巨枝人工林灌木层优势种的种间联结性分析

种间联结的研究对于人工林群落的生物多样性保育和可持续经营与管理具有重要的意义,目前对巨桉人工林灌木层物种之间的作用关系知之甚少。根据野外60个样方的调查数据,运用x^2检验、Jaccard指数和Spearman秩相关系数研究了巨桉（Eucalyptusgrandis）人工林灌木层18个优势种的种间关联和相关关系。结果表明,灌木层优势种具有总体上的正联结性,但在153个种对中,具有显著正联结性的种对数约占总种对数的10％,绝大数种对表现为弱联结性或无联结性,种间关系较为松散,表明巨桉林下灌木种群具有相对独立分布的特性。研究种间关系时,种间关联结合种间相关得出的结果较好。根据分析结果将18个优势种划分为4个生态种组,生态种组内的种其资源利用方式和生态要求相似,而组间表现出明显的差异。生态种组的划分能为巨桉人工林林下灌木层的管理提供理论依据。     

海南热带橡胶园土壤易氧化有机碳空间变异特征研究

为了解热带橡胶园土壤活性有机碳状况,采集了海南全岛13个不同胶园土壤,用高锰酸钾氧化-比色法测定了土壤易氧化有机碳质量分数,分析了其影响因素。结果表明,海南橡胶园土壤易氧化有机碳质量分数平均为2.70 g.kg-1（以C计）,变化在0.92~6.82 g.kg-1之间,变幅达到641%。易氧化有机碳质量分数与土壤有机质、全磷和全氮显著正相关,同时受成土母质的强烈影响,玄武岩发育的土壤最有利于易氧化有机碳累积,砂页岩和花岗岩次之,而变质岩和浅海沉积物形成的土壤易氧化有机碳质量分数较低。土壤易氧化有机碳质量分数也受气候强烈影响,随湿度降低而下降。     

不同栽杉代数根际土壤肥力及生物学特性变化

通过对位于南平溪后安曹下和邓窠２９ａ龄１代、２代、３代实生杉木的根际养分、微生物、酶及生化活性的为期２ａ的研究,结果表明：随杉木连栽代数增加,根际微域土壤酸化趋势增强,有机质和全氮沉积量下降,速效性养分亏缺程度减弱,根际土壤中三大类微生物所占的比例发生一定的变化,真菌和放线菌所占比例增加,细菌所占比例减少,生理类群数量下降,除接触酶活性变化不大外,其它土壤酶和生化活性均有明显下降,体现了杉木多代连栽根际土壤的基本特征;亦是杉木连栽导致地力衰退重要原因之一     

重庆四面山杉木林优势种群径级结构与空间分布格局

种群空间格局分析有利于更好地理解格局形成的潜在生态过程。本研究以重庆四面山杉木林为研究对象,采用单变量和双变量函数分析了样地中杉木林主要种群的空间分布格局以及种群间的空间关联性。结果表明:(1)四面山杉木林共调查到乔木65种、灌木31种、草本20种。杉木种群径级结构呈衰退型,表现为以大树为主,中树次之,无小树;腺萼马银花、元江栲、细枝柃等种群径级结构呈增长型,表现为以小树、中树为主,大树次之。(2)在0~25 m尺度内,杉木种群呈随机分布,栲和元江栲呈聚集分布,而腺萼马银花、细枝柃、光叶山矾和长蕊杜鹃等4个种群则在小尺度下呈聚集分布,随着尺度的增大,呈现出随机分布的趋势。(3)生物学特性以及生境因子的差异导致杉木林主要种群间空间关联差异较大,杉木与元江栲和腺萼马银花种群之间呈负相关,而与光叶山矾、栲和长蕊杜鹃种群呈无相关,因此,在该区杉木纯林的近自然改造上,应优先考虑竞争力强的乡土树种,如长蕊杜鹃、栲、光叶山矾等进行混交。     

Poplar plantation has the potential to alter the water balance in semiarid Inner Mongolia

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.     

不同恢复年限刺槐林土壤碳、氮、磷含量及其生态化学计量特征

地处西秦岭山地的甘肃天水吕二沟小流域土壤侵蚀问题严重,上世纪五六十年代开始,当地政府在研究区实施了多年的生态恢复措施以保持水土,但目前尚未有植被恢复对土壤生态计量特征的系统调查.分析不同林龄人工林土壤碳、氮、磷含量及其生态化学计量特征可在一定程度上揭示土壤养分的限制情况.选取黄土丘陵沟壑区不同生长年限(5、20、40、...     

Using historical ecology to reassess the conservation status of coniferous forests in Central Europe

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.     

论炼山对杉木人工林生态系统影响的利弊及对策

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。     

浅谈企业防污绿化

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。     

Genetic and Environmental Effects Assessment in Scots Pine Provenances Planted in Central Siberia

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.