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1.
Philip M. Perrin Fraser J.G. MitchellDaniel L. Kelly 《Forest Ecology and Management》2011,262(12):2328-2337
Changes in ground flora were monitored over a 32-year period in deer exclosures in a yew-wood and a neighbouring oakwood in Killarney National Park, southwest Ireland; both woods are Annex I habitats under the European Habitats Directive. Comparison was made with unfenced plots adjacent to each of the exclosures. During the period of the study, both woods were heavily grazed by introduced sika deer (Cervus nippon). In the yew-wood exclosures, total ground flora cover increased markedly during the period of deer exclusion, the main species to increase in abundance being Rubus fruticosus agg. and Hedera helix. Herbaceous species increased initially in frequency but subsequently declined; herbaceous species had higher total cover in unfenced plots than in fenced plots at the end of the study. In the oakwood, Luzula sylvatica and Vaccinium myrtillus expanded their cover in one exclosure with cover in ferns declining, but in other exclosures where dense holly thickets developed, it was instead R. fruticosus and H. helix that became more abundant within the fences than outside. Overall, long-term fencing has caused a shift from vegetation characterised by woodland specialist to woodland generalist species and there are indications of a long-term decline in diversity. We conclude that chronic heavy grazing in these woodlands has strongly influenced the overall abundance and composition of the ground flora, but that complete exclusion of grazing is also undesirable due to potential declines in diversity of woodland specialists. 相似文献
2.
T. H. Sparks J. N. Greatorex-Davies J. O. Mountford M. L. Hall R. H. Marrs 《Forest Ecology and Management》1996,80(1-3):197-207
During 1985-6 the vegetation in the rides (forest tracks) of eight English lowland woods, planted on ancient woodland sites was surveyed. Shade was measured in each transect by hemispherical photography. Dicotyledonous species richness and the majority of dicot plant species declined as shade increased. The results for individual species compare favourably with Ellenberg's (L) value in most cases, and a method is suggested for modifying Ellenberg's data in the light of new information. The woodlands contained species of both open and shaded habitats and communities were influenced by soil acidity. Because shade in woodland rides increases as the trees mature, theory states that there will almost certainly be a reduction in plant species diversity. Butterfly populations would also be adversely affected, partly because of the reduction in direct sunlight, and partly because their larval foodplants decline in both quantity and quality since they are generally associated with low to moderate shade. 相似文献
3.
研究合肥市区不同功能区景观林组成与结构,共记录102个样方。结果表明:景观林主要组成种有111种,分属45科、81属;主要优势种是香樟、枫杨、水杉、杨树、桂花、石楠等;不同功能区景观林树种相似性系数分别为0.4(公园与居住区)、0.24(高校与居住区)、0.22(公园与高校);林分平均密度560株/hm2,平均基盖度18.83 m2/hm2,平均胸径16.99 cm,平均树高10.13 m,均为正态分布。群落类型可归纳为5个植被型、16个群系及69个群丛,以落叶阔叶型与常绿落叶阔叶混交型为主。建群树种主要有香樟、广玉兰、女贞、雪松、水杉;群落外貌较整齐,树木整体较为健康,景观效果较佳;但层次结构、树种多样性不高,应丰富树种,增加群落的垂直层次,采用近自然经营。
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4.
Althea L. Davies 《Forest Ecology and Management》2011,261(3):751-763
The long timeframes involved in woodland regeneration and adaptation introduce considerable uncertainty into management and conservation planning as most ecological datasets span only a small part of ecosystem dynamics. This is a particular concern in vulnerable habitats, such as Atlantic birch-oak woods in north-western Britain, where range edge populations are at risk from herbivory and climate change. This study combines historical palaeoecology and stakeholder observations to assess how multiple perspectives can inform existing models, expectations and goals for Atlantic woodland management. Long-term evidence for changing woodland composition addresses stakeholder uncertainties over the currently restricted distribution of oak, alder and hazel. Oak has remained a secondary component of birch-dominated woods and habitat definitions based on oak are too narrow to ensure sustainability. Birch has survived numerous periods of climatic and biotic adversity and shows the strongest positive response to historic reductions in grazing pressure. This has led to a pulse of regeneration since c. AD 1900, so current restoration efforts are taking place within the strongest period of woodland expansion in the last c. 500 years. Positive and negative cultural legacies are evident and intervention is considered a necessary restoration tool. Managed grazing at key stages of habitat development can support continued recruitment and regeneration. A more flexible and integrated management approach is recommended. Long-term ecology can provide direction and address uncertainties, while ecological and stakeholder evidence provide the detail necessary to develop effective management that incorporates ecosystem perspectives. This can help shape management strategies that balance possible conflicts over perceived short-term ‘damage’ to secure longer-term processes. Learning based on multiple temporal perspectives has the potential to contribute to conservation and restoration planning and practice. These principles are more widely applicable in adaptive management. 相似文献
5.
Grazing impacts on spatial distribution of soil and herbaceous characteristics in an Australian tropical woodland 总被引：1，自引：0，他引：1
This study examined effects of different levels of applied grazing pressures on herbaceous vegetation (standing crop, basal
area, size and spacing of grass tussocks) and soil properties (total soil C, total N, total P, and soil-borne plant material
[roots and surface litter] in the A horizon) around grass tussocks of a dry eucalypt woodland (dominant woody components;
Eucalyptus xanthoclada and Corymbia erythrophloia of northern Australia. Grass tussocks influenced total soil C and N at small (<20 cm) spatial scales, and applied grazing
pressures significantly (p<0.05) affected all soil properties except total P. Concentrations of N and C were highest at locations close to plants, and
levels in proximity to plants declined under sustained heavy grazing. Paddocks receiving heavier grazing pressures also produced
less standing crop and tussocks were smaller and more widely dispersed. Further, areas with high amounts of soil C, N and
soil-borne plant materials were smaller and more widely dispersed under heavy grazing. Alternatively, conservative grazing
pressure in combination with wet season grazing deferments allowed conservation of landscape condition. Eucalypt woodlands
in northern Australia have low resistance to disturbance, and limited resilience to recover following disturbance. As such,
the effects of disturbance on these areas should be monitored by combinations of plant (basal area, plant spacing) and soil
(soil-borne plant material, total N) characteristics capable of detecting degradation at the earliest stages possible. 相似文献
6.
Establishment patterns of woody species in low intensity-grazed pastures after the cessation of intensive agricultural use 总被引：1，自引：0，他引：1
Low intensity grazing with large herbivores is increasingly used to steer the development of mosaic landscapes (including wood-pastures) and woodland expansion on former agricultural land. We studied the establishment and early growth pattern of woody species in grasslands (formerly used for high intensity summer cattle grazing) in which a low intensity-grazing regime was set up between 4 and 11 years ago. We tested whether the developing vegetation patches, consisting of tall herbs and scrub, influenced this pattern. Further, we investigated if increased susceptibility to trampling disturbance by large herbivores on wet soils in floodplains influenced sapling establishment.Formerly intensively used grasslands were studied at six sites, four in floodplains and two in interfluvial zones on nutrient rich, heavy soils. In total, we sampled 141 plots with grassland, tall herb or scrub vegetation and recorded individuals of established tree and shrub species, their height, diameter, browsing damage and distance to potential seed sources. In the floodplains, we recorded soil disturbance by large herbivores (hoofprints) in wet and moist soils.Sapling frequencies, with Fraxinus excelsior as the most common species (>50% of all individuals), were two to three times higher in tall herb and scrub patches compared to grassland. Only the spiny Crataegus monogyna established in higher frequencies in grassland plots. In floodplains, we found two to three times more established woody saplings in wet tall herb plots, compared to moist and wet grassland plots and moist tall herb plots.Browsing reduced sapling height in grassland and tall herb patches. Only in scrub patches did average height (±2.5 m) reach above the browse line. We found 30–70% less browsing damage to saplings in scrub compared to damage in grassland and tall herb plots. In particular, damage to the apical shoot was strongly reduced.Our findings show that tree establishment occurs in spatial association with non-grassland patches that offer protection against browsing. Fast growing spiny shrubs like Rubus sp. offer protection for palatable saplings, allowing establishment and growing out beyond the browse line. Alternatively, increased establishment occurs in wet tall herb patches, where soil disturbance by moderate trampling favours germination and, subsequently, saplings are protected at least temporarily against browsing by unpalatable tall herbs. 相似文献
7.
Studies of medieval woodland are few and mostly concern theroyal forests. This account of the Chiltern woods thus goessome way towards filling a significant gap. Assarting had ended in the Chilterns by 1300, leaving a patternof woodland that remained basically unchanged for 300 years.Most woods comprised high forest and underwood. Beech was thedominant species, but many woods also contained much oak andash, especially in the north-east. Private and common woodlandshad become distinctive, often after complex transactions. Private woods were especially valued for fuel, sold in the valeand London—n important factor in their preservation. Therewas no systematic management in the extensive woods of the south-westernand central Chilterns, although selective felling was sometimespractised by the late fifteenth century. In the north-east,where timber was limited, coppicing was widely followed by 1400.Common woods, generally more open in character, provided timber,pannage, and herbage for villagers in hill and vale, but commonrights were often restricted. The sixteenth century brought renewed clearing for cultivationand expanding timber sales. Beech, now usually coppice, becameever more prominent, eventually to be converted to high forestwith the rise of the furniture industry after 1800. 相似文献
8.
This paper describes a model for assessing the potential forsustained management of ancient woodland at the local landscapescale, based on the premise that a ‘normal’ foreststructure is the best option for integrating nature conservationwith provision of a regular supply of timber. The concept of‘normality’ is applied to clusters of small ancientwoods which are considered together and treated as a whole. Data on ancient woodland distribution are used from West Sussex,Essex and North Yorkshire. At ten sample points within eachcounty the woodland area within a 25-km2 block centred on thepoint was considered to see whether a normal forest structurecould be created and maintained by sustained management usinglikely minimum felling rates and average rotation lengths forthe main species for both high forest and coppice systems. Themodel was also tested for situations where small woods or woodswith conservation status were excluded from the system, as wellas for different minimum felling rates. The areas proposed forfelling within ancient semi-natural woods currently listed withinthe Woodland Grant Scheme (WGS) (II) are higher than can bemaintained in the longer term in West Sussex and Essex. The model provides a preliminary method for setting the contextof individual forestry schemes withn the wooded landscape asa whole. 相似文献
9.
《林业研究》2017,(4)
Despite the ecological and economic importance of Acacia senegal, little is known about the effects of anthropogenic disturbances on its natural regeneration patterns and population structure. We investigated the effects of these factors within the Lake Baringo woodland ecosystem. Data was collected from 60 plots of 20 m 9 20 m systematically distributed in four A. senegal-dominated populations within the Lake Baringo woodland. Sample populations spanned a degradation gradient measured by a population disturbance index(PDI). Trees were measured for diameter at breast height(DBH) and categorized by growth stages: seedling, sapling and adult tree. Higher seedling and sapling densities were recorded in lightly than heavily disturbed populations, but only sapling density was significantly different between the two disturbance levels(P = 0.02). Lightly disturbed populations revealed a reversed J-shape size-class distribution(SCD) indicative of stable structure unlike the heavily disturbed populations.The quotient and permutation indices indicated unstable populations with episodic recruitment and mortality.Our study reveals that natural regeneration and population structure of A. senegal were affected majorly by selective harvesting and heavy browsing. Suitable management strategies to control livestock grazing and illegal tree harvesting within the woodland is required to promote conservation of the species genetic resources 相似文献
10.
辽西北地区植被分布组成与土地沙化关系的调查 总被引：3，自引：0，他引：3
在辽西北部地区土地沙化调查中,进行的植被调查结果表明,草本植被平均盖度为71.9%。由于草地面积减少与连年干旱的影响,湿生植物、中生植物分布缩小,而旱生植物分布扩大。出现频度最高的植物共20种,其中1年生田间杂草和沙生植物的总出现次数与数量高于多年生禾草和其他多年生植物,为其1.8倍和2.7倍。因此,该区植被退化与土地沙化发展比较强烈。这20种植物中过度放牧和极度放牧沙化植物的出现次数和数量高于适度放牧(包括不放牧)和重度放牧,可知过度放牧和极度放牧,是植被退化与土地沙化的主要因素。蒺藜草的分布频度达25.0%,多度达23.7%,已经成为当地草原的主要害草。 相似文献
11.
Forest and Woodland in Devon 总被引：1，自引：0，他引：1
Based on the 1980 Census, the distribution, composition andownership of woodland in Devon is described. A large proportionof privately-owned woodland is not under formal management andmuch of this is of coppice origin. Although of indifferent timberquality, these woods are considered important features of thelandscape particularly in relation to the Dartmoor NationalPark. Assessment of small woods and park trees suggests a deficiencyof young oak and an increase in colonising broadleaved species. Over much of the county the physical conditions are suited tothe growth of exotic conifers and plantations of these are capableof the economic production of high quality saw timber to satisfylocal and other markets. The scope for expansion is limitedhowever and the future of much of the broadleaved woodland dependson the attitudes adopted by their owners and the local authoritiestogether with the grant aid available. 相似文献
12.
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. 相似文献
13.
《Forest Ecology and Management》1999,113(1):11-21
A methodological approach to the identification of biodiversity indicators in commercial forest stands is illustrated by analysis of the relationships between syrphid (hoverflies) and carabid (ground beetles) community composition and diversity, and stand structure and field layer vegetation. Data were collected from 12 commercial forest sites encompassing a range of climatic conditions and different crop types (Scots pine, Sitka spruce, Norway spruce and Corsican pine) across the UK. Comparisons were also made between unmanaged semi-natural Scots pine woods and Scots pine plantations. For both syrphids and carabids, no differences in species richness and diversity were recorded between semi-natural stands and plantations; one rare syrphid considered to be restricted to semi-natural pine stands was also found in spruce. Syrphid species diversity and richness was higher in southern spruce sites than in the northern sites. Northern sites had distinctive carabid communities, as did sites in the New Forest, a large ancient woodland in southern England. Of the measured habitat variables, vertical stand structure showed the best correlation with species richness and diversity of both carabids and syrphids. Richness and diversity were less in stands with high vertical cover values for canopy layers. Stands with higher field layer cover supported greater syrphid diversity, but lower carabid diversity. Measures of stand structure could be used as potential indicators of syrphid and carabid diversity, but additional habitat parameters also need to be tested. 相似文献
14.
《Forest Ecology and Management》1997,98(3):229-238
The volume of deadwood was estimated in 24 stands within the temperate deciduous woodland of the Lower Wye Valley and the Forest of Dean. The stands were chosen to represent different forms of management and lack of management in woodland on predominantly well-drained sites within a single district. In mature stands which had not been managed for a century, total volumes and size class distributions had reached a level and variety comparable with long-unmanaged old-growth forests in Continental Europe and Eastern North America. In managed stands, including semi-natural mixtures which had formerly been neglected, volumes were generally no more than 30% of these natural levels and usually very much lower. Large well-rotted logs were extremely rare. This variation is reviewed in terms of the history of management in these woods. 相似文献
15.
植被封禁保护是黄土高原植被恢复的重要措施 总被引：4，自引：0，他引：4
概述了黄土高原地区的植被资源现状及分布规律, 分析了该地区实施植被封禁保护(包括封山育林和禁牧、轮牧)的必要性和可行性。对于封山育林和禁牧的实施效果、存在的问题及对策进行了说明。指出黄土高原地区今后的封山育林工作应该向工程化、规范化的方向发展。提出黄土高原天然次生林区应该长期坚持“封山育林为主, 辅之以人工措施”的经营策略。实行封禁保护为主的林区经营方式, 适当辅助以人工促进(抚育、补植等)措施。另外, 在黄土高原以农牧业为主的厚层黄土区和北部草原区等应该实施封山禁牧或轮牧, 提倡舍饲圈养。黄土高原地区的封山育林和禁牧工作要与农村经济发展和产业结构调整紧密结合, 才能长期实行下去。 相似文献
16.
Little is known about the influence of former agricultural use of soils on the forest recovery process in post-agricultural black alder (Alnus glutinosa) woods – the most fertile and the wettest forest habitats among the European temperate forest types. Thus, studies focusing on edaphic, hydrological and light conditions responsible for colonization mechanisms present in such woodlands adjoining ancient ones were undertaken in south-western Poland. In the 16 m2 quadrats of the 33 transects laid out perpendicularly across the ancient-recent forest boundary, data were collected on herb layer composition, chemical soil properties, as well as illumination level. Additionally, groundwater level in the spring months was recorded in piezometers. The number and cover of true woodland herbs were higher in ancient woods, regardless of forest type. Soils in ancient woodlands reached higher levels of Al3+, K+, cation exchange capacity (CEC), available K, P, and organic C, whereas their pH was lower. The illumination level of the forest floor was greater in recent woods. Linear regression showed that recent wood age had a negative effect on pH and base cations, but positive on Fe2+, Ca2+, available P and Mg, CEC, and on C and N contents. CCA results showed that woodland age, pH, humus type, groundwater level, available Mg and K were always among those variables having the highest contribution in explaining the distribution pattern of woodland species in recent woods. Total N and available P contents were always higher in ancient woodland soils than in recent, and their content grew with time. Thus, they cannot be treated as indicators of former agricultural use of recent alder wood soils. Urtica dioica, Poa trivialis and Galium aparine, the three competitive herbs, avoided sites with a high level of groundwater, combined with poor illumination level. In order to create the best possible conditions allowing for effective forest recovery in habitats of such high fertility, it is essential to maintain a good water regime and shade in the forest floor. This in turn reduces the competitive exclusion of woodland flora by the aggressive herbs and facilitates the immigration of typical woodland herbs. 相似文献
17.
Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5- and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5- and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher (P < 0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands. 相似文献
18.
Stephen F. Omondi David W. Odee George O. Ongamo James I. Kanya Damase P. Khasa 《林业研究》2017,28(4):775-785
Despite the ecological and economic importance of Acacia senegal, little is known about the effects of anthropogenic disturbances on its natural regeneration patterns and population structure. We investigated the effects of these factors within the Lake Baringo woodland ecosystem. Data was collected from 60 plots of 20 m × 20 m systematically distributed in four A. senegal-dominated populations within the Lake Baringo woodland. Sample populations spanned a degradation gradient measured by a population disturbance index (PDI). Trees were measured for diameter at breast height (DBH) and categorized by growth stages: seedling, sapling and adult tree. Higher seedling and sapling densities were recorded in lightly than heavily disturbed populations, but only sapling density was significantly different between the two disturbance levels (P = 0.02). Lightly disturbed populations revealed a reversed J-shape size-class distribution (SCD) indicative of stable structure unlike the heavily disturbed populations. The quotient and permutation indices indicated unstable populations with episodic recruitment and mortality. Our study reveals that natural regeneration and population structure of A. senegal were affected majorly by selective harvesting and heavy browsing. Suitable management strategies to control livestock grazing and illegal tree harvesting within the woodland is required to promote conservation of the species genetic resources 相似文献
19.
Species distributions are determined by complex interplays between multi-scale factors. Conservation management, however, often occurs at a single scale of the site level. This is true for bird communities of restored savannas and mixed woodlands in the central U.S. In this region, many historic open-canopy oak savanna habitats have become closed canopy mixed woodlands due to loss of landscape-scale disturbance from fire and grazing. Site-level management efforts return some mixed woodland habitats back to savanna through fire and mechanical thinning. Savanna and woodland historically formed complex mosaic landscapes at the ecotone between prairies and Eastern deciduous forests and now exist within landscapes that vary in amount of open (e.g., perennial grassland and row crop agriculture) and woodland habitat. To understand the interplay between site and landscape level factors in savanna restoration, we sampled the breeding bird community in four combinations of site and landscape: restored savanna in open landscapes, restored savanna in woodland landscapes, and closed canopy woodland in both landscapes. We found that the outcome of site-level savanna restoration depended on the surrounding landscape. Compared to other treatment types, restored savannas in open landscapes supported a distinctive bird community characterized by high species richness, bird abundance, and percent of ground feeders, shrub nesters, and edge species. Both savanna and woodland sites in the open landscape had a higher percent of species of conservation concern, while at both site and landscape levels, woodland was associated with a higher percent of area sensitive species and habitat specialists. Our results suggest savanna restoration efforts should focus on sites that exist either in open country or on edges where closed canopy forest meets open country. This strategy would combine site and landscape level benefits of savanna restoration for avian diversity, while also preserving the conservation benefits of large tracts of intact forest. 相似文献
20.
Woods and trees play an important part in the formation of theplace-names found on topographical maps. The process of namingwoods began in the earliest times and continues at the presentday. Such place-names frequently provide information on thecharacter of the woodland in the past, and are also deservingof study as a form of forest terminology. In Britain, place-namesare derived from several linguistic sources, including Welsh,Gaelic, Anglo-Saxon, Scandinavian, French, Latin, and ModernEnglish; consequently the name of a wood often provides evidenceof the date of its recognition or formation. A glossary is givenof 136 names of woods and trees which are represented on themaps of Britain. 相似文献