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71.
容器育苗质量问题及其对策(综述) 总被引:10,自引:0,他引:10
综述了国内外先进容器育苗技术,提出了容器苗的质量问题及其改良措施。 相似文献
72.
不同颜色地板的视觉特性研究 总被引:7,自引:1,他引:7
视觉物理量上,不同地板的色度学参数之间存在着较大差别.在L*a*b*色空间中,各种地板的L*值为35~70;红绿轴色品指数a*值为5~25;黄蓝轴色品指数b*值为20~35;色饱和度c*值的分布范围同黄蓝轴色品指数b*较为相似,为20~40;各种地板色调角Ag*的大小为0.9~1.4.在孟塞尔色空间,各种地板的明度V值为2.0~6.0,V值的大小顺序同L*值一致.各种地板色调H值为16~25,分布在Y和GY区间.色饱和度C值为6~18.采用实验心理学中的等级排列法制作顺序量表,再通过PZ转换,将原始测验分数转换成标准分数的方法,得到了各种地板视觉心理量等距量表.不同地板的视觉喜欢程度和视觉高档程度上均具有较大差别.视觉喜欢程度和视觉高档程度上的排序不完全一致,但基本相似.视觉心理量高档、喜欢与视觉物理量中红绿轴色品指数a*之间呈正相关,与明度以及色调之间成负相关,其中与明度值的相关程度相对较高.说明在人们心理上一般认为,明度越低,色调越红的地板越好. 相似文献
73.
74.
以华北落叶松( Larix principis-rupprechtii)播种容器苗为研究对象,采用完全随机设计,试验设置6个处理,通过比较苗木形态指标及苗木根系形态结构的差异,研究了添加不同比例的蘑菇渣堆肥对华北落叶松苗木生长的影响。结果表明:基质的密度、pH值、EC值随着蘑菇渣堆肥比例的增加呈现逐渐增大的趋势,总孔隙度、持水孔隙度与对照无显著差异;苗木苗高、地径、生物量及苗木总根长、总根表面积、总根体积随着蘑菇渣堆肥比例增加呈现逐渐减小的趋势;基质中蘑菇渣堆肥比例在0~20%范围内时,苗木形态指标及苗木根系形态结构均与对照无显著差异,基质中蘑菇渣堆肥比例大于30%时,苗木形态指标及苗木根系形态结构与对照出现显著差异,苗木生长受到不利影响。 相似文献
75.
76.
In order to determine the effect of stocktype and cultivation treatment on the field performance (survival and growth) and
physiological status of Picea abies in cutaway peatlands, small bare-root, large bare-root and containerised seedlings were planted in a deep ploughed and a
control site. Survival after 2 years was good across all treatment (>90%) except for the large bare-root seedlings growing
in the control site (84%). For all the morphological characteristics assessed in this study, there was no significant interaction
between stocktype and cultivation treatment indicating that the growth response to site cultivation was not stocktype dependent.
After two growing seasons, all Norway spruce seedlings performed better in the deep ploughed site and displayed also better
nutritional and physiological status. Regardless of cultivation treatment, mean height, diameter and volume increment were
significantly smaller for the large bare-root seedlings while the small bare-root seedlings displayed the greatest growth
rates. In order to promote early height growth in container and small bare-root stock, large diameter is important. Other
initial characteristics such as foliar nitrogen content may also have a strong influence on first year field performance.
The physiological status of the seedlings during the first year after outplanting was assessed using chlorophyll fluorescence
(CF) measurements. CF measurements detected a higher level of stress for the large-bare root stock (low Fv/Fm). On the other
hand, small bare-root stock displayed highest maximum potential photochemical activity which corresponded to greatest growth
rates. Container seedlings demonstrated higher capacity for photosynthetic electron transport during the first five months
after planting suggesting that they recovered from planting stress quicker and optimised better light interception and utilization
than bare-root stock. It can be concluded that intensive management systems including deployment of best-adapted stocktype
and site cultivation can be used to enhance early height growth of Norway spruce on cutaway peatlands. 相似文献
77.
Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories 总被引:6,自引:0,他引:6
Catharina J.E. Schulp Gert-Jan Nabuurs Peter H. Verburg Rein W. de Waal 《Forest Ecology and Management》2008,256(3):482
Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha−1 (beech) and 29.6 Mg C ha−1 (larch). SOC stocks varied between 53.3 Mg C ha−1 (beech) and 97.1 Mg C ha−1 (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory. 相似文献
78.
Forest amphibians, especially salamanders, prefer forests with shaded, cool, and moist forest floors. Timber harvesting opens the forest canopy and exposes the forest floor to direct sunlight, which can increase forest floor temperatures and reduce soil moisture. These microclimatic changes can potentially degrade the harvested stand for amphibian habitat or affect other biotic resources or ecological processes at the forest floor and in the understory. The degree of forest floor disturbance is directly related to the intensity of harvesting, however, the duration of this effect is unknown. We conducted a study of forest floor temperature and relative humidity over a 12-year chronosequence (1993–2004) of timber harvests. We compared simultaneous, paired measurements of temperature and relative humidity at three positions (soil, forest floor, air) in harvested and control sites over three seasonal survey sessions. Vegetation composition and structure were measured at each survey location. Ambient weather conditions were recorded at three open-field locations across the study area. 相似文献
79.
钢筋混凝土预制板是构成砖混结构房屋的重要构件,但是,其本身由于在构造上存在着一些致命的缺陷,即整体性及抗震性差,因此,在近几年的住宅建设中已逐步被钢筋混凝土现浇板所替代,但是,随着钢筋混凝土现浇板在房屋建设中的大量推广与应用,“住宅楼现浇楼板裂缝问题”也成为了居民住宅质量投拆热点。 相似文献
80.
时连根 《浙江大学学报(农业与生命科学版)》2000,26(5):551-554
研究了甲醛制剂(福尔马林液)和含氯制剂(漂白粉液)对蚕粪、地表层土、蚕体、蛹体、蛾体内微孢子虫(Nosema bombycis)孢子的消毒效果。结果表明福尔马林液的消毒效果明显优于漂白粉液的消毒效果。但是在养蚕生产常规消毒条件下,两种消毒药剂对蚕体、蛹体、蛾体、深处土层、蚕粪(除福尔马林液外)中微孢子虫孢子均没有彻底的消毒效果。 相似文献