不同海拔高度引种秃杉试验初报

在福建省德化葛坑国有林场不同海拔高度的山地引种栽培秃杉,并与杉木、柳杉、福建柏进行造林对比试验。结果表明:18年生秃杉在海拔550 m8、00 m9、80 m与1 650 m的生长差异达显著水平;在不同海拔高度,秃杉与杉木、柳杉、福建柏的生长差异显著,秃杉的单株材积增幅达19.3%~49.3%。说明秃杉宜在海拔500~1 000 m引种,其生长量最大,效益最好,是福建省中高海拔山区杉木采伐迹地的优良更新树种。     

电磁波吸收功能木基胶合板的制备与性能

以纳米炭黑为电磁损耗材料对木质基板进行表面电磁改性,以此为基础设计并制备连续渐变阻抗结构吸波胶合板,研究了电磁改性对木质基板微观形貌以及阻抗的影响,测试了胶合板吸波性能及其他理化性能。结果表明:纳米炭黑在木质基板表面形成均匀、连续、光滑的电磁改性涂层;胶合板对1.8~5GHz电磁波反射率小于-7dB,胶合板层数增加,反射吸收峰向低频方向移动,增加吸收层层数可拓宽吸波频段;胶合板厚度一定时,减少吸收层层数或增加匹配层层数,反射吸收峰强度减弱;胶合强度、静曲强度等其他理化性能均满足标准要求。开发的吸波胶合板在电磁辐射防护领域具有广阔应用前景。     

Structure and regeneration dynamics of dominant tree species along altitudinal gradient in a dry valley slopes of the Bhutan Himalaya

The aim of our study was to characterize the structure and regeneration dynamics of dominant tree species along altitudinal gradient in dry valley slopes of the Bhutan Himalaya. In the typical dry valley slopes of west-central Bhutan, we analyzed forest stratification, tree crown projection, and population structure from lower dry valley bottom (1520 m a.s.l.) to upper humid ridge top (3370 m a.s.l.) across five major forest types: i.e. (1) dry pine forest with Pinus roxburghii as a dominant species; (2) mixed broad-leaved forest with Quercus lanata (evergreen), Quercus griffithii, (deciduous), and Rhododendron arboreum (evergreen) as major canopy species; (3) evergreen broad-leaved forest dominated by Quercus semecarpifolia, Quercus glauca and Quercus oxyodon; (4) cool conifer forest dominated by Abies densa and Tsuga dumosa; (5) cold conifer forest with A. densa and Juniperus recurva as dominants. In general, regeneration pattern of major dominant species shifted from inverse-J (lower altitudes), to sporadic (mid-altitudes), and to uni-modal type (upper altitudes) corresponding to three regeneration trends: (1) invasive at the lower, warm, dry forest under relatively strong human disturbances; (2) stable/balanced at the mid-altitude, in a relatively stable, mature moist evergreen broad-leaved forest with gap regeneration; and (3) poor/low regeneration at the upper, cool, humid conifer forest with a continuously cattle-grazed understory. Overall, regeneration patterns were balanced in all forest types, however care should be taken to prevent excessive exploitation of dry pine forest of lower valley bottom, and to control cattle grazing at higher altitudes. Our findings can be incorporated into management plans for sustainable management and conservation of mountain forests.     

长白山北坡主要建群种种群结构及重要值沿海拔梯度的变化

From 700 m to 1900 m on the northern slope of Changbai Mountain, 13 plots with an interval of 100 m in elevation were investigated to study the variations of population structure and important value of the main edificators along the elevation gradient. In their core distribution areas, most of the edificators had healthy population structure and could regenerate smoothly except Larix olgensis, but important value of Larix olgensis had no obvious variations with elevation changes, which showed that Larix olgensis had its own particularity and strong adaptability. At high elevation above 1800 m, Betula ermanfi was the only species that could form a mono-dominant community. Important values of Pinus koraiensis and Acer mono had similar changing trends, and they had the similar ecological adaptabilities.     

城乡梯度森林土壤原易位N矿化

以位于南昌市城乡生态界面的湿地松(Pinus elliottii)人工林为研究对象,开展城区、郊区、乡村3个不同梯度土壤N原位、易位培养试验.结果表明:培养土壤来源对土壤的氨化、硝化速率影响差异极显著(P＜0.001),对净矿化速率影响差异显著(P＜0.05);氨化速率表现为乡村土壤来源(0.11 mg·kg-1·30 d-1)＞郊区土壤来源(-0.92mg·kg-1·30d-1)＞城区土壤来源(-2.02 mg·kg-1·30 d-1);硝化速率表现为乡村土壤来源(0.44 mg·kg-1·30 d-1)较低,城区(3.18 mg·kg-1·30 d-1)和郊区土壤来源(3.35 mg·kg-1·30 d-1)较高;净矿化速率表现为乡村土壤来源(0.54 mg·kg-1·30 d-1)＜城区土壤来源(1.16 mg·kg-1·30 d-1)＜郊区土壤来源(2.43 mg·kg-1·30 d-1).培养位置对氨化速率影响差异不显著(P＞0.05),对硝化速率、净矿化速率影响差异极显著(P＜0.001);硝化速率和净矿化速率均表现为乡村(0.68 mg·kg-1·30 d-1和-0.29 kg·kg-1·30 d-1)和郊区(1.78 mg·kg-1·30 d-1和1.06 mg·kg-1-30 d-1)较低,城区(4.51 mg·kg-1·30 d-1和3.36mg·kg-1·30 d-1)较高.总体来看,土壤N的矿化过程既与土壤理化特性有关,又明显受到城市化的影响.     

Soil desiccation for Loess soils on natural and regrown areas

In the Loess Plateau, soil desiccation has become a serious problem for forest and grass vegetation. Soil desiccation leads to the formation of a dried soil layer (DSL). This paper presents the results of research carried out in the central part of the Loess Plateau. The objective of the research was to produce a statistically supported set of indicators for evaluating soil desiccation of forestlands, to present a heuristic idea for soil desiccation and to supply scientific support for replacing farmland with forest or grass in the Loess Plateau and other regions of China. Here, we suggest that more attention should be paid to soil desiccation and its effects on the ecosystem of the region in the future. The results showed that natural Quercus liaotungensis forestlands (NQF) retained more water content than regrown Robinnia pseudoscacia forestlands (RRF). Significant DSLs were formed in the RRF but not in the NQF. A possible reason for no formation of DSL in NQF could be due to the presence of an arbor–shrub–herb stand structure and large humus and litter accumulation, which increased the natural forest's (NF) adaptability to the environmental conditions. Soil water content in the north-facing slope was significantly larger than in the south-facing slope. DSLs formed in the 0–500 cm layer of the south-facing slope. When slope gradient was greater than 25°, soil water content deceased sharply and showed significant difference compared with 9°, 15° and 20° (P < 0.05). So, we conclude that plant species, aspect and slope angle could be the predicators for the formation of DSLs. The analysis on soil physical properties of 0–60 cm layer indicated that plant species, aspect and slope angle also have significant effects on bulk density, porosity, plant-available capacity, and hydraulic conductivity, especially in the 0–20 and 20–40 cm layers. In the NQF and RRF with north-facing slope, soil physical properties were improved.     

北京东灵山山地景观格局梯度变化研究

山地景观结构特征决定着景观的功能和生态过程,山地景观结构特征的变化山地景观研究的重要课题。本文以北京东灵山地区为研究点,借助GIS构建了1984年、1994年、2002年3个时间段景观动态序列,结果表明:1)近18年来,东灵山地区景观总体结构呈现破碎化趋势;2)各景观类型受人类活动影响程度不同,农业耕作和采伐后,林地和草地转变为农田和灌丛;3)村庄和农田的斑块小型化为主,边缘复杂程度较高,灌丛、林地和草地仍以大型斑块为主,边缘复杂程度较低。     

秦岭南坡不同海拔土壤肥力的空间分异规律

对秦岭南坡土壤肥力状况、空间分异规律及其与海拔的关系进行研究.结果表明,秦岭南坡土壤肥力指标在整个土壤剖面空间分异范围分别为:土壤pH值5.97～6.89,有机质含量6.6～50.1 g·kg-1,土壤全N含量0.5～3.8 g·kg-1,碱解N含量33.6～257.3 mg·kg-1,速效P含量0.81～5.8 mg·kg-1,速效K含量38.9～262.4 mg·kg-1,粘粒含量11.3%～18.1%,阳离子代换量68.5～310.2 mmol·kg-1;其空间分异程度以速效P、有机质和土壤全N含量较大,土壤粘粒含量和土壤pH值较小;随着土层的加深,土壤pH值、有机质、速效P、土壤粘粒含量和阳离子代换量空间分异程度减小,而土壤全N、碱解N和速效K含量空间分异程度增大.土壤速效K、速效P含量和阳离子代换量水平空间分异程度受海拔的影响较大,而土壤pH值和粘粒含量水平空间分异程度受海拔影响较小.随着海拔的升高,土壤pH值降低,有机质和速效P、K含量增大,土壤肥力空间分异程度减小,这可能与随着海拔升高人为干扰强度降低及林分类型趋向单一有关.