树木水力结构特征季节变化规律研究

在北京林业大学校园内选取侧柏、刺槐等11个针阔叶树种为研究对象,测定1a生枝条小枝水势及水力结构参数季节变化。研究表明：小枝水势及水力结构参数均具有季节变化规律。导水率与比导率季节变化规律基本相似,从树种材性上看均表现为：环孔材树种〉散孔材树种〉无孔材树种,而木质部栓塞化程度也表现为：环孑L材树种〉散孔材树种〉无孔材树种。枝条水势、导水率和比导率季节变化节律均与树木生长发育节律相一致,都表现出枝条木质化时期〉嫩枝生长期〉早春,而木质部空穴和栓塞化程度也存在着季节变化节律,且与比导率季节变化节律相反,即：早春〉嫩枝生长期〉枝条木质化时期。     

金沙江干热河谷主要植被恢复树种叶水势的时空变化规律

2005年和2006年在金沙江干热河谷,选择不同季节的典型晴天测定了18个试验树种的叶水势,结果表明:(1)金沙江干热河谷主要植被恢复树种叶水势在不同季节的日变化曲线均有一个明显的高峰,绝大多数呈单峰状分布,高峰值大多数出现在下午14:00;干热生境中的树种具有丰富的叶水势多样性.(2)元谋干热河谷主要树种的叶水势受季节变化的影响较大,所有树种均表现为3月份叶水势大于5月份叶水势以及5月份叶水势小于10月份水势,5月干热胁迫的加深加剧了树种间水势的进一步分化,而雨季后干热胁迫的解除能降低分化的程度;各树种叶水势日变化在干热的5月份变动幅度最小.(3)各树种叶水势与温度、湿度及光照强度分别呈负、正、负相关,相关性可由线性方程予以恰当描述.(4)不同海拔区域所引起的环境因子与物候的差异能影响到某些树种水势的日变化幅度以及季节变化规律;以坡位而言,相对低的坡位有利于各树种叶水势维持在一个相对高的水平;印楝在3种混交模式中叶水势高低依次为:印楝与大叶相思＞印楝与银合欢＞印楝与久树,这种排序与印楝所受到的竞争强烈程度紧密相关,极度的干热环境降低了不同混交模式对植物水势的影响程度;灌溉有利于缓解或解除5月极度干热所形成的水分胁迫.     

A Discussion on Drought Tolerance Through Hydraulic Architecture of Woody Plants

In this paper, ten woody plants grew on the campus of the Beijing Forestry University were selected for measuring hydraulic architecture parameters and water potential of one-year-old twigs. The results show that day and night change of water potential and hydraulic architecture parameters appear to be obviously convex trend. The relationship models between water potential and hydraulic conductivity, special conductivity and leaf special conductivity were respectively established, which were simulated by equations Y=axb and Y=ax2 bx c, through which the parameters physiological meanings were discussed. The results show also show that embolism vulnerability of ten tree species was Robinia pseudoacacia> Gleditsia sinensis> Acer truncatum> Prunus davidiana> Cornus alba> Platycladus orientalis> Cedrus deodara> Pinus bungeana> Pinus tabulaeformis> Jasminum nudiflorum, and that the water transport efficiency in xylem and embolism vulnerability of the species are ring-porous species> diffuse-porous species>non     

太行山中南部造林树种适宜性评价研究

笔者对太行山中南部主要乔灌木树种的分布及适宜性进行了调查和统计分析。太行山中南部造林过程中不同海拔梯度阳坡、阴坡适宜的针叶树种、阔叶树种、灌木树种的生长适宜性呈现出:耐阴、耐寒、喜湿的树种分布在阴坡且垂直分布跨度大,多度值较高;耐旱、耐热、不耐涝的树种分布在阳坡且垂直分布跨度大,多度值较高的分布规律。并提出了1100 m,1 100 m~1 400 m,1 400 m~1 700 m,1 700 m 4个海拔梯度按阳坡、阴坡划分的8个立地类型适宜的乔灌木树种,为太行山中南部造林树种的选择提供参考依据。     

基于树木径向生长仪监测高寒地区树木生长和水分利用的研究进展

文中综述了树木径向生长仪监测数据的处理和分析方法,重点对基于树木径向生长仪监测高寒森林生态系统树木生长和水分利用的研究进行了总结归纳,指出目前在探索高纬度北方森林树轮宽度对夏季温度敏感性下降原因的过程中仍缺乏普遍的机制解释,而这一普遍机制可能与高寒地区树轮形成的年内季节动态特征有关。另外,尽管树木径向生长仪能够反映高寒地区的树木水分利用状况,但高寒地区树木水分利用对气候变化的响应仍不清楚。基于目前的研究现状,建议未来加强几个方面的研究,即考虑高寒地区树木径向生长的季节动态特征对树木生长与环境因子关系的潜在影响,加强与其他监测手段的比较研究,开展与生态系统水平观测指标的关联分析。     

昆明市城市绿化树种选择

昆明市因其优越的自然条件不仅有丰富的植物品种资源，而且引种外来花木的潜力也很大，然而在目前的城市绿化中还存在着树种单一、结构不合理、观赏类型单调、景观效果差、林荫道少、遮荫避日不够等问题。提出了绿化树种选择与配置的若干原则，并捷供了一批拟选择的乔木、灌木、竹类及攀援植物种类名单。     

喀斯特山地主要适生树种幼苗耗水量季节变化及对土壤干旱的响应

本文通过对柳杉等24个喀斯特山地主要适生树种一年生幼苗不同季节的耗水量进行比较研究、各树种幼苗在不同土壤干旱水平(A:无干旱胁迫;B:轻度胁迫;C:中度胁迫;D:重度胁迫)下的耗水量比较研究,结果表明:各树种幼苗耗水量的季节变化为:常绿树种幼苗耗水量为春季>夏季>秋季>冬季,落叶树种幼苗耗水量为夏季>春季>秋季>冬季。不同土壤干旱水平下,各树种幼苗耗水量均表现为:A>B>C>D。     

黄陵县乡土树种及其在城市绿化中的应用分析

通过对黄陵乡土树种的调查和整理,该县共有乡土树木474种,其中乔木175种,灌木289种,藤本10种;隶属于80科、196属。在此基础上,对其观赏价值和在城市城绿化应用中的作用进行了分析,指出开发利用乡土树木资源不仅可改善城市生态功能,而且是实现绿化地域特色性、创造黄陵独特景观文化的重要手段。     

濒危植物大花黄牡丹与生境地群落特征的关系

在濒危植物大花黄牡丹生境地群落学调查的基础上,划分生境地群落类型,分析生境地群落特征,探讨大花黄牡丹与生境地群落特征的相互关系。研究结果表明:TWINSPAN将大花黄牡丹生境地群落划分为乔木群落和灌木群落。乔木群落中大花黄牡丹多度显著低于灌木群落,但大花黄牡丹平均胸径和平均高则与灌木群落无显著差异。群落特征与大花黄牡丹的相关性分析表明:大花黄牡丹多度及平均胸径与群落总多度、灌木多度及乔木物种丰富度存在显著的相关性,而大花黄牡丹多度与乔木多度存在显著负相关,大花黄牡丹平均胸径与群落平均高也存在显著负相关,大花黄牡丹平均胸径及平均高与藤本物种丰富度则存在显著的正相关,具有相关性的变量之间可用不同的回归方程较好的表述。此外,大花黄牡丹冠幅面积、高度、丛数及幼苗数量均与灌丛的冠幅面积存在显著的正相关,但大花黄牡丹幼苗数量在两种群落间无显著性差异。     

伊春铁力林业局水胡黄天然次生林植物物种组成及多样性分析

对水胡黄天然次生林的植物物种组成及多样性进行分析的结果表明:两个地点所有物种的共有度为0.681;通过调查,标准地中共记录植物物种60种,分别隶属于39科、54属,其中乔木16种、灌木14种(藤本2种)、草本30种;茂林河林场木本植物的物种多样性明显高于建设营林所,其丰富度指数为30,Shannon-Weiner指数达到2.602,均匀度指数为0.914,优势度指数为0.116;而且两个地点的乔木层的多样性指数明显高于灌木层的多样性指数。     

白龙江干旱河谷常见灌木树种叶片持水性能

[目的]以白龙江干旱河谷20种常见灌木树种为材料,研究其叶片形态与持水之间的关系,更好地了解其叶片持水能力,为灌木树种在干旱河谷区的生态适应、优化群落结构提供科学依据,更好地发挥其水土保持、防风固沙的作用.[方法]通过简单的室内浸泡法对叶片持水状况进行测定,测定出每种树种叶片持水量的相关数据及叶片的形态特征,通过因子分...     

Comparative water use by the riparian trees Melaleuca argentea and Corymbia bella in the wet-dry tropics of northern Australia

We examined sources of water and daily and seasonal water use patterns in two riparian tree species occupying contrasting niches within riparian zones throughout the wet-dry tropics of northern Australia: Corymbia bella Hill and Johnson is found along the top of the levee banks and Melaleuca argentea W. Fitzg. is restricted to riversides. Patterns of tree water use (sap flow) and leaf water potential were examined in four trees of each species at three locations along the Daly River in the Northern Territory. Predawn leaf water potential was higher than -0.5 MPa throughout the dry season in both species, but was lower at the end of the dry season than at the beginning of the dry season. Contrary to expectations, predawn leaf water potential was lower in M. argentea trees along the river than in C. bella trees along the levees. In contrast, midday leaf water potential was lower in the C. bella trees than in M. argentea trees. There were no seasonal differences in tree water use in either species. Daily water use was lower in M. argentea trees than in C. bella trees. Whole-tree hydraulic conductance, estimated from the slope of the relationship between leaf water potential and sap flow, did not differ between species. Xylem deuterium concentrations indicated that M. argentea trees along the riverbank were principally reliant on river water or shallow groundwater, whereas C. bella trees along the levee were reliant solely on soil water reserves. This study demonstrated strong gradients of tree water use within tropical riparian communities, with implications for estimating riparian water use requirements and for the management of groundwater resources.     

Variation in water potential, hydraulic characteristics and water source use in montane Douglas-fir and lodgepole pine trees in southwestern Alberta and consequences for seasonal changes in photosynthetic capacity

Tree species response to climate change-induced shifts in the hydrological cycle depends on many physiological traits, particularly variation in water relations characteristics. We evaluated differences in shoot water potential, vulnerability of branches to reductions in hydraulic conductivity, and water source use between Pinus contorta Dougl. ex Loud. var. latifolia Engelm. (lodgepole pine) and Pseudotsuga menziesii (Mirb.) Franco (interior Douglas-fir), and determined the consequences for seasonal changes in photosynthetic capacity. The Douglas-fir site had soil with greater depth, finer texture and higher organic matter content than soil at the lodgepole pine site, all factors that increased the storage of soil moisture. While the measured xylem vulnerability curves were quite similar for the two species, Douglas-fir had lower average midday shoot water potentials than did lodgepole pine. This implied that lodgepole pine exhibited stronger stomatal control of transpiration than Douglas-fir, which helped to reduce the magnitude of the water potential gradient required to access water from drying soil. Stable hydrogen isotope measurements indicated that Douglas-fir increased the use of groundwater during mid-summer when precipitation inputs were low, while lodgepole pine did not. There was a greater reduction of photosynthetic carbon gain in lodgepole pine compared with Douglas-fir when the two tree species were exposed to seasonal declines in soil water content. The contrasting patterns of seasonal variation in photosynthetic capacity observed for the two species were a combined result of differences in soil characteristics at the separate sites and the inherent physiological differences between the species.     

Transpiration increases during the dry season: patterns of tree water use in eucalypt open-forests of northern Australia

Australian savannas exhibit marked seasonality in precipitation, with more than 90% of the annual total falling between October and May. The dry season is characterized by declining soil water availability and high vapor pressure deficits (up to 2.5 kPa). We used heat pulse technology to measure whole-tree transpiration rates on a daily and seasonal basis for the two dominant eucalypts at a site near Darwin, Australia. Contrary to expectations, transpiration rates were higher during the dry season than during the wet season, largely because of increased evaporative demand and the exploitation of groundwater reserves by the trees. Transpiration rates exhibited a marked hysteresis in relation to vapor pressure deficit, which was more marked in the dry season than in the wet season. This result may be attributable to low soil hydraulic conductivity, or the use of stored stem water, or both. Tree water use was strongly correlated with leaf area and diameter at breast height and there were no differences in transpiration between the species studied. These results are discussed in relation to scaling tree water use to stand water use.     

东莞大岭山村边自然次生林群落物种组成特征及其对区域物种库的贡献

对东莞大岭山村边自然次生林（俗称“风水林”）调查表明,群落组成种类复杂并富于热带性,1hm^2样地内共有维管束植物111种,隶属56科89属,其中以木本植物占绝对优势,有67种,占60．36％;群落中种子植物属为热带分布的共有74属,占总属数的92．5％。群落乔木可分三层,以越南山龙眼为主,其在各层的重要值分别为117．12％,129．44％和57．41％;灌木层以罗伞树和九节等为主;草本层植物以乔灌木小苗为主,草本植物仅沿阶草、海芋和半边旗等少数种类。群落木本植物的科、属、种对区域物种库的贡献率较大,分别为37．7％,25．6％和22．5％,以藤本植物的贡献率最高,接近50％,乔灌植物的贡献率也在20％左右．与鼎湖山季风常绿阔叶林比较．两者物种组成结构相似．但组成种娄仍有一定差距．     

重庆金佛山黑叶猴的春季生境选择

2007年3—5月,在金佛山自然保护区调查黑叶猴对生境的选择和利用情况,采用资源选择函数和资源选择指数进行分析,结果表明:影响黑叶猴生境选择的关键因子是上层乔木郁闭度、灌木胸径、人为干扰、洞穴距离。黑叶猴喜欢在郁闭度大于0.5、乔木和灌木密度大于21棵.(400 m2)-1、灌木胸径大于8 cm、人为干扰大于1 000 m、洞穴距离小于500 m、水源距离小于250 m、南坡的乔木-灌木混交林活动。黑叶猴的生境资源选择函数为:logit(P)=-21.964+2.126×DBH+2.108×CA+2.081×HD-1.829×DC(DBH为灌木胸径,CA为上层乔木郁闭度,HD为人为干扰距离,DC为洞穴距离)。黑叶猴对生境的选择概率为:P=elogit(P)/(1+elogit(P))。     

不同类型毛竹林植物物种多样性研究

通过对不同类型毛竹林植物物种多样性的研究,结果表明:毛竹林内物种是丰富的,但较大部分物种是脆弱的;乔木层植物物种多样性指数与林下木本植物物种多样性指数相关显著,与草本植物物种多样性指数相关不显著,乔木层物种多样性指数小于林下植物物种多样性指数;木本植物物种多样性指数,竹阔混交林＞竹针混交林＞毛竹纯林,粗放经营竹林＞中等集约经营竹林＞集约经营竹林;林下草本植物物种多样性指数,竹针混交林＞毛竹纯林＞竹阔混交林,中等集约经营竹林＞粗放经营竹林＞集约经营竹林;竹阔混交林向毛竹纯林转型时,林下木本植物部分丧失,而草本植物将可能增加,也可能减少.     

茂兰喀斯特森林的林隙物种组成动态及更新模式

分析茂兰喀斯特森林林隙物种组成和种间关系随林隙发育的动态变化,并对林隙主要树种的更新模式进行探讨.结果表明:在发育时间为10、20、30和40年的序列上,林隙中乔木层优势度最大的物种分别是小叶柿、黄连木、掌叶木和云贵鹅耳枥;灌木层优势种包括贵州悬竹、革叶铁榄、湖北十大功劳和长梗核果木;草本层优势种包括石韦、瓦韦、翠云草和庐山楼梯草;藤本优势种包括鞘柄菝葜、四川清风藤、藤黄檀和圆锥清风藤.非林隙林分的优势种不明显.在林隙发育过程中乔木层、灌木层、草本层和藤本的平均相似系数分别为0.31、0.42、0.27和0.32,说明在林隙发育过程中,灌木种类具有较高的连续性和稳定性;草本植物则随着林隙环境条件的改变而出现较大的波动性,藤本植物和乔木的稳定性和连续性介于灌木和草本植物之间.依据树木幼苗、幼树和林冠层数量的差异,可将林隙树种的更新模式分为4种类型.     

金沙江干热河谷退耕地植被恢复模式初探

以金沙江干热河谷退耕地为研究对象 ,在金沙江一级支流———小江流域进行了植被恢复模式的探讨 ;初步筛选了 10余种适应于干热生境和退化耕地植被恢复的乔、灌、藤、草植物物种 ;对其开展了乔草、灌草、藤草、草草、乔灌草等复层植物群落模式研究。结果表明 :该植被恢复模式的建立 ,对水土保持效益明显 ,试验区的泥沙流失量平均减少 5 7% ,其中以草草及藤草模式的泥沙减少量最大 ,分别达 73%和 5 1% ;同时 ,由于所营建植被为生态经济型植物群落 ,既改善了环境 ,又给当地增加了经济收入 ,促进了小流域生态和社会经济的持续发展     

马尾松人工林演替进程中生物多样性变化研究

以广西横县国有镇龙林场马尾松2年生、11年生、13年生、16年生、24年生和50年生人工林替代其演替进程,对马尾松人工林生物多样性变化趋势进行研究,结果表明,(1)马尾松人工林演替进程中物种数量的变化是伴随着阳性先锋物种的衰退和中生性顶级植物的发展,物种数量在演替前期(2～16年)迅速增加,在16年生林分达到高峰,随后(16～50年)逐步降低。(2)在乔木层,马尾松纯林首先演替为针叶落叶阔叶混交林,再演替为针叶常绿阔叶混交林;林下灌草层首先被阳性植物占据,其后逐步被常绿植物替代;在50年生马尾松林,藤本植物物种数明显增高。(3)乔木层物种多样性指数和均匀度指数随林龄的增大呈升高的趋势;而优势度指数先升高(2～13年)后降低(13～50年)。灌木层物种多样性指数在演替前期逐渐升高,到16年生马尾松林达到高峰,而后逐渐下降;优势度指数在幼龄林最高,随后逐渐降低,并趋于稳定;均匀度指数则随着演替进程呈升高的趋势。(4)草本层各项指数变化规律都不明显。本研究为马尾松人工林演替进程生态功能量化研究提供科学依据。