Field studies were conducted respectively in Jinghong and Ruili of the southwest monsoon region of Yunnan Province to investigate the principal characteristics of canopy surface temperature (T_c) of rubber forest and their deviation (△T=T_c-T_a) from air temperature (T_a) at 1. 5m higher above the canopy surface by means of an infrared thermometer and microclimatic observations in January of 1991 and 1992. The results showed that the rubber forest canopy appeared a heating effect during the 9:00-18: 00h period with an average of 5-6℃ higher for T_c than for T_a This difference reached 9-11℃ in the afternoon with strong insolation and dry weather. Influences of other environmental factors on T_c or △T were also discussed in detail.It was indicated that a higher T_c was advantageous to the safe overwintering for rubber trees in this region.

On the basis of seven year fixed position observation in Youxi Ecosystem Experimental Station, the nutrient cycle in Chinese fir young plantation ecosystem was studied and the compartment models of N、P、K cycle were established. The results were as follows:The total quantities of N、P、K accumalated in a 7 year old Chinese fir plantation ecosystem were 7308.46, 2022. 96 and 130290. 14kg/hm² respectively, in which about 99. 73% was stored in the soil compartment. The annual absorption of N、P、K was 52. 2kg/hm² with 22. 62kg/hm² of them ratained, 29. 58kg/hm² of them returned. The input through hydrologic way into the ecosystem and the output through runoff out of the ecosystem were 15. 92kg/hm² and 9. 23kg/hm² respectively. And thus, the net accumulation of ecosystem was 6. 69kg/hm².The transformations of N、P、K and results of fertilization in four compartments of ecosystem within 0-10 years were diseribed quantitatively and the balance points at the time when they reach a stable state were calculated.

For examining the variation of foliar mineral element concentration, the needle samples from ten sample trees in each of 26 seed sources within a 12-year old provenance trial located in Anhua County, Hunan Province were collected. For studying seasonal dynamics of mineral element concentrations the needles were collected on the following dates: April 30, July 30 and October 30 of 1991 and January 30 of 1992.At each sampling date the current and previous-year needls on the second whorl from crown top were sampled respectively.Thus at each sampling date there was one sample per needle age class from ten sample trees for analysis. Concentrations of N, P, K, Ca and Mg were determined by the Analysis Centre of Central-Southern Forestry College. The results showed that concentrations of all measured nutrient element among provenances varied significantly and the apparent geographic variation pattern was exist with significant correlation coefficients related to the latitudes and longitude of seed origins. The concentrations of N, P and Ca of northern seed source group were higher than those of southern seed source group and the K and Mg concentration were lower than those of southern seed source, but the pattern of seasonal change in concentration of mineral elements was similar for the two different distinct geographic regions, i. e. Yunnan-Guizhou Plateau and Qinling-Dabashan Mountains.

Through comparative experiment on growth, drought resistance, cold resistance, salt resistance of several indigenous poplars in inner Mongolia, it is shown that the growths of Populus pseudo-simonii var. patula and P. platyphylla var. fiaviflora are faster; the drought resistances of P. intramongolia, P. cana and P. platyphylla var. flaviflora are stronger; the cold resistance and the salt resistance of P. platyphylla var. flaviflora, P. cana and P. hsinganica are stronger. By the method of PCA, the adaptabilities of 7 poplars in dscent order are P. pseudo-simonii var. patula, P. platyphylla var.flaviflora, P. sp, P cana, P. intra mongolia, P. platyphylla var. glauca, P, hisnganica.

The processes and the influence factors of phosphorus absorbed by one-year seedling roots of Platycladus orientalis from three provenances, Taian, Shandong (ST), Liping, Guizhou(GL), Baotou, Inner Mongolia (NB), were studied with isotope atom indicator, ³²P. As a result, the patterns of the P uptaken in the three provenances were similar, while the quntities uptaken were different. The absorption rate of -H₂PO₄ (³²P) varied according to V= V₀exp (K_t). The efflux rate according to E=E₀/ (K_m +t)2, where V₀, E₀, K, K_m are constants, t is time variable. The absorption of phosphorus is influenced by some factors, such as the genetic variation, the physiological activities and the surroundings of the provenances. The half-time (T_1/2) of P(³²P) absorption for ST, Gl and NB were 6. 4, 6. 1 and 5. 8h respectively when cultured in nutrient solution, but they are 40. 7, 18. 4 and 7. 5h, partyly when cultured in soil. The half-time for P(³²P)maxium efflux (K_m) are 0. 9, 53, and 14 min separately. When the parts of root from root-tip to upper 0- 0. 5cm, 0. 5-7. 5cm and 7. 5-14. 5cm Were determined to root-tip or white, yellow-brown and brown sections, respectivly, at the brown section of the root more P (³²P) were uptaken by ST and GL than NB, at the yellow-brown were similar but at the root-tip zone, white section, less were uptaken by the formers than the latter. Most of P(³²P) had entered the seedlings remained in the roots and less were transported up to the part above the ground. The speed of movementin ST, GL and NB were 3. 0, 4. 0 and 2. 2cm/h and the mass removed were GL > ST > NB.

The determination of disease resistance of Casuarina clones to Pseudomonas solanacearum is subject to the variations of plant and bacterial materials, inoculation condition as well as rating method of disease severity. It was demonstrated in this study that the infected clonal ramets and excised twigs exhibited same wilting symptom and similar disease progressing pattern; their relative disease intensities were positively correlated under the same set of inoculum densities, but the ramets were more resistant. Among three types of excised twigs, the lignified brown had highest disease rating, followed by the partially lignified green, and the tender was least susceptible.The bacteria could be consistently cultured for at least 14 days without losing its virulence.While the disease severity of clones under sunshine, fluorescence or in shade were not significantly different, it increased as the inoculum density increased. It was suggested that using the excised brown twigs with relatively low or moderate inoculum densities inside laboratory to detect the bacterial resistance of Casuarina clones would be an efficient and reliable approach.

In this paper, the composition, quantity, distribution of soil animals and Gilpinia lipuensis of Pinus massoniana and their relation with ecologic environment were studied. The result showed that if the canopy density of forest was big, the woodland was lack of shrub and herb, the composition and quantity of soil animals were poor and small, that the kind of soil animal was richer in middle-aged forest which had more complicated vegetation than that in young growth, and that soil animals were more at the foot of a hill than at the middle or top of it. Only one species of sawfly was found in Pinus massonianastand, that was Gilpinia lipuensis Xiao et Huang. Four species of natural enemy were found here, they were Cleptes sp. Pleolophus sp. Olesicampe sp. and Bessa selecta fugax Rondani. The parasitic rate of natural enemies accounted for 57. 5 per cent of the total emergance rate, the sawfly only made up 42. 5 percent. The quantity of empty cocoons amounted to 60. 67 percent of the total cocoons. The occurrence and degree of damage of Gilpinia lipuensis had close relations with temperature, precipitation, topography, distribution of Pinus massoniana, age of forest and structure of forest form.

Strobilomyia melaniola (Fan) is the dominant species among the 6 species of maggots damaging larch seed cones in Da Xinganlin, northeastern China.The emergence starts in early May and lasts until middle of June with peak emergence in mid-May. Ovipositions occurs in late May, 2-3 weeks after supplementary feeding on flowers for newly emerged flies to mature. The examination of cone phenology with development of the fly revealed a close synchrony of the process. Cone water content is found to be a main factor affecting egglaying, whereas larvae enter cones to feed when cone tissues are soft and succulent. Relations of both emergence and oviposition with daily temperature, soil temperature and rain fall are also presented in the paper.

The strong nematicidal activity of aloperine from Sophora alopecuroides L. against pine wood nematode (Bursaphelenchus xylophilus Stener et Buhrer Nickle) is reported for the first time. The nematicidal activity of aloperine against pine wood nematodes was examined by the bioassy in which the medium containing aloperine was used to oulture mycelia of Botrytis cinerea Pers.After 5 days LC= 2. 63 × 10^-5g/ml. Moreover, the nematicidal activity of aloperine increased with time. When the levels of aloperine in the bioassy medium were at 1 × 10^-4g/ml and 2. 63 × 10^-5g/ml, the nematicidal effects after 15 days reached 99. 9% and 94. 3%, respectively. The signifcance of alkaloids from S. alopecuroides in studies on the control of pine wilt desease is discussed.

In this paper the main factors affecting wood density variation in slash pine and loblolly pine were studied, and the method of the combined selection for wood density of slash and loblolly pine was discussed. On this basis 73 slash and loblolly pine elite trees were selected.

The results of wood mechanical tests of Chinese fir (Cunninghamia lancelata (Lam.) Hook) belonging to 16 sampls show that in static bending, toughness, shear parallel to the grain and cleavage wood is more resistent to a force acting on its tangential sections than on its radial sections to a different extent except compressive force perpendicular to the grain. The cause of the difference induced is analysed.

By means of the principle and methodology of systems engineering, a new forecasting method——integrated forecasting method for the demand and supply of Chinese timber market is devised. On the basis of system analysis, quantitative forecasting and qualitative analysis, classification forecasting and global forecasting are integrated; several forecasting models are optimally combined; multiple verification and multiple feedback are executed during the process of forecasting. Therefore, the various defects of the now available forecasting methods are overcome, so that the forecasting results become more precise and more reliable. The method of this paper is successfully applied in forecasting for the demand and supply of Chinese timber market till 2010.

To counter the problems to "the mathematical models of density index and stand characteristics ", the models about stand density index (SDI), basal area, mean diameter and stems are presented mathematically in this paper, and the parameter estimation procedure is also provided. Further more, it is pointed out that we should pay move attention to dual regression and consistent estimation for fitting mathematical models.

Four transgenic Populus nigra plants which were transformed with Bacillus thuringiensis toxin gene and showed high insect resistance were analysed by Western blot method. The result showed that 55kD polypeptides were found in the positive control and four transgenic plants showed Bt. toxin gene was not only inserted into the chromosomes of poplar, but also expressed into protein. The result gave a direct evidence to explain the four plants's high insect resistance.

Located in lean County, Jiangxi Province, with same age, equal site conditions and silvicultural management, the two kinds of stands were compared in growth, yield and growing process of diameter at breast height (DBH), height and volume by means of whole plot examination and cut sample tree analysis. The results show that stands by sprouting grow faster in the first several years and slow down more quickly than stands by planting. At the age of 22, in poor sites, the difference in DBH between stands by sprouting and by planting is significant, whereas in relative good and good sites, no such difference was discovered; difference in height is significant regardless of site condition; annual volume increment of the two stands is still higher than average, meant that they have not reached quantitative maturity; yield of stands by sprouting varies from 237. 7 to 329. 5m³ a hectare compared with 253. 2-405.9m³/hm² of stands by planting which is remarkably high in good sites. Some suggestions about silvicultural techniques, site selection and management goals concerning Chinese fir regeneration through sprouting were made according to above comparison.

During 1990 and 1993, the author made dimensional measurement of the root rots in the internal part of the infected logs in Zhangguangcai moutain range. This paper made following analysis according to the shapes of these rots:①At cross section, where rot entered into the stem the rot became a circle and had a circumference parallel the growth ring; ②At vertical section, 84% of the rots were rectangualar and cuneiform (50% for each).It is concluded that:the root rot in the internal part of stem could not be said cone-shaped simply. Exactly, the root rot was cone-shaped in general, but In specific, it was ladder-cylind narrowing to the top.