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1.
黄土高原丘陵区不同生境小叶杨人工林物种多样性及其群落稳定性分析 总被引:3,自引:0,他引:3
通过样地调查,对黄土高原丘陵沟壑区处于阴坡、半阴坡、半阳坡、阳坡4种生境条件下,经过30年发育的小叶杨人工林物种多样性,群落结构动态和土壤水分养分效应进行了系统研究,结果表明:(1)不同生境小叶杨人工林总体上物种丰富度、多样性指数和均匀度指数均呈现出阴坡>半阴坡>半阳坡>阳坡的趋势,且林内物种多样性指数表现为:草本层>灌木层;(2)不同生境条件下的小叶杨人工林年龄结构分析表明,尽管阴坡小叶杨长势相对较好,但更新幼苗数量相当有限,很难实现种群的自我更新,不适合作为人工林培育;(3)土壤含水量和养分因坡向不同而呈现出明显的差异,尽管阴坡和半阴坡的水分、养分条件相对较好,但也出现了枯梢、病虫害等衰老特征,因此阴坡、半阴坡的生境对小叶杨来说也不合适.未来应该对现有林地在保护的前提下,间伐衰老个体,补植和引入乡土物种,进行天然化培育. 相似文献
2.
Phosphorus nutrition of rice in relation to flooding and temporary loss of soil-water saturation in two lowland soils of Cambodia 总被引:1,自引:1,他引:0
In the rainfed lowlands, temporary loss of soil-water saturation during crop growth is a common factor limiting rice (Oryza
sativa L.) yield but its effects on phosphorus (P) availability are poorly understood. Rice plants were transplanted into
pots containing soils that were either continuously flooded, maintained at field capacity or flooded and then dried to field
capacity for 3 weeks during the vegetative stage. A black clay soil (Kandic Plinthaquult) and a sandy soil (Plinthustalf)
from south-east Cambodia were compared with or without amendments by rice straw and P fertilizer.
Under continuously flooded conditions, the growth of rice was vigorous without straw addition and there was a strong response
of rice growth to the addition of P fertilizer. The soil underwent reduction, which increased pH from 4.2 to 5.5 or 6.0, in
the black clay or sandy soil, respectively. By contrast, a loss of soil-water saturation 3 weeks before panicle initiation
(PI) markedly impaired the growth of rice. This was not through any effect of water stress, and the growth reductions were
not as strong as with continued loss of soil-water saturation from transplanting to PI. Fluctuations in soil pH and Eh corresponded
closely to changes in soil-water regimes. Growth reductions were attributed to reduced shoot P levels resulting from the decline
in P availability during the loss of soil-water saturation. The addition of rice straw stimulated soil reduction and lessened
changes in soil pH and Eh during the loss of soil-water saturation in both soils. Straw addition enhanced P uptake by the
rice plants during loss of soil-water saturation, but its beneficial effects could not be attributed to the direct addition
of P, N or K to the soils. Thus the application of rice straw may be effective in lessening the effects of temporary loss
of soil-water saturation on rice growth in lowland rice soils by minimising the decline in P availability.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
土壤水分条件对克隆植物互花米草表型可塑性的影响 总被引:5,自引:0,他引:5
在互花米草草滩挖掘沙蚕是海岸带常见的行为,会造成土壤结构松散,蓄水能力下降,局部土壤水分含量低.能否利用这些条件,降低互花米草种群的入侵性,并进而对互花米草的控制提供对策是一个重要的生态学命题.为此,实验模拟3种不同土壤蓄水条件,并测定互花米草在该条件下的形态与存活指标、克隆特征参数及生物量积累与分配格局.结果表明:土壤水分条件对互花米草的叶长和根状茎生物量均没有显著影响(p> 0.05);而其株高、分枝强度、克隆存活数、克隆存活率及地上生物量在各土壤水分条件间差异显著(p< 0.05);在低水分条件下,互花米草的芽数、基茎粗、地上生物量比和叶生物量比均显著低于其他两组处理(p< 0.05),地下生物量比则显著高于其他两组处理(p< 0.05);在中等水分条件下,互花米草的根状茎长、根状茎节数、地下生物量和茎生物量比与其他两组处理差异不显著(p> 0.05),而在其他两组处理间差异显著(p< 0.05);在高水分条件下,总生物量、茎生物量和根生物量显著高于其他两组处理(p< 0.05),根状茎生物量比则显著低于其他两组处理(p< 0.05),而这些指标在其他两组处理间均差异不显著(p> 0.05).由此推断,土壤水分条件适中有利于互花米草的生长扩张以占领有利的资源环境,而土壤水分条件低则抑制互花米草的生长繁殖,影响其种群延续. 相似文献
4.
5.
Porous ceramic cup soil-water samplers were treated with solutions containing Na, K, Ca, or Mg to examine any interactions between the cups and the extracted solutions. Acid-washed and non-acid washed cups were evaluated. Results demonstrated simple ion exchange between monovalent and divalent cations on charged sites, and that Na contamination of commercially available cups was effectively removed by acid-washing. 相似文献
6.
NEIL SAINTILAN 《Austral ecology》1998,23(4):322-328
Abstract The height and diameter at breast height (DBH) of mangroves on the Hawkesbury River, New South Wales and the Mary River, Queensland were related to soil-water salinity, soil-water content and distance from the mouth of the estuary. On the Hawkesbury River, both Avicennia marina and Aegiceras corniculatum declined in height and DBH with increasing soil-water salinity and soil-water content, and increased in height with distance from the mouth of the estuary. Both species showed an extensive range of all variables. On the Mary River, where species diversity was higher, no relationship was found between the height and DBH of A. marina and A. corniculatum and soil-water salinity and soil-water content. Both species increased in height with increasing distance from the mouth of the estuary, a characteristic shared with all other species studied (Excoecaria agallocha, Ceriops tagal var. australis, Rhizophora stylosa). The results suggest that growth characteristics of mangroves are not a simple response to salinity gradients in diverse systems and that other variables such as nutrient availability may be important controls on mangrove growth. 相似文献
7.
Isa A. M. Yunusa Sue E. Thomson Keith P. Pollock Lu Youwei Donald J. Mead 《Plant and Soil》2005,275(1-2):195-206
In order to understand how radiata pines respond to declining supply of soil-water in agroforestry systems, we monitored water
potential in xylem (ψ
x
), osmotic potential (ψ) and relative water content (q) for fascicles at pre-dawn and at mid-day for 3-year-old trees that were raised from either seedlings (Seedling) or from
tissue culture (TC3 and TC4), and grown either alone (Control) or over lucerne (Medicago sativa) pasture (Lucerne). Water relations at dawn were mostly similar for all the pines, except late in the season when ψ was lower,
bulk turgor pressure (P), deduced as the difference between ψ
x
and ψ, was higher, for TC3 than for the other two pines. At mid-day, Seedling often had higher ψ
x
and ψ, but because of its poor osmotic adjustment (OA) had lower P, than either TC3 or TC4. The cell walls were more elastic in Seedling with modulus of elasticity (e) of 6.5 MPa compared with 8.1 MPa for both TC3 and TC4, while loss of turgor was estimated to occur at ψ
x
of −1.45 MPa for Seedling, −1.38 MPa for TC3 and −1.35 MPa for TC4. All trees irrespective of their origin had higher ψ
x
, P, CO2 assimilation (A), and stomatal conductance (g
s
), but lower ψ, in Control than in Lucerne in which the soil profile was consistently drier. The trends in ψ
x
, ψ, q and A did not reflect the known differences in dry weight of trees, P was in the order TC3 > TC4 > Seedling, consistent with previously reported tree weights. Both TC3 and TC4 had higher P, due to their larger OA, than Seedling, although the latter had higher A. Thus ψ
x
and A that are routinely measured may not always adequately explain differences in growth amongst pines; it is advisable that ψ
be determined to allow deductions of P be made when using water relations to analyse plant growth. 相似文献
8.
黑河下游土壤水盐对生态输水的响应及其与植被生长的关系 总被引:2,自引:0,他引:2
生态输水作为一项改善黑河下游生态环境的人工输水工程,研究土壤水盐与地表植被对输水的响应对于下游植被的恢复与重建具有重要的理论和实践意义。以2001年和2010年野外土壤和植物样方调查资料为基础,探讨了黑河下游土壤水盐对生态输水的响应及其与植被生长的关系,结果表明:(1)输水后不同深度土壤含水率的增加幅度依次为:胡杨林>柽柳林>草地;(2)不同群落土壤含盐量的增加幅度依次为:苦豆子>柽柳>梭梭>胡杨;同时,土壤盐分主要以HCO3-和Na+为主的轻度盐化土向以SO42-、Cl-及Ca2+等为主的中度和强度盐化土转化;(3)以胡杨为例,土壤含水率小于6%时,密度和冠幅与土壤含水率呈正相关,但大于6%时,冠幅和密度分别介于40-70 m2和0.5-5株/100m2之间;同样,土壤水溶性盐含量小于1%时,密度和冠幅与土壤含水率呈正相关,但大于1%时,密度在0.5-5株/100m2之间,造成上述结果的原因更多是群落的一种"自然稀疏"现象。 相似文献
9.
Dr Prof. Hong-Bo Shao Li-Ye Chu Li-Ye Chu Ming-An Shao 《Molecular membrane biology》2013,30(3):179-191
Aquaporins are important molecules that control the moisture level of cells and water flow in plants. Plant aquaporins are present in various tissues, and play roles in water transport, cell differentiation and cell enlargement involved in plant growth and water relations. The insights into aquaporins’ diversity, structure, expression, post-translational modification, permeability properties, subcellular location, etc., from considerable studies, can lead to an understanding of basic features of the water transport mechanism and increased illumination into plant water relations. Recent important advances in determining the structure and activity of different aquaporins give further details on the mechanism of functional regulation. Therefore, the current paper mainly focuses on aquaporin structure-function relationships, in order to understand the function and regulation of aquaporins at the cellular level and in the whole plant subjected to various environmental conditions. As a result, the straightforward view is that most aquaporins in plants are to regulate water flow mainly at cellular scale, which is the most widespread general interpretation of the physiological and functional assays in plants. 相似文献
10.
Zonal plant distribution and edaphic and micrometeorological conditions on a coastal sand dune 总被引:1,自引:1,他引:0
Some edaphic and meteorological conditions were examined to detect environmental gradients from shoreline to inland at the
Kado-ori coast, Ibaraki, Japan, in 1989. Zonal distribution patterns of coastal dune plant species, including three ubiquitous
perennials,Calystegia soldanella, Carex kobomugi andIschaemum anthephoroides, were described in relation to the environmental gradients. Environmental gradients were found in water availability, evaporative
demand and soil-water salinity. Water availability, evaluated by thickness of capillary water layer, increased from 10 cm
at 20 m to 48 cm at 85 m from the shoreline, reflecting the percentage of fine sand. Evaporative demand, which was evaluated
by the evaporation rate from a wet black filter paper, decreased with increasing distance from the shoreline. Soil-water salinity
was lowest (15 mmol/L) at 85 m from the shoreline and highest (90 mmol/L) at 30m. On the coast,C. soldanella, a salt-tolerant perennial, was distributed mainly in the environmentally harsh area 40–60 m from the shoreline.Ischaemum anthephoroides andC. kobomugi, less salt-tolerant perennials, occurred mainly 70–80 m from the shoreline, where environmental conditions were more hospitable. 相似文献