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莲花山自然保护区青海云杉叶锈病初步研究 总被引：3，自引：0，他引：3
青海云杉叶锈病是莲花山自然保护区云杉林中发生的一种重要病害，病原为祁连金锈菌。该病菌为缺夏[Ⅱ]型，[0]、[Ⅰ]阶段寄生在青海云杉当年生针叶上，[Ⅲ]、[Ⅳ]阶段转主寄生在青海杜鹃上，并在转主寄主青海杜鹃上越冬。每年6月底至8月底发病，病害发生较为严重。25％粉锈宁500倍液防治效果较好，平均防治率达93．2％。 相似文献
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常听到一些林业专家讲,松、杨不能混交栽植,这是为什么呢? 原来落叶松和杨树有一种共同病害,该病是由落叶松杨栅病菌引起的。病菌一年之内有五个发育阶段,每一个阶段产生固定形状的孢子,即性孢子、锈孢子、夏孢子、冬孢子,担孢子。它是一种转主寄生菌,性孢子和锈孢子寄生在落叶松上,夏孢子和冬孢子寄生在杨 相似文献
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落叶松胴枯病Phomopsis cryptomeriae KITAJIMA et KAMEL.是我省林区新发生的一种真菌病害。该病50年代在日本有发生。我国过去未曾发现,国内文献也未见报道。 1979年秋季,在清原县大孤家子林场发现两株10年生日本落叶松树冠枝梢枯萎现象,经检验是由2—3个病斑绕树干一周所致。1980年丹东地区、东沟等林场大面积发生此病,据了解发病面积万亩左右,除华北落叶松12—13年生幼林有发病外,日本落叶松 相似文献
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INTRODUCTIoNSSPCCiesdiversityistheoneofthreekcysubjcctS(Theglobalweatherchange,speiesdiversltyandsustainedecologysystem)inccologicalandenvironmentalscienceinrecenttenyears.Williams(I943)firstputfonvardsPecicsdiversitywhenhestUdiedtherelationbctx`centhcabundanccandinsectspecicsofLcl,i`mptcra.In6()'s~7()'s-ccologicaIscicn-tistshadgotagreatofachicvementsonsPCcicsdlt'crslti'stud\.Sinccl98()-s.somcscientistsstartcdtostud}'sPCcicsdivcrsityinCl1ina.Thcy'havcgotsolnercsultsol1artl1roPOdcom… 相似文献
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基于腾冲县1∶50 000数字化地形图和森林资源二类调查小班图层,利用Arcmap 10.0处理矢量数据、Fragstats 4.1计算景观格局指数、Excel进行数据统计和图表制作,将腾冲县天然林景观分为29个海拔带,选择景观面积、类型面积、面积比例和斑块丰富度4个景观格局指数对天然林景观的垂直梯度变化进行了分析。结果表明:景观面积随海拔梯度先增大后减小,中等海拔梯度天然林面积大,低海拔和高海拔梯度天然林面积小;不同海拔梯度天然林的主要森林类型不同,海拔2 900m以下和3 300 m以上变化较缓和,2 901~3 300 m范围内变化较剧烈;不同海拔梯度的优势森林类型不同,海拔1 400 m以下是云南松林,1 401~3 100 m是栎类林,3 101 m以上是竹林;不同森林类型的适宜分布海拔梯度不同;中等海拔梯度分布的森林类型较多,低海拔和高海拔分布的森林类型较少;海拔2 300 m以下的天然林受人为干扰比较严重。 相似文献
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作为森林生态系统一个重要的呼吸通量,叶片呼吸在森林碳循环中扮演着重要的角色。开展叶片呼吸的机理及其影响因子研究,有助于构建大气和植被之间的呼吸通量模型,预测分析气候变化对森林生态系统生产力和碳源汇功能的影响。通常采用Li - 6400光合测定系统和LAI - 2000树冠分析仪测定森林生态系统叶片呼吸速率。叶片呼吸是一个复杂的生物化学过程,受到大气温度、CO2浓度、土壤水分、叶片寿命、叶龄、比叶面积、叶片氮含量等多种因子的影响。叶片呼吸的日变化通常呈单峰曲线,与温度变化大体一致; 生长季早期和晚期的呼吸速率通常高于中期; 叶片在冠层着生位置影响其呼吸速率,冠层上部叶片的呼吸速率要高于冠层下部叶片。今后叶片呼吸研究应围绕以下4个关键问题:1) 模型构建时需要考虑叶片呼吸的温度驯化;2) 叶片呼吸在昼夜交替时内在调节机制;3) 从叶片呼吸到冠层呼吸的尺度转化;4) 加强和完善叶片呼吸影响因子研究。 相似文献
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Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second- and third-flush stages) in greenhouses at two atmospheric CO2 concentrations ([CO2]) (350 or 700 micromol mol(-1)) and two nitrogen fertilization regimes (6.1 or 0.61 mmol N l(-1) nutrient solution). Combined effects of [CO2] and nitrogen fertilization on partitioning of newly acquired carbon (C) and nitrogen (N) were assessed by dual 13C and 15N short-term labeling of seedlings at the second- or third-flush stage of development. In the low-N treatment, root growth, but not shoot growth, was stimulated by elevated [CO2], with the result that shoot/root biomass ratio declined. At the second-flush stage, overall seedling biomass growth was increased (13%) by elevated [CO2] regardless of N fertilization. At the third-flush stage, elevated [CO2] increased growth sharply (139%) in the high-N but not the low-N treatment. Root/shoot biomass ratios were threefold higher in the low-N treatment relative to the high-N treatment. At the second-flush stage, leaf area was 45-51% greater in the high-N treatment than in the low-N treatment. At the-third flush stage, there was a positive interaction between the effects of N fertilization and [CO2] on leaf area, which was 93% greater in the high-N/elevated [CO2] treatment than in the low-N/ambient [CO2] treatment. Specific leaf area was reduced (17-25%) by elevated [CO2], whereas C and N concentrations of seedlings increased significantly in response to either elevated [CO2] or high-N fertilization. At the third-flush stage, acquisition of C and N per unit dry mass of leaf and fine root was 51 and 77% greater, respectively, in the elevated [CO2]/high-N fertilization treatment than in the ambient [CO2]/low-N fertilization treatment. However, there was dilution of leaf N in response to elevated [CO2]. Partitioning of newly acquired C and N between shoot and roots was altered by N fertilization but not [CO2]. More newly acquired C and N were partitioned to roots in the low-N treatment than in the high-N treatment. 相似文献
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大栗鳃金龟自１９８５年首次在临夏太子山林区发生后，以５年为一周期于１９９０年、１９９５年定期发生。该虫以幼虫和成虫在土壤内越冬，也以幼虫和成虫对林木幼苗造成巨大为害。幼虫期采用５０％辛硫磷乳剂６００倍液、８０％敌敌畏乳剂６００倍液，防治效果达９０％以上。成虫期采用黑光灯诱杀、人工捕捉，２５％氧乐菊酿乳剂８００倍液或“６６６”烟剂防治，均能收到很好的效果。 相似文献
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We investigated growth, leaf monoterpene emission, gas exchange, leaf structure and leaf chemical composition of 1-year-old Quercus ilex L. seedlings grown in ambient (350 microl l(-1)) and elevated (700 microl l(-1)) CO2 concentrations ([CO2]). Monoterpene emission and gas exchange were determined at constant temperature and irradiance (25 degrees C and 1000 micromol m(-2) s(-1) of photosynthetically active radiation) at an assay [CO2] of 350 or 700 microl l(-1). Measurements were made on intact shoots after the end of the growing season between mid-October and mid-February. On average, plants grown in elevated [CO2] had significantly increased foliage biomass (about 50%). Leaves in the elevated [CO2] treatment were significantly thicker and had significantly higher concentrations of cellulose and lignin and significantly lower concentrations of nitrogen and minerals than leaves in the ambient [CO2] treatment. Leaf dry matter density and leaf concentrations of starch, soluble sugars, lipids and hemi-cellulose were not significantly affected by growth in elevated [CO2]. Monoterpene emissions of seedlings were significantly increased by elevated [CO2] but were insensitive to short-term changes in assay [CO2]. On average, plants grown in elevated [CO2] had 1.8-fold higher monoterpene emissions irrespective of the assay [CO2]. Conversely, assay [CO2] rapidly affected photosynthetic rate, but there was no apparent long-term acclimation of photosynthesis to growth in elevated [CO2]. Regardless of growth [CO2], photosynthetic rates of all plants almost doubled when the assay [CO2] was switched from 350 to 700 microl l(-1). At the same assay [CO2], mean photosynthetic rates of seedlings in the two growth CO2 treatments were similar. The percentage of assimilated carbon lost as monoterpenes was not significantly altered by CO2 enrichment. Leaf emission rates were correlated with leaf thickness, leaf concentrations of cellulose, lignin and nitrogen, and total plant leaf area. In all plants, monoterpene emissions strongly declined during the winter independently of CO2 treatment. The results are discussed in the context of the acquisition and allocation of resources by Q. ilex seedlings and evaluated in terms of emission predictions. 相似文献
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An understanding of root system capacity to acquire nitrogen (N) is critical in assessing the long-term growth impact of rising atmospheric CO2 concentration ([CO2]) on trees and forest ecosystems. We examined the effects of mycorrhizal inoculation and elevated [CO2] on root ammonium (NH4+) and nitrate (NO3-) uptake capacity in sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.). Mycorrhizal treatments included inoculation of seedlings with the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith in sweetgum and the ectomycorrhizal (EM) fungus Laccaria bicolor (Maire) Orton in loblolly pine. These plants were then equally divided between ambient and elevated [CO2] treatments. After 6 months of treatment, root systems of both species exhibited a greater uptake capacity for NH4+ than for NO3-. In both species, mycorrhizal inoculation significantly increased uptake capacity for NO3-, but not for NH4+. In sweetgum, the mycorrhizal effect on NO3- and NH4+ uptake capacity depended on growth [C02]. Similarly, in loblolly pine, the mycorrhizal effect on NO3- uptake capacity depended on growth [CO2], but the effect on NH4+ uptake capacity did not. Mycorrhizal inoculation significantly enhanced root nitrate reductase activity (NRA) in both species, but elevated [CO2] increased root NRA only in sweetgum. Leaf NRA in sweetgum did not change significantly with mycorrhizal inoculation, but increased in response to [CO2]. Leaf NRA in loblolly pine was unaffected by either treatment. The results indicate that the mycorrhizal effect on specific root N uptake in these species depends on both the form of inorganic N and the mycorrhizal type. However, our data show that in addressing N status of plants under high [CO2], reliable prediction is possible only when information about other root system adjustments (e.g., biomass allocation to fine roots) is simultaneously considered. 相似文献
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[目的]以甘肃省天水市为例,基于遥感影像变化监测技术,探讨黄土高原丘陵沟壑与小陇山-西秦岭山地交接过渡区域近30年来森林(林地)资源空间分布规律、时间变化趋势及变化影响因素。[方法]以1988—2015年5期夏季Landsat TM/OLI遥感影像为主要数据源,结合辅助数据和外业实地样本点,以光谱特征和指数特征为特征变量,分别利用随机森林(RF)和参数优化支持向量机(POSVM)分类器对土地覆盖类型进行分类,然后基于分类后比较法进行森林资源动态变化监测。[结果]分类结果表明,两种分类器的分类效果均较好,且随机森林分类器在分类精度、效率和稳定性方面明显优于参数优化支持向量机分类器。变化监测结果表明,近30年来森林资源总体变化趋势为林地面积先减少后增加。1990—1996年,林地面积减少0.74%;1996—2002年,林地面积减少2.74%;2002—2008年,林地面积增加1.06%;2008—2015年,林地面积增加8.89%。[结论]本研究采用的基于非参数分类器分类后比较法的变化监测技术是复杂地形地貌过渡区森林资源动态变化监测的一种有效途径,在分类结果分析统计的基础上,得出研究区森林资源变化的总体趋势:以2002年(2002年影像)为界,林地总体趋势为先减少后增加,2002年后林地面积增加显著。 相似文献