不同条件下树木死亡的水力失衡和碳饥饿机制
发布时间：2019-05-23 14:01
【摘要】：对全球气候变化背景下大范围森林死亡的研究是当前的一个热点。树木难以维持碳-水平衡被推测为树木死亡的主要原因。本研究选择了不同降雨水平、虫害与树木物候,以及不同光强和树木大小等三种不同的环境条件或关系,研究水力失衡(Hydraulic failure)和碳饥饿(Carbon starvation)机制对树木生长和存活的影响。包括探索降雨减少后四照花(Dendrobenthamia japonica(DC.)Fang var.chinensis(Osborn.)Fang)、三桠乌药(Lindera obtusiloba Bl.Mus.Bot.)和水榆花楸(Sorbus alnifolia(Sieb.et Zucc.)K.Koch)三个不同的isohydry(等水)-anisohydry(异水)功能型植物的气孔行为和木质部栓塞脆弱性及其植物体内的水-碳变化和三桠乌药的枯死机理;研究虫害叶损失对不同物候树种木荷(Schima superba Gardn.et Champ.)和黄杞(Engelhardia roxburghiana,Wall.)的危害程度;以及光照强度和树体大小如何影响锐齿栎树木的(Quercus aliena var.acuteserrata)碳-水平衡。本研究对认识和预测全球变化背景下森林结构变化和演替具有重要的理论意义。主要结论如下:1、对于宝天曼共生的四照花、三桠乌药、水榆花楸这三个树种,试验结果表明在isohydry(等水)-anisohydry(异水)功能型植物谱中,四照花在isohydry这一端,水榆花楸在anisohydry这一端,而三桠乌药在两者之间。在截雨处理后四照花气孔易关闭而保水,导致其水势在三个树种中最高,但净光合速率和非结构性碳(NSC)降低。而水榆花楸在截雨处理后气孔易维持开放但失水,水势在三个树种中最低,但对气体交换的限制低,在三个树种中最易出现NSC的盈余。即偏anisohydric的水榆花楸相比偏isohydric的四照花中午水势更负,但NSC的积累受到的影响较小。2、经人工截雨处理后,具有偏anisohydric策略的水榆花楸和具有偏isohydric策略的四照花都相对适应了降低的水分环境,但在气孔行为策略上介于二者之间的三桠乌药因水力失衡而严重枯死。除气孔反应类型之外,木质部栓塞脆弱性在树木应对干旱中也扮演重要的角色。三个树种中,三桠乌药栓塞脆弱性最大,亦即抗栓塞能力最低,截雨后出现水力失衡,导致顶端枯死。该研究证明水力失衡不仅取决于气孔反应类型,还受木质部栓塞脆弱性的制约。3、鼎湖山的季节性干旱没有和虫害产生交互作用,而是换叶物候的不同节律造成的碳储备降低导致虫害对木荷和黄杞的危害程度不同。鼎湖山的常绿阔叶树种木荷在二月份换叶,换叶过程本身消耗了大量的NSC。而另一个冠层树种黄杞的换叶时间在五月。鼎湖山虫害爆发是在3-4月,刚好在木荷换叶之后,黄杞换叶之前。基于大树年轮的分析显示在虫害(T.quadraria)爆发年份木荷横向生长降低,而黄杞没有受到抑制。用小树模拟虫害的去叶试验显示:去叶处理显著降低了木荷叶片和枝条的生长,限制了去叶处理后木荷的光合固碳量,阻碍了其根部和木质部NSC的恢复,从而导致了木荷高的死亡率。虽然叶损失也降低了黄杞叶片和枝条的生长,但其降低幅度远小于木荷。在去叶处理10个月之后,黄杞恢复了NSC储备,没有出现树木死亡。因此,NSC储备和虫害对树木的危害程度密切相关。当把物候循环考虑进来的时候,容易解释虫害叶损失对木荷生长、NSC储备和存活的影响大于黄杞。对水分关系的研究表明鼎湖山的季节性干旱没有对两个树种造成损害。4、以锐齿栎大树冠层上部、树冠下部、林下小树和林窗小树四个材料为研究对象。大树冠层上部存在明显的水力限制,导致了大树冠层上部的净光合速率、气孔导度都显著低于光有效性相同的林窗小树。由于树冠顶部经常受到水分胁迫及由此带来的生长下降,使得大树冠层上部叶片和韧皮部的NSC相对积累,而经常性的栓塞修复消耗了木质部大量的NSC。光有效性高的大树冠层上部和林窗小树叶片的光合能力显著大于光有效性低的冠层下部和林下小树;大树冠层下部的光合能力也大于林下小树。综合考虑不同树木大小和受光程度,光照因素对锐齿栎光合作用的塑造起更主要作用。5、宝天曼锐齿栎林下光照强度远低于林外。林下低光环境显著限制了锐齿栎幼树的光合潜能及固碳,其NSC浓度显著低于大树和林窗小树;林下锐齿栎幼树的这种NSC状态很容易因碳饥饿而死亡。另外,盆栽遮阴试验表明遮阴处理显著降低了锐齿栎幼苗的干物质量和NSC浓度。模拟光斑处理显著提高了遮阴幼苗在高光强下的光合潜能,且模拟光斑使得幼苗NSC浓度显著高于一直遮阴处理的幼苗,缓解了遮阴对幼苗碳储备的不利影响,所以高密度的光斑对维持宝天曼锐齿栎林下锐齿栎幼苗净的碳平衡可能有一定的作用。
[Abstract]:The research of large-scale forest death in the context of global climate change is a hot spot in the world. It is difficult for trees to maintain carbon-water balance as the main cause of tree death. In this study, three different environmental conditions or relationships, such as different rainfall levels, pest and tree phenology, and different light intensity and tree size, were selected to study the effects of hydro-imbalance and carbon starvation on the growth and survival of trees. It includes the following steps: to explore the four-shot flowers (Dendrotenham japonica (DC.) Tang var. chinensis (Osborn.) Tang) and three-(Lindera obtusiloba Bl. Mus. Bot) after the reduction of rainfall. ) And Sorbus alngifolia (Sieb.et Zucc). ) K. Koch) The stomatal behavior of three different isohydryry (isowater)-anishanyry (isowater) functional plant and the water-carbon change of the xylem and the mechanism of the dead-death of the water-carbon in the plant, and the mechanism of the dead-death of the triamcinolone; and the study of the loss of the insect-leaf to the Schima superba Gardn.et. ) And Engelhardia roxburghiana, Wall. ) The degree of harm; and how the light intensity and the size of the tree affect the carbon-water balance of Quercus aliena var. acuta. This study is of great theoretical significance for understanding and predicting the change and succession of forest structure in the context of global change. The main conclusions are as follows:1. The experimental results show that in the plant spectrum of isowater, the four-way flower is in the one end of isohydary, and the water elm is in the one end of anisoheyry. And three of them are in the middle of the two. The water potential was the highest in the three tree species, but the net photosynthetic rate and non-structural carbon (NSC) decreased. However, the water loss and water potential are the lowest among the three tree species, but the limitation of gas exchange is low, and the surplus of the NSC is the most common among the three tree species. I. e., the water potential of the anisoheyric water elm is more negative than the water potential at noon, but the effect of the accumulation of the nsc is less. But in the air-hole behavior strategy, the three-drug-black drug between the two is severely dead due to the hydraulic imbalance. In addition to that type of pore reaction, the vulnerability of xylem embolism play an important role in the response of trees to drought. Among the three tree species, the most of the three kinds of Wuyao embolization is the lowest, that is, the anti-embolism ability is the lowest, and the hydraulic imbalance occurs after the cut-off, leading to the dead end of the top. The study shows that the hydraulic imbalance depends not only on the type of pore reaction but also by the vulnerability of the xylem.3. The seasonal drought of the Dinghushan Mountain has no interaction with the insect. But the reduction of the carbon stock caused by the different rhythm of the change of the phenology leads to a different degree of damage to the wood and the yellow soil by the insect. The evergreen broad-leaved tree of Dinghushan is changed in February, and the leaf-changing process itself consumes a great deal of NSC. And the leaf-change time of the other canopy tree was in May. Dinghushan insect outbreaks were in March-April, just after the change of the leaves of the wood, before the change of the leaves. Based on the analysis of the tree-year round, the lateral growth of the wood-to-load was reduced in the year of the outbreak of the pest (T. quadia), while the yellow rice was not inhibited. The leaf-defoliation test showed that the leaf-defoliation treatment significantly reduced the growth of the leaves and branches of the leaves, and restricted the photosynthesis and fixation of the wood-loaded leaves after the defoliation treatment, which hindered the restoration of the root and the xylem NSC, thus resulting in a high mortality rate. Although leaf loss also reduces the growth of the leaves and branches of the yellow leaves, it reduces the amplitude much less than that of the wood. After 10 months of defoliation, the NSC reserve was restored and no tree death was present. Therefore, the NSC reserves and pests are closely related to the degree of damage to the trees. When the phenological cycle is taken into account, it is easy to explain the effect of the loss of the pest leaf on the growth of the wood, the reserve and the survival of the NSC. The research on the relation between the water and water shows that the seasonal drought of the Dinghushan Mountain has no damage to the two tree species.4. The four materials of the upper part of the large crown layer of the sharp-toothed oak, the lower part of the crown, the lower and the lower trees of the forest and the small tree of the forest window are the research objects. There is a significant hydraulic restriction on the upper part of the large crown layer, which results in the net photosynthetic rate at the upper part of the large crown layer, and the air hole conductivity is significantly lower than that of the forest window with the same light efficiency. Since the top of the crown is often subjected to water stress and the resulting decline in growth, the NSCs of the upper and the bast parts of the large crown layer are relatively accumulated, while the recurrent plug repair consumes a large number of the NSCs of the xylem. And the photosynthetic capacity of the lower part of the large crown layer is larger than that of the lower tree. Considering the size and the light-receiving degree of different trees, the light factors play a more important role in shaping the photosynthesis of the Quercus acuminata. The low light environment in the forest significantly limits the photosynthetic potential and the solid carbon of the young trees of the sharp-tooth oak, and the concentration of the NSC is lower than that of the tree and the forest window. The NSC state of the young trees of the Quercus acumen is very easy to die due to carbon starvation. In addition, the pot-shading test indicated that the shade treatment significantly reduced the dry matter quality and the NSC concentration of the sharp-tooth oak seedlings. the simulated light spot treatment obviously improves the photosynthetic potential of the shade seedling under the high light intensity, and the simulated light spot is that the concentration of the seedling NSC is obviously higher than that of the seedling which has been subjected to the shade treatment, and the adverse effect of the shading on the carbon storage of the seedling is relieved, So the high-density light spot can play a certain role in maintaining the net carbon balance of the Quercus acutissima seedlings under the Baotianman sharp-tooth oak forest.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S718.4
，
本文编号：2483957
[Abstract]:The research of large-scale forest death in the context of global climate change is a hot spot in the world. It is difficult for trees to maintain carbon-water balance as the main cause of tree death. In this study, three different environmental conditions or relationships, such as different rainfall levels, pest and tree phenology, and different light intensity and tree size, were selected to study the effects of hydro-imbalance and carbon starvation on the growth and survival of trees. It includes the following steps: to explore the four-shot flowers (Dendrotenham japonica (DC.) Tang var. chinensis (Osborn.) Tang) and three-(Lindera obtusiloba Bl. Mus. Bot) after the reduction of rainfall. ) And Sorbus alngifolia (Sieb.et Zucc). ) K. Koch) The stomatal behavior of three different isohydryry (isowater)-anishanyry (isowater) functional plant and the water-carbon change of the xylem and the mechanism of the dead-death of the water-carbon in the plant, and the mechanism of the dead-death of the triamcinolone; and the study of the loss of the insect-leaf to the Schima superba Gardn.et. ) And Engelhardia roxburghiana, Wall. ) The degree of harm; and how the light intensity and the size of the tree affect the carbon-water balance of Quercus aliena var. acuta. This study is of great theoretical significance for understanding and predicting the change and succession of forest structure in the context of global change. The main conclusions are as follows:1. The experimental results show that in the plant spectrum of isowater, the four-way flower is in the one end of isohydary, and the water elm is in the one end of anisoheyry. And three of them are in the middle of the two. The water potential was the highest in the three tree species, but the net photosynthetic rate and non-structural carbon (NSC) decreased. However, the water loss and water potential are the lowest among the three tree species, but the limitation of gas exchange is low, and the surplus of the NSC is the most common among the three tree species. I. e., the water potential of the anisoheyric water elm is more negative than the water potential at noon, but the effect of the accumulation of the nsc is less. But in the air-hole behavior strategy, the three-drug-black drug between the two is severely dead due to the hydraulic imbalance. In addition to that type of pore reaction, the vulnerability of xylem embolism play an important role in the response of trees to drought. Among the three tree species, the most of the three kinds of Wuyao embolization is the lowest, that is, the anti-embolism ability is the lowest, and the hydraulic imbalance occurs after the cut-off, leading to the dead end of the top. The study shows that the hydraulic imbalance depends not only on the type of pore reaction but also by the vulnerability of the xylem.3. The seasonal drought of the Dinghushan Mountain has no interaction with the insect. But the reduction of the carbon stock caused by the different rhythm of the change of the phenology leads to a different degree of damage to the wood and the yellow soil by the insect. The evergreen broad-leaved tree of Dinghushan is changed in February, and the leaf-changing process itself consumes a great deal of NSC. And the leaf-change time of the other canopy tree was in May. Dinghushan insect outbreaks were in March-April, just after the change of the leaves of the wood, before the change of the leaves. Based on the analysis of the tree-year round, the lateral growth of the wood-to-load was reduced in the year of the outbreak of the pest (T. quadia), while the yellow rice was not inhibited. The leaf-defoliation test showed that the leaf-defoliation treatment significantly reduced the growth of the leaves and branches of the leaves, and restricted the photosynthesis and fixation of the wood-loaded leaves after the defoliation treatment, which hindered the restoration of the root and the xylem NSC, thus resulting in a high mortality rate. Although leaf loss also reduces the growth of the leaves and branches of the yellow leaves, it reduces the amplitude much less than that of the wood. After 10 months of defoliation, the NSC reserve was restored and no tree death was present. Therefore, the NSC reserves and pests are closely related to the degree of damage to the trees. When the phenological cycle is taken into account, it is easy to explain the effect of the loss of the pest leaf on the growth of the wood, the reserve and the survival of the NSC. The research on the relation between the water and water shows that the seasonal drought of the Dinghushan Mountain has no damage to the two tree species.4. The four materials of the upper part of the large crown layer of the sharp-toothed oak, the lower part of the crown, the lower and the lower trees of the forest and the small tree of the forest window are the research objects. There is a significant hydraulic restriction on the upper part of the large crown layer, which results in the net photosynthetic rate at the upper part of the large crown layer, and the air hole conductivity is significantly lower than that of the forest window with the same light efficiency. Since the top of the crown is often subjected to water stress and the resulting decline in growth, the NSCs of the upper and the bast parts of the large crown layer are relatively accumulated, while the recurrent plug repair consumes a large number of the NSCs of the xylem. And the photosynthetic capacity of the lower part of the large crown layer is larger than that of the lower tree. Considering the size and the light-receiving degree of different trees, the light factors play a more important role in shaping the photosynthesis of the Quercus acuminata. The low light environment in the forest significantly limits the photosynthetic potential and the solid carbon of the young trees of the sharp-tooth oak, and the concentration of the NSC is lower than that of the tree and the forest window. The NSC state of the young trees of the Quercus acumen is very easy to die due to carbon starvation. In addition, the pot-shading test indicated that the shade treatment significantly reduced the dry matter quality and the NSC concentration of the sharp-tooth oak seedlings. the simulated light spot treatment obviously improves the photosynthetic potential of the shade seedling under the high light intensity, and the simulated light spot is that the concentration of the seedling NSC is obviously higher than that of the seedling which has been subjected to the shade treatment, and the adverse effect of the shading on the carbon storage of the seedling is relieved, So the high-density light spot can play a certain role in maintaining the net carbon balance of the Quercus acutissima seedlings under the Baotianman sharp-tooth oak forest.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S718.4
，
本文编号：2483957
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