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1.
磴口绿洲防护林不同配置模式防风效应的试验 总被引：3，自引：1，他引：2
通过对磴口绿洲防护林冬季相不同配置模式的7个典型林网进行防风效应和经济效益测算,得出：乔木防护林防风效能和气流均一性优于小乔木和灌木：在结构良好的乔木林网中,蓄积存量达到30m^3．hm^2即可保证林网具有可靠防风效益;在防风效能、蓄积生产率以及经济投入方面,窄带密集渠道林明显优于占地面积较大的宽带防护林。 相似文献
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采用现地调查,结合北疆二类资源清查资料和卫星影像资料,对准噶尔盆地南缘特定区域的农田防护林主林带方向、主副林带间距、林带宽度、行数、树种、林网完整性、林带状况等进行调查测定,分析研究其经营现状及存在的问题,为准噶尔盆地南缘绿洲生态环境建设提供相应的数据基础和决策依据。准噶尔盆地南缘农田防护林存在林网网格过大、林带间距过宽、树种单一、已出现严重退化等问题。建议通过规范林网大小、保证林地灌溉、加强抚育管理、营造混交林、补植林带等措施来加强准噶尔盆地南缘农田防护林林网建设。 相似文献
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东北平原农田防护林规格的研究 总被引：2，自引：0，他引：2
东北平原农田防护林已经形成了比较完整的林网体系。本研究分析了农田防护林网全方位的防风作用、防霜作用以及林网内的综合气候效益场。在林网内,全方位防风效能大于10%的区域为防护效益区。作物产量和质量分析表明,林网的防护范围为25倍树高。根据高生长分析确定了构成农田防护林主要杨树品种的成林高度。根据综合分析确定适宜农田防护林网的规格为400m×400m。图7表3参11。 相似文献
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近四十年来，新疆绿洲林业主要担负生态防护功能。林业部门的主要工作放在大规模造林、营造防护林体系方面。从目前的发展水平看，四个地州、54个县市、115个农垦团场基本上实现了林网化，林网防护面积4000万亩，占规划实现林网化林地面积的85％。防护林面积占整个林种面积的73．9％。这一时期的绿洲林业可概括为：发展战略放在发挥其生态防护功能方面，林业等同于造林；经营目标上以数量性指标为主（如造林成活率、保存率、新增面积等），具有浓厚的产品经济特点；发展模式上以大规模造林方式为主，对绿洲社会经济系统考虑过少，林种、树种… 相似文献
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1 .4 沙区农田防护林建设模式1.4 .1 模式概述 在荒漠、半荒漠绿洲以及半干旱区沙地农田通过营造防护林网 ,防沙治沙 ,保障农业生产的模式。1.4 .2 模式适宜条件 绿洲及沙地农田。这里因干旱多风 ,易风蚀沙化 ,即使有灌溉条件也难以高产 ,须营造农田林网 ,制止风蚀 ,改善环境 ,保障作物正常生长。1.4 .3 技术思路 绿洲及沙区的农田林网有特殊要求 ,为取得良好的防护效果 ,要注意不同沙区农田林网的结构、宽度、有效防护距离、树种选择及合理配置。1.4 .4 主要技术措施 ( 1)林网形式 为有效防治风沙 ,一般采用窄林带小网格的林… 相似文献
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张掖灌区是河西走廊主要的灌溉农业区,从七十年代初期开始,结合农田基本建设,以渠、路为骨架,营造“窄林带,小网格”的农田防护林,基本实现了农田林网化。为了鉴定现有林网对农田的防护性能,探讨林网内小气候形成的农田生态环境与农作物生长发育的关系,为干旱荒漠绿洲灌溉农业区营造农田防护林,建立新的农田生态结构和经济结构提供理论依据,我们于1981——1984年,先后在张掖县境内的九公里试验场、五金站农场,对农田林网的气候效应进行了观测,现将结果报导如下。 相似文献
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本文论述了三北地区6种较典型的草牧场防护林的结构、效益及在草原发展中的意义,强调营造林带、林网、大片林、疏林、绿伞、生物圈、生物墙合为一体的、能在区域范围内自成防护体系的多功能结构的草牧场防护林。 相似文献
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对三北地区农田防护林体系建设的思考 总被引：3，自引：2，他引：1
一自１９７８年国家批准三北防护林工程建设以来,农田防护林始终被置于重点优先发展的地位。２０年来,三北地区共营造农田防护林２４０万ｈｍ２,保护农田２１５３万ｈｍ２,林网化比率达６５％。松辽平原、华北平原、关中平原、黄河河套、河西走廊、新疆绿洲等地基本实... 相似文献
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本文旨在对内蒙古西部乌兰布和沙区周边绿洲农区防护林体系的气候生态效益进行评价,并分析三北防护林工程建设之前,三北防护林工程一期工程和二期工程3个时期的变化趋势,建立防护林体系变化与气候变化的关系模型。研究结果表明：（1）防护林体系的变化对气候因子风速,大风日数,扬沙日数,沙尘暴日数有一定的影响,体现了防护林体系的生态屏蔽作用;（2）防护林体系的变化对年平均温度,湿度,降水量,持续干旱日数和霜期等因子影响不明显,这是因为这些因子的变化主要受大气环流控制所致。 相似文献
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通过凹底镇晚霜对小麦大面积霜冻危害的调查，揭示了农田中设置林带对减轻霜冻的作用，在窄林带树高7倍、宽林带树高15倍范围内，可使小麦少减产27.34%和57.82%。调查结果还表明，防霜效果与林带的走向、迎霜和背霜面、树冠层大小等有关。 相似文献
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杨树的冻裂与预防的初步探讨 总被引：1，自引：0，他引：1
杨树人工林冻裂率为60%以上。冻裂的相关因子为品种、密度、郁闭度、林龄、坡向、植被、抚育一次比抚育三次杨树冻裂少,生长量无大差异。试验证明:对杨树进行涂白、包草和抚育一遍、树干周围留草可以预防杨树冻裂。 相似文献
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Angelo Nolè Angelo Rita Agostino Maria Silvio Ferrara Marco Borghetti 《Annals of Forest Science》2018,75(3):83
Key message
A remote sensing-based approach was implemented to detect the effect of a late spring frost on beech forests in the Mediterranean mountain region. The analysis of spatio-temporal variability of frost effects on normalised difference vegetation index (NDVI) highlighted the distribution of the canopy damage across the forest according to geomorphic factors such as slope, aspect, and altitude.Context
Increased intensity and frequency of extreme temperatures such as late spring frosts and heat waves represent the main drivers affecting forest ecosystem structure and composition in the Mediterranean region.Aims
The main objective of this study was to evaluate the effects of a late spring frost disturbance, which occurred during spring 2016 in southern Italy, through the assessment of the spatial pattern of the damage to the beech forest canopy associated with the peak decrease in normalised difference vegetation index (NDVI), and the analysis of the NDVI temporal recovery after this frost disturbance.Methods
The forest areas affected by frost were detected through the NDVI differencing technique based on Landsat 8 (OLI/TIRS) imagery time series. The influence of local geomorphic factors (i.e., aspect, elevation, and slope) on forest NDVI patterns was assessed by means of a generalized additive model (GAM).Results
A rather counterintuitive NDVI patterns emerged according to the forest exposition, with NDVI significantly higher on the north facing areas than the southerly ones. The main canopy damage occurred at about 1250 m and reached up to 1500 m asl, representing the altitudinal range affected by the frost disturbance. Finally, the full canopy recovery occurred within 3 months of the frost event.Conclusion
The analysis of seasonal Landsat 8 image time series related to local geomorphic factors, such as aspect, slope, and altitude, and plant phenology on a frost event date, contributed to highlight the NDVI spatio-temporal variation and canopy recovery of a Mediterranean mountain beech forest.16.
经济林冻害调查及其防冻措施 总被引：2，自引：0，他引：2
对江西1991年冬季经济林冻害情况进行了调查,比较了各树种、品种的抗冻能力,并分析了地形地势、经营管理水平等因素对冻害的影响,依此指出了防冻措施。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):104-110
The effect of a single night frost during late spring on the current year production of two clones of Salix viminalis was determined in two monoclonal stands that displayed a gradient from virtually undamaged plants, shielded from outgoing radiation by a neighbouring spruce forest, to heavily damaged plants in the unshielded parts. Compared with the undamaged stand parts, frost caused production losses of 47% and 60% in the two clones during the first year of the second cutting cycle. The clone‐specific allometric relationship between shoot dry weight and diameter was changed by the frost in one clone, showing lower shoot weights in damaged shoots compared with undamaged shoots of the same diameter. In the other clone, allometric relations were not affected by the frost. The relative variation in weight between the stools did not differ systematically with frost damage intensity, and therefore it could not be concluded that frost in monoclonal stands would enforce a competitive hierarchy. It was inferred that the single night frost indirectly can have a negative effect on the production of the stands during the years to come. 相似文献
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中国喀斯特高原山地区抗冻耐旱型植被退化现状及恢复对策 总被引：3，自引：1，他引：2
文中提出抗冻耐旱型植被退化特征为次生林比例大、林分结构缺失及缺陷、种间竞争激烈且优势树种功能未充分发挥、树种选育缺乏适应性评价,恢复策略包括恢复生态经济型植被、调整林分树种组成与密度、修复水平与垂直层次的结构缺陷、合理划分功能区以实行分区保护和改变农村能源结构。喀斯特高原山地区抗冻耐旱型植被恢复的基础研究工作尚处于起步阶段。为提高抗冻耐旱型植被的适应与恢复能力,未来需要加强植被适应性修复、树种选择与配置以及水肥管理与土壤培肥改良3个科学问题与关键技术的研究。 相似文献
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文章通过对广东省雨雪冰冻灾害受灾现状调查统计,对受灾林木和林分划分轻、中、重度受灾等级,提出生态公益林、商品林的清理和造林技术要点,选择全面造林、补植套种、封育管护等森林修复技术和修复方式进行森林生态修复,重现广东省生物多样性丰富、抗逆能力强的地带性森林植被。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):523-529
Decline in pH and leakage of base cations have been recorded in beech forest soils in southern Sweden. This study investigated the influence of soil properties on frost sensitivity in beech bark and evaluated the effects on frost sensitivity of soil treatment with lime, wood ash or excessive N fertilization. Beech trees on five experimental sites were studied. The results indicated that beech trees subjected to a comparatively low C/N ratio and low concentration of nutrient elements in the mineral soil layer were predisposed to a higher sensitivity to frost. Seven years after treatment, no effects of N fertilization were detectable in the soil, but positive effects of liming were recorded. There were no obvious effects of bark ash amendments, owing to large differences among blocks at the site. 相似文献