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101.
102.
小报春Primulaforbesii是一种观赏价值高,生态适应性强,具有园林应用潜力的野生花卉.在将其引种后应用于园林的过程中,特别对其引种后在不同光照条件下的生长情况及光合特性进行了研究分析.结果表明:1)在大气CO2浓度下,光强是影响小报春光合作用的关键因子;2)小报春的光补偿点在26.18~43.10μmol·m-2s-1之间,饱和点低于1400μmol·m-2s-1;3)小报春植株有一定的耐荫性,不适合在强阳光直射的地方生长,种植应用时应给予一定的侧方遮荫. 相似文献
103.
以湖南省会同县一块常绿阔叶林为对象,对其林地土壤水分的物理特征、枯枝落叶层的持水特征、土壤水分的下渗特征、降雨雨滴的大小分布及降雨动能特征等进行了测定分析,结果表明,常绿阔叶林生态系统对减少雨水对土壤的侵蚀、涵养水源具有重要的作用. 相似文献
104.
105.
In this study we determined soil moisture storage, evapotranspiration (ET) and light interception in an agroforestry trial consisting of pine trees grown over (1) control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) lucerne (Medicago sativa), and (4) ryegrass only during the third growing season between 1992 and 1993. The results show that:
相似文献
1. | In the period when rainfall was frequent and exceeded the evaporative demand (Epot), ET and depletion of soil moisture were not affected by the ground cover treatments. During summer when rainfall was less frequent, but with moisture readily available in the soil profile, ET was associated with plant canopy, and was significantly higher for the pasture ground covers than for the control. Therefore, the more rapid growth by lucerne caused higher ET in this ground cover than in the ryegrass/clovers ground cover in which the pasture was slow growing. At the end of the study period, total ET was in the following order: lucerne (757 mm) > ryegrass/clovers (729 mm) > Control (618 mm). |
2. | ET was dominated by pasture transpiration (Ep) during most of the growing season, but by tree transpiration (Et) in winter when large parts of the pasture canopy was shaded. Ep was always at least 16% higher for lucerne than for ryegrass/clovers species as a result of a greater radiation intercepted by the former. |
3. | Fraction of incoming radiation intercepted by the tree crowns was in the following order: control > ryegrass > ryegrass/clovers > lucerne. At the end of the one-year period, fraction of intercepted radiation was 140% greater for control than for lucerne ground cover. |
4. | The control produced the largest tree crowns, which were almost twice the tree crowns in the lucerne ground cover which produced the smallest trees. Accordingly, the trees in the control intercepted more radiation and rainfall, with the former being lost to evaporation, than the trees in the pasture. |
5. | The fractions of radiation intercepted and ET accounted for by the trees and pastures were associated with the proportion of the plot area they occupied. |
106.
银木(Cinnamomum septentrionale Hand.Mazz.)系樟科樟属的常绿乔木,主要分布在年平均气温14℃,降水量800 mm以上的四川、陕西南部、甘肃南部、湖南等地区,是自然分布最北面的樟科植物.该树种系典型的北亚热带树种,对水、热条件的要求低于其它樟科植物,既能耐-10℃的低温,又能耐干旱[1].银木树皮灰色、光滑,叶近革质,互生,椭圆状、倒圆状披针形,具有较好的观赏性和较高的开发价值,在湖南、四川等地已人工栽培多年,形成特色鲜明的城市行道树. 相似文献
107.
牡丹峰国家森林公园开发强度控制策略 总被引:2,自引:3,他引:2
通过构建景观敏感度和景观阀值评价体系,对牡丹峰国家森林公园各景区的景观敏感度和景观阀值进行评价;根据评价得到的各个景区的敏感度和阀值级别,分别制定了各个景区相应的开发利用策略。 相似文献
108.
杨树林带抚育间伐技术 总被引:1,自引:0,他引:1
通过对I-69杨和NL-80203树冠生长特性的分析,对同龄杨树林带抚育间伐技术进行了探讨。研究结果表明,杨树林带间伐起始期可以林带平均高度为依据。对Ⅰ地位级的林带,当初植密度较大(3 m×4 m)时,可在林带高度达到15 m左右时进行一次性间伐,间伐强度约70%左右;也可在15 m时进行第1次间伐,间伐强度在30%~40%之间,在25 m左右时进行第2次间伐,强度在40%~50%之间。对初植密度较小(5 m×6 m)的I地位级的林带,可在林带平均高度达20 m时一次性间伐,强度在50%以下,对Ⅱ、Ⅲ地位级的林带,可在林带平均高度为16~20 m左右时进行一次性间伐,间伐后保留木株行距乘积30 m2左右。 相似文献
109.
Most of Pinus brutia (Ten.) Holmboe forests are grazed, as silvopastoralism is well adapted in the Mediterranean environment. However, little
attention has been paid to the demographic dynamic of the understorey vegetation even though it is strongly affected by the
absorbed radiation. The purpose of this study was to examine the adaptation of herbaceous plant species under a Pinus brutia canopy, in Northern Greece. Monocultures of four plant groups (annual and perennial grasses, annual and perennial legumes)
were sown in experimental areas of 50%, 70% and 100% light intensity. The density of annual and perennial grasses and perennial
legumes were decreased by the shade cast by the Pinus brutia canopy. Population density of the annual legumes was little affected by light intensity: the annual grasses Bromus mollis L. and Lolium rigidum Gaudin; the perennial grasses Dactylis glomerata L. var. palestine, Festuca arundinacea and Agropyron cristatum (L.) Gaertn; the perennial legume Medicago sativa L. var. romana; the annual legumes Medicago lupulina L. and all the tested varieties of Trifolium subterraneum adapted well to the 50% light intensity habitat. 相似文献
110.
lNTRoDUCTIONTheon-sitcnon-dcstructit'cmcasurcl11cntofu.oodmoisbocontcntattTactsgrcatintcrcsts.Itpla3'simpor-tantpartsinthescicntificrcscarchsucl1asonthchcatandmasstransportproccssesint"ooddri'ing.thcim-pregnationofliquidinxt'ood.thcmoisturccontcntdistri-b… 相似文献