【作者】 刘娟；

【导师】 陈晓鸣；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2010， 博士

【摘要】 应用昆虫作为指示性生物监测与评估森林健康状况的生物学与生态学研究表明,昆虫种类及种群波动可用于对森林生态系统健康作出快速评估,但如何将这一理论应用到森林保护的实践中,准确评估森林生态系统的健康水平,需要对昆虫危害树木的机制作更加深入细致的研究。林木树势衰弱后常伴有蛀干害虫的出现,林木的健康状况与其生理代谢有着直接联系,本论文主要从光合生理指标、保护酶活力、相关活性物质含量及挥发物变化等方面研究了云南松受云南切梢小蠹和松墨天牛等蛀干害虫危害胁迫后的生理生化响应,分析蛀干害虫危害与云南松健康状况关系,以期为利用蛀干害虫作为指示生物诊断森林健康指标体系的研建提供科学依据。研究结果主要包括以下几个方面。1、受害后云南松光合生理指标的响应。(1)受小蠹蛀梢胁迫后,净光合速率、蒸腾速率、气孔导度等光合指标和针叶叶绿素含量均出现极显著下降(P<0.01)。云南松光合日进程发生了明显的变化,小蠹蛀梢云南松净光合速率的日变化呈“单峰”曲线,最高峰出现时间(12:00)较未受害云南松提前2h,且峰值下降了45%。小蠹蛀梢云南松光合作用主要集中在上午,与未受害云南松相比,净光合速率日均值极显著下降(P<0.01),1d中CO2同化量比未受害云南松下降了55.9%。相关分析表明,未受害云南松净光合速率主要受光合有效辐射的影响,蒸腾速率与环境因子相关性不显著,小蠹蛀梢危害后,云南松净光合速率、蒸腾速率的影响因子增加,对环境因子中的水分变化表现较为敏感,说明小蠹蛀梢后云南松抗性下降,环境因子的变化较易影响其正常生长,最终导致树势衰弱。(2)松墨天牛补充营养取食胁迫对云南松光合生理指标动态变化研究结果表明,松墨天牛取食后云南松净光合速率、蒸腾速率、气孔导度及胞间CO2浓度均出现下降趋势,且随着取食时间的延长和取食强度的增加,各项指标较取食前下降幅度更大。水分利用效率则相反,在实验测定过程中,取食初期稍有下降,之后呈逐渐上升,说明在一定时间里,云南松能通过提高水分利用效率来适应松墨天牛取食胁迫。2、受害后保护酶活力及相关活性物质含量的变化:超氧化物歧化酶、过氧化氢酶、过氧化物酶等3种酶活力和丙二醛、脯氨酸、总蛋白质等活性物质含量在小蠹虫蛀害和松墨天牛取食云南松时表现各异,但也呈现了一些相同的规律性变化。(1)与未受害云南松相比,小蠹蛀害和松墨天牛取食诱导的云南松叶片和韧皮的各种酶活力及各活性物质的含量都发生了变化,但韧皮中各种酶活力及各活性物质含量的变化不如叶片中明显,由于叶片对小蠹虫和天牛危害胁迫较为敏感,更容易发现规律,且反应更迅速,在研究云南松酶活力及活性物质的含量对小蠹蛀害和松墨天牛取食响应时,选择叶片作为测定材料。(2)同未受害云南松相比,除蛋白质含量外,被小蠹蛀害和松墨天牛取食后叶片中酶的活力及相关活性物质含量都出现了不同程度的升高。不同的是有些酶的活力及相关活性物质含量在观测时段内出现了迅速下降,有些则一直处于较高水平。酶的活力及相关活性物质含量的升高显然是植物体对外界刺激应答反映的结果,不同酶的活力及活性物质的含量下降的时间和速率不同可能是由酶及活性物质本身的性质决定的,那些在观测时段内仍处于较高水平的酶及活性物质可能在一定的时间内也会下降,只是没有观测到而已。蛋白质含量之所以出现下降,可能是因为云南松受害后改变了叶内水势、电势等细胞内环境,使大部分与应答反应无关的蛋白质变性、消失。总之,被小蠹蛀害和松墨天牛取食后,云南松叶片中各种酶的活性及相关活性物质含量都出现了规律性的变化,它们都可以作为指示小蠹虫和松墨天牛损害程度的指标,但SOD、POD及MDA对小蠹蛀害和松墨天牛取食的反应更为敏感,是用来指示小蠹蛀害和松墨天牛损害程度的比较理想的指标,其中SOD也是衡量植物健康水平的重要指标,用SOD就可以将松墨天牛损害程度与植物健康水平联系起来。3、受害后云南松释放挥发物成分及相对含量的变化。(1)虽然小蠹虫蛀梢与未受害云南松挥发物种类日变化表现出了相似的规律,且数量差异很小,但挥发物的构成却差别很大,这些差异物质,尤其是小蠹虫蛀梢的云南松特有的挥发物,可能与其防御反应或信息传递有关。(2)与未受害云南松相比,小蠹虫蛀梢、蛀干和松墨天牛取食危害后,云南松挥发物种类构成和数量都出现一定的变化,在这一过程中,种类和数量与虫害程度相关的成分可能是关键成分,例如:α-蒎烯、β-蒎烯、α-水芹烯相对含量的变化,由于这些物质在挥发物中相对含量较高,一方面引起云南松释放挥发物组成相的改变,另一方面较易被害虫接收识别,对其行为产生影响。(3)云南松受不同蛀干害虫(松墨天牛、小蠹虫)危害,不同取食部位(树梢、树干、韧皮),其释放的挥发物中α-蒎烯和β-蒎烯相对含量变化较大,且α-蒎烯/β-蒎烯比值均小于未受害云南松的比值。研究证明,植物释放挥发物中α-蒎烯/β-蒎烯的比值越小表明树势越衰弱。说明蛀干害虫危害导致云南松健康状况的下降,可以用蛀干害虫作为指示昆虫诊断云南松的健康状况。更多还原

【Abstract】 Applying insects as bio-indicators to monitor and assess forest health indicated that insect species and population fluctuations can be used to make a rapid assessment of forest health, but how to apply this theory to forest protection , further studies were needed for the mechanism of insect’s damages to trees. The weakness of forests is often followed by xylophagous insects, and the woods health situation is directly to its physiological metabolism. In this dissertation, it was investigated on physiological and biochemical responses of Pinus yunnanensis Franch. after the attacking by xylophagous insects such as Tomicus yunnanensis and Monochamus alternatus, mainly concerned about photosynthetic-physiological indexes, activities of the protective enzymes, contents of the related active substances and changes of volatiles. By the analysis of relations between the xylophagous insects damage and the pine trees health, it was willing to found indexes system scientifically for judging forest health by the indication from xylophagous insects . The main results of the study were showed as the follows:1.Trees’responses of photosynthetic-physiological indexes after attacking(1) After shoot stress from Tomicus yunnanensis , net photosynthetic rate, transpiration rate, stomatal conductance and other photosynthetic indexes decreased significantly (p<0.01), so did the chlorophyll contents of needle leaves. The pines’photosynthesis procedure during the daytime changed greatly. It was a single peak curve for the day-round of net photosynthetic rate with the summit time at 12:00 in the noon, that was 2 hrs ahead of those of undamaged pines, and the peak value was cut down at the rate of 45%. Photosynthesis of the damaged trees happened mainly in the morning. Compared with the undamaged, the day average net photosynthetic rate of the damaged decreased significantly (p<0.01) and the day-round assimilation amount of CO2 decreased by 55.9%.The corresponding analysis showed that net photosynthetic rate of the undamaged was influenced mainly by the photosynthetic active radiation and with its poor relation to environmental factors on transpiration rate. But for the damaged, the influence factors of net photosynthetic rate and transpiration rate increased, and the trees were sensitive to environmental moisture changes. It can be inferred that the shoot damage lead to the decrease of resistance, and the weakness of pine trees was eventually occurred as their normal growth was affected easily by the changes of environmental factors.(2) Regarding the stress from Monochamus alternatus, during the period of feeding and nutrition supplying, it was showed that decreases were happened after the xylophagous insects feeding, dynamically on trees’photosynthetic-physiological indexes such as net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration . The longer and the stronger the xylophagous insects fed, the lower the indexes went. On the contrary, the water use efficiency went down previously but rose gradually during feeding period. It indicated that the pines were able to handle stress from the xylophagous insects’feeding by improving the water usr efficiency during a certain period.2. Changes of activities of the protective enzymes and contents of the related active substances followed damaging: although it was various for SOD, POD and CAT activities and MDA, proline and total protein contents when the trees were damaged by Tomicus yunnanensis and fed by Monochamus alternatus, there were some changes seemed with same regularities.(1) Induced after damaged or fed, the pines were found with changes of activities of enzymes and contents of active substances both in leaves and phloems by the comparison of those from unattacked trees. But it was more considerable in leaves rather than in phloems of the changes. It should be selected for investigations on the activities and contents to the responses of damaging and feeding with leaf materials determined, due to their sensitive to stress from the two insects, easiness to regularity finding and quickness to reaction.(2) Except protein content, activities of enzymes and contents of active substances in leaves of the damaged or the fed pines increased differently at some extent by the comparison of the undamaged. But during the observing period, some of the activities and contents decreased rapidly and the other of them maintained in high level. Such increase was obviously the outcome of responses answered by the plants themselves to irritation from outside. Variations of some decrease mentioned above both in time and rate were probably due to their characteristics. Maybe it was just not found during the observing period for the decrease of those maintaining-high-level enzymes and active substances. For the reason of protein decrease, it seemed that most of the protein without links to the response-answer reactions denatured and disappeared because of the transfer of inner-cell circummustances such as water and electricity potentials in leaves followed by the damaging. In a word, regular changes were found in these activities and contents so that they were available to indicating the extent of beetle damaging. And SOD, POD and MDA were more sensitive to the damaging or feeding from the two insects than other indexes, thus they were taken as ideal indexes for insects damaging indication. SOD is also known as an important index to vegetable health recognition, then, it become a tie between the damaging extent and plant health level.3. Changes of constituents and relative contents of volatiles released from damaged pine trees(1) It was similar in the day-round changes as the regularity for volatile varieties to both damaged and undamaged pines, even a few differs in amount, but the consists of volatiles varied greatly. These different substances, especially volatiles from Tomicus yunnanensis shoot bored Pinus yunnanensis Franch., were probably related to tree’s defensive mechanism or information transportation.(2) Compared with the undamaged, the varieties and amounts of volatiles from damaged or fed pines changed in some extent. During the period, constituents in kinds and amounts related to xylophagous insects damaging extent were probably key chemicals such asα-pinene,β-pinene andα-phellandrene. For relatively high contents in volatiles, they caused constituents changes of the pine tree volatiles, either affected xylophagous insects’behavior as they were easy to receive and recognised.(3 )Damaged by different xylophagous insects and in different feeding parts, it was large variation of the relative contents ofα-pinene andβ-pinene. And the ratios ofα-pinene versus toβ-pinene were all lower than those in undamaged trees. It was proofed by studies that the smaller the ratio was, the weaker the trees got. The xylophagous insects damaging lead to the worsening of pine tree health, so the xylophagous insects could be indicative insects for health judging to Pinus yunnanensis Franch.更多还原