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61.
茶园土壤氮素组分变化影响茶园土壤供氮能力和氮素循环.以植茶30、50和70 a的茶园土壤为研究对象,探讨不同植茶年限土壤氮素组分变化特征及其与理化性质和酶活性之间的关系.结果表明:①随着植茶年限的增加,粉粒、全磷、脲酶和过氧化氢酶活性逐渐增加,砂粒、黏粒、pH、电导率、有机碳和蔗糖酶活性逐渐降低,碱性磷酸酶活性先增加后降低,土壤含水量和酸性磷酸酶活性无显著变化.②随着植茶年限的增加,酸解性铵态氮、氨基酸态氮和硝态氮含量显著增加,且茶园土壤全氮、酸解性铵态氮、未知态氮和非酸解氮含量显著高于林地.③全磷、碱性磷酸酶和脲酶是土壤氮素组分变化的主要影响因子.其中,有机氮组分与全磷、碱性磷酸酶活性具有显著相关性,无机氮组分与碱性磷酸酶活性具有显著相关性,全氮与砂粒、粉粒、全磷、脲酶和碱性磷酸酶活性具有极显著的相关性. 相似文献
62.
Abhishek Mandal 《Journal of environmental science and health. Part. B》2016,51(3):192-203
The aim of this study was to establish the bark of Eucalyptus tereticornis L. (EB) as a low cost bio-adsorbent for the removal of imidacloprid and atrazine from aqueous medium. The pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD) models were used to describe the kinetic data and rate constants were evaluated. Adsorption data was analysed using ten 2-, 3- and 4-parameter models viz. Freundlich, Jovanovic, Langmuir, Temkin, Koble–Corrigan, Redlich–Peterson, Sips, Toth, Radke–Prausnitz, and Fritz-Schluender isotherms. Six error functions were used to compute the best fit single component isotherm parameters by nonlinear regression analysis. The results showed that the sorption of atrazine was better explained by PSO model, whereas the sorption of imidacloprid followed the PFO kinetic model. Isotherm model optimization analysis suggested that the Freundlich along with Koble–Corrigan, Toth and Fritz-Schluender were the best models to predict atrazine and imidacloprid adsorption onto EB. Error analysis suggested that minimization of chi-square (χ2) error function provided the best determination of optimum parameter sets for all the isotherms. 相似文献
63.
Poplar plantation has the potential to alter the water balance in semiarid Inner Mongolia 总被引:2,自引:0,他引:2
Burkhard Wilske Nan Lu Long Wei Shiping Chen Tonggang Zha Chenfeng Liu Wenting Xu Asko Noormets Jianhui Huang Yafen Wei Jun Chen Zhiqiang Zhang Jian Ni Ge Sun Kirk Guo Steve McNulty Ranjeet John Xingguo Han Guanghui Lin Jiquan Chen 《Journal of environmental management》2009
Poplar plantation is the most dominant broadleaf forest type in northern China. Since the mid-1990s plantation was intensified to combat desertification along China's northwestern border, i.e., within Inner Mongolia (IM). This evoked much concern regarding the ecological and environmental effects on areas that naturally grow grass or shrub vegetation. To highlight potential consequences of large-scale poplar plantations on the water budget within semiarid IM, we compared the growing season water balance (evapotranspiration (ET) and precipitation (PPT)) of a 3-yr old poplar plantation (Kp3) and a natural shrubland (Ks) in the Kubuqi Desert in western IM, and a 6-yr old poplar plantation (Bp6) growing under sub-humid climate near Beijing. The results showed that, despite 33% lower PPT at Kp3, ET was 2% higher at Kp3 (228 mm) as compared with Ks (223 mm) in May–September 2006. The difference derived mainly from higher ET at the plantation during drier periods of the growing season, which also indicated that the poplars must have partly transpired groundwater. Estimated growing season ET at Bp6 was about 550 mm and more than 100% higher than at Kp3. It is estimated that increases in leaf area index and net radiation at Kp3 provide future potential for the poplars in Kubuqi to exceed the present ET and ET of the natural shrubland by 100–200%. These increases in ET are only possible through the permanent use of groundwater either directly by the trees or through increased irrigation. This may significantly change the water balance in the area (e.g., high ET at the cost of a reduction in the water table), which renders large-scale plantations a questionable tool in sustainable arid-land management. 相似文献
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Using historical ecology to reassess the conservation status of coniferous forests in Central Europe
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Péter Szabó Petr Kuneš Helena Svobodová‐Svitavská Markéta Gabriela Švarcová Lucie Křížová Silvie Suchánková Jana Müllerová Radim Hédl 《Conservation biology》2017,31(1):150-160
Forests cover approximately one‐third of Central Europe. Oak (Quercus) and European beech (Fagus sylvatica) are considered the natural dominants at low and middle elevations, respectively. Many coniferous forests (especially of Picea abies) occur primarily at midelevations, but these are thought to have resulted from forestry plantations planted over the past 200 years. Nature conservation and forestry policy seek to promote broadleaved trees over conifers. However, there are discrepancies between conservation guidelines (included in Natura 2000) and historical and palaeoecological data with regard to the distribution of conifers. Our aim was to bring new evidence to the debate on the conservation of conifers versus broadleaved trees at midelevations in Central Europe. We created a vegetation and land‐cover model based on pollen data for a highland area of 11,300 km2 in the Czech Republic and assessed tree species composition in the forests before the onset of modern forestry based on 18th‐century archival sources. Conifers dominated the study region throughout the entire Holocene (approximately 40–60% of the area). Broadleaved trees were present in a much smaller area than envisaged by current ideas of natural vegetation. Rather than casting doubt on the principles of Central European nature conservation in general, our results highlight the necessity of detailed regional investigations and the importance of historical data in challenging established notions on the natural distribution of tree species. 相似文献
68.
论炼山对杉木人工林生态系统影响的利弊及对策 总被引:25,自引:2,他引:25
随着杉木人工林面积的不断扩大,杉木人工林地力衰退问题日益严重,而炼山是导致杉木人工林地力衰退的主要原因之一。本文在国家“七五”攻关子课题《炼山对杉木幼林生态系统影响机理及计量评价研究》连续10a定位研究成果的基础上,对国内外有关炼山对采伐剩余物、水土流失、土壤肥力、杉木生长影响等问题进行全面阐述,同时对炼山利弊问题进行归纳与总结,并提出相应对策,这对变革传统杉木经营制度、可持续利用南方山地资源具有重大指导意义。 相似文献
69.
冯建社 《辽宁城乡环境科技》1998,18(3):8-9
本世纪五十年代以来,对企业绿色赋有防污的要求,本文地防污绿化的概念及要求进行了论述,为工矿的绿化工作提供了科学依据。 相似文献
70.
J. V. Savva E. A. Vaganov 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):269-290
Scots pine provenance trials were established in 1964 in forest-steppe and in 1974 in southern taiga zones of Central Siberia
from seeds collected over whole Russia. Tree-ring characteristics (radial growth and density chronologies) from 12 and 16
provenances planted in those plantations were measured densitometrically. Tree-ring analysis revealed a retention of a genetically
fixed response to climatic factors proper to pines' origin. Trees from higher latitudes keep the orientation towards accelerated
growth at the beginning of a growing season, which is followed by a rapid transition to formation of latewood cells and deceleration
of growth earlier, than in medium-latitude trees. Main climatic factors controlling tree-rings formation differed slightly
between different provenances within plantations. Genetically fixed ability of the provenances are not great (less than 15%),
that proves high adaptability of pines to abrupt climatic change. Tree-ring formation of Scots pine provenances is mainly
determined by the environmental factors. 相似文献