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1.
Ginkgo biloba L. is a precious relic tree species with important economic value. Seeds, as a vital reproductive organ of plants, can be used to distinguish cultivars of the species. We chose 400 seeds from two cultivars of ginkgo(“Fozhi” and “Maling”;200 seeds for each cultivar) as the study material and used the Gielis equation to fit the projected shape of these seeds. The coefficients of variation(CV) in root mean squared errors(RMSE)obtained from the fitted data were used to compare the level of inter-cultivar variations in seed shape. We also used the covariance analysis to compare the allometric relationships between seed weights and projected areas of these two cultivars. The Gielis equation fitted well the seedshapes of two ginkgo cultivars. The lower CV in RMSE of cultivar “Fozhi” than “Maling” indicated a less symmetrical seed shape in the latter than the former. The bootstrap percentile method showed that the seed shape differences between the two cultivars were significant. However, there was no significant difference in the exponents between the seed weights and the projected areas of these two cultivars.Overall, the significant differences in shapes between the seeds of two ginkgo cultivars were well explained by the Gielis equation;this model can be further extended to compare morphological differences in other ginkgo cultivars, and even for plant seeds or animal eggs that have similar oval shapes.  相似文献   

2.
IntroductionBal11booisl11ainfoodoftl1cgial1tpal1daint`.ildal1dman-fedgiantpandattasfCd111ucl1bal11boobcsldcsconccntratestl1atx`erel11adcofgrainPOwdcrtokccpltsfeedingl1abitsinwiId,buttl1cdigestivcratcofcoarsccclluloseisvery'low,il1botl1ttilda11d111a11-fcdpa11das.Wecanfindthattl1eba111boot'asall11ostl1otdigcstcdfrolllthefCccsthatcol1tai11edl11ucI1bal11boosticks.CI1cl1Yucllulletc.(l993)rcPortedt1lattl1edigcstit'eratcil1bal11boocoarsecelluloscisabout25%ol1lv.Tl1cautl1orsdesiglledthiscxPCrilll…  相似文献   

3.
1 INTRODUCTIONThe Loess Plateau is the most drastic soil erosion regionin China, with the most severe water erosion. Thedistribution of types and intensity of erosion not onlyhave regional diversity but also have perpendicularvariation. In the small watershed, there are differencesin erosion characters among its upper, middle and lowerreaches. It is very significant for taking rationalmeasures of soil and water conservation and forpreventing soil and water loss to analyze the relationbe…  相似文献   

4.
Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the modulus of rupture (MOR) of finger-jointed lumber specimens made with four kinds of Eucalyptus (Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis). Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.  相似文献   

5.
IntroductionSchiSandraisadeciduousvineofMopohaceae.ItsthetStaSteofsWed,sour,bitter,PepPeryandsalty.ItisoneOfthetfadihonalChineseherbalmedicine.Schisan-for(Mopohaceae)hasbeenusedasprecioustonicandastriopntdrugforalleviahngcoughsinceanc1enthme.Modemmedicine…  相似文献   

6.
The corrosive rates of 4 types of metals as well as epoxy-coated metal in a variety of preservatives derived from different copper sources and ingredients were .measured in this paper. The main results show that: CCA is less corrosive to red brass and Q235A steel than other copper formulations; Copper-based preservatives such as ACQ and CuAz derived from basic cupric carbonate or cupric hydroxide are much less corrosive to Q235A steel than those from cupric sulfate; Ethanolamine is less corrosive to Q235A steel than ammonia in ACQ derived from cupric hydroxide, while other ingredients are the same; Epoxy resin coating could be used for protecting red brass, Q235A steel and zinc hotdipped galvanized mild steel from corrosion.  相似文献   

7.
Plantation poplar is one of the most important resources for wood industry, its utilization field is vast. The wettability of Populus tomentosa with different drying methods was judged by measurement of contact angle using distilled water in this paper. The results showed that the specimens from conventional drying have the biggest contact angle, and the air dried have the smallest contact angle, air dried lumbers have a better wettability than the kiln dried. The changes of contact angle in a period of tim...  相似文献   

8.
Up until 2009, 2541 nature reserves had been established in China. However, the process of developing this system of nature reserves was not quite smooth. Various kinds of information related to nature reserves, such as annual growth, the type of nature reserves established, motives behind building a nature reserve, legal instructions and the constitution of government sectors, were collected and analyzed in order to highlight the characteristics of the devel- apment of our nature reserve system. As a result, we identify three phases and their characteristics, i.e., the initial phase from 1956 to 1978, the establishment phase from 1979 to 1996 and the management standardization phase from 1997 to 2009, could be clearly identified. It is suggested that since the establishment of this comprehensive structural frame- work in China, the system should be entering a new developing phase. We recommend that more attentions should be paid on how to guarantee effective management and how nature reserves are able to maintain their value and fulfill their abjectives in the future.  相似文献   

9.
This study assessed ecological and socio-economic impacts of a participatory forest management project in the Republic of Benin. The study focused on the Wari-Maro Forest Reserve and the ‘Projet d’Aménagement des Massifs Forestiers’ five years after its completion. A forest inventory was carried out using 37 square plots of 729 m2 each to characterise the population structure of two types of plantations established: plantations with exotic species and plantations with native species. In addition, individual surveys were conducted with local households, organs of joint forest management and forestry officers to evaluate their perceptions about the participatory management of the plantations. Finally, the sustainability of the participatory management was assessed with an established rating system. Results showed that plantations with exotic species were more successful than plantations with native species. Local communities argued that they have not been involved in the plantations design but only in the implementation step and that their standards of living have decreased after the project completion. The rating system used showed that the participatory management of plantations had a short-term sustainability. The findings suggest that future projects should be designed and implemented with better participation of local communities as full partners.  相似文献   

10.
Past studies already showed that the protectiveeffects of shelterbelts varied with the structuralparameter of shelterbelts. To get full use of theprotective effects, we must keep the shelterbelts withoptimal structure. In the former studies, theshelterbelts structure was generally divided into 3 or4 types (Cao Xinsun, 1983). Then two new structuralparameters, porosity (β) and permeability (α) as wellas their optimal values were put forward by the latterresearchers (Caborn, 1957; Cao Xinsun…  相似文献   

11.
1 INTRODUCTIONChinese forest volume ranks high in the world,following Russia, Brazil, Canada and America. Buton the average, there is a great shortage of woodresource in China. With the increase of demandsfor wood and wood products, wood resource isobviously deficient. Though plantations have beenplanted widely in order to reduce the pressure ofdemands for wood to some extent, some of themwere planted blindly and the value in use is still low.How to make full use of the limited forests …  相似文献   

12.
INTRODUCTIONBecause of the interleaving, extensity of multi-factorsaffecting forest ecological benefit in space, and thecomplexity of bio-factors of forest,and in themeantime, because of lacking of consultation forthe transformation between physical and ecologicalquantum and monetary value, the evaluation ofecological benefit of forest is all along one of thedifficult problems in academic field. In recent years,some scholars have made much research andexploration in the theory and practice…  相似文献   

13.
Ultrasound-associated extraction of seed oil of Korean pine   总被引:8,自引:1,他引:8  
Experiment on ultrasound- associated extraction of seed oil of Korean pine (Pinus koraiensis) was conducted in Northeast Forestry University, Harbin, China. The factors affecting extraction yield, such as ultrasonic frequency, extracting temperature, extracting time and the ratio of material to liquid (ratio of Korean pine seed to absolute alcohol), were analyzed under specific condition and the optimal extracting parameters were obtained as the ultrasonic frequency 32 000 Hz, the extracting temperature 80℃, the extracting time 50 rain, and the ratio of material to liquid 1: 30. The study demonstrates that ultrasound is a reliable and great efficiency tool for the fast extraction of Korean pine seed oil。  相似文献   

14.
The study made a monetized valuation of eco-service provided by forests at Saihanba Mechanic Forest Farm in terms of water conservancy, soil conversation, carbon sequestration, micro-climate adjustment, air quality improvement, protection for agriculture, biodiversity maintenance, and landscape recreation. The results revealed that the total value of various eco-services is 3.061 billion yuan/a, while the eco-services of unit area forest values at 42 300 yuan/(ha·a).  相似文献   

15.
A Study of Collecting Robot of Conifer Cone   总被引:1,自引:0,他引:1  
IntroductionIntheforeStp~tion,thecollectionofconifcrconeisalmpsadifficultProblem.AlthoughmanykindsofconecoleCtinmachinehavebeenresearchedandmanufac-~athomeandabroad,forexample,elevator,vibra-tionmachineoftrdetrunkandsoon.ThesemachincshavcnotbeenaPPliedwid…  相似文献   

16.
C.anachoreta causes disease of poplars and willowsthroughout China and reproduces four generationsduring one year in Beijing, lasting the whole growthperiod of forest, not only influencing the landscapebut also bringing economic loss. To produce CaGVand other natural enemies need a large number ofequally developed host insects. For this reason,rearing C.anachoreta is an important subject.CaGV is an obligate parasite with high toxicity andpathogenicity to C.anachoreta. Because of its virion…  相似文献   

17.
Effects of three gaps which are large (118 m^2), medium (86 m^2) and small (20 m^2), respectively, and under canopy of Tsuga longibracteata forest on the seedling establishment of T. longibracteata were studied through seed burial experiments from December 2003 to January 2005 in Tianbaoyan National Nature Reserve of Fujian, China. The results showed that the area of gap had an evident effect on the seedling establishment of T. longibracteata. The seedling emergence rates of T. longibracteata in plots of large gap, medium gap, small gap and under canopy were 10%, 10%, 4% and 6%, representing an increasing trend along with the gap size increasing without a significant difference. Rain eroding and insects feeding were two main factors leading to seedling death. The larger the gap size was, the more seedlings were killed by rain erosion and the fewer seedlings were killed by insects feeding. The emergence time of seedlings was almost same in all plots while their death time was different respectively. The gap size had a significant impact on seedling survival rate. The seedling survival rate was highest in the medium gap plot (27.0%) and next to the highest in large gap plot (7.3%), and seedling in small gap plot and under canopy plot died out after one growing season. Increased light supply in gaps was favorable for the seedlings growth and survival. Increased light supply in the large gap could enhance the growth of seedling leaf and root of T. longibracteata, and the seedling in turn allocated more dry mass to root and leaf, but it has little impact on the growth of stem. This research indicates that T. longibracteata is a pioneer species and its seedling establishment need a medium or large gap (〉50 m^2).  相似文献   

18.
Factor analysis and expert scoring methods were used to rank flammability of 16 major species of trees and shrubs in Daxing’anling area of northeastern China,based on 6 flammability variables,i.e.,air dry moisture content,absolute dry moisture content,ignition point,ash content,heat of combustion and extractive content measured on leaves,barks and twigs.Out of 16 species evaluated,for leaves’ flammability,Larix gmelini was the smallest and Pinus sylvestris var.mongolica was the biggest;for barks’ flammability,Salix koreensis was the smallest and P.sylvestris var.mongolica was the biggest;and for twigs’ flammability,Populus davidiana was the smallest and Ledum palustre var.dilatatum was the biggest.The flammability ranking based on the integrated scores of leaves,barks and twigs suggested that Prunus padus,Betula dahurica,and L.gmelini were the top 3 less flammable species and that L.palustre var.dilatatum,P.sylvestris var.mongolica,and R.simsii were the top 3 more flammable species.This ranking agreed well with current standards and experience and should help the species selection for building fire-break forest belts in the study region.  相似文献   

19.
1 INTRODUCTION1.1 Importance of Green AreasAs countries worldwide move toward developingnations, there is a change in education level, employmentand income pattern of their people, which result in higherpurchasing power, better mobility and more free time.With an increase in urbanization as well as rapiddevelopment of infrastructure throughout the countriesthe people are in the transition of changing their lifestyleto modern society.In this urban modern society recreation is becomingincr…  相似文献   

20.
IntroductionLandscapecanbeconsideredaspatiaI1yheterogeneousarea,andspatialpatter11referstothearra11gementofstructurall1eterogeneityofenvironments,resourceandbiologicalsysteInsinspace(Formanetall986,Tur11erl987,l989-Risserl987,TurneretaI199l).Turner(1987,1…  相似文献   

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