树木对重金属的抗性机理研究进展

土壤重金属污染问题是当今世界较为严重的环境问题之一。树木生物量高,根系发达,一般不进入食物链,一些树木对环境中重金属具有较强的吸收和积累作用,防止土壤金属污染的扩散。为了深入探索树木应对重金属污染的抗性机理,笔者主要从根系分泌物、内生细菌与菌根、螯合作用、抗氧化系统以及区室化作用等方面综述了近年来,尤其是近5年来树木应对重金属的抗性机制研究进展,发现由于重金属对于树木毒害作用的多方面性,树木重金属抗性机理具有复杂性,因此许多机理仍不清晰,今后还需要利用不断更新的技术手段,研究其不同抗性机理的协同作用,对其机制进行更深入系统的研究。最后,笔者展望了通过生物技术手段的改造,将树木应用于环境修复的前景。     

不同林龄杉木林下套种阔叶树对土壤磷组分的影响

套种是杉木人工林经营的重要措施,磷是南方森林生态系统中主要限制性养分元素之一,但套种模式对土壤磷素的影响尚不明确。以亚热带杉木人工林表层(0-10 cm)土壤为对象,研究套种林(杉阔套种幼林、杉阔套种成熟林)和杉木幼林土壤理化性质和土壤各形态磷含量差异,分析套种对杉木人工林土壤磷含量的影响。结果表明:(1)不同套种林显著改变土壤总磷、土壤总无机磷、土壤总有机磷、土壤微生物生物量磷(MBP)和土壤酸性磷酸酶活性(APA),大小顺序均为杉阔套种成熟林>杉阔套种幼林>杉木幼林。(2)土壤各磷组分中活性磷含量较低,其中NaHCO3-Po在活性组分中占主导;土壤NaOH-Po是中等活性磷的主要组分,杉阔套种成熟林尤为显著;闭蓄态磷(Residual-P)在总磷含量中最高。(3)与杉木幼林相比,杉阔套种成熟林显著增加了树脂提取态磷(Resin-Pi)、碳酸氢钠提取态有机和无机磷(NaHCO3-Pi、NaHCO3-Po)、氢氧化钠提取态有机和无机磷(NaOH-Pi、NaOH-Po)、氢氧化钠残留提取态有机磷(NaOHu.s-Po)、盐酸提取态磷(HCl-Pi)和闭蓄态磷(Residual-P)含量;土壤总无机磷、NaHCO3-Po、HCl-Pi、NaHCO3-Pi、NaOHu.s-Pi和Residual-P对杉阔套种幼林的响应不敏感。(4)除含水率外不同林龄下杉阔套种林土壤磷形态与土壤理化性质(土壤总碳氮、土壤可溶性有机氮、土壤微生物生物量磷、酸性磷酸酶)呈正相关性(P<0.05)。冗余分析表明,土壤磷组分的变化主要受MBP调控,且MBP与有机磷组分(NaOHu.s-Po、NaOH-Po)和HCI-Pi呈显著正相关。总之,套种林的土壤磷素有效性高于杉木幼林,土壤养分状况更佳。     

The propagation of Ramón (Brosimum alicastrum Sw.; Moraceae) in Mayan homegardens of the Yucatan peninsula of Mexico

In the Yucatan peninsula of Mexico, Maya natives have been propagating important species for centuries. However, little documentation exists of these methods, and traditional knowledge is fading as younger generations seek work in urban centers. With growing interest in using some of these species for plantation-scale production, this knowledge should be captured to aid in propagation and cultural methods of selected species. One such species, Ramón (Brosimum alicastrum Sw.), is grown in Mayan homegardens primarily as a source of dry season forage. We conducted a survey of Mayan families in several municipalities to determine basic propagation habits and procedures for cultivating Ramón, and used this information to conduct some controlled-environment studies of reproductive ecology of the species. Our survey showed that all or most Maya grow the Ramón tree in homegardens for forage and that the tree is both cultivated from wild seedlings as well as planted on a small scale. Propagation is by seed and young seedlings are irrigated until they are established. We examined the effects of temperature on seed germination and found that maximum germination occurred between 27° and 38 °C, with best germination and growth of healthy seedlings at 33 °C. No germination occurred below 21° or above 44 °C. Simulated Maya irrigation gave a four-fold increase in growth rate of seedlings, aiding early establishment. Watering gave seedlings of greater biomass, greater stem and root length, and greater numbers and size of leaves. This magnitude of response may provide an economic return for plantation culture of Ramón for forage production.     

行道树对重金属污染的响应及其功能型分组

为了筛选出交通污染监测树种,本文选择南京市有代表性的绿化树种作为研究对象,利用化学分析方法和生理指标测定法,在交通要道和城郊稀疏交通区的不同环境下,对14个树种叶片中的重金属(Pb、Cd、Cu)含量和生理指标(可溶性蛋白、游离脯氨酸和丙二醛)变化进行了分析。结果表明:交通要道重金属含量显著高于城郊稀疏交通区,表明交通污染的影响显著;在可溶性蛋白、游离脯氨酸和丙二醛含量方面,交通要道总体高于城郊稀疏交通区,这可能是对交通污染的响应。根据生理指标和重金属变化幅度,紫叶李、雪松和杨树适合交通污染监测,并根据树种重金属累积量的相对差异百分比对其进行功能型的划分。     

果树在城市园林景观营造中的应用

从果树在园林中应用的历史与现状出发,针对果树景观花、果、叶、树形、文化景观等构成要素,提出了果树在城市园林景观营造中的应用原则,包括适地适树,充分发挥果树的生态效益,提高造景搭配的韵律感和艺术性,使用特色性果树品种。探讨了果树在道路绿地、居住区绿地、公园绿地、观光果园等不同园林绿地中的应用,举例说明不同类型树种的适用范围。最后列举出果树在园林中应用所需注意的问题,为进一步在城市园林景观中应用果树提供借鉴。     

Interactions of formal and informal knowledge systems in village-based tree management in central India

This study critiques the idea of a Western science -- indigenous knowledge dichotomy in agricultural knowledge by examining the hybrid nature of knowledge use and incorporation by villagers in Madhya Pradesh, India. By analyzing knowledge systems as multi-leveled structures consisting of concrete practices linked to more abstract, explanatory concepts, this paper illustrates how information from multiple sources is integrated into local bodies of knowledge about tree management. Practices such as urea fertilization from formal global science might be explained by concepts such as that of a hot/cold duality from informal folk science. Similarly, other pieces of knowledge stemming from diverse knowledge systems are shown to become mixed and matched on practical and conceptual levels. Additionally, several knowledge elements used locally appear to be held in common by many knowledge systems around the world, rendering the determination of their origins in one system or another nearly impossible. These observations lead to the conclusion that local knowledge systems of tree management are better characterized as open systems rather than distinct, closed systems. Furthermore, the constant exchange of material between formal and informal, local and global systems renders untenable any strict dichotomy of knowledge systems.     

东兰县森林立地类型的划分及退耕还林树种设计

以东兰县的宜林地为研究对象,参照德国的巴登-符腾堡和美国的巴恩斯等为代表的森林生态因子学派的理论和方法,采用典型抽样的样地调查及总结森林经营经验的方法,研究东兰县森林立地类型的划分及退耕还林树种的设计.结果表明,东兰县森林立地类型共划分为5个类型小区、6个类型组、15种立地类型:退耕还林地主要分布在5、7、8、9、10、11、13等7种立地类型上,退耕还林的3个功能治理区设计主要营造板粟、八角和喜树3种树种.研究将为东兰县退耕还林的林分经营管理提供理论依据.     

行道树国槐不同形态重金属富集效能研究

[目的]揭示不同形态重金属在行道树国槐各器官的富集特征。[方法]采用改进BCR连续提取法对北京市蓝靛厂北路旁的土壤和国槐的叶片、树枝、树皮、树干与树根中Cr、Ni、Mn、Cu、Zn、Cd和Pb等7种重金属元素进行提取,并用ICP-MS测定各形态重金属浓度。[结果]结果表明:树皮中7种重金属元素浓度最高,重金属元素在树根向树干、树干向树枝和树枝向树叶的迁移均以酸溶态为主。树皮和树干为重金属元素的主要贮存器官;重金属元素在叶片中以相对活跃的酸溶态存在。国槐对不同形态重金属的富集效能大小依次为:可氧化态可还原态酸溶态残渣态;国槐对7种重金属的平面富集效能和空间富集效能分别达到372.90 mg·m~(-2)和45.48 mg·m~(-3)。[结论]国槐各器官的重金属浓度存在显著差异;重金属元素在国槐体内的运输以酸溶态为主;重金属元素以相对稳定形态贮存在树皮和树干;国槐对可氧化态重金属的有效净化效率高于其他形态。     

Precipitation as the most affecting factor on soil–plant environment conditions affects the mycorrhizal spore numbers in three different ecological zones in Turkey

Mycorrhizal symbiosis is the one of the most important relationship between microbiota and plants to sustain plant nutrition in relatively unfavourable conditions. Somehow this relation is threatened by time, therefore, definition of the factors effecting mycorrhizal symbiosis has become essential. The aim of this study was to determine the differences in specific mycorrhizal parameters such as sporulation and soil–plant environment conditions in three different regions of Turkey. During 1996?2002, 53 soil series were selected from natural and agricultural plant communities in three different agro-ecological zones of Turkey: Central Anatolia (CA), the Southeastern Anatolian (SA) project area and the Coast of Mediterranean (CM). The arbuscular mycorrhizal fungus (AMF), spore numbers and mycorrhizal root colonization were related to the annual average precipitation, soil characteristics and host plant identity.

In the CM zone (average annual precipitation of 650?mm), soils found under natural vegetation contained a maximum value of 108?spores?g^?1, with bare soils containing a minimum number of 0.1?spores?g^?1. In the CA zone (330?mm annual average precipitation), the maximum number of spores in the soil samples was 46.5?spores?g^?1 with a minimum of 6.8?spores?g^?1 and in the SA soil samples (380?mm annual average precipitation), a maximum of 48.4?spores?g^?1 and a minimum of 14.2?spores?g^?1 were recorded. The overall mean number of mycorrhizal spores g^?1 soil was 15.5?±?14.4, 22.2?±?8.6 and 27.9?±?25.4 for the CA, SA and CM zones, respectively. Mean spore numbers differed in only two of the three zones, with the third zone being intermediate. Precipitation was the most affecting factor on the sporulation of AMF. Also host plant species and certain soil parameters, such as positive correlations with CaCO₃ and N-min and a negative correlation with organic matter, have an influence on sporulation.

The key finding is that the cropping system has a large impact on spore numbers/abundance. Seventeen standing crops as well as bare soil, fallow and natural areas were compared. There are a large number of factors which can affect mycorrhizal development; in the present work, it seems that soil and crop management, and environmental factors (such as precipitation) affect sporulation and root colonization. Covering land surface with mycorrhiza-dependent cover crop, irrigation and less soil till may increase indigenous mycorrhizal spores.     

基于灰色关联的北京城区景观乔木树种评价

以北京市城区主要35种乔木树种为对象,从树木个体的景观美学角度去选择评价指标,用灰色关联度分析法对现有乔木树种进行景观美学评价,按照灰色系统理论关联度分析原理,关联度大的数列与参考数列最为接近,通过各树种每个景观指标的关联度大小,可以明确各树种的优劣.加权关联序结果表明,雪松、银杏、腊梅、悬铃木、梅花、元宝枫、垂柳、山...