基于GIS的生态脆弱区林地生态适宜性研究

为了探讨生态脆弱区林地生态适宜性评价机制,在对广西南丹县典型样地共41个作业区调查基础上,综合考虑与林地生态适宜性密切相关的地形地貌、土壤、植被等因素,利用ARCGIS分析方法对空间数据进行组织与计算,结合AHP方法研究各参评因子权重,并选择适当的隶属函数和模糊算法对南丹县林地生态适宜性进行模糊综合评判。结果表明：林地生态适宜性各等级比重排序为：III级（45.62%）＞IV级（27.84%）＞V级（17.61%）＞II级（8.93%）＞I级（0%）,整体隶属度值为3.5413,位于IV级水平;影响因子排序为：坡度＞石砾含量＞高程＞土层厚度＞郁闭度＞坡向＞灌木覆盖度＞草本覆盖度。同时,根据研究结果,分析了林地生态适宜性较差的主要原因及生态恢复重建的重点。     

Sage Grouse Groceries: Forb Response to Piñon-Juniper Treatments

Juniper and piñon coniferous woodlands have increased 2- to 10-fold in nine ecoregions spanning the Intermountain Region of the western United States. Control of piñon-juniper woodlands by mechanical treatments and prescribed fire are commonly applied to recover sagebrush steppe rangelands. Recently, the Sage Grouse Initiative has made conifer removal a major part of its program to reestablish sagebrush habitat for sage grouse (Centrocercus urophasianus) and other species. We analyzed data sets from previous and ongoing studies across the Great Basin characterizing cover response of perennial and annual forbs that are consumed by sage grouse to mechanical, prescribed fire, and low-disturbance fuel reduction treatments. There were 11 sites in western juniper (Juniperus occidentalis Hook.) woodlands, 3 sites in singleleaf piñon (Pinus monophylla Torr. & Frém.) and Utah juniper (Juniperus osteosperma [Torr.] Little), 2 sites in Utah juniper, and 2 sites in Utah juniper and Colorado piñon (Pinus edulis Engelm). Western juniper sites were located in mountain big sagebrush (A. tridentata ssp. vaseyana) steppe associations, and the other woodlands were located in Wyoming big sagebrush (A. tridentata ssp. wyomingensis) associations. Site potential appears to be a major determinant for increasing perennial forbs consumed by sage grouse following conifer control. The cover response of perennial forbs, whether increasing (1.5- to 6-fold) or exhibiting no change, was similar regardless of conifer treatment. Annual forbs favored by sage grouse benefitted most from prescribed fire treatments with smaller increases following mechanical and fuel reduction treatments. Though forb abundance may not consistently be enhanced, mechanical and fuel reduction conifer treatments remain good preventative measures, especially in phase 1 and 2 woodlands, which, at minimum, maintain forbs on the landscape. In addition, these two conifer control measures, in the short term, are superior to prescribed fire for maintaining the essential habitat characteristics of sagebrush steppe for sage grouse.     

Arbuscular mycorrhizal associations in Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands of Northern Ethiopia

This study assessed the arbuscular mycorrhizal (AM) status of Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands in relation to season, management and soil depth in Ethiopia. We studied 43 woody species in 52 plots in three areas. All woody species were colonized by AM fungi, with average root colonization being relatively low (16.6% – ranging from 0% to 95%). Mean spore abundance ranged from 8 to 69 spores 100 g⁻¹ of dry soil. Glomus was the dominant genus in all study sites. Season had a strong effect on root colonization and spore abundance. While spore abundance was higher (P < 0.001) in the dry season in all three study sites, root colonization showed a more variable response. Root colonization was reduced in the dry season in the site that was least subject to stress, but increased in the dry season in the harshest sites. Management in the form of exclosures (that exclude grazing) had a positive effect on spore abundance in one of the two sites considered. Spore abundance did not significantly differ (P = 0.17) between the two soil depths. Our results show that in this arid region all trees are mycorrhizal. This has profound consequences for rehabilitation efforts of such dry deciduous woodlands: underground processes are vital for understanding species adaptation to pulsed resource availability and deserve increasing attention.     

陕西省退耕还林工程区植被覆盖度的变化分析

利用MODIS NDVI数据和像元二分模型计算的植被覆盖度,比较分析退耕还林工程区与周边区域、主要土地利用类型、不同坡度耕地植被覆盖度变化程度和趋势。结果表明：（1） 陕西省退耕还林区植被覆盖度从2000年到2011年呈现显著的增长趋势,增长速率高于周边区域;（2） 退耕还林区植被覆盖变化百分率≥10%的面积占79.8%,≤-10%所占面积不及1%;（3） 退耕还林区植被覆盖度显著增加的面积占其总面积的70.6%,显著减少的面积仅占0.1%,植被覆盖度显著增加的情况主要出现在未利用地、草地、林地和耕地,显著和极显著降低的发生在城乡、工矿、居民用地和极少部分耕地;（4） 坡耕地植被覆盖改善比例大,坡耕地植被覆盖改善对于耕地植被改善贡献较大。在陕西省气候呈现暖干化发展趋势背景下,退耕还林区植被覆盖度呈现显著增长趋势,增长速率高于周边区域,坡耕地、林地、草地均比其他类型有明显的增加,退耕还林政策实施区域取得了良好的植被恢复效果。     

Impact of Macrotermes termitaria as a source of heterogeneity on tree diversity and structure in a Sudanian savannah under controlled grazing and annual prescribed fire (Burkina Faso)

Macrotermes termitaria are conspicuous features of savannah ecosystems in the Sudanian and Sahelian zones of West Africa. The mounds, alive or abandoned, are a major source of heterogeneity in the landscape. The purpose of the present study was to assess the impact of termitaria on tree community in a state forest of the Sudanian regional centre (Tiogo forest, Burkina Faso), under controlled burning and grazing experiments. A comparative inventory was carried out in a split-plot experiment (16 subplots of 2500 m²): 8 subplots where fire regime and grazing were controlled and 8 subplots exposed to grazing and with annual prescribed fire since 1992. All tree individuals (≥1.5 m) were recorded, both on termitaria and outside and their basal area at stump level was measured. A total of 61 observed (or 65.7 ± 2.4 estimated) tree species were recorded on 28 Macrotermes subhyalinus mounds (54 observed species or 60.8 ± 3.3 estimated), the immediate surroundings (44 observed and 59.0 ± 0.0 estimated species) and the rest of subplots (56 observed and 63.6 ± 0.0 estimated). Specific density was higher on mounds in comparison with the surroundings (P < 0.05). Results showed that termitaria played a key role in maintaining higher species diversity as compared to their surroundings (P < 0.05). Differences in species diversity between termitaria and immediate surroundings appeared more pronounced in disturbed plots (submitted to both fire and grazing). Some species, such as Tamarindus indica, Boscia senegalensis, Cadaba farinosa, Capparis sepiaria and Maerua angolensis are found solely on termitaria. Besides, the density of trees was significantly higher on termitaria compared to the surrounding (P < 0.05), as well as total basal area per unit of 100 m² area (P < 0.05). We concluded that Macrotermes termitaria play an important role as a source of heterogeneity in this Sudanian savannah woodland ecosystem. This role is particularly important in ecosystems under stresses. Termitaria acted as refuge for tree vegetation. The density and dynamics of M. subhyalinus termitaria should, therefore, be taken into account in the global strategy of the forest resources management and conservation.     

立地条件对落叶松人工林生长的影响

通过对日本落叶松(Larix kaempferi)人工林在不同立地条件下的生长调查,结果表明,日本落叶松在生长过程中,受土层厚度、林地位置、立地指数等多方面因素的制约:厚层土胸径年生长量比中层土和薄层土高9.2%～26.7%,树高年生长量高21.8%～44%;生长在N坡,坡度较缓、山地下腹为优;在不同的立地指数级中,生长差异明显,18以上指数级比14～18指数级胸径生长量高25.4%,比14以下指数级胸径生长量高33.8%,树高生长量,18以上指数级比14～18指数级高26.7%,比14以下指数级高36.3%。培育日本落叶松人工林,选择优质立地条件不但可提高林木的生长速度,又能促使林木优质高产。     

Assessment and up-scaling of CO2 exchange by patches of the herbaceous vegetation mosaic in a Portuguese cork oak woodland

Long-term eddy covariance measurements over a montado oak woodland in southern Portugal have documented a vulnerability to predicted decreases in springtime rainfall, since water availability during spring limits annual CO₂ gain, the growth of fodder for animals, and the production of cork by Quercus suber. The current study examined CO₂ exchange of three different herbaceous vegetation components distributed over montado landscapes and within the footprint of long-term landscape eddy covariance monitoring studies. Simultaneous measurements with eddy covariance at two sites and with manually operated chambers at multiple locations revealed that slow drainage of shallow basins, the onset of drying at higher sites and a high release of CO₂ below tree canopies significantly influenced the overall course of montado ecosystem gas exchange during the spring.Hyperbolic light response models were employed to up-scale and compare herbaceous gas exchange with landscape net ecosystem CO₂ flux. The up-scaling demonstrates the importance of the herbaceous understory in determining annual carbon balance of the montado and suggests a relatively small additional CO₂ uptake by the tree canopies and boles, i.e., by the aboveground tree compartment, during springtime. Annual flux totals obtained during the extremely dry year 2005 and a normal precipitation year 2006 for the oak woodland and a nearby grassland were essentially the same, indicating that both ecosystems similarly exploit available resources. Based on comparisons with additional temperate grasslands, we can visualize the montado herbaceous cover as a typical European grassland canopy, but where temperature fluctuations in winter control uptake, and where total production depends on springtime rainfall as it controls phenological events and eventually dieback of the vegetation. On the other hand, tree canopies remain active longer during late spring and early summer, modifying the montado response from that of grassland. Uncertainties in flux estimates via both chamber and eddy covariance methodologies currently prevent a full understanding of vegetation/atmosphere coupling, of the recycling of CO₂ between the understory communities and trees, and of relationships between exchange rates of individual components of the vegetation mosaic and overall carbon and water balances in montado landscapes.     

Effect of Peat-based Container Media on Establishment of Scots Pine,Norway Spruce and Silver Birch Seedlings after Transplanting in Contrasting Water Conditions

Abstract

Urban woodlands are the subject of complex decision-making that requires a strategic overview of the resource. This article contributes a national study of municipal woodland in Denmark. Data were collected among all Danish municipalities through a postal survey (with a response rate of 52%). As much as 83% of the woodland units were located within urban settlements or at their fringe, emphasising that municipalities are important urban woodland providers. Municipal woodland resources were typically divided into many separate units of varying size. On average, the responding municipalities owned 12.6 woodland units with an allocated area of 265 ha, resulting in a mean size of 21.5 ha. A general lack of management plans, and a significant drop in recreational facilities provided with decreasing woodland size indicate that the recreational use potential of small woodland units was largely overlooked. Municipal woodland units frequently bordered other woodland or nature areas of different ownership. Thus even small municipal woodlands can play a key role in the development of multifunctional green infrastructures in the urban landscape. Only municipalities with extensive woodland property had issued a woodland policy, and/or certified woodland management. This indicates a need for development of governance and strategic management instruments attractive to municipalities with limited woodland property.     

英国古林地研究综述

关于古林地研究在西欧尤其是在英国很受重视。通过对古林地的概念和古林地面积的最小限制,英国制作古林地名录清单的方法以及古林地保护与生物多样性的关系等的介绍,为国内开展古林地研究提供可借鉴的理论依据。     

松嫩平原榆树疏林植物组分的结构型

松嫩平原植被是蒙古、东北、兴安和华北4个植物区系成分相接触的区域，在全区所设的10个榆树疏林调查样地40个样方中，共有89种植物，隶属于26个科，6个株生长型，4个根生长型，6个生活型，4个水分生态类型，13个分布区型和6个饲用价值类型。其中，菊科种类最多，占22．5％；禾本科和豆科分别占15．7％和12．4％。株生长型结构以分枝型种类最多，占39％；直立型和丛生型分别为2l％和16％。根生长型结构以直根型的种类最多，占66％；根茎型和刷状根型分别为17％和16％。生活型结构以地面芽植物最多，占43％；地下芽植物和一年生植物次之，各占15％；地面-地下芽植物占12％。水分生态类型结构以中生型种类最多，占63％；中旱生型次之，占19％。分布区型结构以蒙古-东北-兴安-华北分布区型的种类最多，占30％；蒙古分布区型次之，占16％。饲用价值类型以中、低等质量的种类最多，占46％；优、良牧草种类占31％。松嫩平原榆树疏林具有典型的温带地面芽植物气候、中生生境条件、植物分布区型结构复杂、饲用价值较高的特征。