The extent and pattern of Eucalyptus regeneration in an agricultural landscape

The process of natural regeneration is critical for sustaining remnant native vegetation and the ecosystem services it supports. We quantified the extent and pattern of Eucalyptus regeneration within remnant vegetation in a fragmented agricultural landscape in south-eastern Australia. Eucalyptus regeneration was absent at 42% of sites. Using an information-theoretic approach, we explored 13 possible models of Eucalyptus regeneration across multiple scales. The explanatory variables in the four models with empirical support (and their summed Akaike weights) were: grazing intensity (1.0), native ground cover (0.99), remnant area (0.83), tenure (0.67), canopy cover (0.21) and vegetation type (0.11). Averaging across these four models we predicted that the probability of Eucalyptus regeneration was highest (0.95) in relatively unmodified remnant native vegetation, that is, remnant vegetation on public land where grazing was light and the understorey was dominated by native plants. In contrast, the predicted probability of Eucalyptus regeneration was lowest (0.12) in small remnants on private land where grazing was heavy. Our results suggest that a large proportion of all remnant native vegetation in this landscape will disappear under existing land management and farming practices. Reducing grazing pressure within intensively grazed remnants appears to be the single most effective management intervention that will mitigate this threat. This will require a shift in conservation priorities away from large, intact remnants where regeneration does not appear to be affected, to poorer quality remnants—often small remnants or scattered trees—where regeneration is typically absent.     

Visual aspects in urban woodland management

This paper presents a study of woodland management guidelines analysed for their inclusion of visual aspects. The aim of the study was to identify approaches towards the management of visual aspects in urban woodland. For the study, 24 management guidelines from Sweden and the UK were reviewed for scale, degree of operational detail, the visual concepts used, their emphasis and justification. The review revealed that there exists a diversity of approaches towards managing visual aspects regarding the selection and emphasis of visual concepts as well as the scale at which they are applied and degree of operationality. Some general differences between Sweden and the UK where identified. These differences in treatment of visual aspects were mainly related to the use of different scale levels, different levels of abstraction and the basis for justifying the importance of visual qualities in management. These differences are discussed in relation to the wider management context, including landowner structure, landscape history and forestry traditions. We conclude that studying urban woodland management in another context (e.g. geographical and historical) can provide new insights for visual management. We also believe that transferring management strategies across cultures will result in them being altered at the policy and operational levels by the change of context. We further suggest that the use of visual concept could provide one approach for better integration of visual qualities in urban woodland management.     

Management styles and knowledge cultures, past, present and future, related to multiple-use and urban woodlands

This paper is based on interviews with fifteen professionals within ecology, forestry and park and landscape architecture. The interviewees are believed to have had a large influence on woodland planning in Sweden between 1950 and 2000. They have won recognition because of their ability to transform theoretical knowledge into practical action. Their work is translating theory into practice and, as such, it may be regarded as art in its deepest sense. During a long period the educational system as well as the dominating research has been concentrating on providing better facts in a search for the best knowledge, high degrees of generality and objectivity. However, this may cause many disadvantages. It has lead to a standardisation and an oversimplification of knowledge and thereby also to an oversimplification of the landscape. This study is based on a humanistic approach, on theory of knowledge, of how facts coming from the world of natural sciences can be encapsulated in daily woodland management.     

科尔沁沙地家榆林的种子散布及幼苗更新

家榆是典型的风播植物,在科尔沁沙地可以形成单一优势种林地.通过对林缘和孤立树不同方向从树基部向外的有序取样与林下和林窗的随机取样调查,分析了家榆林下和林窗不同生境的种子沉降和幼苗分布特征、林缘和孤立树种子散布方向的差异性与规律性.结果表明,家榆种子密度在林下生境阴坡和阳坡明显大于丘顶和丘底,在林窗生境丘顶明显大于丘底.家榆向周围不同方向种子散布的距离和累积数量均有较大差异,其中林缘和孤立树均以当地多逆风频率的西南方向最近,累积数量也最少;孤立树以多顺风频率的东北方向最远,累积数量也最多.林缘和孤立树共6个方向断面从树基部向外单位面积种子数量频度均适合于韦伯分布和对数-正态分布(X2(a)＜0.500)密度函数,具有相同的种子散布格局.家榆幼苗密度在林下阴坡明显大于阳坡,林下和林窗均为丘顶明显大于丘底.林缘19 m内家榆幼苗呈连续分布.在科尔沁沙地,如果不加限制或人为扰动,家榆林不仅可以很好地进行自然更新,而且可以在适宜的沙地生境逐渐扩大其分布空间.     

水约束下乌兰察布盟林草植被的需水量分析

乌兰察布盟地处中国北方农牧交错带,属于干旱半干旱地区,水资源短缺已成为该地区生态环境修复和经济发展的重要制约因素。文章对该地区水资源特点及存在问题进行了分析,采用统计年鉴资料计算出其草地和林地面积,并分别采用水量平衡法、定额法求出草地和林地植被需水量为120.63亿m3,生态缺水10.83亿~11.37亿m3;据此提出了该地区基于生态需水的林草植被建设措施。     

Interactions of an introduced shrub and introduced earthworms in an Illinois urban woodland: Impact on leaf litter decomposition

This study examined an ‘invasional meltdown’, where the invasion of a Midwestern woodland by an exotic shrub (Rhamnus cathartica L.P. Mill) and the invasion by Eurasian earthworms facilitated one another. Using a litterbag approach, we examined mass loss of four substrates (R. cathartica, Acer saccharum, Quercus rubra, and Quercus alba) along a gradient of Eurasian earthworm density and biomass throughout a 40.5 ha oak woodland in Glencoe, Illinois. Earthworm densities and biomass were greatest in patches where R. cathartica prevailed, and populations were lowest in an upland forest subcommunity within the woodland. At each of three points along this earthworm gradient, we placed replicated litterbags constructed either to permit or to deny access to the litter by earthworms. The treatments were, therefore, plot treatments (low, medium and high earthworm density and biomass) and litterbag treatments (earthworm access and earthworm excluded). We found that earthworms promoted a very rapid loss of litter from R. cathartica bags. Within 3 months greater than 90% of this litter was lost from the litterbags. Earthworm impacts on other substrates followed the sequence A. saccharum>Q. alba=Q. rubra. Effects of both litterbag and plot treatments were found within 3 months for A. saccharum but Quercus species were affected only after a year. We propose that the impact of earthworms on litter breakdown creates conditions that promote and sustain invasion by R. cathartica. Previous work has demonstrated that R. cathartica may alter soil properties in a way that promotes and sustains invasion by earthworms. These findings have implications for the restoration management of these systems, since the legacy of R. cathartica on soil properties and earthworm populations may persist even after the plant has been physically removed.     

马尾松林地土壤物理性质变化及抗蚀性研究

以退耕黄壤坡地为对照，对18年生黄壤马尾松林地土壤主要物理性质变化进行了系统研究，在此基础上对林地土壤抗蚀性能进行了分析。结果表明：马尾松林地演变为具有复层结构的针阔混交林后，土壤物理性粘粒含量和粉粒含量有所提高，土壤表层粘粒含量和不同层次的砂粒含量降低；土壤容重减小，总孔隙度、毛管孔隙度和非毛管孔隙度有一定程度的提高，土壤自然含水量、饱和持水量和毛管持水量增大，林地土壤持水性和透水性得到了提高，土壤结构得到显著改善；林地土壤干筛团聚体以5～2mm大团聚体为主，湿筛团聚体则以1～0．5mm细团聚体为主，且在0～20cm，20～40cm，40～60cm的土壤剖面中均高于对照地。马尾松林地微团聚体变化的总趋势是〉0．01mm的粗粉沙粒级的大团聚体减少，而〈0．01mm的微团聚体含量增加，尤其是0．005～0．001mm的细粉沙粒级；马尾松林地土壤物理性质的变化也综合反映在抗蚀性能方面，在0～20cm，20～40cm，40～60cm三个土壤剖面层次其抗蚀性均高于对照地，表现了良好的水土保持效应。     

林地外部效应及其评估与补偿研究——以浙江省温州茶山森林公园为例

林地的外部效应最为典型，具有存在的普遍性、完全收益权实现的困难性、消费的非排他性等特点，其成因是收益收溢，价格为林地的额外收益价格和外溢收益价格的代数和，有关法律对外部效应的补偿巳作规定，以浙江省温州茶山森林公园为例，研究了林地外部效应评估和补偿问题，指出了调控林地外部效应意义重大。     

森林草莓转录因子MYB 12基因克隆及蛋白特性分析

采集森林草莓(Fragaria vesca)植株叶片,TRIzol法提取样本总RNA,设计特异性引物RT-PCR扩增转录因子MYB 12基因,获得1条约1 kb大小的特异性片段,克隆并测序。序列分析表明,该片段序列全长988 nts,含有完整的MYB 12基因开放阅读框(ORF),ORF长度为855 nts,编码285个氨基酸。序列比对发现,森林草莓MYB 12基因与来源于5种蔷薇科植物MYB基因的序列相似性较高,为75%~76%,而与其他7种非蔷薇科植物MYB基因的序列相似性相对较低,为47%~68%。构建MYB基因系统关系树,发现森林草莓与其他5种蔷薇科植物的MYB基因聚成一个分支,说明森林草莓与蔷薇科植物亲缘关系较近。生物信息学分析表明,MYB 12蛋白具有一定的亲水性,其N-端有2个MYB结构域,属于R2R3-MYB亚族。MYB 12蛋白二级结构主要以α-螺旋为主,并含有一些不规则的卷曲(Random coil)结构。这为研究该基因在植物生长发育及生理代谢过程中的调控机制奠定了基础。     

广西钟山县林地功能分区及差别化管理探讨

根据钟山县的自然环境条件,结合县域林地保护利用基本情况,将全县林地划分为东北部水源涵养及水土保持林区、西北部针叶用材林及乡土阔叶林发展区、中部石漠化综合治理区、南部工业原料林及特色经济林区共4个功能区,对各区域林地保护利用方向、规划目标以及差别化管理措施进行探讨,并提出严格保护林地,保护北部生态屏障区、江河沿岸及重要水源区,加强中部石漠化地区综合治理,支持重大基础设施用地布局等建议。