鼎湖山异龄马尾松针叶长度序列元素分布

 利用植物体元素化学分析结果来诊断环境污染对森林健康影响和监测环境污染程度已成为诸多生态学家和环境学者广为采用的方法之一。该研究选择广东肇庆鼎湖山健康马尾松(Pinus massoniana)前年生针叶和当年生针叶为研究对象, 将相同年龄针叶分为叶尖、 叶中、叶基等长3段, 分析了两种针叶全S、全P、K、Mg、Na、Ca、Al、Mn、Zn、Cu、Fe、Pb、Cr、Cd和Ni15种元素及相应Ca/Al值在叶尖、叶中部、叶基部和叶鞘的分布模式。结果表明: 前年生针叶元素平均值除全S、全P、K和Cd外, 其它元素浓度都高于当年生针叶, Ca/Al 值则是当年生针叶小于前年生针叶, 表明当年生针叶受Al毒大于前年生针叶; 在针叶长度序列不同部位间, 元素分布不均匀, 全S、Na、Ca、Al和Mn在两种针叶长度序列上没有显著性 差异, K、Mg、Zn、Fe、Cr、Cd、Ni和Ca/Al值差异均达显著水平, 而全P、Cu、Cd和Pb仅在前年生针叶不同部位间差异显著; 针叶Al浓度和Ca/Al值都表明马尾松已经处于严重Al毒胁迫下; 两种针叶各部位Fe、Zn和Cu浓度远超出该地区马尾松元素的背景值, 暗示马尾松针叶已受到严重重金属毒害; 马尾松叶鞘Fe、Cu、Zn、Pb、Cd、Ni和Cr含量显著高于针叶其它部位, 表明叶鞘能累积环境重金属, 可以作为马尾松在污染环境下遭受重金属危害指标加以利用, 是一种有广泛应用前景的生物指示物。该研究所采用的技术和方法对环境监测, 尤其是对利用生物化学方法评价环境污染对森林健康影响评价体系的完善和生物监测指标的利用具有指导意义, 可为今后评估相似环境污染地区森林健康和树木正常生长提供参考。

DISTRIBUTION OF ELEMENTS ALONG THE LENGTH OF DIFFERENT AGED NEEDLES OF PINUS MASSONIANA AT DINGHUSHAN

Chemical analysis of plant tissues, such as in pine trees, is a frequently used method to evaluate the changes of forest health caused by air pollution. Pine needles also have been used widely as bioindicators of atmospheric pollution due to their wide distribution and easy identification. However, the results of whole needle analysis may ignore differences in elemental concentrations in particular needle parts. To date, only limited research has described the concentrations of different elements in various parts of needles injured by pollutants. Masson pine (Pinus massoniana) is a pioneer species widely spread throughout Southern China. Six separate trees were selected from Dinghushan, Guangdong Province and cut down. The healthy looking current year (C) and previous year (C+1) needles were separated from branches at the upper, middle and lower crown. The needles were cut into three sections, defined as tip section (T), middle section (M) and base section (B), proportional to the needle length. The sheath (S) of each needle-age group also was collected. All parts of the different-aged needles were dried and ground for chemical analysis of the elements, total S, total P, K, Mg, Na, Ca, Al, Mn, Zn, Cu, Fe, Pb, Cr, Cd and Ni. The Ca/Al ratios of each needle component were calculated. The mean concentrations of the elements in the C+1 needles were higher than in the C needles, except for total S, total P, K and Cd which were not significantly different, whereas the Ca/Al ratios were lower. The elements were unevenly distributed along the length of the needles. The total S, Na, Ca, Al and Mn did not show significant differences among the different needle sections whereas K, Mg, Zn, Fe, Cr, Ni and the Ca/Al ratios differed statistically among the different sections of the C and C+1 needles. The total P, Cu, Cd and Pb were significantly different among the sections in the C+1 needles only. The element patterns along the needles were mainly caused by air pollution. The needles were under Al stress as determined by the Al concentrations and Al/Ca ratios, especially in the base section. Values of Al and/or Ca/Al ratios in the base of the needle potentially can be used as an early diagnostic index of Al toxicity. Concentrations of Cu and Pb in the area were far above background values for Masson Pine needles implying that excessive heavy metals might damage the needles. Concentrations of Fe, Cu, Pb, Zn, Cd, Ni and Cr in the needle sheath were significantly higher than in the other three sections of the needle suggesting that the needle sheath might be a better bioindicator of those elements than other needle parts. The results of this study and the techniques employed constitute a new contribution to the development of biogeochemical methods for environmental monitoring. These methods may be of value for follow up studies aimed at the assessment of municipal and industrial pollution.