribution with most dominant populations located in the second classes. Strong exclusion was noted with P in Ilex elmerrilliana and with Zn in Cyclobalanopsis glauca. Accumulation of K in Schefflera octophylla, Na and K in Diplospora dubia, and N in Pithecellobium clypearia and Lithocarpus glaber were found. However, with uneven-aged leaves, accumulation Of two-year-old leaves in the third group were more plentiful than one-year-old leaves. Low nutrient content of leaves for Castanopsis carlesii showed it could grow in a hardscrabble site, and low P in leaves of I. elmerrilliana and low Zn in leaves of Cyclobalanopsis glauca meant they could tolerate thishabitat and could be suitable tree species for afforestation. [Ch, 3 fig. 3 tab. 31 ref. ]