六盘山香水河小流域典型坡面的土壤电阻率空间变异

为了解坡面土壤水文特征的空间分布,采用多电极电阻仪法(ERT),于2009年5月初在宁夏六盘山香水河小流域一个长约600 m的华北落叶松人工林典型坡面上,设置了从坡顶至坡底的1条纵向样线及处于不同坡位的水平分布的3条横向样线,多点测定了多层土壤的电阻率值并分析其空间变异特征。结果表明,土壤电阻率在纵向样线上总体有较好的空间连续性及一定的空间变异性,随着坡位下降,电阻率呈现出由坡上至坡中上逐渐减小和然后又恢复性增大的过程。由于局部特殊的土壤特征、地貌及植被分布差异,使土壤电阻率沿坡面纵向变异程度大于不同坡位的横向变异程度。在土层垂直方向上,由于石砾含量和岩石比例随深度逐渐增多,电阻率表现为随深度增加逐渐增大。电阻率与土壤总孔隙度和体积含水率相关最紧密,尤其与体积含水率相关较好,说明通过测定坡面电阻率推求土壤水分等土壤特性的坡面变化是可行的。     

大兴安岭山地樟子松天然林土壤水分物理性质及水源涵养功能研究

对大兴安岭山地樟子松天然林土壤水分物理性质及水源涵养能力进行研究,结果表明,0-20 cm土层土壤含水量、土壤毛管孔隙度、总孔隙度、枯落物蓄积量和蓄水量均表现为:坡下>坡中>坡上,土壤含水量变化范围为278.71~377.98 g/kg,平均值为327.67 g/kg;整个坡面土壤毛管孔隙和总孔隙度平均值分别为29.08%和53.15%;枯落物蓄积量和最大蓄水量分别为16.72,53.24 t/hm2。0-20 cm土层土壤容重随坡位降低有减小趋势,其平均值为0.84 g/cm3。土壤非毛管孔隙、土壤毛管蓄水量、有效蓄水量、最大蓄水量均表现为:坡下>坡上>坡中。整个坡面平均毛管蓄水量、有效蓄水量和最大蓄水量分别为625.90,499.05,1 130.29 t/hm2。樟子松天然林林地蓄水能力也表现为:坡下>坡上>坡中,坡下为1 358.51 t/hm2,坡上为1 102.09 t/hm2,坡中为1 058.85 t/hm2,平均蓄水量为1 183.54 t/hm2。由此可见,山地樟子松天然林蓄水能力受坡度和坡位影响较大。     

祁连山东段青海云杉林土壤有效氮研究

通过野外取样和实验室分析,对祁连山东段青海云杉林的土壤有效氮状况进行了研究。结果表明:(1)青海云杉林0—40 cm土层土壤总有效氮(铵态氮+硝态氮)的变化范围为17.26~20.76 mg/kg,铵态氮是土壤有效氮的主要存在形态,其含量占到总有效氮的66.72%以上;(2)土壤铵态氮含量随土层深度的增加而较少,硝态氮则无明显的变化规律,而且土壤硝态氮较土壤铵态氮对土壤微环境敏感;(3)土壤铵态氮与有机质相关关系显著(p<0.05),土壤硝态氮与有机质无显著相关性。研究区铵态氮为土壤有效氮的主要赋存形式,它在很大程度上取决于该区土壤pH中性值,较低温度和较高的水分含量。     

Yellow pine regeneration as a function of fire severity and post-burn stand structure in the southern Appalachian Mountains

We used pre- and post-burn fire effects data from six prescribed burns to examine post-burn threshold effects of stand structure (understory density, overstory density, shrub cover, duff depth, and total fuel load) on the regeneration of yellow pine (Pinus subgenus Diploxylon) seedlings and cover of herbaceous vegetation in six prescribed-fire management units located within western Great Smoky Mountains National Park (GSMNP) in east Tennessee, USA. We also evaluated the utility of the Keetch-Byram Drought Index (KBDI) as a predictor of post-burn stand and fuel conditions by comparing post-burn stand variables for different ranges of KBDI (23-78; more wet, and 328-368; more dry). We found that yellow pine seedlings were effectively absent in post-burn forests until overstory density was reduced over 40%, understory density was reduced over 80%, and post-burn shrub cover was 10% or less. We also observed that a reduction in total fuels of 60% and a post-burn duff layer depth of less than four cm were required for successful regeneration of yellow pine. Total herbaceous species cover exhibited near identical responses with increased cover following an 80% reduction in understory density and a post-burn duff depth of less than 4 cm. We observed strong positive relationships between high KBDI values and burn severity, changes in forest structure, reductions in fuels, and post-burn yellow pine reproduction. We observed continuous recruitment of yellow pine seedlings 5 years after fire in high KBDI burns while low KBDI burns showed little change in yellow pine density through time. An intense outbreak of the southern pine beetle (SPB; Dendroctonus frontalis) occurred within 2 years of our high KBDI burns and reduced shading resulting from overstory mortality likely enhanced the survival of yellow pine seedlings. The results of this study provide targets for the application of prescribed fire to restore yellow pine in the southern Appalachians. Continued research and monitoring will help determine how prescribed fire can best be applied in combination with other disturbance agents such as SPB to perpetuate yellow pine forests.     

华中五味子栽培条件下果穗生长发育动态规律研究

在秦岭北麓地区栽培条件下,对华中五味子果穗生长发育过程观察研究表明：其果穗生长动态呈现快、慢节律,生长期内有减慢现象,其粗度、长度、体积生长动态及加粗、伸长生长相互关系符合三次函数曲线。末花期——第二次生理落果期果穗体积增长最快,占总产量的90.6%,是产量和优质果品形成的关键时期,并对田间管理提出了指导建议。     

黄龙山林区油松毛虫发生原因分析及防治措施

在研究清楚油松毛虫生物特性的基础上,以黄龙山林区为例,分析了该林区油松毛虫发生的原因,提出了应重视松毛虫的监测与预报,积极采用航天遥感与航空遥感技术作为监测松毛虫发生的手段,做到早发现早治理;加强松树的抗性机制与分子机理、抗性品种的开发等方面的研究,提高松林对松毛虫为害的抵抗力;综合采取营林防治、生物防治、人工物理防治以及化学药剂防治等措施,将松毛虫的危害减少到最小程度,促进森林的可持续经营。     

武夷山土壤有机碳和黑碳的分配规律研究

The objective of this study is to investigate the distribution pattern of organic carbon and black carbon in soils of Wuyi Mountains. The results indicated that the contents of organic carbon in 2000-250 μm fraction, 250-50 μm fraction and <50 μm fraction ranged from 7.16 to 78.78 g·kg^-1, 1.48 to 10.30 g·kg^-1 and 0.58 to 3.86 g·kg^-1 respectively. The contents of black carbon in corresponding fraction varied from 0.58 to 22.19 g·kg^-1, 0.11 to 3.57 g·kg^-1 and 0.07 to 0.87 g·kg^-1, which indicated that the organic carbon and black carbon were mainly presented in 2000-250 μm fraction. The regression analysis showed that there was a significant linear or logarithmic relationship between soil organic carbon and black carbon in corresponding fractions and whole soil, and the proportion of black carbon to organic carbon was 6%-35% in different soils. The data also suggested that the black carbon had a high relative content in <50 μm fraction of red soil, yellowish red and yellow soil, but in 250-50 μm fraction of meadow soil.     

云南哀牢山古茶树群落优势树种的种群结构与分布格局

用种群结构、存活曲线、扩散系数、最近邻体指数及Ripley's K函数等分析了云南哀牢山野生古茶树群落优势树种的种群结构和分布格局.结果表明:1.2 hm2样地内记录到胸径≥1.0 cm的乔木2 894株,隶属于22科38属48种.普洱茶个体数量最多,重要值排名第一,木果石栎重要值排名第二,但具有最大的相对优势度.该群...     

天山中部林区主要树种理化性质及燃烧性分析

对天山中部林区9种主要树种的含水率、热值、灰分及抽提物进行测定,利用多元统计方法和可燃性指数综合评价体系,对天山中部主要树种的变化特征进行综合评价.树种燃烧性大小依次为:方枝柏＞天山云杉＞黑果小檗＞山楂＞忍冬＞欧洲山杨＞山柳＞天山花楸＞宽刺蔷薇.这些研究可为新疆天山森林林火发生预报、林火行为预报、灭火指挥、营林用火、生物防火等方面提供重要依据.     

南岭山区广西龙脊壮族传统文化中蕴涵的生态智慧

以广西龙脊壮族为对象,研究壮族传统文化中蕴含的生态观.从壮族核心文化,即物质文化的代表"稻作文化",精神层面的宗教信仰文化,以及两者的制衡点"乡规民约"制度文化3方面阐述该地区民族文化和生态保护间的关系,分析南岭山区壮族传统文化中生态环境保护意识观对现代社会的价值和借鉴意义.