共查询到20条相似文献，搜索用时 108 毫秒
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我国国土辽阔,地跨寒、温、热3带,树木种类繁多,分布区域又广,并且这几年气候反常严重,各种园林树木常常受到不同程度的冻害.针对北方地区冬季至早春树木极易遭受冻害,轻则部分枝条受害枯干,重则全株死亡的现象,介绍了树木发生冻害的部位和原理,并就此提出了北方地区绿化树木冬季越冬防寒的主要技术措施,为防治冬季树木冻害、保证树木的健康生长提供借鉴. 相似文献
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一、森林现状
甘肃省地处我国西北内陆,省域呈东南至西北倾斜的狭长带状分布,地跨青藏、黄土、内蒙古三大高原,地形地貌以山地和高原为主,丘陵、平川、河谷、沙漠、戈壁等地貌兼而有之.甘肃是全国唯一兼有东部季风、西北干旱和青藏高原高寒气候的省份,具有亚热带湿润、暖温带湿润、温带半湿润、温带半干旱、温带干旱、暖温带干旱、高寒半干旱和高寒湿润等多个气候类型. 相似文献
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根据树木的特性及外界因素,探讨了树木在不同的生长期、不同的气候、不同的土壤等条件下对水的需求,为园林工作中适时、适量地给树木补充水分以保证树木的正常生长提供了参考. 相似文献
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Xylem conductivity and vulnerability to cavitation of ponderosa pine growing in contrasting climates
We examined the effects of increased transpiration demand on xylem hydraulic conductivity and vulnerability to cavitation of mature ponderosa pine (Pinus ponderosa Laws.) by comparing trees growing in contrasting climates. Previous studies determined that trees growing in warm and dry sites (desert) had half the leaf/sapwood area ratio (A(L)/A(S)) and more than twice the transpiration rate of trees growing in cool and moist sites (montane). We predicted that high transpiration rates would be associated with increased specific hydraulic conductivity (K(S)) and increased resistance to xylem cavitation. Desert trees had 19% higher K(S) than montane trees, primarily because of larger tracheid lumen diameters. Predawn water potential and water potential differences between the soil and the shoot were similar for desert and montane trees, suggesting that differences in tracheid anatomy, and therefore K(S), were caused primarily by temperature and evaporative demand, rather than soil drought. Vulnerability to xylem cavitation did not differ between desert and montane populations. A 50% loss in hydraulic conductivity occurred at water potentials between -2.61 and -2.65 MPa, and vulnerability to xylem cavitation did not vary with stem size. Minimum xylem tensions of desert and montane trees did not drop below -2.05 MPa. Foliage turgor loss point did not differ between climate groups and corresponded to mean minimum xylem tensions in the field. In addition to low A(L)/A(S), high K(S) in desert trees may provide a way to increase tree hydraulic conductivity in response to high evaporative demand and prevent xylem tensions from reaching values that cause catastrophic cavitation. In ponderosa pine, the flexible responses of A(L)/A(S) and K(S) to climate may preclude the existence of significant intraspecific variation in the vulnerability of xylem to cavitation. 相似文献
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植被类型变化对民勤地区土壤肥力的影响 总被引：3，自引：0，他引：3
民勤是受干旱,风沙威胁最为严重的地区之一,综合治沙是改变该区环境的重要手段之一,其中植物固沙是综合治沙的关键。文中就几种沙生植物群落对土壤肥力影响的研究结果表明：不同植被类型对土壤肥力的影响不同,Ｎ、Ｐ、Ｋ的转化速度也不同。 相似文献
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白蜡树属树种的园林应用探讨 总被引：2，自引：0，他引：2
目前对城市环境的要求越来越高,而提高环境质量的诸因素中,搞好园林绿化是最直接最有效的措施。构成园林绿化的主要材料是园林植物,其主体是树木。作为1个城市,当然是园林树木品种越多,越能构成丰富多彩的园林空间。但是由于地域、气候、科技、经济与自然因素和人为因素的制约,园林树木品种的利用也受到了限制。园林树种的选择不仅要适合本土生长,还要形成地方特色和风格。 相似文献
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民勤沙区降水及干旱特征分析 总被引：4，自引：0，他引：4
民勤干旱沙区降水稀少，３４年年平均降水量为１１３．２ｍｍ，且季节分布不均，年际变化大，平均降水变率为２４．５％，降水年变化规律呈正态分布。降水性质多以日降水量≤１０．０ｍｍ的小雨为主。持续干旱日数长，发生频率高，属典型干旱荒漠气候。 相似文献
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东北地区园林设计中秋季观赏树木的选用 总被引：2，自引：0，他引：2
由于地理位置及气候因素,造就了我国东北地区秋季园林景观的特殊性.本文介绍了我国东北地区秋季园林设计中树木选择的前提,原则,树种及建议等.为东北地区秋季园林设计过程中选用树木提供参考. 相似文献
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为了寻找促进干旱半干旱沙区抗旱造林的新途径,文章在野外自然条件下,对新型抗旱造林产品-"春之霖"固体水进行了应用研究。结果表明,虽然固体水处理后不同苗木不同土层土壤含水量变化不同,但缓慢释放的固体水主要集中在植物根系附近,提高根系层含水量,明显改善苗木的水分状况,减轻水分胁迫。使用固体水的供试苗木成活率均在90%以上,其中沙柳和杨树的成活率分别比对照高于12.5%和14.2%。经固体水处理后的苗木净高生长量、地上生物量、地下生物量均高于对照,固体水附近苗木侧根分布量最多。 相似文献
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湖南长沙、株洲、湘潭三市园林绿化植物区系分析 总被引：4，自引：1，他引：4
通过调查湖南长沙、株洲、湘潭城市群园林绿化植物,结果表明:3个城市共有种子植物86科,183属,266种,占湖南种数的5 5%。3个城市绿化植物分布有5个种以上的科18科,143种,占3个市种数的53 7%。3个市植物区系具有热带性亲缘、温带性成分较多的特征,这些与湖南植物区系特征相似。在3个市绿化植物种数中,国外种占1/4多,这些种将面临3个市周期性的特殊气候;经受突然冰冻和夏秋的高温干旱的考验,3个市园林绿化植物的发展方向应以中亚热带植物为主。 相似文献
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随着城市化的不断推进以及全球气候变化的加剧,高温、干旱等极端气候频发,对城市园林绿化造成重大影响。城市道路绿化作为城市绿地一种典型的带状绿地,其对高温干旱气候的响应机制尚不明确。以2022年南昌市所遭受的极端高温干旱气候为契机,对南昌市经开区十五条主次干道绿化树种进行受害特征调查分析,结果表明：(1)受高温旱害影响的植株分布呈现出一定的空间聚集性和规律性,南北向道路植物受灾较为严重,东西向道路植物受灾情况相对较轻;(2)随着树下铺装面积的增加,乔木、灌木受损情况呈上升趋势;随着铺装透水率的增加,乔木、灌木受损情况呈下降趋势;(3)乔木个体越大、长势越好,其抗干旱能力越强;(4)对耐旱性较差、小胸径及低矮的树种及时养护。适当增加南北朝向道路的人工浇灌及管护频次。选择透水性较好的铺装,并适当减少树下铺装的面积,以此来缓解高温干旱对城市道路绿化的影响。 相似文献
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G. Moser C. Leuschner D. Hertel D. Hölscher M. Köhler D. Leitner B. Michalzik E. Prihastanti S. Tjitrosemito L. Schwendenmann 《Agroforestry Systems》2010,79(2):171-187
In South-east Asia, ENSO-related droughts represent irregularly occurring hazards for agroforestry systems containing cocoa
which are predicted to increase in severity with expected climate warming. To characterize the drought response of mature
cocoa trees, we conducted the Sulawesi Throughfall Displacement Experiment in a shaded (Gliricidia sepium) cocoa agroforestry system in Central Sulawesi, Indonesia. Three large sub-canopy roofs were installed to reduce throughfall
by about 80% over a 13-month period to test the hypotheses that (i) cocoa trees are sensitive to drought due to their shallow
fine root system, and (ii) bean yield is more sensitive to drought than leaf or stem growth. As 83% of fine root (diameter
<2 mm) and 86% of coarse root biomass (>2 mm) was located in the upper 40 cm of the soil, the cocoa trees examined had a very
shallow root system. Cocoa and Gliricidia differed in their vertical rooting patterns, thereby reducing competition for water. Despite being exposed for several months
to soil water contents close to the conventional wilting point, cocoa trees showed no significant decreases in leaf biomass,
stem and branch wood production or fine root biomass. Possible causes are active osmotic adjustment in roots, mitigation of
drought stress by shading from Gliricidia or other factors. By contrast, production of cocoa beans was significantly reduced in the roof plots, supporting reports
of substantial reductions in bean yields during ENSO-related drought events in the region. We conclude that cocoa possesses
traits related to drought tolerance which enable it to maintain biomass production during extended dry periods, whereas bean
yield appears to be particularly drought sensitive. 相似文献