为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨...为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨树为对照,研究不同强度修枝对10年生毛白杨生长和生理特性的影响。结果表明:对于10年生中高龄杨树,修枝对树高、胸径、材积增长率无显著影响,但重度修枝能提高剩余叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s)),增强单叶水平上物质合成的能力,而修枝对瞬时水分利用效率(WUE)影响不显著。从生长和光合角度综合分析,修去树冠下部1/2枝条能够改善10年生毛白杨生理状况,但对林木生长无明显促进作用。展开更多
The secondary forests on northern slope of Mt. Changbai were sampled to investigate the effect of human disturbance on their tree species diversity and community structure. Compared with broad-leaved Korean Pine (Pinu...The secondary forests on northern slope of Mt. Changbai were sampled to investigate the effect of human disturbance on their tree species diversity and community structure. Compared with broad-leaved Korean Pine (Pinus koraiensis) forests, secondary forests were much lower in tree species diversity, community structure indices and stand volume. Secondary forests were dominated by pioneer species, and nearly no natural regeneration of Korean Pine was observed in most of our plots. Stepwise regression revealed that, stand volume was the most powerful predictor for tree species diversity. Tree species diversity decreased with the decrease of volume in secondary forests, while increased in broad_leaved Korean Pine forests. Community structure indexes also dropped significantly with decreasing stand volume in secondary forests under different human disturbances. However, broad_leaved Korean Pine forests did not show significant change in community structure under natural disturbance. These results indicated that, broad_leaved Korean Pine forests were strongly resistant to natural disturbance, while secondary forests were sensitive to human disturbance. The analysis of variance showed that the tree species diversity declined significantly under intensive disturbance (volume was below 100 m3·hm -2),the community structure was influenced significantly under moderate disturbance (volume was below 150 m3·hm -2). Our results suggested that the secondary forests were poor in stand quality, and the tree species diversity and community structure index were sensitive to human disturbance. More effort should be make to protect secondary forests, together with human regeneration of Korean Pine under canopy, in order to promote the recovery of the secondary forests to the broad_leaved Korean Pine forests.展开更多
As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took i...As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took into account,whereas management after planting was ignored,which had much detrimental effect on woodland’s quality and productivity. The paper studied the topic to find a scientific pruning model that could provide a guideline for the management in forest production. The plantation and the intercropping of poplar-crop were pruned in four different levels in Hebei and Shandong province. The levels were respectively light p1 (1/6 crown was pruned),medium p2 (2/6 crown was pruned),strong p3 (3/6 crown was pruned),heavy p4 (4/6 crown was pruned) and the control (unpruned). Heights and diameters at breast height(DBH) were measured. Diameter growth and cutting-area increment in one year from ten parsed trees were counted. The volume growth of trunk (below 9 m) was calculated. The results were:1) the difference of relative growth rate for different pruning treatment was not significant (P<0.05),which demonstrated the nutrition for height growth came from the branches and leaves of the top crown; 2) The difference of relative growth rate of DBH was significant(P<0.01). That is,the greater of pruning intensity,the smaller relative growth in the DBH. 3) The stem growth of parsed disk at different height was fluctuant among the different treatments. From stem base (0.0 m) to 9 m height of the trunk,the stem increase of the lower half reduced along with the increase of pruning intensity,while the growth of the upper half in pruning trees was bigger than that of non-pruning ones. 4) The difference of volume growth rate for different treatments was significant,all of the pruning treatments were bigger than the control. The medium p2 had the biggest growth,and the order was CK<p4<p1<p3<p2,which suggested that reasonable pruning can improve the growth of volume. However an excessive pruning reduced volume growth. 5) Pruning can decrease relative taper of trunk,make trunk straight and satiety,and increase the rate of volume increasing for one year. 6) In conclusion,in the process of production,the reasonable pruning should be moderate intensity as pruning p2,in which 1/3 crown length was removed.展开更多
It is an effective way to save and take full advantage of limited water resource in China by breeding and applying water-saving cultivars of plant. Relative studies showed that water use efficiencies （WUE） of poplar...It is an effective way to save and take full advantage of limited water resource in China by breeding and applying water-saving cultivars of plant. Relative studies showed that water use efficiencies （WUE） of poplar were obviously different among clones, but its physiological mechanism was not very clear. Therefore, an experiment was conducted in field to probe it through surveying WUE of different age leaves, diurnal dynamics of leaf WUE of 4 clones with the portable photosynthesis system of LI-6400, and the experimental clones were XMH4 （Populus deltoides×P.nigra）, MH8 （P.trichocarpa×P.deltoides）、XMH12 （P.deltoides×P.nigra）、DMH3 （P. trichocarpa× P.nigra）. The results indicated that: 1) WUE was remarkably different between clones, and the WUE of XMH12 and DMH3 was higher than that of XMH4 and MH8. 2) In general, the leaves distributing at middle part of stem had higher WUE than those locating at two ends of stem. This reflected that WUE changed from low to high, then to low with leaf aging. 3) Diurnal dynamics of WUE generally declined from morning to evening. 4)The main physiological factors to influenc WUE were stomatal aperture, intercellular CO2 concentration, and activity of photosynthestic system. And the ecological factors included PAR intensity, temperature, air humidity,etc. It was clear that the regulation of stomatal aperture was central to the water use efficiency. Light, temperature, humidity and carbon dioxide concentration will all act in some way either directly or indirectly on the stomatal aperture, together with internal circadian rhythms, leaf water status and xylem borne signals.展开更多
文摘为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨树为对照,研究不同强度修枝对10年生毛白杨生长和生理特性的影响。结果表明:对于10年生中高龄杨树,修枝对树高、胸径、材积增长率无显著影响,但重度修枝能提高剩余叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s)),增强单叶水平上物质合成的能力,而修枝对瞬时水分利用效率(WUE)影响不显著。从生长和光合角度综合分析,修去树冠下部1/2枝条能够改善10年生毛白杨生理状况,但对林木生长无明显促进作用。
文摘The secondary forests on northern slope of Mt. Changbai were sampled to investigate the effect of human disturbance on their tree species diversity and community structure. Compared with broad-leaved Korean Pine (Pinus koraiensis) forests, secondary forests were much lower in tree species diversity, community structure indices and stand volume. Secondary forests were dominated by pioneer species, and nearly no natural regeneration of Korean Pine was observed in most of our plots. Stepwise regression revealed that, stand volume was the most powerful predictor for tree species diversity. Tree species diversity decreased with the decrease of volume in secondary forests, while increased in broad_leaved Korean Pine forests. Community structure indexes also dropped significantly with decreasing stand volume in secondary forests under different human disturbances. However, broad_leaved Korean Pine forests did not show significant change in community structure under natural disturbance. These results indicated that, broad_leaved Korean Pine forests were strongly resistant to natural disturbance, while secondary forests were sensitive to human disturbance. The analysis of variance showed that the tree species diversity declined significantly under intensive disturbance (volume was below 100 m3·hm -2),the community structure was influenced significantly under moderate disturbance (volume was below 150 m3·hm -2). Our results suggested that the secondary forests were poor in stand quality, and the tree species diversity and community structure index were sensitive to human disturbance. More effort should be make to protect secondary forests, together with human regeneration of Korean Pine under canopy, in order to promote the recovery of the secondary forests to the broad_leaved Korean Pine forests.
文摘As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took into account,whereas management after planting was ignored,which had much detrimental effect on woodland’s quality and productivity. The paper studied the topic to find a scientific pruning model that could provide a guideline for the management in forest production. The plantation and the intercropping of poplar-crop were pruned in four different levels in Hebei and Shandong province. The levels were respectively light p1 (1/6 crown was pruned),medium p2 (2/6 crown was pruned),strong p3 (3/6 crown was pruned),heavy p4 (4/6 crown was pruned) and the control (unpruned). Heights and diameters at breast height(DBH) were measured. Diameter growth and cutting-area increment in one year from ten parsed trees were counted. The volume growth of trunk (below 9 m) was calculated. The results were:1) the difference of relative growth rate for different pruning treatment was not significant (P<0.05),which demonstrated the nutrition for height growth came from the branches and leaves of the top crown; 2) The difference of relative growth rate of DBH was significant(P<0.01). That is,the greater of pruning intensity,the smaller relative growth in the DBH. 3) The stem growth of parsed disk at different height was fluctuant among the different treatments. From stem base (0.0 m) to 9 m height of the trunk,the stem increase of the lower half reduced along with the increase of pruning intensity,while the growth of the upper half in pruning trees was bigger than that of non-pruning ones. 4) The difference of volume growth rate for different treatments was significant,all of the pruning treatments were bigger than the control. The medium p2 had the biggest growth,and the order was CK<p4<p1<p3<p2,which suggested that reasonable pruning can improve the growth of volume. However an excessive pruning reduced volume growth. 5) Pruning can decrease relative taper of trunk,make trunk straight and satiety,and increase the rate of volume increasing for one year. 6) In conclusion,in the process of production,the reasonable pruning should be moderate intensity as pruning p2,in which 1/3 crown length was removed.
文摘It is an effective way to save and take full advantage of limited water resource in China by breeding and applying water-saving cultivars of plant. Relative studies showed that water use efficiencies （WUE） of poplar were obviously different among clones, but its physiological mechanism was not very clear. Therefore, an experiment was conducted in field to probe it through surveying WUE of different age leaves, diurnal dynamics of leaf WUE of 4 clones with the portable photosynthesis system of LI-6400, and the experimental clones were XMH4 （Populus deltoides×P.nigra）, MH8 （P.trichocarpa×P.deltoides）、XMH12 （P.deltoides×P.nigra）、DMH3 （P. trichocarpa× P.nigra）. The results indicated that: 1) WUE was remarkably different between clones, and the WUE of XMH12 and DMH3 was higher than that of XMH4 and MH8. 2) In general, the leaves distributing at middle part of stem had higher WUE than those locating at two ends of stem. This reflected that WUE changed from low to high, then to low with leaf aging. 3) Diurnal dynamics of WUE generally declined from morning to evening. 4)The main physiological factors to influenc WUE were stomatal aperture, intercellular CO2 concentration, and activity of photosynthestic system. And the ecological factors included PAR intensity, temperature, air humidity,etc. It was clear that the regulation of stomatal aperture was central to the water use efficiency. Light, temperature, humidity and carbon dioxide concentration will all act in some way either directly or indirectly on the stomatal aperture, together with internal circadian rhythms, leaf water status and xylem borne signals.
