在25 a生马尾松林下分别套种1 a生火力楠、闽粤栲、苦槠、格氏栲、青栲和拉氏栲等阔叶树种的幼苗,16 a后形成郁闭的针阔混交异龄林.通过定位监测和化学分析,对上述6种混交林类型及林下未套种阔叶树的马尾松纯林的森林凋落量及养分通量...在25 a生马尾松林下分别套种1 a生火力楠、闽粤栲、苦槠、格氏栲、青栲和拉氏栲等阔叶树种的幼苗,16 a后形成郁闭的针阔混交异龄林.通过定位监测和化学分析,对上述6种混交林类型及林下未套种阔叶树的马尾松纯林的森林凋落量及养分通量进行了研究.统计结果显示,6个混交群落的年凋落量分别为7 137.3 kg hm-2、6 741.1 kghm-2、8 041.7 kg hm-2、7 151.3kg hm-2、7 533.2kg hm-2和6 149.1 kg hm-2,而马尾松纯林的年凋落量仅3 442.8 kghm-2.在所有林分的凋落物组成中,枯叶占绝对优势,占凋落物总量的49.7%～71.5%,其余依次为枯枝(5.7%～26.1%)、其它组分(5.5%～17.1%)、树皮(7.7%～18.9%)和果实(0.7%～2.0%).各混交林分中来自马尾松的凋落物占50.4%～58.0%,而来自阔叶树的凋落物占42.0%～49.6%,且两者的组成存在明显差异.各林分总凋落量的季节动态呈双峰型,第1次峰值出现在2～4月份,第2次峰值出现在8、9月份.凋落物中主要养分元素的含量依林分类型、凋落物组分和凋落时间不同而异,N、P、K、Ca和Mg的含量范围依次为3.25～12.98 g kg-1、0.23～0.97 g kg-1、0.42～4.02 g kg-1、7.34～32.57 g kg-1和1.34～5.58 g kg-1.不同的林分类型,凋落物中各养分元素的年通量大小均为:Ca＞N＞Mg＞K＞P.马尾松纯林中,通过凋落物的5种养分元素的年流通量为142.01 kg hm-2;而在林下分别套种上述6种阔叶树后,其养分年流通量依次增加到204.95 kg hm-1、223.93 kg hm-2、304.12 kg hm-2、288.46 kg hm-2、213.77 kg hm-2、238.05 kg hm-2.展开更多
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We inv...Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.展开更多
文摘在25 a生马尾松林下分别套种1 a生火力楠、闽粤栲、苦槠、格氏栲、青栲和拉氏栲等阔叶树种的幼苗,16 a后形成郁闭的针阔混交异龄林.通过定位监测和化学分析,对上述6种混交林类型及林下未套种阔叶树的马尾松纯林的森林凋落量及养分通量进行了研究.统计结果显示,6个混交群落的年凋落量分别为7 137.3 kg hm-2、6 741.1 kghm-2、8 041.7 kg hm-2、7 151.3kg hm-2、7 533.2kg hm-2和6 149.1 kg hm-2,而马尾松纯林的年凋落量仅3 442.8 kghm-2.在所有林分的凋落物组成中,枯叶占绝对优势,占凋落物总量的49.7%～71.5%,其余依次为枯枝(5.7%～26.1%)、其它组分(5.5%～17.1%)、树皮(7.7%～18.9%)和果实(0.7%～2.0%).各混交林分中来自马尾松的凋落物占50.4%～58.0%,而来自阔叶树的凋落物占42.0%～49.6%,且两者的组成存在明显差异.各林分总凋落量的季节动态呈双峰型,第1次峰值出现在2～4月份,第2次峰值出现在8、9月份.凋落物中主要养分元素的含量依林分类型、凋落物组分和凋落时间不同而异,N、P、K、Ca和Mg的含量范围依次为3.25～12.98 g kg-1、0.23～0.97 g kg-1、0.42～4.02 g kg-1、7.34～32.57 g kg-1和1.34～5.58 g kg-1.不同的林分类型,凋落物中各养分元素的年通量大小均为:Ca＞N＞Mg＞K＞P.马尾松纯林中,通过凋落物的5种养分元素的年流通量为142.01 kg hm-2;而在林下分别套种上述6种阔叶树后,其养分年流通量依次增加到204.95 kg hm-1、223.93 kg hm-2、304.12 kg hm-2、288.46 kg hm-2、213.77 kg hm-2、238.05 kg hm-2.
基金This research was sponsored by National Natural Science Foundation of China (Grant No. 39630240 and 3000132).
文摘Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.
