【作者】 乔海莉；

【导师】 骆有庆； 田呈明；

【作者基本信息】 北京林业大学 ， 森林保护学， 2007， 博士

【摘要】 本文系统地研究了新疆天然胡杨Populus euphratica Oliv．林树栖真菌、土壤微生物、昆虫的种类和多样性，以及光肩星天牛对天然胡杨林的入侵风险等诸多因子对天然胡杨林健康的影响。主要结果如下：1．胡杨林树栖真菌较为丰富，通过对胡杨叶片、枝皮、干皮等组织的分离培养，共得到41种真菌，其中接合菌亚门1种，子囊菌亚门3种，担子菌亚门1种，其余36种均为半知菌亚门。叶栖真菌共检出20种，不同形状叶片上的种类数基本相当；枝栖真菌共检出33种，中壮林胡杨上的种类和数量明显多于幼龄胡杨和过熟胡杨；干栖真菌共检出31种，随着树龄的增大干栖真菌的种类趋于减少。在41种树栖真菌中有内生真菌35种，共297个菌株，归属于4亚门、7目、22属，其中树干部位163株、25种，枝条部位103株、24种，叶片部位31株、12种。对胡杨树栖真菌群落中物种多样性进行分析得出，叶栖真菌中，针型叶片的多样性高，均匀性也高；枝栖真菌种群的多样性指数以中壮林最高，其次是过熟林，幼龄林最低；干栖真菌种群的多样性指数随着树龄的升高逐渐降低，均匀度指数的变化也是如此。因此，根据真菌多样性与均匀度越高，病害发生的可能性越低这一普遍规律，初步判断出中壮胡杨林受到病菌侵害的可能性最小，因而目前的健康状况优于其他类型胡杨林。2．在4种不同发育阶段胡杨林内，土壤微生物数量随着土层深度的增加逐渐减少，以31～40cm范围内最少。其中细菌在不同发育阶段胡杨林的各个土层中均有分布，数量明显高于放线菌和真菌，而在部分林地内的土层中没有分离到放线菌和真菌。真菌作为组成森林土壤生物量的重要组成部分，在试验中共分离出11属，其中曲霉属Aspergillus为各发育阶段胡杨林土壤中的优势菌属。3．胡杨林昆虫资源比较丰富，共采集到昆虫12目，61科，141种。其中有害昆虫90种，天敌昆虫(包括捕食性昆虫和寄生性昆虫)32种，其它类昆虫19种。不同功能类群、不同目昆虫和不同发育阶段胡杨林内昆虫的物种数、个体数、多样性、均匀度和优势度各不相同。其中植食性昆虫的种类数和个体数显著高于天敌昆虫和其它类昆虫，为明显的优势类群，但在多样性和均匀度指数方面，捕食性昆虫所占的比重最大。各目昆虫中以鳞翅目和鞘翅目昆虫群落的多样性指数和均匀度指数最高，均为全年中的优势目昆虫。不同发育阶段胡杨林以中壮林的昆虫最为丰富，为11目、52科、107种，幼龄林为10目、45科、76种；过熟林为11目、30科、58种；衰亡林仅有鞘翅目昆虫1个类群。由此说明，胡杨林内天敌昆虫的自然控制力很弱，一旦害虫大爆发，则只能依靠人为措施来加以控制，致使胡杨林生态系统因受到人类干扰而变得越来越脆弱。4．春尺蠖Apocheima cinerarius是目前胡杨林内最重要的爆发性害虫，可作为评价森林生态系统健康的指示物种。通过调查其幼虫虫口密度，发现有虫株率均达100％，且在中壮林内的发生数量稍高于幼龄林和过熟林。通过3种不同形状叶片饲养春尺蠖幼虫，发现过渡型胡杨叶片更利于其幼虫的生长发育。5．光肩星天牛Anoplophora glabripennis(Motschulsky)可以对胡杨造成危害。当胡杨的树皮厚度小于7mm时光肩星天牛便可侵入危害。根据胡杨树皮厚度的变化规律，以及光肩星天牛在胡杨上的危害特点，初步推测它对胡杨选择危害的结果如下：幼龄胡杨的树皮较接近光肩星天牛在杨树上产卵的最佳树皮厚度，因此天牛一旦侵袭，极有可能是优先选择较幼小的胡杨进行危害，并可侵害整个主干的各个部位及枝梢处；中壮胡杨和过熟胡杨可能危害的高度分别为3m以上和4m以上的主干或树皮较薄的枝梢处。6．光肩星天牛作为危险性害虫，可以对胡杨和其他造林树种均造成危害，其抗性高低序列为：桑树、沙枣＞胡杨、圆冠榆、新疆杨、白榆、箭杆杨＞复叶槭、旱柳、馒头柳。根据胡杨和某些试验树种上出现的羽化孔来判断，光肩星天牛在新疆巴州地区1年发生1代，且能在胡杨上顺利完成世代发育和造成危害。由此说明光肩星天牛对塔里木天然胡杨林存在很大的潜在危险性，可以在林内定殖并危害。更多还原

【Abstract】 The effect of species and diversity of dendrocola fungi, soil microorganism and insects, and invasive risk of Anoplophora glabripennis on ecosystem health in Populus euphratica forests was studied systematically. The main results were as follows:1. Forty-one species of fungi were isolated and identified from leaves, branches and stems of P. euphratica, in which 1 species belonged to Zygomycotina, 3 species belonged to Ascomycotina, 1 species belonged to Basidiomycotina and 36 species belonged to Deuteromycotina. 20 species of fungi were obtained from leaves. The species of fungi on different shape of leaves were similar. 33 species of fungi were obtained from branches. The species and quantities of middle-aged P. euphratica were apparently more than that of younger and mature P. euphratica. 31 species of fungi were obtained from stems, and the species quantities were increased with the tree age. 297 strains endophytic fungi were isolated from P. euphratica, which were identified belonging to 7 orders, 22 genera, and 35 species. There were 160 strains endophytic fungi isolated from stems which belonged to 35 species. And 103 strains, 24 species endophytic fungi were isolated from branches. 31 strains, 12 species were isolated from leaves of P. euphratica.The result of analysis to diversity in dendrocola fungi community of P. euphratic showed that diversity and evenness of foliage habiting fungi of needle leaves were the highest. The indices of diversity of fungi on branches were the highest on middle-age P. euphratic, lesser on mature and least on younger P. euphratica. According to the orderliness what the more the diversity and evenness of fungi, the less the probability of disease occurrence, the probability of disease occurrence on middle-age P. euphratica forests was least. Therefore it was healthier than other P. euphratica forests.2. There were evident differences in the microorganism biomass and composition rates of four kinds of natural P. euphratica forests in Xinjiang, and the dominant and special microorganism existed in all different layers of soil section. The vertical distribution showed that the microorganism biomass decreased with the increase of soil depth and the population of microorganism was the least in 31-40 cm depth of soil. The microorganism consisted of bacteria, which were the chief content and distributed widely, and actinomycetes as well as fungi, which were scarce in some layers of soil section. Aspergillus was the dominant genus among the 11 genera of fungi isolated from soil in the different ageP. euphratica forests.3. The insect resource was very abundant in P. euphratica forests. There were 141 species collected which belonged to 12 orders, 61 families. Among them 90 species were pests, 32 species were natural enemies (predacious and parasitical insects) and other insects included 19 species.Four functional groups of insect communities were divided according to nutritional relation of insect communities in P. euphratica forests. The species and individuals of phytophagous community were more abundant than natural enemy community and other insect community significantly, and it was dominant community in P. euphratica forests. Diversity and evenness of predacious community were highest in 4 functional groups of insect communities. Among different insect communities, Coleoptera and Lepidoptera were dominant orders whole year. The insect was very abundant in the middle-age P. euphratica forests, and there were 107 species collected which belonged to 11 orders, 52 families in it. 76 species were collected in younger P. euphratica forests which belonged to 10 orders, 45 families. And there were 58 species in mature P. euphratica forests which belonged to 11 orders, 30 families. But there was only one genera isolated in effete P. euphratica forests. Therefore, it indicated that the control effect of natural enemies was very weak. When the firestorm of pests happened, excessive man-made control measure would make the the ecosystem become more and more weaker.4. Apocheima cinerarius was the most important and dangerous pest species. It could be as bioindicator for assessment of forest ecosystem. The investigation of larval density indicated the ratio of harmed trees was up to 100%. The quantities of larval were little higher in the middle-aged forests than that in the younger and mature forests. A. cinerarius was favor of the imitative leaves of P. euphratica as food.5. Anoplophora glabripennis would damaged in P. euphratica if the bark thickness was less than 7mm. Forecasting A glabripennis ’harm choice to P. euphratica according to variance of bark thickness, we found the appropriate bark thickness to A. glabripennis’ oviposition was conformed to bark thickness of younger P. euphratica. The younger P. euphratica was much easier to be damaged, and the damage height was extended to all stem. And the heights were over 3 meter and 4 meter for middle-aged and mature P. euphratica respectively.6. The insect-resistance of 9 species trees in Xinjiang was identified. The resistant sequence from high to low was: Morus alba Linn., Elaeagnus angustifolia Linn. > Populus euphratica Oliv., Ulmus densa Litv., Populus alba var. pyramidalis Bunge., Ulmus pumila Linn., Populus nigra var. thevestina (Dode) Bean. > Acer negundo Linn., Salix matsudana Koidz., Salix matsudana f. umbraculifera Rehd. Based on the emergence holes, A. glabripennis was one generation in one year in Bayingolin Mongolia Autonomous district of Xinjiang Province. It could finish one generation on P. euphratica. So it indicated that A. glabripennis was dangerous to P. euphratica potentially.更多还原