Development and characterization of microsatellite loci in western larch (Larix occidentalis Nutt.)

Western larch (Larix occidentalis Nutt.) is an important ecological and commercial species in the Pacific Northwest. We isolated nine microsatellite loci with variable polymorphism ranging from five to 19 alleles per locus. Observed and expected heterozygosities averaged 0.42 and 0.64 and ranged from 0.11 to 0.83 and from 0.48 to 0.80, respectively. These markers, along with those already existing, will be useful for the species' gene resource management activities.     

采伐干扰对华北落叶松细根生物量空间异质性的影响

以华北落叶松天然林为研究对象,选择采伐干扰林分(样地A)和未采伐干扰林分(样地B),利用根钻法分3层(0—10cm,10—20cm,20—30cm)获取各径级细根(≤1mm、1—2mm、2—5mm3级活细根,≤2mm死亡细根)生物量数据。采用地统计学变异函数和经典统计相结合的数据分析方法对采伐干扰造成的细根生物量空间异质性的变化进行定量研究。主要研究结果如下:采伐干扰林分样地A各经级细根生物量均值减少;同一土层相同径级细根生物量样地A与样地B相比差异显著(P<0.05);不同土层的细根生物量异质性具有显著差别(P<0.05)。0—10cm土层,未采伐干扰林分≤1mm细根生物量呈现较明显的空间自相关变异,采伐干扰林分则表现为随机性变异特征,采伐干扰导致≤1mm细根生物量空间分布特征更加复杂(分维数D=1.978);10—20cm土层,采伐干扰林分各径级细根生物量异质性程度明显降低,只有未采伐干扰林分的5.4%—88.9%。20—30cm土层,未采伐干扰林分≤1mm细根生物量在较小尺度范围(<2.9m)表现出明显的空间自相关变异(结构方差比86.1%),受采伐干扰林分各径级细根生物量异质性程度只有未采伐干扰林分的8.9%—45.9%,且呈现随机性变异。各径级细根生物量空间异质性的垂直分异均表现为随土层深度的增加异质性强度明显降低。     

不同光照强度对兴安落叶松几种主要防御蛋白活力的影响

林木组成抗性对抵御害虫危害发挥着重要作用。为了研究环境因子对其组成抗虫性的影响,以兴安落叶松幼苗为试验材料,通过搭建遮阳棚设置3个光照强度(自然光照作为对照、50%和25%自然光照强度),模拟森林幼苗生长的林缘、林窗和林下3种不同的光环境,分析不同光照强度对其针叶内与植物抗虫性有关的几种主要防御蛋白活力的影响。研究结果表明,不同光照强度对针叶内主要防御蛋白活力有显著影响(P<0.05)。50%和25%光照强度下,POD、SOD、PAL、PPO和CI的活性显著高于自然光照下的(P<0.05),POD和CI的活性在50%光照强度下最高,SOD、PAL和PPO的活性在25%光照强度下最高;自然光照条件下CAT的活性显著高于50%和25%光照强度下的(P<0.05);遮荫处理对TI的活性有显著影响(P<0.05),但在不同月份中波动较大,规律性不明显。相同的光照强度条件下,主要防御蛋白活力在3个月中也有显著变化(P<0.05)。7月和8月份保护性酶POD和CAT的活性显著高于6月(P<0.05);防御性酶PAL、PPO以及蛋白酶抑制剂CI的活性在6月份最高。综合以上研究结果,光照可影响兴安落叶松针叶中几种主要防御蛋白活力,这也说明在较荫蔽的光照环境下,兴安落叶松有较强的抗性。其中SOD、CAT、PAL、PPO和POD是植物次生物质生成过程中的关键酶,其活性的改变在一定程度上表征着植物防御体系在变化。研究环境因子与植物防御之间的关系具有重要的理论和实际应用价值。     

黄土高原樟子松和落叶松与其他树种枯落叶混合分解对土壤的影响

通过采集树木枯落叶与土壤进行室内混合分解培养试验,研究了黄土高原常见的樟子松和落叶松与其他树种枯落叶混合分解对土壤性质的影响及存在的相互作用,从而为不同树木种间关系的探索和该地区人工纯林的混交改造提供科学指导。结果表明:12种枯落叶单一分解均明显提高了土壤脲酶(54%—110%)、脱氢酶(85%—288%)和磷酸酶(81%—301%)活性以及有机质(29%—55%)和碱解N(12%—49%)含量,但对土壤速效P含量和CEC的影响存在较大差异。综合而言,樟子松分别与白桦、刺槐、白榆、柠条和落叶松枯落叶混合分解在对土壤性质的影响中存在相互促进作用,而分别与小叶杨、沙棘、紫穗槐、侧柏和辽东栎枯落叶混合分解在对土壤性质的影响中存在相互抑制作用;落叶松分别与刺槐、白桦、小叶杨和紫穗槐枯落叶混合分解在对土壤性质的影响中存在相互促进作用,而分别与柠条、侧柏、辽东栎、沙棘、油松和白榆枯落叶混合分解在对土壤性质的影响中存在相互抑制作用。     

基于CENTURY模型模拟火烧对大兴安岭兴安落叶松林碳动态的影响

火作为森林生态系统重要的自然干扰因子之一,对森林的碳动态有着不可忽视的影响.本研究使用CENTURY模型模拟了大兴安岭呼中林区兴安落叶松林的碳收支对不同强度火烧的响应.结果表明:在不同强度火烧后,土壤总碳库呈先升后降再逐渐恢复的变化趋势,而林分生物碳库则先降后升,其中,林分细小组分碳库的恢复速度明显快于大组分,各碳库的波动程度随火烧强度的增大而增大.森林植被的净初级生产力(NPP)和土壤异养呼吸在火后均先降后升,但NPP的恢复快于土壤异养呼吸,二者的动态变化改变了林分的碳源/汇作用.轻微火烧后,兴安落叶松林仍表现为弱碳汇,并很快恢复到火前水平;其他强度的火烧使兴安落叶松林在短期内(9～12年)表现为碳源,随后逐渐转为碳汇.较低强度的林火不仅可以促进落叶松林的更新、减少死可燃物,也不会对林分的碳汇功能造成太大影响;高强度的严重林火对土壤和林木碳库造成严重损失,延缓森林的恢复,并可使林分表现为较长时间的碳源.     

采伐干扰对林下草本根系生物量与土壤环境异质性关系的影响

结合统计学和地统计学的理论,探讨了采伐干扰对华北落叶松林下草本根系生物量空间异质性及与林下土壤含水量、全氮、硝态氮、铵态氮、pH及华北落叶松细根生物量空间异质性的关联性。结果表明,采伐干扰样地草本根系生物量为 31.17 g/m²,明显小于未干扰样地(72.01 g/m²);采伐干扰导致草本根系生物量更多地向表层积聚。0~10 cm土层,采伐干扰样地草本根系生物量的空间异质性(C₀+C=31330.0)和空间自相关性(C/C₀+C=92.5%)明显增强,表现出较强的空间依赖性。采伐干扰后,土壤水分、全氮、硝态氮和铵态氮对草本根系生物量的相关性增强;未采伐干扰样地华北落叶松细根生物量与草本根系生物量的相关性较强。     

Estimation of fine root production, mortality and turnover with Minirhizotron in Larix gmelinii and Fraxinus mandshurica plantations

Fine root turnover is a major pathway for car-bon and nutrient cycling in forest ecosystems. However, to estimate fine root turnover, it is important to first understand the fine root dynamic processes associated with soil resource availability and climate factors. The objectives of this study were: (1) to examine patterns of fine root production and mortality in different seasons and soil depths in the Larix gmelinii and Fraxinus man-dshurica plantations, (2) to analyze the correlation of fine root production and mortality with environmental factors such as air temperature, precipitation, soil temperature and available nitrogen, and (3) to estimate fine root turn-over. We installed 36 Minirhizotron tubes in six mono-specific plots of each species in September 2003 in the Mao'ershan Experimental Forest Station. Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005. We calculated the average fine root length, annual fine root length production and mortality using image data of Minirhizotrons, and estimated fine root turnover using three approaches. Results show that the average growth rate and mortality rate in L. melinii were markedly smaller than in F. mandshurica, and were high-est in the surface soil and lowest at the bottom among all the four soil layers. The annual fine root production and mortality in F. mandshurica were significantly higher than in L. gmelinii. The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F. mandshurica and 24.0% and 51.2% in L. gmelinii. The majority of fine root mortality occurred in spring and summer for F. mandshurica and in summer and autumn for L. gmelinii. The turnover rate was 3.1 a-1 for L. gmelinii and 2.7 a-1 for F. mandshurica. Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the varia-tions of the fine root seasonal growth and 95% of the seasonal mortality. In conclusion, fine root production and mortality in L. gmelinii and F. mandshurica have dif-ferent patterns in different seasons and at different soil depths. Air temperature, precipitation, soil temperature and soil available nitrogen integratively control the dynamics of fine root production, mortality and turnover in both species.     

大兴安岭兴安落叶松(Larix gmelinii)天然林分级木转换特征

通过调查样地,作树干解析,分析了不同结构兴安落叶松天然林分级木（优势木、平均木和被压木）转换特征。研究表明：（1）不同结构的兴安落叶松天然林分级木转换年龄、方向和转换率均不同。兴安落叶松分级木转换率29.4%。分级木中,优势木、平均木和被压木转换率分别35.3%、41.2%、11.8%。分级木转换中,优势木与平均木相互转换比例较高,优势木转平均木占83.3%,平均木转优势木占85.7%;优势木向被压木转换比例仅为16.7%;被压木不能转换成优势木,只能转换成平均木,被压木中无转换占88.2%,在森林经营和抚育采伐中应考虑伐除这些被压木。（2）在林分年龄36～65a范围内,随着林分年龄增大,其转换率呈增加趋势。林分年龄30～39a、50～59a和60～69a时,其转换率分别0、33.3%和46.7%。（3）随着林分密度增加,分级木转换率呈增高趋势。当林分密度小于2500株.hm^-2时,主要于优势木与平均木间转换。当林分密度大于2500株.hm^-2时,才出现其它分级木与被压木相互转换现象。（4）不同林型分级木转换率和转换方向不同。草类-落叶松和杜香-落叶松林分级木转换率分别50%和9.5%。（5）不同水平格局林分分级木转换率不同。聚集分布和随机分布时,其转换率分别61.1%和13.3%。     

Comparative ecophysiology ofLarix kaempferi (Lamb.) Carr. andAbies veitchii Lindl. II. Mechanisms of higher drought resistance of seedlings ofL. kaempferi as compared withA. veitchii

The underlying mechanisms of drought resistance in seedlings ofLarix kaempferi as compared with those inAbies veitchii were investigated. First, seedlings of the two species were desiccated in air of differing water potential, and their survival rates were compared to detect any difference in desiccation tolerance between them. Contrary to differences in their drought resistance,A. veitchii showed higher survival. Next, the shoot heights and root depths of the two species were compared to detect any difference in desiccation avoidance. Although the shoot height differed little between the two species, the roots ofL. kaempferi seedlings were much deeper than those ofA. veitchii seedlings, and the death rate under progressing drought was well correlated with the root extensibility of each species. It was thus concluded thatL. kaempferi seedlings are able to avoid desiccation by extending their roots in deep soil faster thanA. veitchii seedlings, thereby resisting to drought. This paper is dedicated to Prof. Toshiro Saeki to mark his fruitful career in plant ecology.     

增温和光周期变化对东北地区兴安落叶松主要物候期的影响

兴安落叶松在东北地区森林生态系统的结构与功能中起着重要作用,气候变化背景下东北地区气温增加且光照缩短必将影响兴安落叶松的变化,特别是物候这一气候变化的敏感指标。弄清其物候对气候变化的响应有助于揭示兴安落叶松的变化趋势。但是,当前关于兴安落叶松物候对温度、光周期及其协同作用的响应机制仍不清楚。针对东北地区温度剧增、日照时数减少的特点,2019年4月至11月开展了3年生兴安落叶松幼苗主要物候期响应温度和光周期变化的大型人工气候室模拟控制实验。结果表明：(1)不同程度的增温对兴安落叶松生长周期(展叶始期至完全变色期)无显著影响,但显著缩短生长盛期(展叶盛期至叶变色普期),且增温2.0℃较增温1.5℃对生长盛期影响更大。(2)长光照显著增加兴安落叶松的生长周期(9.25 d),短光照对兴安落叶松生长周期的影响不显著,且长光照和短光照均使兴安落叶松生长盛期缩短,二者对兴安落叶松生长盛期影响表现一致。(3)长光照、短光照分别与增温协同作用均使兴安落叶松生长盛期缩短,其中增温2.0℃与长光照协同作用对生长盛期缩短更显著(34.67 d)。(4)与生长始期(展叶始期)和末期(完全变色期)相比,兴安落叶...