检索结果-南通市图书馆

Does white-tailed deer density affect tree stocking in forests of the Eastern United States?

Ecological Processes 2019年第1期8卷 371-382页

作者： Brice B.Hanberry Marc D.Abrams USDA Forest Service Rocky Mountain Research StationRapid CitySD 57702USA Department of Ecosystem Science and Management Pennsylvania State University307 Forest Resources BldgUniversity ParkPA16802USA

Background:White-tailed deer(Odocoileus virginianus)have increased during the past century in the *** deer densities may reduce tree regeneration,leading to forests that are understocked,where growing space is not filled completely by *** deer pressure,a major transition in eastern forests has resulted in increased tree ***:To reconcile conflicting trends,we applied generalized linear mixed models to compare deer densities during 1982 and then 1996 to tree stocking after about 30 years and 15 years of potential reductions of small trees by deer,for the entire eastern US and 11 ecological *** also compiled deer browse preferences and compared preferred browse with trends in tree species composition from historical(1620–1900)and current tree ***:The forested area of the eastern US,including a prairie ecological province,was equally well-stocked(52%)and understocked(48%)during 2011–2017 tree *** 1982 deer densities,38%of area had deer densities>5.8 deer/km2 and for 1996,66%of area had deer densities>5.8 deer/*** densities and tree stocking were not related significantly for the entire eastern *** may reduce tree stocking in the Laurentian Mixed Forest;however,this province had both lower deer densities and greater tree stocking than other ***,major tree species trends did not match tree browse ***:Rather than too few trees,too many trees is an ecological problem where historical open oak and pine forests had herbaceous understories,and currently,trees have captured growing *** attribute other drivers than deer to explain this transition.

关键词： Driver Fire Herbivory Open forests Transition tree density

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Environmental parameters and tree physiology in two semiarid land use systems in Brazil

引用

Journal of Forestry Research 2019年第2期30卷 397-407页

作者： Marlete Moreira Mendes Ivanov Claudivan Feitosa de Lacerda Francisco Eden Fernandes Paiva Ana Clara Rodrigues Cavalcante Teogenes Senna de Oliveira Departamento de Biologia Universidade Federal do Piaui Departamento de Engenharia Agricola Campus do PiciUniversidade Federal do Ceara Embrapa Caprinos e Ovinos Departamento de Solos Universidade Federal de Vicosa

To determine if reduced tree densities(number of trees per unit area) lead to changes in micro-meteorological and tree physiological characteristics, two areas with different tree densities were assessed. One was an agrosilvopastoral system(AGP) with low tree density, and the other, a secondary forest(SF) with greater tree numbers, both located in a semiarid region of Brazil. Data were collected simultaneously by two automated weather stations: rainfall, air(T_a) and soil temperatures(T_(s5 cm)), relative humidity(RHair), photosynthetically active radiation(PAR), soil moisture at two depths(M_(s30 cm)and M_(s50 cm)),and wind velocity(Vw). Net photosynthesis in Cordia oncocalyx Allema?o trees was measured with an infrared gas analyzer in February, March, May, July, August and September 2011, which encompasses a rainy period followed by a dry period. Average values of Ta, T_(s5 cm), Vwand PAR were greater and average values of RHairand M_(s50 cm) were lesser in the AGP. Photosynthetic rates were greater in plants growing under the AGP at the onset of the dry season when Vw, PAR and T_(s5 cm)were greater and M_(s50 cm) was lesser. Photosynthetic rates correlated strongly with physical parameters during the dry season, especially under SF. Differences in tree numbers between AGP and SF led to differences in physical environmental parameters;however, the latter had less influence on photosynthetic rates in C. oncocalyx during the rainy season. During the dry season, all physical parameters had an impact on net photosynthesis under SF but not under AGP. This indicates a certain independence of plants in AGP.

关键词： Agrosilvopastoral system Net photosynthesis Secondary forest tree density

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Infectivity of Arbuscular Mycorrhizal Fungi in Naturally Regenerating,Unmanaged and Clear-Cut Beech Forests

引用

Pedosphere 2011年第1期21卷 65-74页

作者： I.CLOSA N.GOICOECHEA Department of Plant Biology Section of Plant BiologySchool of SciencesUniversity of Navarra

Clear-cutting, a management practice applied to many beech forests in the North of Spain, modifies microclimate and, consequently, the composition of the understory plant community in the disturbed areas. The objectives of this study were to assess if changes in the understory vegetation caused by altered light microclimate after clear-cutting affect the infectivity of arbuscular mycorrhizal fungi （AMF） on herbaceous plant species in beech （Fagus sylvatica L.） forests naturally regenerating from clear-cutting and to test if the use of bioassays for studying the infectivity of native AMF could provide useful information to improve the management of clear-cut areas. Three nearby beech forests in northwest Navarra, Spain, a region in the northwest part of the Pyrenees, were selected： an unmanaged forest, a forest clear-cut in 1996, and another forest clear-cut in 2001. High stem density in the forest clear-cut in 1996 （44 000 trees ha-1） attenuated photosynthetic active radiation （PAR） and impaired the growth of herbaceous species within the ecosystem. The percentage of AMF colonization of plants in bioassays performed on soil samples collected from the forest clear-cut in 1996 was always lower than 10S. In the forest clear-cut in 2001, where soil was covered by perennial grasses, PAR was high and the infectivity of native AMF achieved minimum values in spring and autumn and a maximum value in summer. In contrast, the infectivity of native AMF in the unmanaged forest remained similar across the seasons. Our results demonstrated that changes in the composition of understory vegetation within beech forests strongly affected the infectivity of native AMF in clear-cut areas and suggested that the assessment of the infectivity of native AMF through bioassays could provide helpful information for planning either the removal of overstory when the tree density is so high that it impairs the correct development of herbaceous species or the plantation of new seedlings when high

关键词： bioassays herbaceous plant species photosynthetic active radiation tree density understory vegetation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Structure and floristic composition of old-growth wet evergreen forests of Nelliampathy Hills, Southern Western Ghats

引用

Journal of Forestry Research 2013年第1期24卷 37-46页

作者： V.S. Ramachandran K. Swarupanandan Forest Ecology and Biodiversity Conservation Division Kerala Forest Research InstitutePeechiThrissur-680653KeralaIndia.

We analyze the structure and composition of old-growth wet evergreen forest of Nelliampathy hills, the chain of hills lying immediately south of Palghat Gap, in the southern Western Ghats of India. We sampled 30 plots of 0.1 ha each （50 m × 20 m） at six locations enumerating all plants ？ 10 cm girth at breast height. We pooled the data and computed various structural parameters. There were 152 species of 120 genera and 51 families of the study area. Of these, 118 （77%） were trees, 24 were climbers （16%） and 10 were shrubs （7%）. Species richness varied from 58–99 per 0.5 ha sample and Shannon indices of diversity ranged from 4.4 to 5.2. Fifty-nine per cent （89 species） of the species were Indian Sub-continent elements and 34% （51 species） are endemic to the Western Ghats. Fifteen species are listed in various threat categories. Aglaia and Litsea were the most species-rich genera. Numbers of families ranged from 27–43 per 0.5 ha sample. Euphorbiaceae and Lauraceae were the most species-rich families. Stand density varied from 1714 to 2244 stems·ha？1 and basal area from 53.6 to 102.1 m2·ha？1. The vegetation was dominated by 3–6 species and six dominance patterns characterized the species composition within the hill complex. The old-growth evergreen forests of Nelliampathy exist as small fragments rich in biodiversity and can be used as benchmarks for comparison with disturbed forests.

关键词： Old-growth evergreen forest Nelliampathy Western Ghats species richness tree density relative abundance stand structure.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of soil moisture variation by forest cover structure in lower western Himalayas, India

引用

Journal of Forestry Research 2013年第2期24卷 317-324页

作者： J. V. Tyagi Nuzhat Qazi S. P. Rai M. P. Singh National Institute of Hydrology Forest Research Institute

Soil moisture affects various hydrological processes, including evapotranspiration, infiltration, and runoff. Forested areas in the lower western Himalaya in India constitute the headwater catchments for many hill streams and have experienced degradation in forest cover due to grazing, deforestation and other human activities. This change in forest cover is likely to alter the soil moisture regime and, consequently, flow regimes in streams. The effect of change in forest cover on soil moisture regimes of this dry region has not been studied through long term field observations. We monitored soil matric potentials in two small watersheds in the lower western Himalaya of India. The watersheds consisted of homogeneous land covers of moderately dense oak forest and moderately degraded mixed oak forest. Observations were recorded at three sites at three depths in each watershed at fortnightly intervals for a period of three years. The soil moisture contents derived from soil potential measurements were analyzed to understand the spatial, temporal and profile variations under the two structures of forest cover. The analysis revealed large variations in soil moisture storage at different sites and depths and also during different seasons in each watershed. Mean soil moisture storage during monsoon, winter and summer seasons was higher under dense forest than under degraded forest. Highest soil moisture content occurred at shallow soil profiles, decreasing with depth in both watersheds. A high positive correlation was found between tree density and soil moisture content. Mean soil moisture content over the entire study period was higher under dense forest than under degraded forest. This indicated a potential for soil water storage under well managed oak forest. Because soil water storage is vital for sustenance of low flows, attention is needed on the management of oak forests in the Himalayan region.

关键词： soil moisture oak forest soil matric potential tree density degraded forest

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Extensive pollen immigration and no evidence of disrupted mating patterns or reproduction in a highly fragmented holm oak stand

引用

Journal of Plant Ecology 2014年第4期7卷 384-395页

作者： Joaquín Ortego Raúl Bonal Alberto Muñoz JoséMiguel Aparicio Grupo de Investigación de la Biodiversidad Genética y Cultural Instituto de Investigación en Recursos Cinegéticos-IREC(CSICUCLMJCCM)Ronda de Toledo s/nE-13005 Ciudad RealSpain Departamento de Ecología Evolutiva Museo Nacional de Ciencias Naturales(CSIC)C/JoséGutiérrez Abascal 2E-28006 MadridSpain Departamento de Didáctica de las Ciencias Experimentales Facultad de EducaciónUniversidad Complutense de MadridC/Rector Royo Villanova s/nE-28040 MadridSpain Centre de Recerca Ecològica i Aplicacions Forestals(CREAF) Cerdanyola del VallèsE-08193 BarcelonaSpain

Aims Forest fragmentation and reduced tree population densities can poten-tially have negative impacts on mating patterns,offspring genetic diversity and reproductive *** aim of the present study is to test these hypotheses comparing an extremely fragmented,low tree density(~0.02 trees/ha)holm oak(Quercus ilex l.)stand from Central spain with a nearby high tree density stand(~50 trees/ha).Methods We genotyped adult trees and seeds from the low-density stand(436 seeds from 15 families)and the high-density stand(404 seeds from 11 families)using nine microsatellite *** these data,we performed paternity analyses,determined pollen flow,mating patterns and pollen pool structure,and estimated progeny genetic diversity in both *** also studied seed set and production and performed a pollen supplementation experiment to determine whether reduced tree density has limited foreign pollen *** Findings We have found extensive pollen immigration(>75%)into the low tree density stand and monte Carlo simulations revealed that pollen moves larger distances than expected from null models of random *** patterns and differentiation of pollen pools were similar in the high-density stand and the low-density stand but we found higher inter-annual differentiation of pollen pools in the *** genetic diversity and self-fertilization rates did not dif-fer between the low-density stand and the high-density *** set rates were significantly lower in the low-density stand than in the high-density stand and experimental cross-pollen supplementation evidenced that foreign pollen availability is indeed a limiting factor in the ***,seed crops did not differ between the low-density stand and the high-density stand,indicating that limitation of foreign pollen is not likely to be of great concern in terms of reduced seed production and potential *** forest regeneration due to other ecological and human fac

关键词： forest fragmentation genetic diversity paternity analyses pollen dispersal pollen pool structure selfing tree density

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Aboveground biomass and carbon stock in the largest sacred grove of Manipur,Northeast India

引用

Journal of Forestry Research 2018年第2期29卷 420-423页

作者： Aahen Chanu Waikhom Arun Jyoti Nath P.S.Yadava Department of Ecology and Environmental Science Assam University Department of Life Sciences Manipur University

Aboveground biomass and carbon stock in the largest sacred grove of Manipur was estimated for trees with diameter [10 cm at 1.37 m *** aboveground biomass,carbon stock,tree density and basal area of the sacred grove ranged from 962.94 to 1130.79 Mg ha;,481.47 to 565.40 Mg ha;C,1240 to 1320 stem ha;and79.43 to 90.64 m;ha;,*** in diameter class of 30–40 cm contributed the highest proportion of aboveground biomass（22.50–33.73%）.The aboveground biomass and carbon stock in research area were higher than reported for many tropical and temperate forests,suggesting a role of spiritual forest conservation for carbon sink management.

关键词： Allometric models Carbon stock Sacred forest Basal area tree density

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of landscape fragmentation of plantation forests on carbon storage in the Loess Plateau,China

引用

Journal of Arid Land 2024年第2期16卷 266-281页

作者： LEI Hangyu DUAN Dantong CHEN Yi GUO Huifeng LI Jiangtao LI Xiang College of Landscape Architecture and Art Northwest A&F UniversityYangling 712100China

tree plantation and forest restoration are the major strategies for enhancing terrestrial carbon sequestration and mitigating climate *** Grain for Green Project in China has positively impacted global carbon sequestration and the trend towards fragmentation of plantation *** studies have been conducted on changes in plantation biomass and stand structure caused by fragmentation,and the effect of fragmentation on the carbon storage of plantation forests remains *** study evaluated the differences between carbon storage and stand structure in black locust forests in fragmented and continuous landscape in the Ansai District,China and discussed the effects of ecological significance of four landscape indices on carbon storage and tree *** used structural equation modelling to explore the direct and indirect effects of fragmentation,edge,abiotic factors,and stand structure on above-ground carbon *** at breast height(DBH)in fragmented forests was 53.3%thicker,tree density was 40.9%lower,and carbon storage was 49.8%higher than those in continuous forests;for all given DBH>10 cm,the trees in fragmented forests were shorter than those in continuous *** patch area had a negative impact on carbon storage,i.e.,the higher the degree of fragmentation,the lower the density of the tree;and fragmentation and distance to edge(DTE)directly increased canopy ***,canopy coverage directly decreased carbon storage,and fragmentation directly increased carbon storage and tree *** non-commercial forests,fragmentation reduces the carbon storage potential of plantation,and the influence of patch area,edge,and patchy connection on plantation should be considered when follow-up trees are planted and for the plantation ***,expanding the area of plantation patches,repairing the edges of complex-shaped patches,enhancing the connectivity of similar patches,and applying nutrients to plantation forests at regular i

关键词： landscape fragmentation plantation carbon storage tree allometry tree density structural equation modelling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Species Composition and Stand Structure of Primary and Secondary Moist Evergreen Forests in the Tanintharyi Nature Reserve (TNR) Buffer Zone, Myanmar

引用

Open Journal of Forestry 2020年第4期10卷 445-459页

作者： Idd Idd Shwe Zin Ralph Mitlöhner University of Forestry and Environmental Science Yezin Nay Pyi Taw Myanmar Department of Tropical Silviculture and Forest Ecology Georg-August University Goettingen Germany

The habitat structure and floristic composition examined for this study are of great importance, providing a scientific baseline of information for developing a biodiversity database and in supporting crucial information for the management decision-making process of the buffer zones. The primary objective of this study was to examine the current status of species composition and stand structure of moist evergreen forests distributed in the TNR buffer zone. Forest inventory was conducted in the primary moist evergreen forest (~1 ha) and secondary moist evergreen forest (~1 ha). In the TNR buffer zone, 83 species belonging to 31 families in the primary moist evergreen forest and 86 species belonging to 32 families in the secondary moist evergreen forest were found. The most dominant families in the primary moist evergreen forest were Dipterocarpaceae, Sapindaceae, Meliaceae, Myrtaceae, and Myristicaceae;at species level;this forest was composed of Nephelium lappaceum, Myristica malabarica, Nephelium laurium, Aglaia andamanica, and Diospyros peregrine. The most dominant families in the second

关键词： tree density Basal Area Floristic Similarity Index Floristic Composition Moist Evergreen Forest

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：