This article studied on Phyllostachys heterocycla cv.pubescens forest density effect for timber use quantitatively by using methods of orthogonal rotation of two factors and quadratic regression, and built bamboo high-yield model for timber use forest, and then analysed the effects of single factor, interaction as well as the interaction of density and D.B.H.on yield. The result showed that the optimum density is 4283 stems per hectare, the mean D.B.H.is 9.0 cm, the highest yield of bamboo forest will be up to 54801 kg/hm².

The rational density structure for shoot use forest, timber use forest, as well as both shoot and timber use forest was analyzed in the 203 plots established in the northwest bamboo area of Fujian Province, using K-C normal distribution test and the theory of half peak width, judging by the frequency.The research results show that the rational density interval for bamboo shoot use forest, bamboo timber use forest, both shoot and timber use forest is 1650~2250 culm/hm², 4050~4950 culm/hm² and 2100~2700 culm/hm² respectively.

In the bamboo forest ecosystem, the bamboo yield is the essentially quantitative features of the economic targets and the ecological index.The correlation between the yield of branches and leaves and the factors of the bamboo stand are elaborated in this paper, and the mathematical linear and non-linear models are simulated. According to the correlation coefficient and the standard error, the models are primarily chosen. With the colinearity determination to decide which to use and to compare the C_p value with VIC (Variance inflation factor), the optimum mathematical models were obtained, which were high precision and practical, so as to guide production practice.

The investigation and analysis were carried out to compare the influences on soil properties among six mixed forests of Chinese fir and Phyllostachys heterocycla cv. pubescens, pure Chinese fir stands, and pure Phyllostachys pubescens stands. The results showed that the mixed stands, comparing with the pure Chinese fir stands and the pure Phyllostachys heterocycla cv. pubescens stands, resulted in not only the improvement of physical and chemical properties of soil, but also the enhancement of soil fertility. Moreover, the mixed stands of 1350 culms of Chinese fir per hectare had the best effect on soil properties and the growth of culms, and produced the outstanding economic profits. Chinese fir and Phyllostachys heterocycla cv. pubescens mixed forests may become a powerful and efficient treatment to prevent soil from degradation and exert the soil fertility in the southern China.

By using the data from 758 plots, the primary selection was carried out by correlation coefficient and standard error, then the optimum mathematical models were selected by the variance inflation coefficients in the determinations of C_p value and colinearity. The results show that at the soil depth of 0~40cm the closest relationships were found between the amount of bamboo shoot emergence and the rhizome diameter, the internode length, and the rhizome root weight of the young and healthy rhizomes, and the weight of bamboo shoot closely related to the internode length, the healthy buds, and rhizome root weight of the young and healthy rhizome. At the soil depth of 0~60cm, the closer relations were found between the amount of new bamboo and the rhizome diameter, the internode length, the rhizome weight, and healthy bud of the young, healthy, and old rhizome, and a closest relation between the weight of new bamboo and the rhizome diameter of the young rhizome, the healthy rhizome, and the old rhizome.

The relationship between culm numbers and yield of forest use for both bamboo shoot and timber use grown in 131 plots in three regions of Sanming, Longyan, and Nanping in Fujian Province, have been investigated and analyzed in this paper. After testing and log-linear simulating, the results showed that the amount of standing bamboo to be suitable for these areas is 2100~2700 culm/hm², the yield of bamboo forest will amount to 23.1~32.7t/hm².

The data investigated in 131 plots located in the bamboo high-yield regions of Fujian Province were analyzed and simulated.The results showed that the new bamboo yield was related to the numbers of bamboo culm on-year evidently, and which become more obvious with increasing the numbers of culm on-year.

In this paper, 738 plots of high-yield bamboo stand were collected from planting area of bamboo in northwest of Fujian, through which elements of stand and environment were measured. Based on the bamboo stem yield and the shoot yield of stand, which are considered as the dependent variables, yield model was established as follows: R=0.98 Eight restricted conditions were suggested in combination with the need of production, the model can be used to optimize age structure of bamboo stand of different quality, density, and under different site condition and level of management, by which the yields of both shoot and timber can be increased obviously.

180 plots of high yield bamboo forest in main production areas of Phyllostachys heterocycla cv. pubescens in Fujian Province, the underground structure of high-yield bamboo forest were studied and analyzed through two small sampling plots in every plots The results showed that the bamboo rhizome mainly distributed in 0~40cm layer of soil, and that the orders of total length of rhizomes of high-yield bamboo forest were:shoot and timber use forest > timber use forest > shoot use forest, but more than 96% of total rhizome length was in this layer for three kinds of bamboo forests. The total weight of rhizome was in the following order: timber use forest > shoot and timber use forest > bamboo shoot use forest. The length and the weight of young rhizome of high yield bamboo shoot use forest were higher than those of timber use forest, and which of healthy rhizome were timber use forest > both shoot and timber use forest > shoot use forest.There were about 55~66 percent of healthy rhizome in the depth of 0~40cm soil layer. The growth direction of bamboo rhizome was largely parallel, which accounted for 63.2% in the timber use forest, 48.8% and 47.2% in the shoot and timber use forset and the shoot use forest respectively. The buds grown on rhizome were mostly the healthy buds, which made up 77.5% for the timber forest, 77.9% for both shoot and timber forest, and 78.0% for the shoot forest. The results showed that the bamboo forest are in the vigorous stage of shoot emergence.

The regressive models have been established by the relations of the biomass of an individual bamboo with the diameter at breast height(D), height (H), numbers of standing culm (N), and ages (A), through which the biomass and productivity of bamboo forests which are in the north of Fujian Province can be estimated. The biomass standing stock of bamboo forest in this area is 8238.03g/m² after comparing with the biomass of bamboo produced in the other parts of the world, among which the biomass of bamboo accounts for 99.2%

With the systematic studies on the correlation between the growth factors and the fertility of soil in the bamboo forest, such as the yield and the soil physical and chemical properties, D.B.H. and the soil physical and chemical properties, the nutrient content of the leaves and that of soil, three more suitable regressive models have been established, which have higher theoretical value for guiding productive management of bamboo forest.

According to the investigating of the factors of stands, shoots emergence and new culms in 96 plots of high-yield bamboo forest built in distributive area of Phyllostachys heterocycla cv.pubescens in Fujian Province, the biomass of every organs, D. B. H., height, and node number of 96 standard culms were measured. Based on these datas, the forecasting models of shoot emergence, new culms, and the biomass of every organs, have been established by mono regression models and multiple regression models.The weight, basal diameter and maximum diameter of 277 spring shoots have been determined. The shoot weight estimation model also has been established, which is significantly correlative by F test, high precision and reliable, and can be applied to forest production.

In this paper, the law that the amount of bamboo shoot increases with the increasing of time has been studied by applying the Logistic model of the shooting amount.The results indicate that about 13% of the total shoot can be produced at the earlier stage of shoot emergence(the first 10 days), 80% at the middle stage of shoot emergence (10~ 20 days), and 7% at later stage (after 20 days). The studies on description of the degraded shoot characteristics and its law shows that the amount of the degraded shoot is lower at the earlier stage and later stage of shoot emergence, but the percentage of shoot degradation is higher, whereas the amount of the degraded shoot is higher at the middle stage of shoot emergence, but the percentage of shoot degradation is lower, which can be used to guide bamboo shoot production, and provide a basis for the quantity of digging and taking bamboo shoots emergence.

By analyzing the biomass and the energy of the bamboo forest and their mutual relation, the results show that the energy storage is 161603.1 kJ/m², amounting for 99.3 percent of the Phyllostachys heterocycla cv. pubescens community. The layer-distributed structure of the energy shaped in the pyramid and reverse pyramid are established. With the use of the energy structure, the energy flow can be predicted and controlled to guide production management and to tap the potential of bamboo forest ecosystem fully.

Five kinds of growth regulative substance and trace element, which bamboo needs for growth, have been selected and used in experiment and practice, according to five element rotation quadratic orthogonal design method, Based on the experimental data, an optimum combining scheme has been formed by computer simulating and optimizing. After application, the output of bamboo shoot and standing shoot can increase 80 to 100 percent, the shoot emergence time is earlier 7 to 10 days, and the degraded shoot period will prolonged for 15 to 20 days.

This paper studied the anatomy of leaves at different ages in four sample plots, nutrient solution was injected into the base of bamboo culms in three plots in 1996.The results showed that the leaf vein bundles of bamboo injected with nutrient solution become small, which improved transporting ability of water and fertilizer, the mechanical tissue was not developed, long column cells in palisade tissue obviously increased and multi-cycle cell of mesophyll decreased. All of these were useful for photosynthesis, accumulating organic matter, and high-stable yield.

Four sample plots were built in high-yield bamboo forest in 1996, the bamboo nutrient solution was injected into the base of bamboo culm in three plots, the other plot was used as control.In 1997, the photosynthetic characteristics of leaves at each age were studied.The results showed that the specific weight of bamboo leaf, chlorophyll content and dark respiration rate and net photosynthetic rate of leaves increased and light respiration, CO₂ compensation point and light compensation point obviously decreased after injecting nutrient solution.The changes in these indexes were useful to increase photosynthetic function, to improve accumulation of organic matter and cultivate high and stable yield bamboo forest.

IAA, GA₃, KT and ABA play an important role in regulating and controlling the growth and development of Phyllostachys heterocycla cv.pubescens.With the help of high-performance liquid chromatography, the content and distribution of the above hormones in leaves, culms, rhizomes and current healthy shoots of the 1~6-year-old bamboo were studied during the period of shoot emergence.The results showed that the contents of IAA, GA₃, and KT promoting plant growth and cell division are high in bamboo plant on-year, which are low off-year.And the content of IAA in bamboo plant decreases with the increase of ages.The contents of ABA inhibiting plant growth in bamboo foliage and stem are lower in on-year, which are higher in off-year. The contents of 4 endogenous hormones in foliage are higher, the distribution law of GA₃ is foliage>rhizome>stem, that of KT is rhizome>foliage>stem, both IAA and ABA are foliage>stem>rhizome. The content of IAA in bamboo foliage increases basipetally, while that of ABA in foliage and stem decreases basipetally. The metabolism of bamboo stems grown on the same rhizome and rhizome system have a relative independence, therefore it is possible to regulate on-year and off-year of bamboo by the remaining and cultivating in off-year.