1994 Vol. 7, No. 4
This paper reports leaf spot disease of seedlings of Khaya senegalensis A.Juss.caused by fungus of Sclerotium coffeicola Stahel,which can incur much severer disease favored by high temperature and humidity,especially from May to October.The disease fun-gus is propagated mainly by wind,rain and leaf contact.The effect of control is 63.6%,69.8% and 70.1%,respectively,spraying on leaves with water soluble carbendazim solution of 500,1000 and 1500 ppm.
By using the biological law that height growth of dominant tree is inde-pendent of its plantation density and it's a function of the site an stand age and that diametergrowth can indicate a multifactor effect,and by the use of taking the dominant height as anindependent variant and introducing it into other related models,a yield modelling system forChinese fir plantation has been constructed.It helps to provide a growth modelling fornatural growth and post-thinning growth of Chinese fir plantation.It can help to build astandard tree height curve,a compatible predicting model for diameter and cross-sectionalarea and a thinning modelling system.In addition,a mathematical equation on the nongrowthincrease caused by thinning can be deduced.
rattan species,22 rattan roots and their soil samples have been investigated and collected from different climate zones and site condition in Guangxi,Guangdong and Hainan Province.The results show that 10 VA Mycorrhizal fungi exist in among the 11 sam-ples of rattan roots with infective rate of 8.3%～43.O%;But VAM fungi spores exist in all 11 soil samples.13 species of VAM fungi have been identified.They belong to Glomus and Scutellospora,Acaulospora and Scerocystis respectively.Four newly reported VAM species belong to Glomus and Scutellospora.Glomus sp.No.1,Sclerocystis pachycaulis and Acaulospora mellea are common species in rhyzosphere of rattan.
Conducting the method of typical investigation to collect 172 profiles of thesoil in the main Ph.pubescens stands in Zhejing and Fujian Province,633 samples of soil havebeen tested to analyse the available Si content.As a result,1.Contents of available Si in different soils vary because different kinds of rock,types of soil,geography(different of latitudes,or altitudes etc.).The soil available Si content is quite low in general igneous rock except for granite and tuff of higher elevation in this investigations,and is comparatively high insedimentary rock.But in metamorphic rocks it appearss in random.The order of the avail-able Si content in each kind of soil in order is:mountain yellow earthcalcareous soilmountain yellow-brown earthmountain red earth≥yellow-red earthacid purple soil≥low hill red earth.It indicated that the distribution of the soil available Si has a rising latitu-dinal zonality law of from the south to the north and a rising vertical zonality law of the altitudes from the bottom to the top.2.Average of soil available Si content in that area are:45.13 mg/kg(A horizon),76.56 mg/kg(B horizon),and its degree of variation Was thelargest.A distribution map of low available Si content regions in that area has been madebased on the cluster analysis
Provenance test of 9-year-old loblolly pine plantation has been conducted.The results show that the effects of seed sources on the growth and wood properties are significant.Latitudinal geographic model on the height,volume,stem form,whorls of branchesand summer wood % are obviously correlated with the temperature of the original seedsources.The tracheid length was controlled by longitude,There is no geographic variationamong the destity of the wood.There is no correlation between the density of wood and volume growth.The stem with thin branches is straight for the fast-growing seed sources.Based on the selection index,comprehensive selection has been made according to the different requirements of the timber.
The results demonstrate that pine caterpillars are quite sensitive to the illumination of fluorescent lamp and they even can perceive the light in intensity below 0.1 lx.However,these pests show sheer opposite responses to the light spectrum below or above 570 nm,they lost the physiological response to the light above 570 nm.Consequently,the twilight can be neglected in calculating thenatural photoperiods,because twilight does not contain the light below 570 nm,even though its illumination can reach 300 lx.The influence of photoperiodic reaction of pine caterpillar on its population dynamics is also discussed considering the effects of forest on sun light through the canopy's reflection and absorption.
From 1990～1993,the wirulence of 9 isolates of Bursaphelenchus xylophilusfrom Japan(S-6),Canada(STJ,STW,BxBC)and China and 5 isolates of B.mucronatus from France(Bspfrance),Canada (Q1426),Norway(Norway)and China was tested.Each isolatewas inoculated(1500～2000 nematodes/per seedling)on 3～6-yr-old seedlings of 8 pinespecies through cutting the bark of the stem.As a result,the virulence of B.xylophilus iso-lates is significantly higher than that of B.mucronatus wherever they are from.For each iso-late inoculated,the graph of host mortality of 8 pine species is different even within the samenematode species.The most virulent B.xylophilusn among them,are 5 isolates from China.Isolates from Japan and Canada are moderate while isolates of B.mucronatus are less virulentor avirulent.The result of disease development is related not only to mortality but to meandeath speed(MDS).The MDS is different for different host pines inoculted with the sameisolate and is different for the same pine species inoculted with different isolates as well.Two isolates from China(both from Pinus massoniana in Nanjing and Shenzhen Cities)have asomewhat higher MDS than other isolates.P.massoniana is the most resistant pine afterinoculation while P.thunbergii and P.armandi are the most susceptible.The relationshipamong host,nematode and other factors is also discussed.
During the period of the seventh five year plan,an experiment on the silviculture and management of dense plantation and extra-short rotation has been conducted in 26 experimental sites belonging to 13 experimental regions covering 5 natural ecological regions,12 Provinces of China.The density of fuelwood stand is 5 000～10 000 stems/hm2 generally,15 000～20 000 stems/hm2 in the southern coastal regions.The rotation is 1～2a,3～5 a in partial region of North China.The biomass yield of experimental forest are 3～5 times more than that of theordinary fuelwood stand,5～8t/(hm2·a)in northwest China experimental region,7～10t/(hm2·a)in northeast and North China,6～20t/(hm2·a)in Central China,10～20t/(hm2·a)in Southwest China, 20～25t/(hm2·a)in Southeast coastal region.At the same time,60 fine fuelwood species have been screened out from the traditional fuelwood species and native forest species all over China.
The experiment of the effect of different tending methods on the growth andeffect of soil and water conservation were conducted in the juvenile Chinese fir plantation inthe Experimental Centre of Subtropical Forestry,CAF in Fenyi County,Jiangxi Provincefrom 1991 to 1993.The experimental site was located in the central production area of Chinese fir in middle-subtropical zone.There were 12 sample plots in the experimental areawhere the secondary shrubs were distributed before.The soil was yellow soil with a depth of1 m surface soil and 25 cm of humus,and the site index was 16～18.The Chinese fir treeswere planted after burning on the ground.Three tending methods were used as follows:M.1,a thorough weeding without soil-loosening,M.2,a thorough weeding with partial soil-loosening,M.3, a thorough weedingwith soilloosening.The results indicated that the differences of tree growth among themwere not significant.The vegetation biomass of M.3 was less than that of M.1 and M.2(M.1-5.87 t/hm2,M.2-5.89 t/hm2,M.3-4.99 t/hm2).Soil erosion of 1.71 t/hm2 causedby M.3 was the highest,that of M.2,the second,1.15t/hm2 and that of M.1 was 1.08t/hm2.For the consumption of labour,M.1 was the least one of 9.2 labour-day/hm2,M.2 thegreatest one of 16.7 labour-day/hm2,M.3 12.6 labour-day/hm2.Therefore M.1 was themost satisfactory method, which should be adopted on a large scale,especially for the youngplantation without the distribution of Miscanthus floridulus,Imperata clindrica,and Phyllostachys congesta which have to be got rid of from the young Chinese fir stand when they appear.
The results of species/provenance trial involved 11 species and 79provenances at 5-year-old in the east part of Hainan Island showed that the growth differences among 79 provenances within the different species were highly significant while thegrowth differences among provenances within the same species were also highly significant.The ratios of the best provenance and the worse ones on volume per hectare for E.urophylla,E.tereticornis,E.camaldulensis and E.grandis were respectively 8.46:1,5.86:1,5.32:1and 4.03:1.The height growth,DBH and volume per hectare of E.tereticornis,E.camaldulensis and E.grandis were respectively significant and there were negative correlations with the latitude of native habitat while the height growth,DBH and volume perhectare for E.urophylla was highly significant and with negative correlations with the altitude of native habitat.The paper have put forward some other species and provenances suitable for planting in the east part of Hainan Island.
In order to find out the simple method for estimation of biomass and volumeprdocuction of Acacia auriculiformis plantations, this paper selected two models of W(V)1=aDb and W(V)2=a(D2H)b to establish two groups of regression equations that can be usedfor the estimation of the biomass,components(stem,branch and leaf),total above groundbiomass and volume production based on the data of sample trees collected in the fuelwoodresearch.Comparison of the two groups of equations showed that the first model was thebest fit model.Its precision was high and its independent variable(D)was an easy-to-measure parameter that can further improve the precision of estimation.So the biomass andvolume tables were established based on the regression equation drawn from the first model.
Bamboo bleeding often occurred during the growth season after cutting andconcentrated in 24 hours after cutting,which accounted for 94.2% of the total bleedingamount.The bleeding amount changes with the change of season,beginning to increase fromlate March,reaching the peak in May, and decreasing then until the late September.No significant correlations were found between bleeding amount and bamboo DBH,but bleedingamount from young or middle-age bamboo outclassed that from old-age bamboo during thesame growth season within biennial cycle period.Site conditions,especially soil water content and precipitation,affected the bleeding amount obviously.The content of organic andmineral nutrients in bleeding was high,and changed with the change of season arid site conditions.Burning had more evident effect on bleeding than that of several other coating techniques.
From 1990～1992,experiment on the effect of nutrition adjustment on the young loblolly pine plantation in polluted region has been conducted in Sichuan Province through fertilization treatment.The size of the experimental plot is around 6 hm2 and the area for observation 1.8hm2.The result showed that the effects of different treatments on the growth height,DBH and ground diameter of the trees were very significant(α=0.01),Fertilizer containing Ca,P,N was the best one among the 6 treatments.After 3 years,the height growth of the best treatment increased by 80%～166% than that of the control.After fertilization,the symptom of pollution damage lessened; yellow needles reduced by 13%～60%;fallen needles reduced by 25%～77% in May of the following year.It showed that using nutrition adjustment to reduce the pollution damage is effective.
In view of the relationship between productivity and climatic parameters,themodels of forest climatic productivity within China were developed based on the selecteddatum of forest net productivity versus the corresponding climatic variables,by which thedistributive pattern of the actual productivity of forests in China was successfully simulated.At the same time,the competerized maps of forest productivity within China predicted fromclimatic parameters were drawn by using the plotting software of climatic information.Theestablished models by means of the plotting software were allowed to be used to simulate andpredict the potential changes in growth and productivity of forests in China.
Resin samples of 37 provenances were collected from masson pine genepool in Fuyang County,Zhejiang Province,and 13 chemical components were analysed.It was measured that there were evident negative geographical variation pattern among provenance latitude and longifolene,trans-carypohyllene,sesquiterpene,pimaric acid,isopiramic acid,palustric acid+levopimaric acid and diterpene contents,significant correlation between monoterpene content and provenance longitude,negative correlation between neoabietic acid content and provenance yearly precipitation,and correlation between longifolene,pimaric acid contents and provenance cumulative temperature.According to the main component and cluster analyses from 13 resin components it showed that China's masson pine provenances could be divided into three geographical categories:the southern,middle-eastern and northern geographical patterns.
According to the data of 31 sample plots and 19 analytical trees of loblolly pine in Eastern Anhui and Northwest and Southeast of Zhejiang Province,it shows that the site index of the area,where the loblolly pines are distributed is 10～24 in general,mostly 14～18.In the region of site index 20～24,the interlock point of the average yearly growth of height and the successive yearly growth is at the age of 8 for the tree height and at the age of 10 for the DBH; while in the region of site index 14～18,they are at the age of 12 and 10 respectively;while in the region of site index 10～12,the interlock point for DBH is postponed to the age of 16.In the regions of above mentioned three site indexes,the successive yearly growth of volume and the average growth of volume doesn't meet at the age of 20.Another analysis shows that the correlation coefficient for the density and diameter is r=0.652 87·;while for the diameter with bark 0.368 4+1.074 850x(x is the diameter without bark).In the investigated area,the form-factor of the loblolly pine is 0.58 at the age of 10;0.54 at the age of 15; 0.49 at the age of 20.The regression equation for crown width and diameter Y=0.88+0.188 9x(x is DBH),which has a significant correlation.The heightdiameter ratio of this tree species changes with the change of region and cultivation density,when it is at the age of 15～20,the regression equation for density(trees/hm2)and DBH Y=46.32+0.096 4x(x is density).The suitable cultivation density is 1 800 trees/hm2.
The results of treatment with TDS regulator before or during male inflorescence showed that:1.the growth of the male inflorescence was inhibited,the developmentof a few potential female buds was accelerated and the ratio of female flower to male inflorescence changed from 1:7.12 to 1:2.66.2.the chlorophyll and sucrose contents in leaves onflowering branch by treatment with TDS regulator increased by 24.9% and 55.2% respectively.3.the nutrition composition in fruit of Chinese chestnut by treatment with TDS regulator was no better than that of the control,but the soluble sugar content increased obviously.In addition,the physiological effect of TDS regulator was discussed from the point ofview of carbon nutrition.
According to the investigation from 1987～1990 in Pangquangou Natural Reserve,Shanxi Province,the cones of Larix principis-rupprechtii Mayr were seriously damagedby the cone flies belonging to Genus Strobilomyia.The cone and seed damaged rate reached 92.3% and 70.1% respectively.The thousand-seed-weight was 3.8 g and germination rate 9.9%.There were 3 species of cone flies:Strobilomyia infrequens(Ackland),S.melanioia(Fan) and S.laricicola(Karl),which formed a special pest group.According to the larvaland adult anatomical characteristics,their specific names were identified.According to theiramounts calculated,S.laricicola and S.melaniola were the main pest species.
Coal ash from thermal power factory was filled in the collapsed area formed by coal-digging,and then 30 cm of soil is covered onto the coal ash.The result was that four tree species grew normally under proper fertilization and irrigation condition.Their biomass are:4-year-old poplar 51.95 kg,5-year-old Robinia 76.56kg,5-year-old Salix 44.15 kg,5-year-old Ulmus 38.98 kg.Biomass distribution of the inside tree was:trunk 46.3%～63.0%,branches 17.4%～23.4%, roots 14.3%～25.9% and leaves 2.5%～4.6%.The conclusion was that the planting of alkaline resistant tree species or shrubs on the reclaimed coal ash is an effective way in the improvement of ecological environment and soil utilization.
Tests have been conducted for the gradation of the raw lac produced by threespecies of lac insects along with the contents of hard and soft resins respectively.The resultshave shown that the content of soft resin excreted by K.chinensis Mahd.in summer generation is lower than those by K.sindica Mahd.and No.4 lac insect,K.lacca Kerr.by 1%～2%.In winter generation it is comparatively higher and the content of yellow pigment isricher in both generations especially in summer one.It is 1～4 times that of each of the lattertwo.The soft resin content of the latter two is higher in both generations though somewhathigher in winter period.On the contrary,the yellow pigment content in the raw lac yieldedby K.chinensis Mahd.is lower both in summer and winter generation.
A sampling procedure for volume estimation is presented,in which volume is computed as the product of average basal area per hectare and average volume-basal-arearatio(R).The basal area estimate is obtained by point sampling,and R is estimated by subsampling point/sampled trees.Expression for the variance of the product estimator is also given.Simulated tests show that for the same degree of precision,using this sampling method is over that of the double sampling for ratio estimator.
Daimio tethys moorei Mabille is a major pest of Dioscorea zingiberensis C.H.Wright.It occurs 5 generations a year,overwinterting in the pupal stage in the infested rolled leaves.Adults begin to appear in the following April.85% of the adults emerge between 9:00 am and 15:00 pm.Then the adults mate and lay eggs.The duration of egg stage lies between 5 and 12 d(average 7.5d).The larvae have 5 instars.The duration of the pupal stage is 5～10 d long(average 7.5d)and that of the adults is 1～8d(average 4d).There are two major natural enemies e.g.Apanteles sp.and Brachymeria lasus(Walker).Control tests showed that spraying 2.5% of deltamethrin have the best control effect.