Clearance of understory in urban woodlands: Assessing impact on bird abundance and diversity

Clearance of understory to enhance the recreational value of the forest is common in urban woodlands. Open forests are generally perceived as safe and pleasant, but clearance is likely to be negative for woodland birds as the shrub layer is important for foraging and protection. In this 3-year experiment with a before after control impact (BACI) design, the effects from understory clearance on woodland bird abundance and diversity in five suburban broadleaved forests in south-western Sweden were studied. Understory clearance was either made in regular patches, with 50% removal of understory, or as “Complete” (90%) removal. Adjacent stands of equal size were left unmanaged as controls. Woodland birds and understory vegetation were surveyed before and after the management. The total density of breeding forest birds decreased in the plots with “Complete” removal of the understory compared to plots with “Patchy” clearance. “Patchy” clearance had no significant effect on bird density. Bird diversity was not affected by the management. Woodland birds are highly valued animals in urban green areas and the impact on bird fauna should therefore be taken into consideration in the development of management plans for urban woodlands. The present study has demonstrated that clearance of understory can have negative effects on bird abundance if carried out over large areas. Clearance in patches was not found to have negative effects on bird abundance and can promote recreational values by increasing visibility and structural variation of the forest.     

集体林分权条件下的林地细碎化程度及与农户林地投入产出的关系——基于江西省8县602户农户调查数据的分析

以江西省8个县602户农户调查数据为基础,运用定量统计方法,分析集体林分权条件下的林地细碎化程度、农户投入水平及与林地产出的关系,以验证集体林权制度改革后的农户林地细碎化经营是否具有经济合理性.实证结果表明:以S指数衡量,江西省样本县林地细碎化的程度达到0.55,受访农户林地细碎化程度与地貌特征之间未出现明显的关联性;以户均数据衡量,受访农户从家庭收入中用于林业投资的比例维持在30％左右,且传统林业重点县的农户林业投入比例要明显高于非林业重点县.计量模型计算结果表明,S指数衡量的林地细碎化程度对农户林业投入和林地产出水平均构成负向影响趋势;曲线模型临界值分析表明,当农户林地细碎化程度低于0.23或高于0.69时,农户投资林业的积极性则随着林地细碎化程度高低呈现正向变化趋势,当林地细碎化程度低于0.22或高于0.67时,林地细碎化程度对林地产出水平表现为负向影响趋势.     

Carbon sequestration and biodiversity of re-growing miombo woodlands in Mozambique

Land management in tropical woodlands is being used to sequester carbon (C), alleviate poverty and protect biodiversity, among other benefits. Our objective was to determine how slash-and-burn agriculture affected vegetation and soil C stocks and biodiversity on an area of miombo woodland in Mozambique, and how C stocks and biodiversity responded once agriculture was abandoned. We sampled twenty-eight 0.125 ha plots that had previously been cleared for subsistence agriculture and had been left to re-grow for 2 to ∼25 years, and fourteen 0.25 ha plots of protected woodlands, recording stem diameter distributions and species, collecting wood for density determination, and soil from 0 to 0.3 m for determination of %C and bulk density. Clearance for agriculture reduced stem wood C stocks by 19.0 t C ha⁻¹. There were significant relationships between period of re-growth and basal area, stem numbers and stem biomass. During re-growth, wood C stocks accumulated at 0.7 t C ha⁻¹ year⁻¹. There was no significant difference in stem C stocks on woodlands and on abandoned farmland 20–30 years old. Soil C stocks in the top 0.3 m on abandoned land had a narrower range (21–74 t C ha⁻¹) than stocks in woodland soils (18–140 t C ha⁻¹). There was no discernible increase in soil C stocks with period of re-growth, suggesting that the rate of accumulation of organic matter in these soils was very slow. The re-growing plots did not contain the defining miombo species, and total stem numbers were significantly greater than in woodland plots, but species richness and diversity were similar in older abandonments and miombo woodlands. Wood C stocks on abandoned farmland were capable of recovery within 2–3 decades, but soil C stocks did not change on this time-scale. Woodland soils were capable of storing >100 t C ha⁻¹, whereas no soil on a re-growing area exceeded 74 t C ha⁻¹, so there is a potential for C sequestration in soils on abandoned farmland. Management should focus on identifying C-rich soils, conserving remaining woodlands to protect soil C and preserve defining miombo species, and on investigating whether fire control on recovering woodland can stimulate accumulation of soil C and greater tree biomass, and restore defining miombo species.     

加强林地林权管理 筑牢林业发展根基——在全国林地林权管理工作会议上的讲话

全面提高对林地林权管理的认识；明晰产权，落实林地保护利用规划，构建林地林权管理的制度体系和长效机制；不断强化责任意识，把林地林权管理落到实处。     

城市森林规划中的城市森林分类——以新疆阿克苏市为例

文章以阿克苏城市森林规划为例,提出了城市森林规划"二分法",论述了其必要性和应采取的分类原则,并详述了"二分法",即针对用地的林地分类和针对树木的植被分类的具体应用。       

城市森林游憩需求特征分析——以武汉市居民为例

通过对729位武汉市居民的问卷调查,发现城市居民的森林游憩需求十分旺盛,在不同距离、不同类型的旅游地中,更倾向于到城郊尤其是城区边缘区生态环境好、森林集中分布的区域进行森林游憩活动;居民希望城市森林进行适度游憩开发,提供良好的旅游服务设施和体现森林生态特色的活动项目。调查结果对于城市生态建设、城市森林游憩地的规划与开发具有现实意义。     

珠海市城区林地管理与集体林权制度改革

介绍珠海市城区林地管理和收入情况,以及林业生态建设现状.阐述城区森林资源林权制度历史沿革和管理情况.分析城区集体林地不适宜进行集体林权制度改革的原因,包括城区农业人口已全部转为城镇居民;林地主要为生态公益林地;历次林改不彻底,林地纠纷多等,并提出了将其转变为国有林地经营和管理的途径.     

Woodland Management and Public Good Outputs: Appraising the Trade-offs in English Woodlands

This paper examines the trade-offs between woodland management for timber and public good outputs in English woodlands. Recent evidence suggests that some public good values may be declining as a result of a lack of woodland management. Such under-management has been attributed to the decline in timber values and reduction in the productivity of woodlands and forests for timber products. It is argued that assessing the management needs of woodlands in order to enhance public good outputs presents a complex challenge and often depends on a variety of factors, including location, type of woodland, age, condition, substitutability and ownership motivation. However, in most instances a moderate level of management (whether for timber or otherwise) is likely to be beneficial for public good outputs.

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。     

Forestry in Nottinghamshire

Forestry in Nottinghamshire is best known for its historicalassociations with the old Royal Forest of Sherwood. The historyof the County's woodlands is described against the backgroundof its physical geography and human development. The part played by the Forestry Commission and other landownersin the past and present management of woodlands is described.The high population density of the County produces a numberof pressures on woodland but also provides a number of positivemanagement opportunities. The future development possibilities for forestry in the Countyare discussed with reference to these and other influences.     

集体林区林地产权制度改革途径研究

林地产权制度改革是实现林业可持续发展的需要。本文在分析集体林区林地产权制度缺陷的基础上,提出了林地产权制度改革途径。     

Efficiency of inventory plot patterns in quantitative analysis of vegetation: a case study of tropical woodland and dense forest in Benin

The main issue in forest inventory is the reliability of data collected, which depends on the shape and size of inventoried plots. There is also a need for harmonisation of inventoried plot patterns in West Africa. This study focused on the impact of plot patterns on the quantitative analysis of two vegetation types of West Africa based on case studies from Benin. Twenty and fifteen plots of 1 ha each were demarcated in dense forest and woodland, respectively. Each 1 ha plot was divided into 100 quadrats of 100 m² each and diameter at breast height (dbh) of trees was recorded in each quadrat. The required time to measuring trees diameter in each 1 ha plot was also recorded to compute the mean inventory effort. From the 100 quadrats in each 1 ha plot, 14 subplots of different shapes and sizes were considered by grouping together adjacent quadrats. The basal area of each subplot was computed and the relationship between estimation bias of the basal area and the size of subplots was modeled using Smith's Law (Smith 1938). The mean absolute error of the shape parameter c of Weibull distribution was computed for each of the subplot shape, size and direction. The direction and shape of subplots did not influence significantly (P > 0.05) the precision of the quantitative analysis of vegetation. However, square subplots were suitable in practice. On the contrary, plot size was significantly (P < 0.05) and inversely correlated to estimation efficiency. The optimal plot size for quantitative analysis of vegetation was 1 800 and 2 000 m2 with an inventory effort of 0.51 and 0.85 man-days per subplot in woodland and dense forest, respectively. It is concluded that use of standard sample sizes will help to harmonise a forestry database and to carry out comparisons at regional level.     

人工诱导阔叶红松林改良土壤效果分析

文章通过比较不同类型红松针阔混交林和红松纯林的林分枯落物含量、土壤理化性质及土壤酶活性等性状可知,单位面积枯落物总量红松针阔混交林比红松纯林高40%~60%,其半分解的枯落物量均高于未分解的枯落物量,而红松纯林则相反;红松针阔混交林中枯落物的持水量较红松纯林高26%~75%,养分含量明显高于红松纯林;红松针阔混交林土壤理化性质及酶活性都明显优于红松纯林。     

城市游憩林建设

文章对城市园林绿化系统及游憩林的内涵作了介绍,着重从中外对比的角度阐述了作者的观点,强调游憩林建设保护原生植被的重要性并提出有关建议。       

Visualization and landscape laboratories in planning, design and management of urban woodlands

Although participatory approaches are increasingly used in planning and management of urban woodlands, efficient tools are also needed to make the processes work. In urban forest planning impacts of proposed management regimes on aesthetic and recreational values are among the factors that interest the local residents the most. This article explores two potential methods for improving collaborative urban forest planning and design in Europe, based primarily on experience gained in the Nordic countries. The methods relate to the use of (i) computer-based visualization methods and (ii) demonstration forests and landscape laboratories. We suggest that use of both methods may lead to a major enhancement in forest planning and design.     

Private Ownership and Public Good Provision in English Woodlands

There is increasing emphasis on multipurpose forestry within UK national and regional forest strategies, with the aim of co-delivering the social, environmental and economic benefits of woodlands. Private woodland ownership is also changing, with an increase in owners without a farming or forestry background. However, there is little substantive evidence relating to the motivations of private woodland owners and, in particular, their ability and willingness to deliver public goods. A qualitative study is adopted, using semi-structured interviews in three areas in England, to address this theoretical gap. Exploratory findings indicate that private woodland owners have a diverse range of objectives, motivations and management regimes which influence the potential for public good delivery. It is shown that some private woodland owners, such as those less motivated by economic return, may be better placed than others to deliver certain public goods; that conflicts can arise between the provision of recreation and nature conservation, especially in smaller woodlands; and that many private woodland owners are sceptical about becoming involved in grant schemes which may help foster public good provision in the private sector.     

论集体林区林地产权制度变迁的路径

林地产权制度改革是实现林业可持续发展的需要。文中在分析集体林区林地产权制度缺陷的基础上，提出了林地产权制度变迁的路径。     

Farmers’ objectives toward their woodlands in the upper Midwest of the United States: implications for woodland volumes and diversity

This paper reports the results of a study that explores the relationship between farm woodland owners’ stated intentions for owning woodland, and the structure and composition of these woodlands in the states of Illinois, Indiana and Iowa in the upper Midwest of the United States. Data from two sample-based inventories conducted by the USDA Forest Service, Forest Inventory and Analysis (FIA) program were combined for this analysis—the FIA forest resources inventory and the National Woodland Owner Survey (NWOS). We looked for relationships between product value and investment in woodlands, as reflected in volumes and tree quality. We also examined whether measures of diversity reflected specific management focus. Our results partially supported our hypotheses. Woodland-focused ownership reasons were found to have larger volumes and individual tree sizes. We found that a passive woodland ownership reason—that woods were “part of the farm”—generally had lower volumes per hectare. Although we were not able to differentiate between different forest product classes and measures of volume, we did find that those landowners who harvested veneer had more volume than those who harvested for firewood. Woodland owners who salvage-harvested their woodlands—a harvesting reason that is more reactive than proactive—exhibited lower volumes per hectare than those who harvested for more proactive, product-focused reasons. Biodiversity was also found to be related to the ownership focus and harvest intent. Generally, there was lower diversity in overstory species when the woodland was viewed merely as “part of the farm,” when the product harvested was fence posts and when timber was harvested for salvage or land clearing. The small sample size limits our analysis, but we can conclude that focusing the woodland owners on management of their woodlands—regardless of what the specific management goals might be—should increase productivity and biodiversity of those woodlands.

Dynamics of soil carbon stock,total nitrogen,and associated soil properties since the conversion of Acacia woodland to managed pastureland,parkland agroforestry,and treeless cropland in the Jido Komolcha District,southern Ethiopia

ABSTRACT

In the arid, low biomass producing areas of Ethiopia, Acacia woodlands suffered a severe degradation due to exploitation for various uses, and conversion to grazing and cultivated lands. However, little is known on the impact of agricultural land uses on soil organic carbon (SOC), total nitrogen (TN) stocks, and other soil quality indicators. This study was planned to evaluate SOC and TN stock changes under parkland agroforestry (PAF), managed pastureland (MPL), and treeless cropland (TLCL) regimes by considering the remnant protected woodland (PWL) as a reference. We found that SOC and TN stocks were significantly higher in PWL and MPL areas. Conversion of Acacia woodlands to MPL, PAF, and TLCL resulted in the loss of SOC stock by 23, 50, and 56%, respectively. Higher SOC and TN stocks were found under PWL (144.3 Mg ha^?1) and MPL (108.2 Mg ha^?1). Significant changes in available phosphorous (P), exchangeable cations, and cation exchangeable capacity were observed following the woodland conversion to different land use types. Available P was the highest in MPL compared with the other land use regimes. Within the study area, the MPL land use type was the best land management option for protecting SOC and TN soil stocks.     

Recent Changes in the Conservation Value of Woodlands in Rockingham Forest

Surveys of all woodlands within Rockingham Forest, Northants,in 1946 and 1972 show that, whilst the total area of woodlandremains almost unchanged, considerable changes have taken placein woodland distribution, management systems, crop species,and physiognomy. These changes are quantified and their impacton the value of the woodlands for wildlife conservation andfeatures of interest is assessed by reference to criteria relatedto the development of the woods. It is concluded that therehas been a substantial decline in the conservation value ofRockingham Forest woodlands, caused mainly by State forest policyand open-cast mining, and that this decline is likely to continue.