检索结果-南通市图书馆

Disturbance history,species diversity,and structural complexity of a temperate deciduous forest

Journal of Forestry Research 2020年第2期31卷 397-414页

作者： Jonathan D.Goode Carson R.Barefoot Justin L.Hart Daniel C.Dey Department of Geography University of AlabamaTuscaloosaAL 35487USA Northern Research station USDA Forest ServiceColumbiaMO 65211USA

Stand structural complexity enhancement is an increasingly popular management objective,especially on public *** stand structures are hypothesized to support a relatively high degree of native forest diversity and be more resistant and resilient to *** structures are characterized by the presence of deadwood and heterogeneity of tree-size classes and tree *** little is known about how discrete disturbance events affect structural complexity and compositional diversity in Quercus-dominated stands at fine spatial scales(***).We established 200.05 ha fixed-radius plots on the Sipsey Wilderness of William *** National Forest in northern Alabama to quantify woody plant species composition and *** were mapped on each plot to quantify overstory structural complexity and compositional *** extracted two cores from all canopy Quercus spp.C 5 cm diameter at breast height to quantify age,recruitment pulses,and reconstruct canopy disturbance *** species diversity in the sampled area was 1.75 for trees,2.08 for saplings,and 1.69 for *** alba had the greatest basal area,and Ostrya virginiana had the highest *** stand exhibited a reverse J-shaped distribution with a q-factor of *** oldest Quercus dated to 1795,and the largest recruitment pulse occurred in the *** mean return interval for intermediateseverity disturbance was 38 *** we documented no relationships between disturbance frequency and compositional diversity at the neighborhood scale(0.05 ha),less frequent disturbance was associated with higher structural complexity(r^2=0.258,p=0.026)at the neighborhood *** suggest that localized disturbance increases species diversity and structural complexity,but these processes are manifest at the stand level and not at the neighborhood *** conclude that the spatial variability(***,shape,orientation,microsite conditions)is likel

关键词： Canopy gap Quercus(oak) Stand development Succession

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

Afforestation,restoration and regeneration——Not all trees are created equal

引用

Journal of Forestry Research 2014年第1期25卷 3-20页

作者： Shaneka S.Lawson Charles H.Michler USDA Forest service Northern Research StationHardwood Tree Improvement and Regeneration Center (HTIRC)Purdue UniversityDepartment of Forestry and Natural Resources

Undulations in weather patterns have caused climate shifts of increased frequency and duration around the world. The need for additional research and model data on this pressing problem has resulted in a plethora of research groups examining a particular tree species or biome for negative effects of climate change. This review aims to （1） collect and merge recent research data on regeneration within old- and new-growth forests, （2） highlight and expand upon selected topics for additional discussion, and （3） report how shade tolerance, drought toler- ance, and inherent plasticity affect tree growth and development. Al- though shade and drought tolerance have been well studied by a number of research groups, this review reveals that in-depth analysis of a single or a few species in a given area will not generate the data required to implement a successful regeneration plan. Studies using historical accounts of previous species composition, information regarding site sea- sonality, species competition, and individual responses to drought and shade are needed to （1） develop best management plans and （2） ensure future modeling experiments are focused on a greater variety of species using more innovative methods to evaluate climate change effects.

关键词： Climate change shade tolerance drought tolerance canopy gaps invasive species

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

Transcriptional Responses to Gibberellin and Abscisic Acid in Barley Aleurone

引用

Journal of Integrative Plant Biology 2006年第5期48卷 591-612页

作者： Kegui Chen Yong-Qiang Charles An Department of Agronomy University of Wisconsin Madison Wl 53706 USA United States Department of Agriculture Agricultural Research Service Cereal Crops Research Madison Wl 53726 USA

Cereal aleurone has been established as a model system to investigate giberrellin （GA） and absclslc acid （ABA） responses. Using Barley 1 GeneChip, we examined the mRNA accumulation of over 22 000 genes In de-embryonated barley aleurone treated with GA and ABA. We observed that 1 328 genes had more than a threefold change In response to GA treatment, whereas 206 genes had a more than threefold change in response to ABA treatment. Interestingly, approximately 2.5-fold more genes were up-regulated than downregulated by ABA. Eighty-three genes were differentially regulated by both GA and ABA. Most of the genes were subject to antagonistic regulation by ABA and GA, particularly for genes related to seed maturation and germination, such as genes encoding late embryogenesis abundant proteins and storage mobilization enzymes. This supports the antagonistic roles of GA and ABA in seed maturation and seed germination. Interestingly, we observed that a significant percentage of the genes were coordinately regulated by both GA and ABA. Some GA-responsive genes encoded proteins involved in ethylene, Jasmonate, brasslnosterold and auxin metabolic and signaling transducUon pathways, suggesting their potential Interaction with the GA response. We also identified a group of transcription factor genes, such as MYB and Homeobox genes, that were differentially regulated by GA. In addition, a number of GA- and/or ABA-responsive genes encoded components potentially Involved in GA and ABA signal transducUon pathway. Overall, the present study provides a comprehensive and global view of transcript expression accompanying the GA and ABA response in barley aleurone and Identifies a group of genes with potential regulatory functions in GA- and ABA-slgnallng pathways for future functional validation.

关键词： abscisic acid barley gene regulation gibberellin microarray signal transduction.

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

Cooperative sensing,communication and computation resource allocation in mobile edge computing-enabled vehicular networks

引用

Journal of Information and Intelligence 2024年第4期2卷 339-354页

作者： Zhenyu Li Yuchuan Fu Mengqiu Tian Changle Li State Key Laboratory of Integrated service Networks Xidian UniversityXi'an 710071China Research Institute of Smart Transportation Xidian UniversityXi'an 710071China

The combination of integrated sensing and communication(ISAC)with mobile edge computing(MEC)enhances the overall safety and efficiency for vehicle to everything(V2X)***,existing works have not considered the potential impacts on base station(BS)sensing performance when users offload their computational tasks via *** could leave insufficient resources allocated to the sensing tasks,resulting in low sensing *** address this issue,we propose a cooperative power,bandwidth and computation resource allocation(RA)scheme in this paper,maximizing the overall utility of Cramer-Rao bound(CRB)for sensing accuracy,computation latency for processing sensing information,and communication and computation latency for computational *** solve the RA problem,a twin delayed deep deterministic policy gradient(TD3)algorithm is adopted to explore and obtain the effective solution of the RA ***,we investigate the performance tradeoff between sensing accuracy and summation of communication latency and computation latency for computational tasks,as well as the relationship between computation latency for processing sensing information and that of computational tasks by numerical *** demonstrates that compared to other benchmark methods,TD3 achieves an average utility improvement of 97.11%and 27.90%in terms of the maximum summation of communication latency and computation latency for computational tasks and improves 3.60 and 1.04 times regarding the maximum computation latency for processing sensing information.

关键词： Integrated sensing and communication Mobile edge computing Resource allocation Reinforcement learning

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

Compost Input Effect on Dryland Wheat and Forage Yields and Soil Quality

引用

Pedosphere 2018年第3期28卷 451-462页

作者： Francisco J. CALDERON Merle F. VIGIL Joseph BENJAMIN United States Department of Agriculture-Agricultural Research service (USDA-ARS) Central Great Plains Research Station Akron80720 CO( USA)

Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha^(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha^(-1) BFC treatment,but not the 22.9-t ha^(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content *** feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha^(-1) BFC after three applications, but not with 22.9 t ha^(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha^(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha^(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.

关键词： organic agriculture soil C soil enzyme activity soil N pea triticale

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

A review on biosynthesis and genetic regulation of aflatoxin production by major Aspergillus fungi

引用

Oil Crop Science 2020年第4期5卷 166-173页

作者： Junhua Liao Zemin He Youlin Xia Yong Lei Boshou Liao Nanchong Academy of Agricultural Sciences NanchongChina Oil crops Research Institute Chinese Academy of Agricultural SciencesWuhanChina

Aflatoxins(AFs)are a group of secondary metabolites belonging to polyketide-derived furanocoumarins produced by Aspergillus *** one type of mycotoxins,AFs are the most carcinogenic and toxic compounds for human and animal health,which might lead to serious contamination on agricultural products including peanut,maize and ***,AF contamination in food chain was difficult to be *** review summarizes the research progress on the types,producers and properties of AFs,gene clusters,AF biosynthesis and genetic regulation in major Aspergillus fungi,aiming to provide comprehensive information for developing cost-effective strategies on control of AF contamination in agriculture production and consequent food chain.

关键词： Aflatoxin Aspergillus fungi Biosynthesis Regulation

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

Satellite Multi-Temporal Data and Cropping Pattern Approach for Green Gram Crop Management in the Lower Midland Zone IV and V in Kenya

引用

Advances in Remote Sensing 2024年第2期13卷 41-71页

作者： Kalekye Hilda Manzi Shadrack Ngene Joseph P. Gweyi-Onyango Department of Agriculture Science and Technology School of Agriculture and Enterprise Development Kenyatta University Nairobi Kenya Kenya Wildlife service Spatial Ecology and Biodiversity Monitoring Nairobi Kenya

Creation of a spectral signature reflectance data, which aids in the identification of the crops is important in determining size and location crop fields. Therefore, we developed a spectral signature reflectance for the vegetative stage of the green gram (Vigna. radiata L.) over 5 years (2020, 2018, 2017, 2015, and 2013) for agroecological zone IV and V in Kenya. The years chosen were those whose satellite resolution data was available for the vegetative stage of crop growth in the short rain season (October, November, December (OND)). We used Landsat 8 OLI satellite imagery in this study. Cropping pattern data for the study area were evaluated by calculating the Top of Atmosphere reflectance. Farms geo-referencing, along with field data collection, was undertaken to extract Top of Atmosphere reflectance for bands 2, 3, 4 and 7. We also carried a spectral similarity assessment on the various cropping patterns. The spectral reflectance ranged from 0.07696 - 0.09632, 0.07466 - 0.09467, 0.0704047 - 0.12188,0.19822 - 0.24387, 0.19269 - 0.26900, and 0.11354 - 0.20815 for bands 2, 3, 4, 5, 6, and 7 for green gram, respectively. The results showed a dissimilarity among the various cropping patterns. The lowest dissimilarity index was 0.027 for the maize (Zea mays L.) bean (Phaseolus vulgaris) versus the maize-pigeon pea (Cajanus cajan) crop, while the highest dissimilarity index was 0.443 for the maize bean versus the maize bean and cowpea cropping patterns. High crop dissimilarities experienced across the cropping pattern through these spectral reflectance values confirm that the green gram was potentially identifiable. The results can be used in crop type identification in agroecological lower midland zone IV and V for mung bean management. This study therefore suggests that use of reflectance data in remote sensing of agricultural ecosystems would aid in planning, management, and crop allocation to different ecozones.

关键词： Multi-Temporal Cropping Patterns Spectral Signatures Landsat 8 Crop Identification

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

Relationship Between Leaf C/N Ratio and Insecticidal Protein Expression in Bt Cotton as Affected by High Temperature and N Rate

引用

Journal of Integrative Agriculture 2014年第1期13卷 82-88页

作者： ZHANG Xiang LU Chun-hua CHEN Yuan WANG Gui-xia CHEN Yuan CHEN De-hua Jiangsu Provincial Key Laboratory of crops Genetics and Physiology Yangzhou University Yangzhou 225009 P.R.China Department of Soil and Crop Sciences Texas A&M University College Station 77843 USA

Expression of insecticidal protein for transgenic Bacillus thuringiensis （Bt） cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio （C/N） and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-l, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of inseetiocidal efficacy in Bt cotton, especially in peak boll period.

关键词： Bt cotton C/N ratio Bt protein insecticidal efficacy

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

Modified Method for Estimating Organic Carbon Density in Discontinuous Karst Soil Using Ground-Penetrating Radar and Geostatistics

引用

Journal of Mountain Science 2015年第5期12卷 1229-1240页

作者： LI Lei XIA Yin-hang LIU Shu-juan ZHANG Wei CHEN Xiang-bi ZHENG Hua QIU Hu-sen HE Xun-yang SU Yi-rong Key Laboratory of Agro-ecological Processes in Subtropical Region Institute of Subtropical Agriculture Chinese Academy of Sciences Huanjiang Observation and Research station for Karst Eco-systems University of Chinese Academy of sciences Guangxi Institute of Subtropical crops

The conventional method which assumes the soil distribution is continuous was unsuitable for estimating soil organic carbon density(SOCD) in Karst areas because of its discontinuous soil distribution. The accurate estimation of SOCD in Karst areas is essential for carbon sequestration assessment in China. In this study, a modified method,which considers the vertical proportion of soil area in the profile when calculating the SOCD, was developed to estimate the SOCD in a typical Karst peak-cluster depression area in southwest China. In the modified method, ground-penetrating radar(GPR) technology was used to detect the distribution and thickness of soil. The accuracy of the method was confirmed through comparison with the data obtained using a validation method, in which the soil thickness was measured by excavation. In comparison with the conventional method and average-soil-depth method,the SOCD estimated using the GPR method showed the minimum relative error with respect to that obtained using the validation method. At a regional scale, the average SOCDs at depths of 0-20 cm and 0-100 cm, which were interpolated by ordinary kriging,were 1.49(ranging from 0.03-5.65) and 2.26(0.09-11.60) kgm-2based on GPR method in our study area(covering 393.6 hm2), respectively. Therefore, the modified method can be applied on the accurate estimation of SOCD in discontinuous soil areas such as Karst regions.

关键词： Discontinuous soil Organic carbondensity Soil distribution Estimation method Ground penetrating radar Karst Peak clusterdepression

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

Survivorship, attained diameter, height and volume of three Paulownia species after 9 years in the southern Appalachians, USA

引用

Journal of Forestry Research 2020年第6期31卷 2181-2191页

作者： Erik C.Berg Stanley J.Zarnoch W.Henry McNab University of Montana Bureau of Business and Economic ResearchMissoulaMT 59812USA USDA Forest service Southern Research station AshevilleNC 28806USA

Little is known of the tree and stand dynamics of varied species of planted Paulownia left unmanaged until harvest in the southeastern United *** sought to remedy this lack of information needed by land managers to make informed decisions by investigating diff erences in survivorship,attained diameter breast height(DBH),diameter at ground level,total height,tree volume and standlevel volume yields of planted ***,***,and *** in the cool-moist environment of the southern Appalachian *** 9 years,combined-species survivorship was only 27.3%.Low survivorship was likely related to several inclement weather *** was signifi cantly smaller in DBH and total *** combined-species stem(bole)volume models were developed as functions of(1)DBH squared,(2)the product DBH squared and total height,and(3)the product diameter ground line squared and total *** total volume production of unmanaged stands was greatest for *** and *** 4 years after planting;by the 9th year,total volume of *** was greater than the other two *** of our study provide managers information on productivity of three species of Paulownia that can be used for estimating plantation yields.

关键词： Diameter Tree height Stand structure Stem volume Paulownia

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

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

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

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：