Sheet Mulching as an Aid to Broadleaved Tree Establishment: I. The Effectiveness of Various Synthetic Sheets Compared

In two experiments growth of ash (Fraxinus excelsior L. ) andhornbeam (Carpinus betulus L. ) transplants was greatly increasedby various synthetic sheet mulches. Killing the weeds with herbicidesbefore laying the mulches increased tree growth a little. Clearpolythene gave the highest soil temperatures and reduced ashsurvival. However, soil temperature appeared to have littleeffect on tree growth, tree growing well despite the low soiltemperatures induced by aluminium foil. The ability of the mulchto remain intact and resist weed invasion was more importantthan soil temperature. Opaque mulches were found to be preferableto translucent ones, since weeds grew beneath the latter anddislodged them. Tree growth was better with impermeable thanpermeable translucent mulches: it is suggested that this differencewas related to the mulches ability to retain moisture transpiredby the weeds beneath them. Practical recommendations for sheetmulching are made.     

The Concept of Actual and Potential Production as an Aid to Forest Management

The environmental and biological factors which influence treegrowth are analysed to provide a concept for estimating thepotential production of a tree crop on any site. Some of thefactors which influence growth cannot be controlled by management,and therefore set an upper limit to the growth which shouldbe possible. This is termed the Management Potential Production.The idea of considering the actual tree growth on a site asbeing some fraction of the potential, rather than as a basison which to improve, is discussed in relation to the managementand research implications.     

无边界可溶数据库技术初探——以贵州省息烽、修文两县长防林工程信息管理为例

自然资源管理具有数据量大,数据种类多,数据之间包溶性强的特点。采用何种数据库技术才能适应这些特点,使资源管理行为回归到以数据库为中心的管理模式,本文为此提出了“无边界可溶数据库技术”。通过对两个县长江防护林工程信息管理系统建立近60万个数据的数据库技术处理过程证明,“无边界可溶数据库技术”对于资源管理实践有很大的指导作用,对于决策分析有不可替代的地位。