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1.
Celia A. Harvey Cristobal Villanueva Rene Gómez Jorge Martinez 《Forest Ecology and Management》2011,261(10):1664-1674
Trees dispersed in pastures are a prominent feature of many Central American landscapes, particularly in cattle producing regions where farmers retain trees to serve as shade, fodder, timber and firewood. The presence of dispersed trees in pastures is often considered as important for the conservation of biodiversity by providing habitat and enhancing landscape connectivity. However, despite their critical productive and environmental roles, little is known about tree distribution within pastures or how farmers’ management decisions influence the trees themselves and their impact on farm productivity and biodiversity conservation. Here, we present a synthesis of (a) the abundance, composition, and size of dispersed trees in four important cattle producing regions of Costa Rica (Caňas and Río Frío) and Nicaragua (Rivas and Matiguás), based on inventory of 18,669 trees on 1492 ha of pasture, (b) the local knowledge, management and use of trees by cattle farmers, and (c) opportunities for ensuring sustainable management of dispersed trees in pasture-dominated landscapes. Dispersed trees were common in all four landscapes, with mean frequency ranging from 8.0 trees ha−1 in Caňas to 33.4 trees ha−1 in Matiguás. A total of 255 tree species were found in pastures across the four landscapes. The total number of tree species per landscape varied from 72 in Rivas to 101 in Caňas and Rio Frio, with mean species richness per farm ranging from 22.9 in Rio Frio to 45.9 in Matiguás. In all four landscapes, a handful of tree species dominated the pastures, with the ten most abundant species in each landscape accounting for >70% of all trees recorded. Most of these common tree species provide fruits or foliage eaten by cattle, or are important timber or firewood species, and are deliberately retained by farmers for these uses. In all four landscapes, farmers had a detailed knowledge of tree attributes affecting pasture and animal productivity, and influenced tree cover through pasture management activities and occasional tree cutting. Current farm management practices are gradually decreasing the diversity of trees in pastures, and in some cases also tree density, reducing their contribution to farm productivity and biodiversity conservation. To reverse this trend, incentives are required to encourage cattle farmers to retain and enhance tree cover in pastures, through the adoption of pasture management practices that favor the regeneration and persistence of a diverse range of tree species. 相似文献
2.
Remnant trees may play an important role in conserving biodiversity within agricultural systems because they provide habitats
and resources that are otherwise absent from agricultural landscapes. In order to determine the potential importance of remnant
trees for conservation, we surveyed the density and species composition of remnant trees occurring in pastures of 24 dairy
farms near Monteverde, Costa Rica. In addition, we conducted interviews with farmers to determine why they leave trees in
pastures and how they manage them. In our survey of 237 ha of pastures, we counted 5583 trees of 190 species (mean density
of 25 trees/ha). Primary forest trees accounted for 57% of all of the species and 33% of tree individuals. Over 90% of the
species are known to provide food for forest birds and other animals. In addition, many of the species are important locally
for humans as sources of timber (37%), firewood (36%) or fence posts (20%). Farmers mentioned 19 reasons for leaving trees
in pastures. Of these, shade for cattle, timber, fruits for birds and fence posts were most commonly cited. Most farmers were
well aware of both the economic and ecological benefits of pasture trees, and were interested in the possibility of increasing
tree cover within their pastures. Although the current densities and richness of pasture trees in Monteverde are high, the
size distribution indicates that diversity will decrease substantially in future years, both because farmers are harvesting
trees and because saplings of primary forest trees are scarce within the pastures.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
In the Swiss Alps, 15% of Swiss mountain forests are grazed during summer, mainly by cattle. The forest laws of various Swiss
cantons characterise forest grazing as a detrimental form of land use and stipulate that this grazing practice should be restricted.
However, little is known about tree damage actually caused by cattle. Seven subalpine ranges in the Swiss Canton Grisons,
grazed by cattle at different stocking rates, were investigated. The condition of naturally regenerated young trees (Picea abies (L.) Karst.) was assessed before and after the cattle grazing period. In order to characterise the influence of wild ungulates
on the young trees during winter, the assessment of tree condition was repeated in the proximate spring. In total, 4% of the
young trees were browsed on the apical shoot, 10% were browsed on lateral shoots, 13% of the trees showed other damage. The
variation among ranges could almost completely be explained by the cattle stocking rate (livestock units per hectare). During
winter, wild ungulates browsed 3 times as many young trees as the cattle during summer. The results suggest that cattle stocking
rates on subalpine wood pastures should not exceed one livestock unit per hectare in order to avoid intensive browsing and
other damage by cattle on young Norway spruces. 相似文献
4.
Pessimistic forecasts often suggest that widely spaced trees enjoying free growth (no competition with other trees) will fail
to provide high quality timber. This challenges the temperate agroforestry practice of planting widely spaced trees to produce
high quality timber. We analyse tree growth data from recent temperate agroforestry plantations aged three to eight years,
featuring low tree plantation densities (50 to 400 stems ha−1), the association of trees with intercrops (silvoarable systems)
or animals (silvopastoral systems), and the use of plastic shelter tubes to protect trees (1.2 to 2.5 m high) and avoid damage
by cattle or sheep in pastures or facilitate maintenance in silvoarable systems. The plantations are located in climates ranging
from Mediterranean, dry central temperate plains, cold and wet central uplands to mild oceanic areas. Some plantations included
a forestry control (high density of plantation, no tree shelter, no intercropping nor grazing). Trees were evaluated for height
and diameter growth and stem form (straightness and absence of knots). Trees in most agroforestry plots grew satisfactorily,
often faster than in forestry control plots. In some experimental plots, average annual height increments as high as 1 m and
diameter increments as high as 1.5 cm were observed. Few agroforestry plantations were unsuccessful, and the reasons for the
failures are discussed: animal damage in silvopastoral plots, but also a wrong choice of tree species unsuitable for local
soil and climate characteristics. From these early results we can formulate some guidelines for designing future agroforestry
plantations in temperate climates, concerning tree density, use of tree shelters and care required for widely spaced trees.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Latin American pastures usually include trees that may be important in sustaining productivity and conserving resources and
biodiversity. A participatory survey of trees in seasonally dry pastures of 54 farms in the Caribbean region of Colombia,
followed by cluster and correlation analyses, revealed a multistrata configuration. Trees of large stature (e.g., Tabebuia rosea, Albizia caribaea and Sterculia apelata) provided shade and produced timber. The most important fodder trees were those of medium stature (Albizia saman, Guazuma ulmifolia, and Cassia grandis) that produced fruits or pods, while other species were managed as shrubs producing green leaf fodder (e.g., Crescentia cujete and Gliricidia sepium, which was also ubiquitous as living fence posts). Trees were present on between 26 and 69% of the pastures on each farm,
at densities varying from less than 3 to more than 50 trees ha−1. There were more trees in drier areas, of lower fertility, with extensive grazing, where milk as well as meat was produced.
Most farmers planted timber trees, encouraged regeneration of fodder trees, and knew about fodder species preferences of cattle
and the effects of trees on pasture and animal productivity. Their knowledge of tree phenology was less certain and varied
even amongst farmers in similar locations. There is scope to develop silvopastoral systems with woody species familiar to
farmers, but it is critical to determine how important different vegetation strata are for sustainability of cattle production.
An experiment has been established to achieve this, with treatments based on an analysis of how trees are presently used on
farms in the region.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
The enrichment of live fences with native tree species has been proposed as a conservation strategy in agricultural landscapes; however, little research has explored ways to do this in tropical areas. This study examines selection of native tree species, effects of damage caused by mammals (mainly cattle) in performance (survival and growth) of transplanted seedlings, and cost-benefit balances as critical steps to enrich tropical live fences. Seven native tree species, with ecological and socio-economic importance, were selected in a Mexican agricultural landscape to grow as seedlings, and six of them were transplanted into live fences of cattle ranches with different levels of cattle activity (none/moderate/high). Costs associated with propagation and seedling protection in the field were calculated, and performance and damage in seedlings were measured over 2 years. We developed an index to identify species with the best performance and lowest costs in sites with cattle activity. Our results showed that damage, caused mainly by cattle, reduced the performance of transplanted seedlings. The effect of this damage varied depending on its severity (level and frequency) and the identity and life history of species. All selected species performed well in the site without cattle access. Dendropanax arboreus was the best species at site with moderate cattle activity, and Trema micrantha and Saurauia scabrida at site with high cattle activity. These species are recommended for enriching live fences because of good cost-benefit balance. This approach could be an important quantitative method to select species useful not only in agroforestry but also in restoration projects, which normally remain under the pressure of domestic and wild animals. 相似文献
7.
When combining pine and cattle production on improved pastures, grazing may have to be delayed for several years until trees
are large enough to resist injury. During this period forage would be lost unless harvested for hay. This study in south Georgia,
USA, examined hay production during the first 3 years, cattle production during the next 3 years, and effects of this management
system on survival and growth of slash pine(Pinus elliottii) planted in widely-spaced rows within the pastures.
Pines were planted at 225 trees/ha in configurations of 3.0 x 14.6 or 4.9 x 9.1 m in pastures recently sprigged or seeded
with Coastal bermudagrass (Cynodon dactylon) or Pensacola bahiagrass(Paspalum notatum). Pastures were fertilized annually and cut for hay four or five times each year.
Wide-row spacings permitted haying operations, but tree rows and turning areas removed 5 to 8 percent of the area from production.
However, hay yields and liveweight gains by yearling cattle were near normal for this locale.
Slash pine planted in these fertilized pastures survived well, grew rapidly, and only a few trees were killed during haying
operations. After 6 years, 83 percent of the trees survived and averaged 6.5 m in height and 13.2 cm in diameter. Cattle killed
a few trees by rubbing during the 4th year.
Wide-row spacing of pines permits harvesting forage for hay while waiting for the trees to become large enough to permit grazing.
This approach to agroforestry produces annual returns to the landowner while awaiting maturity of the pines. 相似文献
8.
Deforestation principally to establish cattle pastures has created large expanses of land dominated by exotic grass prior to the establishment of the Cerro Blanco Protected Forest in Ecuador. A dry forest restoration program was carried out from 2008 to 2017. Tree planting sites were cleared in parallel lines through abandoned pasture and secondary vegetation using manual labor. Native tree species were produced in a nursery on site and used in yearly plantings during the rainy season. A total of 637 hectares were planted at an average stocking density of 1,000 trees per hectare. Growth data was collected from trees planted in nine sites from 2008 to 2017. Mortality rates were determined from a sample of 400 trees of twenty-two species. Survival of all species was greater than 50%. Ten species had survival rates greater than 90%. Vitex gigantea, with high survival rates, also had significantly greater growth rates than the other species (p < 0.0001) and showed the greatest yearly accumulation of total carbon (2.07 Kg C yr ?1 stem?1). Other species with high growth rates were Cordia alliodora and Centrolobium ochroxylum. This restoration program demonstrates that the dry forest restoration with timely maintenance and protection from fire and grazing is possible with intensive tree planting of native species. 相似文献
9.
Establishing trees in an Appalachian silvopasture: response to shelters, grass control, mulch, and fertilization 总被引：1，自引：0，他引：1
In order to successfully introduce trees into existing pastures, it is important to determine and recommend a whole range
of tree establishment practices. In the spring of 1995, approximately 350 bare-root seedlings each of black walnut (Juglans nigra L.) and honeylocust (Gleditsia triacanthos L.) were planted in six randomized paddocks within a silvopastoral study area at the Agroforestry Research and Demonstration
Site in Blacksburg, Virginia. Three seedling establishment studies were tested, including (1) a tree protection study, (2)
a water retention study, and (3) a fertilization study. Seedlings were planted using two different tree shelters (60 cm-tall
poultry wire cage and 1.2 m-tall plastic Tubex), two water retention treatments (mulch and herbicide spray), and one fertilizer
treatment. All treatments were compared to untreated controls. Tree survival, damage, and stem volume were compared for each
species. Tree survival was comparable among all studies over three growing seasons. Tree establishment using poultry wire
and Tubex shelters resulted in significant reduction of deer damage and significant increase in stem volume from 1996 to 1998.
Tubex shelters had a pronounced positive impact on tree height and also on stem form; height of both black walnut and honeylocust
was twice the height of control seedlings. Mulch and herbicide treatments for moisture control resulted in significant stem
volume increases over thecontrol treatment from 1997 to 1998. However, mulching was less effective than the herbicide treatment.
There was no significant tree growth response resulting from fertilization during this same period.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Cutting and resprouting of Detarium microcarpum and herbaceous forage availability in a semiarid environment in Burkina Faso 总被引：1，自引：0，他引：1
The tree-shrub savanna ‘Forêt Classée de Nazinon’ (Burkina Faso) is submitted to a management of grazing and rotational cutting
of Detarium microcarpum. This species resprouts after cutting. In order to investigate whether this silvopastoral land use
system is sustainable, aboveground herbaceous biomass was measured on subplots under uncut trees (‘uncut’), next to the stubs
of cut trees (‘cut’) and on subplots not influenced by the (former) crowns of trees (‘open grassland’) in four lots. These
lots were cut one, three, six and seven years before the study. Vegetation composition of the lots and the composition of
the diet of cattle were also determined. Comparisons were made between treatments and lots. Herbaceous biomass was lower in
the open grassland subplots than in uncut or cut subplots. We speculate that soil enrichment and more efficient precipitation
input in (former) tree crown zones could have resulted in this pattern. Cutting and subsequent resprouting of trees did not
lead to significant differences in herbaceous biomass between cut and uncut subplots. The most simple explanation for this
is that the trees could extend their roots beyond the location of their neighbouring trees. Biomass and coverage of perennial
grasses, mainly Andropogon ascinodis and Andropogon gayanus, did not change in lots cut one, three or six years before the
study, but decreased dramatically in lots that were cut seven years before the study. When foraging, cattle spent more than
90% of their time feeding on these species. This indicates that, as a consequence of tree cutting, forage availability may
be reduced to the point where local herdsmen are forced to take their cattle to another region.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
Although vascular epiphytes contribute substantially to the biodiversity of tropical montane forests, it is unclear how their diversity and community composition is affected by forest alteration. We studied the response of vascular epiphyte assemblages to different intensities of land-use in a montane wet forest of northeastern Ecuador: (1) unmanaged mature forest; (2) mature forest with mid- and understorey opened for cattle grazing; and (3) isolated remnant trees in cattle pastures. The numbers of individuals and species of epiphytes per host tree did not differ significantly between land-use types, neither did total epiphyte species richness (n = 30 trees). However, total species richness of pteridophytes was significantly lower on isolated remnant trees compared to unmanaged forest, whereas several taxa rich in xerotolerant species (Bromeliaceae, Orchidaceae, Piperaceae) exhibited the opposite trend. An analysis of floristic composition using ordination (NMS) and randomisation techniques (MRPP) showed that epiphyte assemblages on isolated remnant trees were significantly distinct from unmanaged forest while managed forest was intermediate between those two vegetation types. Ordination analysis further indicated reduced floristic heterogeneity in disturbed habitats. These results suggest considerable, rapid species turnover since land-use change 6 years prior to study, with pteridophytes being replaced by more xerotolerant taxa. We attribute this floristic turnover primarily to changes in microclimate towards higher levels of light and desiccation stress associated with forest disturbance. Our results support the notion that community composition offers a more sensitive indicator of human disturbance than species richness. 相似文献
12.
台风“山竹”对粤港澳大湾区城市园林树木的影响调查 总被引：6，自引：6，他引：0
2018年9月,台风"山竹"对粤港澳大湾区城市的园林树木造成重大伤害,调研粤港澳大湾区6个城市的园林树木的受损情况,统计各树种的综合受损率及受损表现,应用聚类分析法,对受损树种进行分级,并确定树种整体受损等级。通过记录树木受损情况及分析树种自身的抗风特性,分析总结影响园林树木抗风性能的主要因素,包括树种本身的抗风特性、台风风力与风向、立地土壤环境、种植穴空间、植物群落密度、迎风口种植位置等,并提出建立完善的树木风险评估体系,加强园林绿化建设及养护管理,以增强城市园林树木抗风能力。 相似文献
13.
Much information on restoration and management exists for wet tropical forests of Central America but comparatively little work has been done in the dry forests of this region. Such information is critical for reforestation efforts that are now occurring throughout Central America. This paper describes processes of degradation due to land use and provides a conceptual framework for the restoration of dry tropical forest. Most of this forest type was initially harvested for timber and then cleared for cattle in the last century (1930-1970). Only 1.7% remains largely restricted to infertile soils and remote areas on the Pacific coastal side of Panama, Costa Rica, Nicaragua and Mexico. These cleared areas are again in a state of transition due to a combination of decreasing land productivity, and land speculation for tourism development. Some farms have been sold to new landowners who are interested in reforesting to increase biodiversity and forest cover. Attempts have therefore been made to reforest by protecting the land from fire and cattle, by supplementing natural regrowth with enrichment planting, or through use of tree plantations. Experimental studies have demonstrated the ability of these lands to grow back to forests because of native species ability to sprout after cutting, and the capacity of remnant trees in field and riparian zones to provide seeds and to moderate edge environment for seed germination and seedling establishment. However, research also shows that on sites with long histories of land clearance, species diversity will remain low with functional groups missing unless some active management occurs. Under-planting with late-successional native tree species can add structure and diversity; enrichment planting with large-fruited shade-intolerant species can initiate new islands of more diverse regeneration beneath their canopies; and plantings of fast-growing, nitrogen-fixing trees that provide light canopy shade can moderate the environment below, promoting regeneration establishment of late-successional species. Plantations are the only option for lands that have lost almost all remnants of native forest, and where soils and vegetation have changed to new states of structure and function. Conversion of pastures to tree plantations that can facilitate natural regeneration beneath them is appropriate when pastures are prone to fire and/or lack immediate seed sources nearby. After the grasses have been shaded out, natural recruitment can slowly occur over a 10-15 years period. Under-planting of shade-tolerant late-successional species can supplement species composition and structure. 相似文献
14.
The most common trees on farm homesteads in Bangladesh were bamboo (several spp.), jackfruit (Artocarpus heterophyllus), mango (Mangifera indica), betelnut (Areca catechu), and jujube (Zizyphus jujube) in all agroecological zones studied. There were regional differences in the less common species. Species for new homestead
planting were chosen mainly by women and tended to include indigenous fruit trees and a few exotics of high timber value.
Choices were later influenced by new experience with exotic tree species and by perceptions from secondary information sources.
Farmer-managed action-research was used to test the survival and performance of new trees planted under the Village and Farm
Forestry Programme (VFFP). The main factors influencing tree survival were the role of women in selection of species and planting
site, the degree of personal attention paid aftercare by the owner, and the quality and size of the planting stock. Biophysical
factors and agroecological zones were unimportant. Main recorded causes of tree mortality were, in order of importance: damage
by livestock, pests or diseases, physical damage by people (mainly children playing), and drought. Cause of death could not
be attributed in about 35% of mortality, suggesting that the recorded causes should be treated with caution.
Previous articles 1 and 2 in the series appeared in Agroforestry Systems 25: 193–216 and 31: 39–57 with slightly different
main titles. 相似文献
15.
基于2018年郑州市古树普查数据及实地调研数据,利用Excel、ArcGIS、SPSS等软件对郑州市中心城区古树资源现状及保护现状进行分析。调查结果显示,郑州市中心城区古树共222株,属于17科26属27种,其中一级古树数量最多,三级古树数量最少,树龄结构稳定,生长态势良好;古树资源呈聚集状态,并多分布于生态环境良好的地区;古树生长主要受环境、土壤、市政建设、养护、病虫害、人为损害等影响;古树保护中存在保护措施粗放、保护力度不够、专业队伍缺失、财政保护资金不足、古树保护宣传力度弱等问题。以期为城市中的古树名木的调查统计和保护提供了数据依据及具有科学性和实施性的策略。 相似文献
16.
在全面普查和专项补充调查的基础上,基于树形与生长方面的9个量化指标对安徽省广德县古树树势与健康状况进行综合评价。结果认为,全县古树总体上树势一般,呈中等健康水平,但不同的树种差别较大,其中生长缓慢的大乔木树种,凡处于中年阶段的古树,大多树势生长旺盛,健康等级高;乡土树种古树适应当地自然条件的能力较强,生长较好,健康等级较高;而速生树种或引入归化树种的古树,在处于生长的末期阶段,一般长势不佳,健康等级较低;具有量多面广的同一古树,树势旺盛,健康等级较高。不同保护级别的古树,树势和健康等级也各有差异,总的趋势是保护级别越高,树势越差,健康等级越低。生理老化、自然灾害、环境恶化、病虫危害、管护不善等则是当前影响古树树势和健康的主要因素。 相似文献
17.
Mirco PlathKarsten Mody Catherine PotvinSilvia Dorn 《Forest Ecology and Management》2011,261(3):741-750
Plantations of native timber species established on former pasture are a potential strategy to reduce the logging pressure on remnant natural forests in the tropics. Such plantations may help to mitigate or reverse the negative impacts of land degradation, and they may contribute to the long-term livelihood of livestock farmers. Planting native trees is, however, perceived as a risky activity due to limited knowledge of their performance and due to marked losses of newly established seedlings attributed to insect pests. Our study focuses on the small-scale effects of environmental heterogeneity, tree diversity and insecticide treatment on the performance of three native Central American timber species two years after establishment, and on damage inflicted by insect herbivores. Growth, survival and herbivore leaf damage were quantified for Anacardium excelsum (Anacardiaceae), Cedrela odorata (Meliaceae) and Tabebuia rosea (Bignoniaceae) planted in an experiment in Panama as (1) monocultures, (2) mixed stands, and (3) mixed stands protected by insecticides. Our study revealed that small-scale effects can have a substantial impact on the success of timber trees planted on former pasture. Growth performance and survival of the three species was strongly affected by small-scale environmental heterogeneity, which was expressed as significant differences in growth and survival among different plantation plots at the same study site. Establishment of trees in mixed stands did not have significant effects on tree survival and growth compared to pure stands, although it reduced herbivore pressure in one of the studied tree species. All tree species grew best and suffered lowest leaf damage when protected by insecticides, indicating a general influence of insect herbivory on growth of newly established trees. In contrast to growth performance, survival was not significantly affected by different management practices or herbivory. The large variability among plots in tree survival and growth, and also in the effects of management practices such as planting design and insecticide treatment, emphasizes the importance of small-scale environmental heterogeneity on tree survival and growth. 相似文献
18.
Almost 20 million acres of non-forest cropland in the South can be classified as marginal. Demand projections for forest products call for a 40 percent increase by year 2030. Recent regenerated tree acres lag behind harvested acres. Multiple land use practices combining trees and grazing adjust cash flows forward mitigating negative flow period associated with conventional forest production. Profit opportunities for private, non-industrial landowners can be increased by ranking inputs in order of changes to net present value(NPV). A sensitivity analysis of an agroforestry scenario, including trees, beef cattle, and pasture, allows producers to concentrate management efforts where returns are greatest. Model results show greatest returns to NPV was realized from improvement to Chip-N-Saw income. The least increase in NPV came when the cost of control burns was changed. 相似文献
19.
Axel Albrecht Marc Hanewinkel Jürgen Bauhus Ulrich Kohnle 《European Journal of Forest Research》2012,131(1):229-247
Storms represent the most important disturbance factor in forests of Central Europe. Using data from long-term growth and
yield experiments in Baden-Wuerttemberg (south-western Germany), which permit separation of storm damage from other causes
of mortality for individual trees, we investigated the influence of soil, site, forest stand, and tree parameters on storm
damage, especially focusing on the influence of silvicultural interventions. For this purpose, a four-step modeling approach
was applied in order to extract the main risk factors for (1) the general stand-level occurrence of storm damage, (2) the
occurrence of total stand damage, and (3) partial storm damage within stands. The estimated stand-level probability of storm
damage obtained in step 3 was then offset in order to describe the damage potential for the individual trees within each partially
damaged stand (4). Generalized linear mixed models were applied. Our results indicate that tree species and stand height are
the most important storm risk factors, also for characterizing the long-term storm risk. Additionally, data on past timber
removals and selective thinnings appear more important for explaining storm damage predisposition than for example stand density,
soil and site conditions or topographic variables. When quantified with a weighting method (summarizing the relative weight
of single predictors or groups of predictors), removals could explain up to 20% of storm risk. The stepwise modeling approach
proved an important methodological feature of the analysis, since it enabled consideration of the large number of observations
without damage (“zero inflation”) in a statistically correct way. These results form a reliable basis for quantifying forest
management’s direct impact on the risk of storm damage. 相似文献
20.
Forest pasturing of free-roaming livestock is a common practice in many parts of the world, but knowledge on how it affects tree regeneration in boreal forests is lacking. We mapped tree density, livestock site use and accumulated damage to young trees of commercial interest(Norway spruce, Picea abies L. Karst.) on 56 clearcuts inside and outside a fenced forest area used for livestock pasturing in Ringsaker, Norway. Inside the fence 56±1.8% of spruce trees were damaged compared to 37±3.4% outside. Proportion of damaged spruce trees was positively related to cattle use of the clearcut, but not so for sheep. On the most intensively used clearcuts, four out of five trees were damaged. The density of deciduous trees was five times lower inside compared to outside of the fence(varying with plant species). While livestock grazing may reduce resource competition in favour of spruce, the current animal density clearly is impeding forest regeneration in the study area. 相似文献