Sheep vegetation management for controlling competing vegetation in young conifer plantations in the central interior of British Columbia,Canada

In British Columbia, sheep vegetation management (SVM) is a relatively new technique; thus, limited data are available for examining its benefits on conifer growth. We collected field data from young mixed-conifer plantations of lodgepole pine (Pinus contorta) and hybrid spruce (Picea glauca × P. engelmannii) in blocks which had been grazed in 2005 and 2006 as well as from ungrazed blocks. Our main objective was to determine if sheep grazing had a significant effect on the growth of hybrid spruce. We measured stem diameter at 15 cm height above the root collar (D15) and cumulative internodal length (IL). Cumulative IL was calculated from the node corresponding to the year 2002–2010 (positions 2–10). The height to diameter ratio (height to the base of the leader (position 10)/D15; HDR) was calculated to determine if seedlings prioritized growth in terms of height or diameter. There was no significant grazing treatment effect on D15 and HDR when compared to the control treatment; however IL was significantly affected after the second grazing treatment in 2006 (position 6) and became increasingly important with time (positions 7–10). Based on our results, we suggest that SVM could be an effective method for controlling competing vegetation and thus, increase annual tree growth for areas with similar site characteristics as those found within the plantations sampled.     

Biogeography of mangrove and saltmarsh vegetation: implications for conservation and management in Australia

Despite an undeserved reputation for being dull and homogenous systems, mangal and saltmarsh in Australia have highly complex patterns and processes. Their role as key edge systems between land and sea has implications for many species which have larval stages in mangal and saltmarsh, but spend adult life as benthic, pelagic or demersal species. Many such species are also important commercially. Mangal and saltmarsh are both highly dynamic systems, reacting rapidly to changes in hydrological condition and sedimentation. In many areas of the world mangal and saltmarsh are threatened systems, especially near human habitation. Appropriate management strategies for mangal and saltmarsh are therefore critical for both conservation and sustainable use, the two key objectives of the Convention on Biological Diversity. Clearing and associated development, invasion of alien species, pollution effects and poor management are the key threats to these systems. Management at a bioregional level, including the development of a comprehensive system of protected areas, is identified as the key management strategy which will ensure an adequate future for these dynamic systems.     

Secondary edge effects in regenerating forest landscapes: vegetation and microclimate patterns and their implications for management and conservation

Forest regrowth is expected to gradually mitigate edge effects in forest landscapes fragmented by timber harvest, but our understanding of edge effect persistence and dynamics over time is still incomplete. Our main objective was to take a critical look at the role of forest regrowth in mitigating the initial edge effects on microclimate and understory vegetation in northern hardwood forests of the eastern United States. We compared canopy closure, hourly air temperature, soil moisture, and understory vegetation at increasing distances from forest edges (0, 5, 10, 20, and 30 m) along twelve transects placed across new and older forest edges (3–4 or 16–19 years old) created by forest harvest. Open, new forest edges exhibited pronounced edge effects on microclimate and shade-intolerant plants, but these were almost completely moderated by forest regrowth on the cleared side of older edges where dense young forest developed with a new canopy comparable in cover to adjacent mature forest. There were no initial edge effects on shade-tolerant vegetation across new forest edges, but the shade-tolerant vegetation declined in mature forest near old forest edges adjacent to dense young forest that supported only sparse understory vegetation. These delayed secondary edge effects of young dense forests on adjacent mature forests have not been previously documented and they should be more explicitly included in forest management considerations. We suggest an integrated system for managing and mitigating both the immediate primary and delayed secondary edge effects in those working forest landscapes where biodiversity conservation is of high priority.     

森林采伐更新作业与林地生产力的维护

根据森林资源可持续发展的要求,分析了采运作业可能引起林地生产力下降的因素,并提出了减缓措施。     

Short-term effects of selection and clear cutting on the shrub and herb layer vegetation during the conversion of even-aged Norway spruce stands into mixed stands

The conversion of even-aged Norway spruce (Picea abies (L.) H. Karst.) stands into more site adapted mixed stands is the main silvicultural goal in Germany and many other European countries. The conversion will primarily be achieved with the help of selection cutting, removing single target diameter trees and creating small gaps. At sites highly susceptible to windthrow, however, small scale clear cutting (up to 1 ha) might be an appropriate alternative. Both selection and clear cutting will affect the understorey vegetation, an important component of forest biodiversity and ecosystem functioning. Thus, with the help of a BACI-experiment (before–after/control–impact), the short-term effects of selection and small scale clear cutting on the herb and shrub layer vegetation were studied at two sites in the Solling Hills (Lower Saxony, Germany). Both treatments led to an increase in herb and shrub layer species numbers, due to persistent and invading (mainly pioneer tree species and indicators of disturbance) species and to a shift in plant traits. Most responsible for the changes in vegetation was a higher light availability, and to a lesser degree soil disturbance. The number of annuals and ruderals, however, increased only immediately after clear cutting, whereas on selection cutting plots the numbers remained high. Gaining in number and coverage were competitive perennials (Epilobium angustifolium, Juncus effusus, Rubus idaeus) especially on the clear cuttings, fulfilling a nutrient retention function. The competitives did not deter tree species from regenerating in the clear cut plots, whereas on selection cutting plots the large expansion of R. idaeus appeared to be hindering tree colonisation. Suffering under clear cut conditions were predominantly shade-tolerant, closed-forest species, but no loss of these species could be detected. This indicates the potential for a fast recovery of these forest species, as soon as, pioneer trees expand.     

山新杨嫩枝扦插繁殖技术的研究

以山新杨半木质化组培枝条为材料进行嫩枝扦插试验，从插穗部位、激素种类、激素剂量、基质种类、插穗叶片留量5个方面进行了研究，结果表明，上述5个因素均对插穗生根及无性苗的发育有很大的影响。     

Therapeutic use of plants by local communities in and around Rema-Kalenga Wildlife Sanctuary: implications for protected area management in Bangladesh

Traditional systems of medicine have become a topic of global importance recently. Increased commercialization of economically important medicinal plants has resulted in overharvesting, threatening their survival. The present study was carried out to document the indigenous uses of medicinal plants by the local communities in and around Rema-Kalenga Wildlife Sanctuary, Bangladesh. Data collection was predominantly qualitative recording the species use, identifying their relative importance (RI) and assessing the informants’ consensus factor (F_ic) on associated knowledge. We interviewed 140 households of the local community and 5 local herbal practitioners. A total of 44 plant species were in use to treat 33 ailments under 10 broad disease categories. Five species were found to have high use versatility (RI > 1), Emblica officinale L. being the most versatile. Respiratory problems scored the highest F_ic value (0.56) involving the use of 30% of the species recorded. Terminalia bellerica Roxb., Sterculia villosa Roxb., Dillenia pentagyna Roxb. and Terminalia arjuna Bedd. were being harvested commercially. Use by the community, particularly for subsistence consumption, seemed to be sustainable, but commercial extraction of some species appeared unsustainable. Buffer zone-based commercial farming of medicinal plants with a commercial value could serve a dual purpose of assuring sustainable alternative income generation for local communities as well as conserving the natural resources in protected areas.     

Woodland vegetation and its implications for archaeological survey using LiDAR

Archaeological surveys in woodland have always been problematicand many woodlands contain an unrecorded archaeological resource.For other types of rural landscape, aerial photographs are oftenused to map archaeological features but woodland cover has alwaysimpeded such disclosure. Remote sensing methods are rapidlyevolving and are used both within forestry and archaeologicaldisciplines for a range of applications. This paper considersthe exciting application of the remote sensing technique ofairborne Light Detection and Ranging (LiDAR) to reveal archaeologicalevidence previously hidden below a woodland canopy. Our researchshows how different types of woodland canopy and understoreyvegetation greatly influence the effectiveness of the LiDARto perform these surveys. A simple, visual vegetation mappingassessment is tested and its ability to predict the potentialof the LiDAR considered. This work highlights the importanceof vegetation awareness when considering both a new LiDAR surveyfor a woodland, and when interpreting the data. Simple estimatesof LiDAR penetration of the woodland canopy and understoreyvegetation can be used to predict the effectiveness of a LiDARsurvey in disclosing archaeological evidence and aid the interpretationof results.     

受冻害桉树林分的切干更新技术

简述了怀化市石门桉树基地的基本情况,分析了基地桉树的冻害程度,并针对受严重冻害桉树林分,提出了切干更新技术措施,其技术要点为:基部切干、开沟施肥、及时除萌、培蔸防折、抚育除草。切干后萌发率高,树势恢复快,效果好。     

关于敖汉旗农田防护林更新采伐年龄的论证

文章根据农田防护林质量和采伐利用现状,通过标准地实测测算出10～28a的每公顷平均生长量,以此确定农田防护林的更新采伐年龄。     

皆伐对杉木林土壤物理性质的短期影响

用环刀采集皆伐半年后的杉木林皆伐迹地土壤剖面0～5、5～10、10～15、15～20、20～25、25～30、30～35、35～40、40～45、45～50、65～70和90～95 cm土层的土样,测定其土壤容重、毛管孔隙度、非毛管孔隙度、总孔隙度和毛管持水量等。结果表明:随着土层深度的增加,皆伐迹地的土壤容重和毛管孔隙度增加,非毛管孔隙度波动性下降,总孔隙度和毛管持水量下降后微升;与杉木林地表土层的土壤相比,皆伐迹地表土层土壤的容重、孔隙度和毛管持水量均有所下降。     

The effect of cutting operation on higher plants diversity

Investigation of higher plant diversity in different age cutovers indicated those diversity indices of herb, xylophyta and advanced plants increased gradually in the cutovers from 1984 to 1994, and diversity indices had obviously positive correlation with richness and evenness.     

浅谈开花竹林的更新

通过对竹子开花的时期、竹子开花后造成竹株死亡以及竹子开花原因的说明,根据以往成功经验,提出抑制或延迟竹子的开花的措施及恢复开花竹林的方法。     

Water relations characteristics of competing singleleaf pinyon seedlings and sagebrush nurse plants

Encroachment of singleleaf pinyon (Pinus monophylla) into adjacent low sagebrush (Artemisia arbuscula) and basin big sagebrush (Artemisia tridentata ssp. tridentata) communities may be enhanced by the efficient use of limited water resources by tree seedlings. Seedlings and sagebrush nurse plants were monitored over two growing seasons to determine water-use patterns. Predawn xylem water potential of low sagebrush declined rapidly, reaching −3.5 to −5.5 MPa by late summer. Big sagebrush values dropped to −2.0 to −3.0 MPa during summer drought. The drop in sagebrush xylem water potential was related to the decline in soil water potential (r=0.68 and 0.82). The change in pinyon predawn xylem water potential was moderate, declining to values of −1.5 to −2.5 MPa. An apparent diurnal threshold xylem water potential (−2.3 to −3.0 MPa) that results in stomatal closure enables pinyon seedlings to maintain a seasonally stable xylem water potential. Water use by pinyon seedlings declined by 50% from May to August in association with a reduction in stomatal conductance. Despite reduced stomatal conductance, sagebrush water use continued to increase during summer and reached levels up to five times greater (per unit leaf area) than associated pinyon. Pinyon seedlings appear to have greater drought avoidance than sagebrush nurse plants.     

Effects of strip wise tillage in combination with liming on chemical and physical properties of acidic spruce forest soils after clear cutting

We investigated the initial effects of strip wise soil loosening (0–35 cm depth) on soil chemical and physical parameters by using a deeply working rotary cultivator in combination with liming and mixing of the dolomite with the soil material of acidic forests. The investigations took place 8 months after the treatment. pH values and contents of exchangeable Ca and Mg increased significantly at the tilled depth whereas the content of exchangeable Al and easily soluble P decreased. The rate of mineralisation increased at this depth which was shown by a loss of Corg, Ntot and short-term loss of NO₃-N. The treatment led to a mobilisation of Mn at the tilled depth. However, the content of exchangeable Pb decreased due to an increased pH value. Below the tillage depth of 35 cm only partly significant changes of exchangeable Mn and NO₃-N were found. The total porosity and bulk density at 10–15 and 40–45 cm depths were not significantly different from those in the control plot, but the rate of infiltration increased significantly.     

塞罕坝落叶松人工林皆伐作业的必要性及可行性分析

作为我国华北地区最大的人工林林场,如何调整和优化人工林林分结构是塞罕坝机械林场一个重要课题,通过分析塞罕坝机械林场森林资源现状,阐述了实施皆伐作业的必要性,探讨了实施皆伐的可行性,提出了迹地更新造林的保障措施,充分肯定了皆伐作业对调整林分结构的重要性。     

沙棘嫩枝扦插的水分管理

介绍了沙棘嫩枝扦插苗木生根过程中的水分管理，可供生产实践参考。