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《林业与社会》2000,(2)
ItiswellknownthatthecharacteristicsofChina'ssituationsareoverpopulation,poorfoundation,lowculturalandscienceandtechnologylevels,lackandunevendistributionofresources,andlowrankingofpercapitaGDP.Owingtothebackwardofscienceandtechnologyandmanagement,therelativelyshort-suppliedresourceshasnotbeenutilizedproperly.Takingforestryforexample,thecoverisonly13.92%,lowerthantheworld'saverageof22%;China'spercapitaaverageofforestlandislessthan0.13ha,whiletheworld'saverageis1.lha;Chinaisalsolowinforestqual… 相似文献
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Abu Hena Mustafa Kamal Mohammed Muzammel Hoque Mohd Hanafi Idris Osumanu Haruna Ahmed Md.Khurshid Alam Bhuiyan Md.Masum Billah Md.Nesarul Hoque Zamri Rosli 《林业研究》2020,31(2):613-623
Decaying mangrove detritus plays a significant role in nutrient cycling and fueling in both the forests and aquatic habitats where the detritus stems from estuarine and coastal food webs.Detrital decay rates partly depend on the type of detritus,but most studies have thus far focused on leaf litter decay and decomposition,whereas other detrital sources(except for roots)have largely been ignored.We compare the decay rates of Rhizophora apiculata and Xylocarpus granatum non-leafy detritus(flowers,propagules,stipules,and twigs)with mangrove leaf litter in field studies,using litter bags during the dry and the wet seasons in the tropical mangrove forest of Sibuti,Sarawak,Malaysia.We observed higher microbial decay rates of stipules,flowers,propagules,and twigs for both the R.apiculata and X.granatumduring the wet months.By contrast,leaf decay rates were higher during the dry months.Decay rates depended on the lignin content of the detrital sources of both species,both during dry and wet months.Accordingly,the half-life(T0.5)and 95%lifespan(T0.95)of non-leaf materials(flowers,propagules,stipules and twigs)for both species were remarkably longer than those of leaf litter.Slowly decaying non-leafy detritus may play a significant role in nutrient and carbon cycling over longer time,when leaf litter is either being decomposing rapidly and/or being washed away by tidal flush and river runoff.Hence,non-leafy(flowers,propagules,stipules and twigs)detritus should be taken into account when budgeting organic matter turnover in mangroves. 相似文献
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Emmanuel Kombiok 《Southern Forests》2017,79(2):153-160
Shea (Vitellaria paradoxa) butter is an important internationally recognised economic commodity because of its food and medicinal potentials. However, access to finance for small-scale forest enterprises such as shea butter production and marketing remains a fundamental problem, which affects the growth and performance of these enterprises. This study, therefore, assessed the financing schemes and delivery mechanisms available for the production and marketing of the product in Tamale, Northern Region of Ghana. It also identified the financial structures available to shea butter producers, including constraints of the financial delivery mechanisms. Using a social survey, the study purposively selected and interviewed 83 women who engaged in shea butter processing. Of these, 86% were full-time processors of shea butter and 14% were involved in other businesses, such as petty trading, groundnut and rice processing. The study revealed low patronage of financial services as only 18% of the respondents took loans. A high proportion (82%) of the respondents were under contract financing with companies that purchased the shea butter. This financing arrangement made it difficult for the women to expand their activities as they usually were unable to negotiate and receive competitive prices for their shea butter. Non-governmental organisations and some financial organisations were involved in providing technical support services to the producers. However, there was an absence of continuous support services in credit management. The high illiteracy rate (97%) of shea butter producers made it challenging for the women to access formal training programmes to make them aware of opportunities that exist for financing their business. There is the need for targeted collaboration among stakeholders to improve existing financing schemes. In the long term, there should be policies to standardise the activities of the shea butter industry to improve access to credit, which could lead to the sustainable growth of these enterprises. 相似文献
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The highest deforestation and forest degradation rates in Africa occur in the dry forests and woodlands where pressure for land is increasing, poverty is rampant, livelihood options are few and climate change effects are severe. This paper examines factors that cause land and forest degradation in the Sahel and dry forests and woodlands of eastern and southern Africa and highlights some successful restoration practices, technologies and approaches. In the Sahel, enclosures are used to protect young growing trees while in East Africa enclosures are implemented on degraded land as a mechanism for environmental rehabilitation with a clear biophysical impact. The choice of techniques for rehabilitating specific degraded areas depends first on the priorities and management objectives of stakeholders followed by the costs and benefits associated with available rehabilitation techniques and the economic, social, and environmental values of the land resources in their current and desired future states. In the Sahel, sustainable land management is considered to be an imperative for their sustainable development and the practices include soil and water conservation activities and structures. In all regions, natural forest rehabilitation has used both natural and assisted regeneration to promote the growth of especially indigenous species through coppice regrowth and root suckers rather than seeds. Assisted regeneration was especially prevalent in the Sahel where indigenous tree species have been identified to dominate the degraded sites during early stages of secondary forest succession. The success of any rehabilitation activities depends on community-based natural resources management. In addition, the forest policies and their related policies need to be enabling in order to address issues of concern, including (1) the full participation of communities, (2) clear land and tree tenure and (3) equitable benefit sharing. 相似文献
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The title compounds 4,4'-oxobis(propham) ((?)n) (C20H24N2O5, Mr.=372.41) was synthesized by the addition reaction of corresponding 4,4'-oxobisphenyl diisocyanate with isopropanol. The crystal structure was determined by X-ray diffraction method. The crystal is triclinic system, space group P-1 with a=8.5107(17), b=9. 1164(18), c=14.5701(3)A, α=80.44(3),β=85.25(3), γ =62.88(3)°, V=992.2(3)A3, Z=2 , Dc=1.247g/cm3, F (000)=396, R =0.0520 , wR2=0.1434 for 4336 observed reflections with [I>2 σ(I)]. X-ray analysis reveals that interatomic distances for O(2)-C(7) is 1.2142(19), O(4)-C(17) is 1.2136(18)A, obviously show they form C=O double bonds. 相似文献
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In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones). 相似文献
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Naoko Yamaguchi Susumu Shiraishi Yoshinori Sasaki Chiaki Yamamoto 《Journal of Forest Research》2000,5(1):35-38
Leyland cypress (×Cupressocyparis leylandii) has been regarded as an intergeneric hybrid between Monterey cypress (Cupressus macrocarpa) and Alaska cypress (Chamaecyparis nootkatensis) in the Cupressaceae. Each partial sequence of the 18S-rDNA from nuclear and therbcL from chloroplast DNA genomes was determined using above three species. At the 59th site from the 5′ end of the 152 bp of
the determined 18S-rDNA sequence, one base difference was identified between Monterey cypress (T) and Alaska cypress (A). However, Leyland cypress
showed either nucleotide A or T at this site. Since nuclear DNA is inherited by biparental mode, this result shows genetic
evidence that the nucleic genome of Leyland cypress originates from Monterey cypress and Alaska cypress and that this species
is of hybrid origin. 相似文献
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《林业与社会》2000,(2)
TheprojectofSichuanCommunityForestry,fundedbytheFordFoundationandassistedandguidedbyRECOFTC,isaseriesofactivitiesofresearch,practiceandpromotionofthebestmanagementandoperationalmodesimplementedintheareaoftheprojectofYangtzeriverprotectiveforest.Since1992,SichuancommunityforestryhascarriedoutsomepilotworksinQuxiancounty,PingchangcountyandButoucounty.1.ThethinkingandfeaturesofcommunityforestryCommunityforestryisacompletelynewthinkingandmethodofworksintroducedfromabroad.Itisaproductofcombi… 相似文献
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《Forest Policy and Economics》2001,2(2):195-201
The beginning of the land rent theory is closely related to the German forest economists Friedrich Wilhelm Leopold Pfeil and Johann Christian Hundeshagen (1828). It was further developed by Gottlob König (1864), Johann Heinrich v. Thünen, Max Robert Preßler, Gustav Heyer, Max Endres and in particular by Martin Faustmann (1849). His 1849 published and well known formula may be seen as the center of the land rent theory. However, the application of this concept demanded a considerable change of forest management practice due to the reduction of usual rotations and stocking density. Eventually, the land rent theory conflicted with the principle of sustained yield which had become the central idea of forestry in Germany in the 19th century. Since forestry under German conditions did not start as an investment on bare forest land, but had to manage existing forests under the principle of sustainability, the theory of the highest revenue seemed to be a more appropriate guideline for forestry. However, the maximization of the highest revenue assumed a marginal interest rate of 0% because the time span between input and output was not considered. Besides that, this principle also conflicted with the reality of forestry, because the scarcity of financial funds was not regarded. So far, both theories have not delivered solutions useful to real forest economic decision problems in Germany. Using an example from Lower Saxony, it is demonstrated that considering the objective of sustainability leads to results which are in accordance with the reality and the economic theory. 相似文献
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New Forests - Permanent landscape attributes such as topography (elevation [m]) and microtopography (local variation in elevation [cm]) can increase the risk of cold air drainage down-slopes and in... 相似文献
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1 INTRODUCTIONUrban Forestry is an emerging science and art in thePhilippines. Its concepts and principles are quite similarwith traditional forestry being both resourcemanagement systems. However, urban forestrysobjectives are more focused on the protective,ameliorative, aesthetic and amenities rather than onproductive roles.As a resource management strategy, urban forestryinvolves wise use, management and/or manipulationof the resources that include individual trees and otherplants com… 相似文献
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１三棘华枝ＳｉｎｏｐｈａｓｍａｔｒｉｓｐｉｎｏｓｕｍＣｈｅｎｅｔＣｈｅｎ，ｓｐ．ｎｏｖ．本新种与臀沟华枝ＳｉｎｏｐｈａｓｍａｌａｔｉｓｅｃｔｕｍＣｈｅｎｅｔＣｈｅｎ近似，但本种雄性臀节端部较窄，纵沟浅裂．背面具有３个排列成倒三角形的锥形突，第９节背板隆起成直角下垂等不同，可相区别．模式标本保存在中山大学．２单棘华枝ＳｉｎｏｐｈａｓｍａｕｎｉｓｐｉｎｏｓｕｍＣｈｅｎｅｔＣｈｅｎ，ｓｐ．ｎｏｖ．本新种与三棘华枝ＳｉｎｏｐｈａｓｍａｔｒｉｓｐｉｎｏｓｕｍＣｈｅｎｅｔＣｈｅｎ近似，但本种雄性臀节较狭长，两侧端叶扩展成瓣状；端部无纵沟，背面具有１个明显的锥形突，下生殖板形状以及第９节背板明显不同等，可相区别．模式标本保存在中山大学．３拟异尾华枝（雌性）ＳｉｎｏｐｈａｓｍａｐｓｅｕｄｏｍｉｒａｂｉｌｅＣｈｅｎｅｔＣｈｅｎ本种发表于１９９６年，当时仅报道其雄性，近在中山大学昆虫标本馆发现１对雌雄，其雌性与异尾华枝ＳｉｏｎｐｈａｓｍａｍｉｒａｂｉｌｅＧüｎｔｈｅｒ雌性相似．但本种头部形状，第７腹节腹板与腹瓣伸至的位置，以及尾须的形状等明显不同，可与之区别．模式标本保存在北京林业大学和中山大学． 相似文献
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He Qingtang Song Conghe College of Forest Resources Environment Beijing
Forestry UniversityBeijing l P.R. China 《中国林学(英文版)》1994,(2)
ＥｆｆｅｃｔｓｏｆＦｏｒｅｓｔｏｎｔｈｅＢｕｄｇｅｔｓｏｆＷａｔｅｒ，ＥｎｅｒｇｙａｎｄＧａｓｅｓｉｎｔｈｅＥｎｖｉｒｏｎｍｅｎｔＨｅＱｉｎｇｔａｎｇ，ＳｏｎｇＣｏｎｇｈｅＣｏｌｌｅｇｅｏｆＦｏｒｅｓｔＲｅｓｏｕｒｃｅｓａｎｄＥｎｖｉｒｏｎｍｅｎｔ，... 相似文献
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Variability of the seeds and cones and key taxonomic charactersselection of Larix in Northeast China
IntroductionLarisoIgensiSHenryandLarisgmeIinii(Rupr.)Rupr.areboththenativetreespeciesinChina,buttheirdiStributingcentersarenotwithintherangeofChina.LarisoIgen$isismainlydistributedinNoFthKoreaandadjacentNortheastChinaandRussia(Dylis1961).lnChina,itsdistributingcenterisintheChangbaiMountains.Nevertheless,LarisgmeliniiismainlydistributedintheFar-EastandEastSiberiaofRussiaandNortheasternChina.ItsdistributingcenterinChinaisintheDaxing'anMountains.Thecharac-tersofthesexuaIreproduction… 相似文献
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Cao Jin-zhen Li Li-dan Liu Zhi College of Materials Science Engineering Beijing Forestry University Beijing P. R. China 《中国林学(英文版)》2005,7(4)
In this study, the contact angles of three different reference liquids (including distilled water, diiodomethane, and formamide) and PF resin on the surfaces of Chinese fir (Cunninghamia lanceolata) samples untreated or treated with different con- centrations of ACQ-D (ammoniacal copper quat Type D) solutions were measured. Then, the surface free energy was calculated by two approaches: acid-base approach and geometric mean approach. ACQ-D treatment caused higher contact angles and lower surface free energies at a retention level corresponding to the commodity treated wood products. When wood was treated with much higher concentrations of ACQ-D, the total surface free energy of wood would be higher than the untreated control. Acid-base/polar compo- nents related with the hydrogen bonding state in wood were considered to be responsible for the observed changes according to the applied approaches. The hydrophobic properties and also higher contact angles of PF resin drop on wood surfaces after ACQ-D treatment at a reasonable retention level confirms the changes on surface free energy. 相似文献
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本文研究了长江三峡花岗岩地区林地土壤流失特性．结果表明由鳞片状面蚀导致的土壤流失量月分布与月降雨量的分布趋势基本一致，二者呈现出较为明显的线性相关关系．植物盖度≥０．７０的林地土壤流失多集中发生在６～９月份，土壤流失量在５０００ｔ·ｋｍ－２·ａ－１以下．盖度＜０．７的林地土壤流失年内分布时间多在３～１０月份，土壤流失量为５００～６０００ｔ·ｋｍ－２·ａ－１． 相似文献