1993 Vol. 6, No. 1
According to the experimental results, the background value of both semi-deciduous monsoon forest and mountain rain forest ecosystems on the plant, Htterfall, surface soil, rock, throughfall, seepage water and stream were shown. The biogeochemical action on the elements capital aggregation and migration were synthetically analysed and estimated. Strong action of the biological absorption, decomposition, returned back and the leaching had been found. The substance exchange between the plant and the soil is strong. The tropical forest ecosystems keep a tightness balance on the substance cycle because the input content is more than the output. The intensity and velocity on the biochemical aggregation of the semi-deciduous monsoon forest ecosystem are larger and faster than that of the mountain rain forest ecosystem, but whose accumulation is contrary. It is obvious that the hydrochemical regulating function of the mountain rain forest ecosystem is superior to that of the semi-deciduous monsoon forest ecosystem. The characteristics on the elements aggregation and migration in the two type ecosystems have some differences. It is pointed out that the litterfall plays an important dominant part in the nutrient cycle direction and acts as a material base on the forest land fertility, which must be paid great attention to.
Hardwood cuttings of Japanese Larch. (Larix leptolepis Gord) with bursting buds collected from 2~4-year-old stock have been successfully propagated with mist irrigation under natural condition. Effects of donor stock's age, hormones and their interactions on rooting were studied. According to the results, rooting rate can be as high as 96.7% when suitable rooting agents PL3 and PL4 were used. The result also show that cuttings collected from different ages of donor stock need to be treated with different kinds and concentrations of agents. 35 000 rooted cuttings of the current year transplanted successfully on July 7, 1992 with a survival rate of 97.1%. These young plants grew well after planting. Promising results is also obtained softwood when cuttings were planted on the same bed after the first batch rooted cuttings were removed. This shows that it is possible to propagation L. leptolepis vegetatively twice a year.
This is the first time that seven new clones have been successfully selected from the eastern cottonwood seedlings introduced from North America in 1982 in China. Among the seven new clones, four clones are attributed to the southern ecotype whose characteristics of growth, adaptability, resistance and wood quality are superior to those of P. deltoides cv. 69/55 and P.euramericancc cv. 72/58. Those clones can be planted in the temperate zone and subtropic zone of China. The other three clones are the northern ecotype which have better characteristics of growth, adaptability, resistance and wood quality than those of P.euramericana cv. I-214. They can be planted in the moist northern and eastnorthern areas of China. Those new clones will be the good cultivars to be used for poplar plantations with short rotation.
According to the experimental results of fertilizing in five seed orchards in Zhejiang and Guangdong Province from 1983~1990, it shows that the best result is from the unfertile soil. The sort of fertilizer and its making up should match with the soils in local sites, that are, N, P or N,P, K complex or mixed fertilizer on unfertile soil which is short of N and P; P, K mixed fertilizer on the soil which is short of P or K, but the concentration of N is above middle level. The time of fertilizing should be matched with the developing rhythm and differentiation of flower bud, the best time for fertilizing is likely to be June and followed by August and April. It is suitable to fertilize the trees two times per year,and had better to use not only chemical fertilizer but also farmyard or green manure. The amount of fertilizer used should be matched with the age of trees, that is generally 40~170g N, 100~250g P2O5 or 50~100g K2O per tree per time. The amount of seeds can be increased by 30%~50% with the best making up fertilizer and also increase the seed output rate of cone, weight of 100 seeds and germination percentage.
No report about the effect of ecological factors on the swarming of white wax scales has been seen both at home and abroad yet. The swarming of white wax scales, which concerns the production of white wax directly, is conditioned by some ecological factors. With this question in mind, we made observations and experiments on it from 1980 to 1981 in Jingdong County, Yunnan Province. Under normal conditions, the swarming occurs at 8:00 to 11:00 in the morning, seldom in the afternoon, and never in the evening or at night. The starting temperature, humidity and illumination are respectively 12℃, 80% and 100 lx; the optimum 18~25℃, 25%~45%, 12500-16000 lx; and the ending 30℃, 22% and 20 000 lx. Our results indicate that the swarming of the white wax scales are greatly affected by the ecological factors such as temperature, illumination, rainfall, humidity, wind and congestus, key factors among which are temperature, rainfall and illumination.
Root-cut seedling of Acacia mearnsii were inoculated with Agr-obactfrium rhizogences A4, 9402, and rooting was promoted on MS medium. The rooting ratio was 96%~98%, and the average number of new roots per seedling was 17~19, but the root-cut seedling treated with medium alone didn't root. Opine assay indicated that there was stable maintenance of T-DNA in these new roots. There was some relationship between auxin and A. rhizogencs T-DNA in the induction of rooting.
The properties of annual growth of Paulownia clones were simulated by Logistic curve, and the maximum points of growth rate per day and durations of fast-growing stage were estimated. The clonal growth curves were approached by cross cut polynomiad and the coefficients β0、β1 and β2 which made up the growth curves were tested. The results show that the differences of growth curves are significant. The annual growth process of Paulownia clones was classed into early, intermediate and later three periods.
Nestling food composition and consumption of great tits (Parus major Linnaeus) in the Poplar plantation was studied using 230 preys collected from the nestling crops at Yihe Forest Farm, Yinan County, Shandong Province during May to July in 1991. The average food consumption amounted to 1377.6 preys per clutch and 1294.9 preys per ha in May, 1002.2 preys and 310.8 preys in June, 1383.3 preys and 864.7 preys in July. Based on the nestling food composition, the food selection of breeding great tits was discussed preliminarily combining with the sample data of insects taken from the branches and frass in the Poplar plantation. Changes in insect species and numbers showed changes in diet from May to July. More pupae and larvae of Apatura metis Freyer were found in May, more adults of Lymantridae and Parathrene tabaniformis Rottenberg in June, and more insect species in July.
The geographic variation of photoperiodic response was studied in the pine caterpillar (Dendrolimus spp., in short: pc) at latitudes from 29.4 to 39.8N in China. The result demonstrated that the critical photoperiod for diapause induction observed at 27~28℃ was 14 h 30 min for Beijing strain (39.8N), 14 h 2 min for Jincheng (35.5N, Shanxi Province) and 13 h 24 min for Yongchuan (29.4N, Sichuan Province). The critical photoperiod increases about 30 min for each increase in latitude of 5N.Sensitivity of pc to photoperiod during the larval stage varied with age and latitude. The overwinter larvae originated from North China displayed a stronger diapause and can usually survive a longer period under 28℃ but those originated from the South showed a weaker diapause and can only survive a shorter period at the same temperature.It was revealed that photoperiodic diapause is the key factor to control the differentiation of generation in pc. Under shortdays condition, the larvae entered diapause in the third and fourth instar and were unable to continue development without terminating diapause even under a high temperature condition. When the natural photoperiod exposed to the larvae equal to its critical photoperiod the day reaches the critical point (date) of differentiation. The critical date plays a decisive role to determine the ratio of differentiation of pc. Moreover, temperature and nutrition can modify the ratio by affecting the critical date. The larvae hatched before the critical date can produce one generation more than those hatched after the critical date.In this paper, the relation between the enviromental factors and the ratio of the third generation of pc was discussed in Jinsishan Forest Farm (in Anhui Province).
Glyptapanteles liparidis (Bouche) has 4 generations a year in northern China and parasitizes Lymantria dispar in its first two generations. The hosts of the later two generations are Pine Caterpillars. It overwinters in the overwintering larvae of Dendrolimus spp.. The lifespan of egg-larval stage is about 25~35d, pupal stage 6~8 d, adult stage of ♀8~14 d, ♂5~10 d. The adults come out from cocoons consistently and have a high rate of emergence. The 2nd-instar larvae of the hosts is the best fitness stage for parasitization. It has a high reproduction rate of 636±176 per female and the maximum 953. Cold-stored pupal stage cocoons have no effects on the emergence, but when cold-storage takes place in the prepupal stage, the rate of emergence can be reduced obiviously. All the adults which emerge-nced from the cold-stored cocoons have a tendency of shortened lifespan. Both the rearing density and the diet for adults are important factors for its longevity.
The effect of water stress by treating with PEG (MW 6000) solution with different osmotic potential (-0.4MPa, -1.0MPa, -1.6MPa) on the net photosynthesis rate (Pn) of leaves of popular clones are studied in growth culture chamber. As for six clones of natured-drought, they are grouped into 3 fast-and 3 slowergrowing clones according to the significant difference in growth parameter. During 24 hours of various water stress, the Pn is obviously declined. After release from the water stress, the Pn of recovery of two growth types of clones shows that all clones survive in mild (-0.4 MPa), but not in moderate (-1.0MPa) and severe (-1.6 MPa) osmatic stress at the end of two weeks. During stress and also after release of stress, the net photosynthesis rate of fast-growing clones decreased and also recovered faster than those of other slower growing clones, especially a faster-growing clone with water tolerant appearing the slowly dropping and fast recovering. Pn seems to be its significant growth contribution. This result will be helpful to identify the fast and drought tolerance clones in early-selection of poplar breeding.
Based on the technique of small watershed and the method of permanent observation plot, the runoff yield had been studied in the regenerative tropical mountain rain forest at Jiangfengling, Hainan Island. The results indicated that the total annual rainfall, runoff, quickflow and surface runoff were 2881.5, 1282.1, 321.6 and 26.8mm respectively, and the annual runoff coefficient and hydrologic response were 44.5% and 11.2% in the hydrologic year from May 1989 to April 1990. It was found that the surface runoff was far less than the baseflow, the former only 2.1% and the latter up to 74.9% in the annual runoff. The authors pointed out that there are three typical types of storm-runoff hydrograph and that main runoff pattern is saturated runoff formation in the forested watershed. According to the analysis of runoff, it was considered that the regenerative tropical mountain rain forest has a good hydroecological effect on reducing flood peak discharge, delaying flood period and increasing runoff in dry season.
Three studies were established to look at the effects of cutting season, stump diameter and cutting tool on the sprout regeneration of Acacia auriculiformis at Yangjiang (11030' E, 1814'N), Qionghai County of Hainan Province. In the first study, a 3-year-old plantation was cut at a stump height of 60cm in the four months of March, May,September and December. The greatest survival percentage of the stumps was obtained with cutting in December, followed by cutting in May and March. Cutting in September resulted in the least survival percentage of the stumps. In the second study, 46-month-old trees varying in DBH from 0.1 to 12.0cm were cut at a stump height of 60cm. The survival percentage of the stumps decreased with the increases of DBH greater than 4 cm. However, the growth of diameter and height of the sprouts increased with the increases of DBH. In the third study, 3-year-old tree were cut at two stump heights, 60cm and 100cm, with axe and handsaw. The number of sprouts produced per stump, and diameter and height of the sprouts were significantly different by stump height but not by cutting tool. Both stump height and cutting tool had no significant effect on the sprouting and survival percentages of the stumps, and no significant effect of interaction between stump height and cutting tool was found for all variables.
Through using the methods of digging ditches for salt extraction, growing sweet clover for green manuring and spreading plastic film on the surface above root, Pinus sylvestris var. mongolica Litv. was introduced in the arid and semiarid area. After 9 years' growth, the average height of the trees was 4.25m, the average diameter at breast height was 7.0cm. The salt content of soil decreased from 0.26% to 0.11%. When the salt content of soil was 0.17%, the growth of P. sylvestris var. mongolica slowed down significantly. The salt content of soil in Hetao Region of Northwest China is 0.12%, P. sylvestris var. mongolica can be used for the plantation in this area.
Physiology of seed germination of Diospyros lotus was studied, and the result showed that there is no obvious dormancy period in D. lotus seeds collected from Beijing and Xingtai district, Hebei Province. The seeds were soaked in water of 45℃ for 48 hours before sowing, and they germinated in dark condition, on agar medium, under the changing temperature from 30℃ at daytime to 20℃ at night. Initial germination occurred on the fourth day and the germination rate reached 96% on the tenth day. If the seeds were stratified in humid sand at 17℃ for 20 days, the germination rate would reach 96% within 6 days, and the initial germination day could also be earlier.
To explore the evaluation method of site quality in the Taih-ang Mountain, this article evaluated the site quality of Robinta pseudoacacia L. in this region from the aspect of its productivities, ecological properties and economic benefit by a series of qualitative and quantitive methods. The site productivities were measured by site index and standard stand volume, the ecological properties by soil erosion durability and water conservation, and the economic benefit by site expectation price.
Seedling height, collar diameter, root growth capacity, net accumulation and distribution of dry biomass, and water-content in different medium layer are related to the material, structure and volume of a seedling container. The paper container adhibitted by a thinner polythene film has the features of faster water penetration and lower capacity of water conservation as compared to the normal polythene container. The paper container specially for crops has a smaller volume and its medium goes dry easily because of faster penetration. Seedling grown in paper container for root growth capacity is similar to that grown in polythene container, but for seedling height, collar diametre and accumulation of net dry biomass, the former is superior to the latter. The inversive triangle type occurred in distribution pattern of net dry biomass of seedling grown in paper container ranked from leaf-stem-root, which improves seedling growth, and the dumbbell type in that of seedling grown in polythene container, which inhibites seedling growth of the above-ground part. The paper container could be considered as one of the new type container which is suitable to raise vigorous black wattle stocks.
On the basis of 500 sample bamboo culms and 5 500 original data obtained from the south of Zhejiang Province, the author analysed the single and double factor relationship between the weight of culm, the weight of branchs and leaves, the total weight of ground part with the height of culm and diameter of breast height measuring tree factor of Bambusa atrovirens Wen, B. textilis McClure, B. pachinensis var. hirsutissima W. C. Lin, Lingnania wenchouensis Wen and Sinocalamus latiflorus McClure, the relationship and close level between the breast diameter with the ground diameter, breast diameter with the height of culm etc. and selected out 78 regressive equations.
The brushfooted butterfly Lethe europa Fabricius is a serious pest of the bamboo, Phyllostachys pubescens Mazel ex H. de Lehaie, Phyllostachys bambusoides Sieb. et Zucc. According to our observation, this insect has three generations a year and overwi nters as pupa in Shaowu, Fujian Province. The adults begin to appear in mid April the following year. They lay their eggs on the underside of the leaf. The egg stage lasts 6 to 9 days. Six instars are observed in the larval development. Larvae of the first to third instar aggregate on the leaf. Beginning from the fourth instar, the larvae tend to disperse and curl up the leaf. The larval stage of the three generations lasts from 40 to 62,27 to 46, and 32~50 days respectively. The pupal stage of the first generation lasts 12 to 16 days, the second 8 to 14 days and the third 180 to 199 days. Its major natural enemies are ants and tachina flies. The following control measures are effective: collecting larval bag; DDVP used as smoke or spraying with 2.5% Deltamethrin.