1988 Vol. 1, No. 2
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1988, 1(2): 123-131.
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Abstract:
The preliminary study indicates that the nutrient concentration of throughfall has increased obviously in man-made forests of Cunninghamia lanceolata and Pinus massoniana as compared with rainfall in adjacent openning. The relative abundance of nutrient content for precipitation was NCaKMgP. The relative abundance of nutrient content for throughfall was KNCaMgP. The total amount of nutrient input with rainfall in two stands account for 48-53% of total nutrient returns. More amounts of N, K, Mg were transferred to the soil through throughfall than litterfall while more Ca and P were added to the soil through litterfall. Nutrient return approximates precipitation closely in a semi-log curve, indicating a limited and gradual supply of nutrients from their respective sources between the intervals of rain.
The preliminary study indicates that the nutrient concentration of throughfall has increased obviously in man-made forests of Cunninghamia lanceolata and Pinus massoniana as compared with rainfall in adjacent openning. The relative abundance of nutrient content for precipitation was NCaKMgP. The relative abundance of nutrient content for throughfall was KNCaMgP. The total amount of nutrient input with rainfall in two stands account for 48-53% of total nutrient returns. More amounts of N, K, Mg were transferred to the soil through throughfall than litterfall while more Ca and P were added to the soil through litterfall. Nutrient return approximates precipitation closely in a semi-log curve, indicating a limited and gradual supply of nutrients from their respective sources between the intervals of rain.
1988, 1(2): 132-139.
Abstract:
Development of pollen and embryo sac in Populus euphratica Oliv. were observed in brightfield and fluorescence microscopes, and scanning electron microscope. The resultus are as follows.The anther is tetrasporangiate. The mature anther wall comprises an epidermis, a layer of endothecium, 2 middle layers, and a single-layered tapetum. The epidermis is persistant. The endothecium develops fibrous thickenings. One of the middle layer becomes flattened and crushed by the uninucleate pollen stage, and the other may delay its disintegration until prior to the dehiscence of the anther. Glandar tapetum, the tapetal cell is uninucleate at the early stage and becomes binucleate at PMC (pollen mother cell) meiotic stage. The Ubisch bodies are studded on its inner tangential walls, manifesting bright green, auramine orange induced fluorescence. SEM micrograph shows "bridge" between the Ubisch body and the exine of pollen grain. The meiotic division does not exhibit a high degree of synchrony. It may be asynchronous within a pollen sac or in two different pollen sacs of the same anther. Simultaneous cytokinesis in the PMCs follows meiosis and the majority of microspore tetrads are tetrahedral and rarely isobilateral.The deposition of callose during microsporogenesis starts at the corner of the PMCs and extends gradually to enveloping PMC by metaphase I, reaches its peak by metaphase Ⅱ, and separates the microspore tetrads along cellular plates. Subsequently, prior to the spore release, the callosic envelop begins to dissolve, and then the callosic cellular plates appear. Pollen grains are 2-celled at shedding stage.The ovule is anatropus, bitegmic at MMC (megaspore mother cell) stage, and the inner integument is arrested in development and becomes unitegmic by the time of megasporogenesis. The nucellus is crassinucellar, containing usually one but sometimes two MMCs. Cytokinesis in the MMC accompanies meiosis and the megaspore tetrads are linear or T-shaped. Callose appears in the transverse walls (linear type) or in the transerve and vertical walls (T-shaped type) formed after each meiotic division but never appears in the side walls (outer walls). The chalazal or subchalazal megaspore is functional, which develops into a Polygonum type embryo sac.Generally, the mature embryo sac comprises a 3-celled egg apparatus, 3 antipodal cells and a central cell with the secondary nucleus. Occasionally, the polar nuclei remain distinct even though the sperm has adhered to one of them. Owing to the degeneration of the nucellus at the micropyle pole during megagametogenesis, the egg apparatus pole of the mature embryo sac directly contacts with the integument and more or less penetrates into the micropyle.
Development of pollen and embryo sac in Populus euphratica Oliv. were observed in brightfield and fluorescence microscopes, and scanning electron microscope. The resultus are as follows.The anther is tetrasporangiate. The mature anther wall comprises an epidermis, a layer of endothecium, 2 middle layers, and a single-layered tapetum. The epidermis is persistant. The endothecium develops fibrous thickenings. One of the middle layer becomes flattened and crushed by the uninucleate pollen stage, and the other may delay its disintegration until prior to the dehiscence of the anther. Glandar tapetum, the tapetal cell is uninucleate at the early stage and becomes binucleate at PMC (pollen mother cell) meiotic stage. The Ubisch bodies are studded on its inner tangential walls, manifesting bright green, auramine orange induced fluorescence. SEM micrograph shows "bridge" between the Ubisch body and the exine of pollen grain. The meiotic division does not exhibit a high degree of synchrony. It may be asynchronous within a pollen sac or in two different pollen sacs of the same anther. Simultaneous cytokinesis in the PMCs follows meiosis and the majority of microspore tetrads are tetrahedral and rarely isobilateral.The deposition of callose during microsporogenesis starts at the corner of the PMCs and extends gradually to enveloping PMC by metaphase I, reaches its peak by metaphase Ⅱ, and separates the microspore tetrads along cellular plates. Subsequently, prior to the spore release, the callosic envelop begins to dissolve, and then the callosic cellular plates appear. Pollen grains are 2-celled at shedding stage.The ovule is anatropus, bitegmic at MMC (megaspore mother cell) stage, and the inner integument is arrested in development and becomes unitegmic by the time of megasporogenesis. The nucellus is crassinucellar, containing usually one but sometimes two MMCs. Cytokinesis in the MMC accompanies meiosis and the megaspore tetrads are linear or T-shaped. Callose appears in the transverse walls (linear type) or in the transerve and vertical walls (T-shaped type) formed after each meiotic division but never appears in the side walls (outer walls). The chalazal or subchalazal megaspore is functional, which develops into a Polygonum type embryo sac.Generally, the mature embryo sac comprises a 3-celled egg apparatus, 3 antipodal cells and a central cell with the secondary nucleus. Occasionally, the polar nuclei remain distinct even though the sperm has adhered to one of them. Owing to the degeneration of the nucellus at the micropyle pole during megagametogenesis, the egg apparatus pole of the mature embryo sac directly contacts with the integument and more or less penetrates into the micropyle.
1988, 1(2): 140-147.
Abstract:
The increase of oil content in the ripening seeds of tung tree (Aleurites fordii) was negatively correlated with water content, but water stress greatly affected the synthesis of triacylgly cerols and fatty acids. From 25 August to 15 September, the oil content of the seeds rose by 23.87% and the water content fell by 24.55%. The elaeostearic acid content also rose while the palmitic, stearic, oleic, linoleic and linolenic acid contents decreased. Elaeostearic acid comprised 79.42% of the total fatty acids. The most active period for synthesis, accumulation and transformation of fatty acids was in the first 10 days of August and the first 10 days of September, during that time, water supply was critical.An obvious difference was obtained from the comparisons among the compositions of fatty acid of 33 varieties. More differences (about 16.06%) appeared in the percentage of elaeostearic acid. 15 varieties of them had their elaeostearic acid more than 76%. They are all belong to A. fordii. 12 varieties of them have few flowers and single fruit. The contents of this acid in all varities of A. montana were less than 70%. The quality of oil in A. fordii was better than that of A. montana. The varieties of the type with few flowers and single fruit had more content of elaeostearic acid, and less contents of linoeic and oleic acid.
The increase of oil content in the ripening seeds of tung tree (Aleurites fordii) was negatively correlated with water content, but water stress greatly affected the synthesis of triacylgly cerols and fatty acids. From 25 August to 15 September, the oil content of the seeds rose by 23.87% and the water content fell by 24.55%. The elaeostearic acid content also rose while the palmitic, stearic, oleic, linoleic and linolenic acid contents decreased. Elaeostearic acid comprised 79.42% of the total fatty acids. The most active period for synthesis, accumulation and transformation of fatty acids was in the first 10 days of August and the first 10 days of September, during that time, water supply was critical.An obvious difference was obtained from the comparisons among the compositions of fatty acid of 33 varieties. More differences (about 16.06%) appeared in the percentage of elaeostearic acid. 15 varieties of them had their elaeostearic acid more than 76%. They are all belong to A. fordii. 12 varieties of them have few flowers and single fruit. The contents of this acid in all varities of A. montana were less than 70%. The quality of oil in A. fordii was better than that of A. montana. The varieties of the type with few flowers and single fruit had more content of elaeostearic acid, and less contents of linoeic and oleic acid.
1988, 1(2): 148-152.
Abstract:
The study is a new attempt that uses Landsat TM image and some ground sampling plots by multi-analysis method to estimate forest stock volume. In this method, independent variables include Qualitative and Quantitative factors. The Qualitative factors are colour hue and group of tree species; the Quantitative factors are density value and ratio of the bands. In this way, potentiality of remote sensing data can be bring into better play.The result shows that the accuracy of estimating forest stock volume is more than 80%, when this method is used. It's a convenient and economical method.The sampling method of ground sampl plots, plot sizes and establish equation according to basins etc. corresponding problem have been discussed in this article.
The study is a new attempt that uses Landsat TM image and some ground sampling plots by multi-analysis method to estimate forest stock volume. In this method, independent variables include Qualitative and Quantitative factors. The Qualitative factors are colour hue and group of tree species; the Quantitative factors are density value and ratio of the bands. In this way, potentiality of remote sensing data can be bring into better play.The result shows that the accuracy of estimating forest stock volume is more than 80%, when this method is used. It's a convenient and economical method.The sampling method of ground sampl plots, plot sizes and establish equation according to basins etc. corresponding problem have been discussed in this article.
1988, 1(2): 153-161.
Abstract:
An irrigation experiment was conducted in an intensively cultivated poplar plantation (Populus dcltoidrs Bartr. cv. "Lux" ex. I-G9/55) in 1983-1986. The relationship between the indices of tree growth, water physiological indices and water supply in the field was studied. The results reveal that artificial water supply can greatly promote the growth of tree. In comparision with the control (rainfall only) the average height, D. B. H. and volume increment increased by 17.2-24.6%, 10.7-22.1% and 22.0-42.6% respectively under irrigation. Water supply has a great influence upon the structure of tree, increasing dry weight of stem and branch, leaf number and leaf area, favouring the accumulation of assimilation and it's transport to branch. The enlargement of leaf area of crown promotes the increase of volume increment.
An irrigation experiment was conducted in an intensively cultivated poplar plantation (Populus dcltoidrs Bartr. cv. "Lux" ex. I-G9/55) in 1983-1986. The relationship between the indices of tree growth, water physiological indices and water supply in the field was studied. The results reveal that artificial water supply can greatly promote the growth of tree. In comparision with the control (rainfall only) the average height, D. B. H. and volume increment increased by 17.2-24.6%, 10.7-22.1% and 22.0-42.6% respectively under irrigation. Water supply has a great influence upon the structure of tree, increasing dry weight of stem and branch, leaf number and leaf area, favouring the accumulation of assimilation and it's transport to branch. The enlargement of leaf area of crown promotes the increase of volume increment.
1988, 1(2): 162-168.
Abstract:
Several methods for recovery procedure of the polyhedral inclusion bodies of nuclear polyhedrosis virus of the poplar looper, Apocheima cinerarius, were compared. Recovery tests indicated that the PIB of AciNPV were precipitated from the concentrated suspensions in 7.4-8.4% solutions of lactose by adding acetone. Counts of the final preparation showed 4.96×1010 PIB/g. Yields of 80.5% were obtained. Bioassay tests indicated that the pathogenicity of the fresh preparations recovered was very good for the early third-instar larvae. The LC50 and 95% fiducial limits acre 2.84×103 PIB/ml and 1.70×103-4.96×103 PIB/ml respectively.In this procedure, costly centrifugal equipment was omitted, 1500-3000g diseased larvae could be reduced to final production in 3hr with laboratory general equipment. In this case, the virus formulation prepared may be used to control the poplar looper larvae in about 30-65 ha in the forest. Mass production has been proved to be a useful replacement for the centrifugation method, and the cost of the recovery virus is cheap.
Several methods for recovery procedure of the polyhedral inclusion bodies of nuclear polyhedrosis virus of the poplar looper, Apocheima cinerarius, were compared. Recovery tests indicated that the PIB of AciNPV were precipitated from the concentrated suspensions in 7.4-8.4% solutions of lactose by adding acetone. Counts of the final preparation showed 4.96×1010 PIB/g. Yields of 80.5% were obtained. Bioassay tests indicated that the pathogenicity of the fresh preparations recovered was very good for the early third-instar larvae. The LC50 and 95% fiducial limits acre 2.84×103 PIB/ml and 1.70×103-4.96×103 PIB/ml respectively.In this procedure, costly centrifugal equipment was omitted, 1500-3000g diseased larvae could be reduced to final production in 3hr with laboratory general equipment. In this case, the virus formulation prepared may be used to control the poplar looper larvae in about 30-65 ha in the forest. Mass production has been proved to be a useful replacement for the centrifugation method, and the cost of the recovery virus is cheap.
1988, 1(2): 169-178.
Abstract:
According to the mean annual increment in height and D. B. H. of 65 sample trees of different species, three growing types, i.e. fast-growing, medium and slow-growing, for the major species of tropical forest at Jianfengling area were classified. There are 83.1% of the total sample trees belonging to the medium-growing type and the growing process models in height, diameter and volume for the three types had been prepared separately. The volume increment in three types is still increasing and the age of quantitative maturity has not been found.In order to shorten the selection fellings cycle, technical maturity is need to be consideration. The regressive estimation shows that the increment of D. B. H., tree height and the individual tree volume would have reached 32cm, 23m, 0.9m3 respectively at the age of 40 in the fast-growing type, MO in the medium and 180 in the slow-growing type, these ages might be considered as a cutting cycle of selection.
According to the mean annual increment in height and D. B. H. of 65 sample trees of different species, three growing types, i.e. fast-growing, medium and slow-growing, for the major species of tropical forest at Jianfengling area were classified. There are 83.1% of the total sample trees belonging to the medium-growing type and the growing process models in height, diameter and volume for the three types had been prepared separately. The volume increment in three types is still increasing and the age of quantitative maturity has not been found.In order to shorten the selection fellings cycle, technical maturity is need to be consideration. The regressive estimation shows that the increment of D. B. H., tree height and the individual tree volume would have reached 32cm, 23m, 0.9m3 respectively at the age of 40 in the fast-growing type, MO in the medium and 180 in the slow-growing type, these ages might be considered as a cutting cycle of selection.
1988, 1(2): 179-185.
Abstract:
The paper presents the results of utilization of entomopathogenic nematodes for controlling the long-horn beetle, Anoplophora glabripennis, and carpenter-worm, Holcocerus insularis. The mortality of the beetle infected by various strains of Steinernema bibionis reached 61-94%. The mortality of the carpenter-worm infected by S. feltiae was as high as 99.8%. Nematodes breeded very well in dead hosts. The results indicated the entomopathogenic nematode might become an effective bio-control agent to control certain wood borers.
The paper presents the results of utilization of entomopathogenic nematodes for controlling the long-horn beetle, Anoplophora glabripennis, and carpenter-worm, Holcocerus insularis. The mortality of the beetle infected by various strains of Steinernema bibionis reached 61-94%. The mortality of the carpenter-worm infected by S. feltiae was as high as 99.8%. Nematodes breeded very well in dead hosts. The results indicated the entomopathogenic nematode might become an effective bio-control agent to control certain wood borers.
1988, 1(2): 186-190.
Abstract:
Phloeosinus sinensis Schedle is an important insect pest which bores the stem bark of the Chinese fir (Cunninghamia lanceolata). It has one generation a year in Zhejiang and Anhui Provinces and lives through winter in adult stage. Its aggregating and dispersing cycle, the boring habit of the adults and the larvae, and the environmental factors for this bark beetle's occurrence have been studied. Chemical control of using 80% DDVP or 75% phoxim emulsions to kill the aggregated adults under bark and using wood-baits to attract the adults then to spray them with chemicals have been suggested as control measures.
Phloeosinus sinensis Schedle is an important insect pest which bores the stem bark of the Chinese fir (Cunninghamia lanceolata). It has one generation a year in Zhejiang and Anhui Provinces and lives through winter in adult stage. Its aggregating and dispersing cycle, the boring habit of the adults and the larvae, and the environmental factors for this bark beetle's occurrence have been studied. Chemical control of using 80% DDVP or 75% phoxim emulsions to kill the aggregated adults under bark and using wood-baits to attract the adults then to spray them with chemicals have been suggested as control measures.
1988, 1(2): 191-194.
Abstract:
This paper reports the results from the observations on the stylet and the parasitic site segment of Japanese pine bast scale (Matsucoccus matsumurac Kuwana) on Masson's pine (Pinus massoniana).The results show that the stylet of the just hatched nymph coils as tendril on venter. When parasitizing, it stretches from the back of the inter-coxa of the anterior leg as a bundle composed of four equal needles, among which two needles embedded together. The average lengths of stylets for the initial parasitic and second instar nymphs are 1.209 mm and 1.625 mm respectively.It has been shown from the observation on parasitic site segment that its stylet can penetrate the phloem and injure the xylem of the pine tree. Then a small canal, which is 2.0-4.5 mm in length and 0.35-0.50 mm in width, will be formed in the xylem. But no tracheids can be found in the canal.On the same branch of the pine tree, the density of nymph population at the shady side is 3.71 times of that at the sunny side so that more injury will occur at the shady side of the branch.The results of observation on parasitic site segment of this pest show that the stylets stuck out from the nymphs penetrated phloem and injuried xylem of the pine trees, and induced a sheath shaped symptom in xylem. The length of sheath was 2.0-4.5 mm, and a width 0.35-0.50 mm. There were no tracheids visible in sheath.
This paper reports the results from the observations on the stylet and the parasitic site segment of Japanese pine bast scale (Matsucoccus matsumurac Kuwana) on Masson's pine (Pinus massoniana).The results show that the stylet of the just hatched nymph coils as tendril on venter. When parasitizing, it stretches from the back of the inter-coxa of the anterior leg as a bundle composed of four equal needles, among which two needles embedded together. The average lengths of stylets for the initial parasitic and second instar nymphs are 1.209 mm and 1.625 mm respectively.It has been shown from the observation on parasitic site segment that its stylet can penetrate the phloem and injure the xylem of the pine tree. Then a small canal, which is 2.0-4.5 mm in length and 0.35-0.50 mm in width, will be formed in the xylem. But no tracheids can be found in the canal.On the same branch of the pine tree, the density of nymph population at the shady side is 3.71 times of that at the sunny side so that more injury will occur at the shady side of the branch.The results of observation on parasitic site segment of this pest show that the stylets stuck out from the nymphs penetrated phloem and injuried xylem of the pine trees, and induced a sheath shaped symptom in xylem. The length of sheath was 2.0-4.5 mm, and a width 0.35-0.50 mm. There were no tracheids visible in sheath.
1988, 1(2): 195-200.
Abstract:
A fungus, isolated from blue stain timbers of Hevea brasiliensis and Pinus massoniana, was identified as Botryodiplodia theobromae Pat.. The fungus was also found to be capable of infecting the wood samples of Eucalyptus citriodora, Acer mono and Calamus cgregius.The results of the tests on its temperature tolerance showed that the fungus survives within the stained Rubberwood subjected to a temperature of 75℃ for 24 hours and within the stained wood samples of Pinus massoniana subjected to a temperature of 60℃ for 96 hours. The hyphae of this fungus were observed to occupy the rays primarily and to follow the rays into the wood mainly through pits. They mainly distributed within the vessels of the stained Rubberwood and the resin canals and rays of the stained wood of Pinus massoniana.
A fungus, isolated from blue stain timbers of Hevea brasiliensis and Pinus massoniana, was identified as Botryodiplodia theobromae Pat.. The fungus was also found to be capable of infecting the wood samples of Eucalyptus citriodora, Acer mono and Calamus cgregius.The results of the tests on its temperature tolerance showed that the fungus survives within the stained Rubberwood subjected to a temperature of 75℃ for 24 hours and within the stained wood samples of Pinus massoniana subjected to a temperature of 60℃ for 96 hours. The hyphae of this fungus were observed to occupy the rays primarily and to follow the rays into the wood mainly through pits. They mainly distributed within the vessels of the stained Rubberwood and the resin canals and rays of the stained wood of Pinus massoniana.
1988, 1(2): 201-205.
Abstract:
Incompatible barriers to the pre-fertilization of intersectional crossing in Poplars is one of the major barriers. Pollen and stigma were treated with n-hexane then to be pollinated before intersectional crosses were made by using Poqvlvs alba as the female parent and P. nigra, P. nigra var. italica, P. deltoides "Shan Hai Guan" and P. simonii as the males. The results showed that pollen germination percentage, short tubes percentage, and pollen tubes getting into the stigma percentage have not been raised. Hybrid seeds production and quality have not been increased. Above methods have not overcome incompatible barriers to the pre-fertilization of intersectional crossing in Poplars.
Incompatible barriers to the pre-fertilization of intersectional crossing in Poplars is one of the major barriers. Pollen and stigma were treated with n-hexane then to be pollinated before intersectional crosses were made by using Poqvlvs alba as the female parent and P. nigra, P. nigra var. italica, P. deltoides "Shan Hai Guan" and P. simonii as the males. The results showed that pollen germination percentage, short tubes percentage, and pollen tubes getting into the stigma percentage have not been raised. Hybrid seeds production and quality have not been increased. Above methods have not overcome incompatible barriers to the pre-fertilization of intersectional crossing in Poplars.
1988, 1(2): 206-212.
Abstract:
Three densities for planting experiment of Mytilaria laosensis plantation have been studied. The result of experiment showed that the planting densities have not significant effect on the tree height growth in the early stage of young plantation, but it has significant difference in the growth of D.B.H (Diameter Breast Heigh). The crown diameter and the root system have highey positive correlation with both D.B.H and tree volume, but highly negative correlation with tree bole of under crown length. Total growing index in different densities in 3×2m2×2m1×2m, in the former (i.e. largest spacing) which, uniformity of forest physiognomy, occupied a considerable proportion of trees of larger dimeter classes, higher in available timber. Under the natural prunning, the largest spacing obtained the best effect after five years. It is suggested that the 3×2m is the most suitable density for the Mytilaria laosensis planting.
Three densities for planting experiment of Mytilaria laosensis plantation have been studied. The result of experiment showed that the planting densities have not significant effect on the tree height growth in the early stage of young plantation, but it has significant difference in the growth of D.B.H (Diameter Breast Heigh). The crown diameter and the root system have highey positive correlation with both D.B.H and tree volume, but highly negative correlation with tree bole of under crown length. Total growing index in different densities in 3×2m2×2m1×2m, in the former (i.e. largest spacing) which, uniformity of forest physiognomy, occupied a considerable proportion of trees of larger dimeter classes, higher in available timber. Under the natural prunning, the largest spacing obtained the best effect after five years. It is suggested that the 3×2m is the most suitable density for the Mytilaria laosensis planting.
1988, 1(2): 213-216.
Abstract:
The authors used the leaves of Wood oil tree (Vernida montana Lour), Tung tree (V. fordii (Hemsl) Airy Shaw), and Belgaum walnut (Aleurites moluccana (L.) Willd) as testing materials to study their differences of chlorophyll, free amino acid, protein, RNA and DNA contents. The results have shown that there is no difference between these two genera's DNA contents, but Belgaum walnut's chlorophyll and protein contents are higher than Wood oil tree's and Tung tree's, and on the contrary, its free amino acid and RNA contents are obviously lower than the Vernida's. Thus, from the biochemical view, it is reasonable that Airy Shaw has recently separated Vernida from Aleurites.
The authors used the leaves of Wood oil tree (Vernida montana Lour), Tung tree (V. fordii (Hemsl) Airy Shaw), and Belgaum walnut (Aleurites moluccana (L.) Willd) as testing materials to study their differences of chlorophyll, free amino acid, protein, RNA and DNA contents. The results have shown that there is no difference between these two genera's DNA contents, but Belgaum walnut's chlorophyll and protein contents are higher than Wood oil tree's and Tung tree's, and on the contrary, its free amino acid and RNA contents are obviously lower than the Vernida's. Thus, from the biochemical view, it is reasonable that Airy Shaw has recently separated Vernida from Aleurites.
1988, 1(2): 217-223.
Abstract:
In order to learn the photosynthetic productivity of the bamboo canopy, an 18 meter iron tower has been established in Miao Shan Wu Maozhu (Phyllostachys pubescens) stand for measuring the changes of Pn at different position of the canopy by IRGA made in England. Then we measure and calculate the light transmissity, the changes of the leave's increase and decrease of the canopy, the leaf area index and the distribution of leaf area at different position in the canopy. The results are as follows:1.There are litters being collected in the whole year, but the first and second peak values occur in April to May and November to December respectively. The maximum LAI of the experimental area is 8.02, but those in the upper, middle and low tiers of the canopy are 1.38, 4.36, 2.28 respectively.2.The light transmissivities in the canopies different tiers as mentioned in result 1 are 50%, 20% and 4-5% respectively.3.The light compensation point of bamboo leaves is about 50μmolm-2S-1, and the light saturation point of the various tiers of the canopy shows different values, i.e. the upper about 1000μmolm-2S-1, the mid about 400-600 μmolm-2S-1, and the low about 200-400μmolm-2S-1.4.The value of Pn of leaves at the upper part of the canopy is higher. It is about 15 μmolm-2S-1 under a proper environment. A noontime snooze will take place at a high temperature and a low moisture. So usually, the curve of daily changes of Pn is a double peaked curve. Due to the low transmissivity at the mid and low part of the canopy, the density of photon is less, and the Pn within a day often shows a negative value.
In order to learn the photosynthetic productivity of the bamboo canopy, an 18 meter iron tower has been established in Miao Shan Wu Maozhu (Phyllostachys pubescens) stand for measuring the changes of Pn at different position of the canopy by IRGA made in England. Then we measure and calculate the light transmissity, the changes of the leave's increase and decrease of the canopy, the leaf area index and the distribution of leaf area at different position in the canopy. The results are as follows:1.There are litters being collected in the whole year, but the first and second peak values occur in April to May and November to December respectively. The maximum LAI of the experimental area is 8.02, but those in the upper, middle and low tiers of the canopy are 1.38, 4.36, 2.28 respectively.2.The light transmissivities in the canopies different tiers as mentioned in result 1 are 50%, 20% and 4-5% respectively.3.The light compensation point of bamboo leaves is about 50μmolm-2S-1, and the light saturation point of the various tiers of the canopy shows different values, i.e. the upper about 1000μmolm-2S-1, the mid about 400-600 μmolm-2S-1, and the low about 200-400μmolm-2S-1.4.The value of Pn of leaves at the upper part of the canopy is higher. It is about 15 μmolm-2S-1 under a proper environment. A noontime snooze will take place at a high temperature and a low moisture. So usually, the curve of daily changes of Pn is a double peaked curve. Due to the low transmissivity at the mid and low part of the canopy, the density of photon is less, and the Pn within a day often shows a negative value.
1988, 1(2): 224-230.
Abstract:
Pinus elliottii E. and P. taeda L. have been introducted in Zhejiang province for more than 40 years and the species have been afforested for seven thousand ha.. The productive practice shows that these species have fast growth, straight stem, extensive distribution range and better adaptability, higher resistance to pests and diseases and other good characters. The earlier introductive trees have flowered and fruited and juvenile forests of the second generation have been established. It has important significance for riching the afforestation species and for raising the productive ability of forest land by successful introducing these exotic troe species in this province.
Pinus elliottii E. and P. taeda L. have been introducted in Zhejiang province for more than 40 years and the species have been afforested for seven thousand ha.. The productive practice shows that these species have fast growth, straight stem, extensive distribution range and better adaptability, higher resistance to pests and diseases and other good characters. The earlier introductive trees have flowered and fruited and juvenile forests of the second generation have been established. It has important significance for riching the afforestation species and for raising the productive ability of forest land by successful introducing these exotic troe species in this province.
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