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Enhanced structural complexity Index:An Improved Index for Describing Forest structural complexity

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Open Journal of Forestry 2013年第1期3卷 23-29页

作者： Philip Beckschafer Philip Mundhenk Christoph Kleinn Yinqiu Ji Douglas W.Yu Rhett D.Harrison Chair of Forest Inventory and Remote Sensing Georg-August-Universitat GottingenGottingenGermany State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunmingChina School of Biological Sciences University of East AngliaNorwichUK Key Laboratory for Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMenglunChina

The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the structural complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced structural complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.

关键词： Forest Structure Index structural complexity Stem Map Species Composition NMDS

Sub-stand diameter distribution types vary along an old-growth Douglas-fir chronosequence into the horizontal diversification development stage

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Journal of Forestry Research 2023年第2期34卷 415-424页

作者： JeriLynn E.Peck Eric K.Zenner Department of Ecosystem Science and Management The Pennsylvania State UniversityUniversity ParkPA 16802USA

Managing mature Douglas-fir[Pseudotsuga menziesii(Mirb.)Franco]stands to emulate the structural complexity of natural old-growth forest requires identifying structural targets at the sub-stand level at which neighborhood dynamics and patchy disturbance shape *** therefore sought to describe the archetypal shapes of predominant sub-stand diameter distribution types(DDTs)observed in natural tree neighborhoods in stands comprising a chronosequence(ca.120-450+yrs)encompassing mature,vertical diversification,and horizontal diversification development *** ten 1.0 ha stands are located in the southcentral Oregon Cascades,*** on the known spatial position of each tree,natural tree neighborhoods were identified using the floating neighborhood approach based on spatial tessellation connecting neighboring trees at the first-(mean 61 m2)through fifth-(mean 2058 m2)order *** analysis was then used to objectively identify the most predominant DDTs among the relative tree size distributions observed in the trans-scale neighborhoods within each *** measures regression was used to classify each DDT to one of six observed archetypal shapes:negative exponential,unimodal,rotated sigmoid,bimodal,concave,or *** three of the 81 observed DDTs deviated by50%(maximum 83%).Within each stand,five to ten predominant DDTs were observed,which deviated from the stand average by 30-48%and were characterized by two to five different archetypal ***,in some stands the majority of tree neighborhoods were best characterized by a different shape from that assigned at the stand *** from the stand average increased from the youngest stand in the mature development stage through the middle stands in the vertical diversification stage to the oldest stands in the horizontal diversification *** complexity of DDT shapes tended to increas

关键词： Diameter distribution type Floating neighborhood Restoration silviculture Small-scale structural complexity

Taxonomic and community composition of epigeal arthropods in monoculture and mixed tree species plantations in a deciduous forest of Ghana

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Journal of Forestry Research 2023年第3期34卷 641-653页

作者： Frederick Gyasi Damptey Emmanuel Opuni-Frimpong Collins Ayine Nsor James Addai Daniel Kwame Debrah Benjamin Schnerch Felicity Bentsi-Enchill Henn Korjus Department of Ecology Brandenburg University of Technology Cottbus-Senftenberg03046 CottbusGermany CSIR-Forestry Research Institute of Ghana KumasiGhana School of Natural Resources University of Energy and Natural Resources(UENR)SunyaniGhana Department of Forest Resources Technology Kwame Nkrumah University of Science and TechnologyKumasiGhana Forest Service Division of the Forestry Commission Accra Department of Biology Education Faculty of Science EducationUniversity of EducationWinnebaGhana Institute of Forestry and Rural Engineering Estonian University of Life SciencesTartuEstonia

Tropical forests provide several ecosystem services and functions and support approximately two-thirds of the world’s biodiversity but are seriously threatened by *** to counteract this menace have revolved around aff orestation with several or a single tree *** thus investigated how plantation forests with either a single or several tree species infl uenced arthropod taxonomic and community composition using pitfall traps to sample selected groups of epigeal arthropods(Araneae,Coleoptera,Orthoptera and Hymenoptera)and with environmental variables assessed *** results revealed 54 taxonomic groups with signifi cantly higher taxonomic richness,activity density,and diversity in the mixed stands than in the monoculture *** significant differences in community composition were mainly driven by families including Lycosidae,Formicidae,Staphylinidae,Scotylidae,Hydrophilidae,Gryllidae and Scarabaeidae and were explained by distinct habitat characteristics(canopy openness,litter depth,deadwood volume,and tree height).While the diverse tree communities and heterogeneous vegetation structure off ered food and habitat resources for diverse arthropod groups,the allelopathic nature coupled with homogenous stand characteristics of the Tectona grandis stands in the monoculture suppressed the growth of understorey vegetation that could otherwise serve as food and habitat resources for arthropods,which might have led to limited activities and diversity of arthropods in the monoculture plantation *** fi ndings thus highlight the need to promote mixed tree plantations in degraded tropical areas,especially when restoring biodiversity is the prime management focus.

关键词： Arthropod community Forest plantations structural complexity Tree diversity Tropical deforestation

Some structural Properties of SAT

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Journal of Computer Science & Technology 2000年第5期15卷 439-444页

作者：刘田 Department of Computer Science and Technology Peking University Beijing P.R. China

The following four conjectures about structural properties of SAT are studied in this paper. (1) SAT ∈ PSPARSEnNP; (2) SAT ∈ SRTDtt; (3) SAT ∈ PttbAPP; (4) FPttSAT = FPlogSAT. It is proved that some pairs of these conjectures imply P = NP, for example, if SAT E pSPARsEnNP and SAT 6 PttbAPP, or if SAT E SRTDtt and SAT E PttbAPP, then P = NP. This improves previous results in literature.

关键词： structural complexity SAT sparse set approximable set truthtable reduction non-adaptive search reducible to decision.

A　Measure　of　the　Structured　Degree　for　Decision　Problems

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Systems Science and Systems Engineering 1997年第1期7卷 112-115页

作者： XIAO Renbin Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China

Analysis on the taxonomy of decision problems is made and some fundamental views on decision problems are stated in this paper. Based upon understanding of decision problem and its structure in depth, a measure of the structured degree for decision problems is obtained by constructing a monotonic mapping. The corresponding relation between the measure value and division of the structured degree for decision problems is given in quantity and theories of decision support are enlarged.

关键词： decision problem measure structural complexity decision support system

Post-stack reverse-time migration using a finite difference method based on triangular grids

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Applied Geophysics 2008年第2期5卷 115-120页

作者：郭书娟李振春孙小东叶月明滕厚华李芳中国石油大学(华东)地球资源与信息学院山东东营257061

Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurate and not affected by strong subsurface structure complexity and horizontal velocity variations. The difference method based on triangular grids maintains the simplicity of the difference method and the precision of the finite element method. It can be used directly for forward modeling on models with complex top surfaces and migration without statics preprocessing. We apply a finite difference method based on triangular grids for post-stack reverse-time migration for the first time. Tests on model data verify that the combination of the two methods can achieve near-perfect results in application.

关键词： reverse-time migration structural complexity triangular grids finite difference

Static Requirement and Type＇s complexity in the Diagnostics Phase

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Journal of Civil Engineering and Architecture 2012年第4期6卷 489-495页

作者： Antonella Guida Antonello Pagliuca Department of European and Mediterranean Culture: Architecture Environment Cultural Heritage (DICEM)

The preservation of a historical building, whatever its architectural and/or artistic value, is more successful when undertaken with a deep understanding of the building＇s history, development, materials and construction techniques. The preliminary phase of any restoration intervention must start with data acquisition regarding the characteristics and conditions of the building, including a survey of significant alterations. In a great number of cases, restorations are not respectful of the building＇s static efficiency, so its static requirement is weakened. In fact, a very high percentage of instances in which a restoration effort results in building damage is attributable to such modification＇s indifference to the structural balance of a structure, as consolidated over time. This study focuses on the restoration intervention on two trilobate pillars that separate the central space from the presbytery in the Cathedral of Matera, located in southern Italy. Through the use of sonic tests - carried out despite the complexity of the shape of the building and constructive elements that characterize these pillars -- it was possible to show the effectiveness of the implemented intervention, highlighting critical points and weaknesses. The research aims to show how -- despite the complexity of some structural elements of a building -- in-depth knowledge of a structure＇s structure and history is essential to for the success of restoration interventions, which are respectful of a building＇s type and material peculiarities.

关键词： structural complexity static requirements refurbishment interventions diagnosis phase conservation

An Efficacious Synthetic Strategy for cis-Clerodane Diterpenoids

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Chemical Research in Chinese Universities 2001年第Z1期17卷 112-页

作者： LIU Hsing-Jang Department of Chemistry National Tsing Hua University Hsinchu

Clerodane diterpenoids are widely distributed in nature and constitute one of the largest and, yet, still rapidly growing family of secondary metabolites. Of the relatively few clerodanes tested for biological activity, many were found to possess interesting antifeedant and medicinal properties and are potentially useful as insecticidal, antitumour, antifungal, antibiotic, anti-peptic ulcer, and psychotropic agents. The structural complexity and biological activity associated with this class of natural products have attracted extensive effort towards their total synthesis. In most of the reported syntheses, the synthetic sequence is specific to the target molecule. We have recently developed a versatile synthetic approach which is applicable to the synthesis of a large number of target molecules with minor modifications. The key operation of this approach is the face-selective Diels-Alder reaction of dienone ester 1. The successful application of this approach has culminated in the total synthesis of several cisclerodane diterpenoids. We have since made considerable improvement on this general synthetic approach, in terms of the overall efficiency, making use of compounds 2 and 3 as dienophiles. This newly developed general synthetic approach towards clerodane diterpenoids will be presented.

关键词： biological activity total synthesis structural complexity secondary metabolites psychotropic agents natural products