广州城市林带森林群落的生物化学吸储效应

为了科学地计量、评估城市森林的生态效应,采用群落生态学和植物化学监测的研究方法,对广州市城市典型林带森林群落地上年增生物量及吸储C、N、S、Pb、Cd、Cu、Hg的生态效应进行了定位观测研究,结果表明:6年生林带森林群落地上生物固碳量平均达39.6t.hm-2,年均生物量增加13.7t.hm-2、年净吸储CO223.5t.hm-2;群落地上生物吸储氮、硫的质量分别达到299.1、63.9kg.hm-2,高出3年生林分的11.8倍以上;换算成地上生物年均吸储NO2、SO2质量分别为162.3、20.3kg.hm-2,分别是3年生林分的5.3、5.5倍;群落对痕量元素Pb、Cd、Cu、Hg的吸储效应同样是6年生林分较高。6年生林带森林群落地上树干中有机C、Cu、Pb、Cd的储量分布占器官总储量的37.0%以上,C接近60%。同时,枝中C、Cu、Cd元素的质量储量较叶高,而群落的叶中N、S、Hg的质量储量显著高出树干、树枝,占地上器官总储量的44%以上,表明6年生林带森林群落叶体吸储这3种元素的单位含量较高,即这些元素向叶体的生理迁移积累速率较高。城市林带森林群落的吸储效应可有效地减少这些元素可能随地表径流输出至生活环境的危害,缓解在土壤中长期积累而构成的污染负荷,对于城市环境区域非常有益。

Bio-absorption and Reserves of Urban Forest Community in Guangzhou

Annual increase of biomass and bio-reserve of elements in woodland of typical urban forest communities was studiedby means of the community ecology aimed to estimate ecological effects of urban forests in Guangzhou. Result indicatedthat bio-fixed mass of C, N and S in woodland reached 39.6 t · hm~(-2), 299.1 kg · hm~(-2) and 63.9 kg·hm~(-2) respectivelyfor the 6-year-old forest community, which was 11.8, 5.3, and 5.5 times higher than that of the 3-year-old forest community.Mean annual biomass and converted mass of CO_2, NO_2, SO_2 in woodland were remarkable and increased by 13.71·hm~(-2)and 23.5 t·hm~(-2), 162. 3 kg· hm~(-2), and 20. 3 kg·hm~(-2) respectively in the same forest. The fixed weight of C,Cu, Pb and Cd in trunk accounted for 37.0 percent of the total and C was close to 60. 0 percent in the 6-year-old forestcommunity. Moreover, fixed weight of N, S and Hg in leaf occupied 44.0 percent of that of all the aboveground organs inthe same forest, which was a useful token of high transfer velocity of elements in the ecosystem. The bio-fixed effect couldeffectively decrease the burthen of habitat because these elements form pollution along with surface runoff in the urban forest.And the eco-effect is very beneficial for the urban environment.