南亚热带森林木本植物种子萌发和储存

研究了南亚热带森林90种木本植物的种子和果实的大小、含水量等特征及种子萌发,并对其中有足够萌发个体的种(45种)进行了萌发分析和对有足够萌发个体和足够种子的种(41种)进行了种子或果实储存对萌发影响的研究.肉质果实种子和肉质种子萌发率较干燥种子高,两者差异显著.大多数种播种60 d内萌发.肉质果实的种子和肉质种子较干燥种子的休眠期长,留土萌发种子较出土萌发种子休眠期长.大种子种与小种子种之间、夏季成熟的肉质果实的种子与冬季和春季成熟的肉质果实的种子之间休眠期长短差异不显著.萌发率与新鲜种子含水量无显著的相关,但种子中水分含量的减少明显影响萌发率,尤其是在种子自然干燥的最初3 d.当种子的水分含量减至20%(约在种子自然干燥10～14 d)时,种子萌发率降至很低.萌发率随储存时间(密封,(4±1) ℃)而下降,但储存一个月下降不大(-8.3%),储存3个月后,显著下降.果实储存与种子储存之间、大种子种与小种子种储存之间、肉质果实的种子和肉质种子储存与干燥种子储存之间,萌发率差异一般不显著.     

南亚热带森林木本植物种子萌发和储存

研究了南亚热带森林 90种木本植物的种子和果实的大小、含水量等特征及种子萌发 ,并对其中有足够萌发个体的种 (45种 )进行了萌发分析和对有足够萌发个体和足够种子的种 (41种 )进行了种子或果实储存对萌发影响的研究。肉质果实种子和肉质种子萌发率较干燥种子高 ,两者差异显著。大多数种播种 6 0d内萌发。肉质果实的种子和肉质种子较干燥种子的休眠期长 ,留土萌发种子较出土萌发种子休眠期长。大种子种与小种子种之间、夏季成熟的肉质果实的种子与冬季和春季成熟的肉质果实的种子之间休眠期长短差异不显著。萌发率与新鲜种子含水量无显著的相关 ,但种子中水分含量的减少明显影响萌发率 ,尤其是在种子自然干燥的最初 3d。当种子的水分含量减至 2 0 % (约在种子自然干燥 10～ 14d)时 ,种子萌发率降至很低。萌发率随储存时间 (密封 ,(4± 1)℃ )而下降 ,但储存一个月下降不大 (- 8.3% ) ,储存 3个月后 ,显著下降。果实储存与种子储存之间、大种子种与小种子种储存之间、肉质果实的种子和肉质种子储存与干燥种子储存之间 ,萌发率差异一般不显著。     

不同光强下生长的两种榕树叶片光合能力与比叶重、氮含量及分配的关系

观测了不同光强下生长的两种榕树幼苗叶片的光合能力、比叶重(LMA)、氮含量及在光合机构中的分配.结果表明,两种榕树幼苗的最大净光合速率(Pmax)均随生长光强的升高而升高,这与LMA、单位面积氮含量(NA)和光合氮利用效率随生长光强的升高而升高有关.除36%光强下外,相同光强下生长的喜光的斜叶榕(Ficus tinctoria)的Pmax均显著高于耐荫的假斜叶榕(Ficus subulata),这与其叶片中氮在羧化组份和生物力能学组份中的分配系数、LMA和NA较高有关.     

不同光环境下亚热带常绿阔叶树种和落叶阔叶树种幼苗的叶形态和光合生理特征

由于地球环境的演变,亚热带常绿阔叶林中常有落叶阔叶成分的存在,但从生态角度,其存在的机理尚不清楚.通过比较研究常绿阔叶优势树种大头茶与落叶阔叶树种枫香幼苗的叶形态和光合生理特征对不同光环境(旷地、林窗、林下)的响应,尝试解释落叶成分遗留的基础.结果表明:①枫香具有较小的比叶重(LMA)和较高的光合氮利用效率(PNUE),在高光环境中,并未受到光抑制,具有较高的光合可塑性,尤其在林窗,表现出较大头茶高3倍的光合能力(Pnmax),保证了其在较短的生长季节积累更多的光合产物,增强与常绿树种的竞争力;②常绿阔叶树种大头茶具有较大的LMA,在旷地受到严重的光抑制,将更多的氮用于化学防御中.在林窗和林下具有相对高的Pnmax,生长幅度较广,但在林下将更多的氮投入到比生长更为重要的生存消耗中.而枫香在林下响应表现为Rubisco活性降低,光合受阻;③两树种在林窗均表现出较高的光合适应性,具有最大的光合能力(Pnmax)及合理的氮在光合机构中的分配系数,说明林窗是它们更新的最佳环境.但枫香的光合作用更依赖于光照,而大头茶则更依赖于CO2浓度;④总之,落叶阔叶树种以其较高的形态可塑性和对高光的光合生理可塑性能够在常绿阔叶林种生存、生长,并成为常绿阔叶林中固有成分的主要原因之一.     

UV-B辐射对南亚热带森林木本植物幼苗生长的影响

研究了UV -B辐射对广东省南亚热带森林木本植物九节、鸭脚木、猴耳环、半枫荷、山乌桕和绿化树种大叶合欢幼苗生长的影响。实验结果表明 ,UV -B辐射降低叶片光合色素的含量 ;显著降低幼苗的净光合速率、蒸腾速率和气孔导度 ;降低干物质的增长 ;抑制大叶合欢幼苗根瘤的形成     

我国南亚热带几种人工林生态系统碳氮储量

以我国南亚热带格木(Erythrophleumfordii)、红椎(Castnopsis hystrix)和马尾松(Pinus massoniana)人工林为研究对象,对其碳氮储量及分配格局进行研究.结果表明,不同树种体内碳的分布与器官年龄的关系不明显,而氮的分布与年龄的关系则较为密切,表现为幼嫩器官中的氮含量大于老化器官,而老化器官的C/N比值大于幼嫩器官.格木人工林生态系统内各组分的氮含量均高于其他两种人工林生态系统,并且3种人工林生态系统碳氮在土壤表层具有明显的富集作用.格木、红椎和马尾松人工林碳储量分别为236.22、267.84、200.57 t/hm2,氮储量分别为17.91、12.38、10.59 t/hm2.乔木层碳储量分别占42.57％、36.31％和40.28％,0-100 cm土壤碳储量分别占55.77％、62.52％和57.83％;氮储量则是土壤占绝对优势,分别为92.00％、93.72％和95.53％.说明3种人工林生态系统碳氮储量主要分布在土壤中,且红椎人工林生态系统具有较高的固碳能力.     

基于FvCB模型的几种草本和木本植物光合生理生化特性

为研究不同生活型植物的光合能力及其叶片光合机构,采用直角双曲线修正模型和C3植物FvCB模型对7种木本植物和4种草本植物的CO₂响应曲线进行拟合,并对不同木本植物、不同草本植物和2种生活型植物的最大净光合速率(P_{n max})、Rubisco酶最大羧化速率(V_{c max})、最大电子传递速率(J_max)、光合暗呼吸速率(R_d)和叶肉阻力(r_m)等参数进行比较.结果表明: 7种木本植物P_{n max}大小顺序为乌桕、苎麻>润楠、海桐>青冈、苦槠、娜塔栎;乌桕、苎麻、润楠和海桐的V_{c max}显著大于青冈和苦槠;J_max大小顺序为乌桕>苎麻、海桐>娜塔栎、苦槠和青冈;润楠和苦槠的r_m显著大于乌桕、海桐和苎麻.商陆的P_{n max}显著大于藿香蓟和土牛膝;4种草本植物的V_{c max}无显著差异;商陆的J_max显著大于藿香蓟;龙葵和土牛膝的r_m显著大于藿香蓟;商陆的R_d显著大于藿香蓟和土牛膝.木本植物的P_{n max}、V_{c max}、J_max和r_m光合参数均显著大于草本植物,但二者的R_d无显著差异.不同物种之间以及2种生活型植物光合能力的差异主要是由叶片内部Rubisco酶羧化能力、电子传递能力和叶肉阻力等差异引起的.     

海南岛热带山地雨林幼苗幼树光合与叶氮、叶磷及比叶面积的关系

以海南岛吊罗山热带山地雨林101个物种的幼苗幼树为试验材料,测定其光合、叶片氮、磷含量及比叶面积;检验其相关关系,并按乔木,乔灌木(小乔木至大灌木)和灌木3个生活型组进行分组检验。研究结果表明,单位叶面积(Aarea)和单位叶重量的光合速率(Amass)均表现出灌木>乔木>乔灌木,方差分析表明,灌木和乔灌木之间Aarea差异显著;灌木和乔木以及灌木和乔灌木之间Amass差异显著(p<0.05)。Aarea与叶氮含量之间的相关性在不同生态型组和所有物种之间均达到极显著水平(p<0.0001);与叶磷之间的相关关系在灌木(p=0.0038),乔灌木(p=0.0002)以及所有物种(p<0.0001)之间达到极显著水平,但是在乔木中未达到显著水平(p>0.05);与SLA之间在灌木(p=0.0006)、乔木(p<0.0001)和所有物种(p<0.0001)之间达到极显著水平,但是在乔灌木中未达到显著水平(p>0.05)。Amass与叶片氮含量、SLA的相关关系在不同生活型组和所有物种中都达到极显著水平(p<0.0001);与叶磷含量之间的相关性在灌木(p=0.0004),乔灌木(p=0.0018)及所有物种(p<0.0001)中极显著,在乔木生活型组中也达显著水平(p=0.0377)。逐步回归表明,与Aarea相比,Amass估计结果更接近于实际测值。由此可见,海南岛热带山地雨林林下幼苗幼树的光合和叶氮、磷含量及SLA之间相关关系与基于成树的研究非常相似,并且A比A更能稳定体现这种相关性。     

氮磷添加对金露梅叶片化学计量及光合特征的影响

通过三种养分添加处理,氮添加(5、10和15 g??m-2)、磷添加(梯度同氮添加)、氮磷同时添加[(5 g N＋5 g P)??m-2、(10 g N＋10 g P)??m-2、(15 g N＋15 g P)??m-2],对照(无养分添加),探讨养分添加对金露梅叶片性状氮含量(Nmas )、磷含量(Pmas )、氮磷比(N∶P)、比叶重(LMA)、净光合速率(Pn )和光合氮利用效率(PNUE)的影响,以及各性状之间的相互关系.结果表明：在处理水平上,除N或P显著提高金露梅叶片的N∶P外,氮、磷添加对叶片其它性状无显著影响;不同氮、磷处理下添加水平对金露梅叶片的Nmas、N∶P、Pn和PNUE均有显著影响,随着养分水平提高,各性状的变化模式各不相同,叶片Pmas无明显变化,而叶片LMA虽有降低的趋势但不显著.回归分析表明,叶片Pmas与Nmas之间呈显著正相关(R2＝0．347,P＜0．001),叶片Nmas 与N∶P之间也呈显著正相关(R2＝0．018,P＜0．05),而叶片Pmas与N∶P呈显著负相关(R2＝0．505,P＜0．001);叶片LMA与Pn之间显著负相关(R2＝0．02,P＜0．05),而与PNUE之间显著正相关(R2＝0．077,P＜0．001).这表明在一定范围内,环境变化可以改变金露梅叶片的养分保持能力、光合能力以及养分利用效率.     

5种木本植物对NaHCO_3胁迫的光合生理响应

以5个抗盐性不同的树种白榆、新疆枸杞、南蛇藤、小叶丁香、樟子松的一年生实生苗为实验材料,研究光合生理参数作为植物抗盐性评价指标的有效性。结果表明:5个树种的抗盐性由强到弱依次为新疆枸杞、白榆、南蛇藤、小叶丁香、樟子松。5个树种对NaHCO_3胁迫有一致的光合响应,即净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、细胞间隙CO_2浓度(C_i)和气孔限制值(L_s)等光合参数均呈下降趋势。与对照相比,重度胁迫下白榆、新疆枸杞、南蛇藤、小叶丁香、樟子松P_n分别下降33.97%、31.40%、54.97%、71.18%和72.25%,5个树种苗木P_n下降幅度顺序为樟子松小叶丁香南蛇藤白榆新疆枸杞;重度胁迫下5个树种苗木T_r分别比对照下降36.18%、48.49%、46.07%、53.55%和71.82%,5个树种苗木T_r下降幅度顺序为樟子松小叶丁香新疆枸杞南蛇藤白榆;重度胁迫下5个树种苗木G_s分别比对照下降58.73%、72.16%、19.82%、48.22%和74.15%,5个树种苗木G_s下降幅度顺序为樟子松新疆枸杞白榆小叶丁香南蛇藤。研究表明,在低NaHCO_3胁迫下白榆和新疆枸杞叶片光合下降的原因是气孔限制,在高NaHCO_3胁迫时,则为非气孔限制;南蛇藤和樟子松为气孔限制因素;小叶丁香为非气孔因素。在NaHCO_3胁迫条件下,抗性较强的白榆和新疆枸杞净光合速率降低的程度明显小于抗性较弱的小叶丁香和樟子松。     

黔中喀斯特9种木质藤本叶功能性状研究

为揭示喀斯特生境中藤本植物的生态策略,对中国科学院普定喀斯特生态系统观测研究站的陈旗流域中9种木质藤本的叶片功能性状及其相关性进行了研究.结果表明,叶面积、叶厚度、叶绿素含量、比叶面积、叶组织密度和叶干物质含量6个叶功能性状均存在不同程度的变异,性状的种间变异为9.24％～98.18％,种内变异为0.64％～39.71...     

南亚热带不同演替阶段森林优势树种叶片构建成本与机械抗性的协同关系

为探究不同演替阶段森林优势种叶片资源获取策略的差异以及叶片构建成本与机械抗性的关系,对我国南亚热带不同演替阶段森林14优势种的叶片构建成本、机械抗性、角质层厚度和比叶重等结构性状进行测定。结果表明,与演替早期相比,演替晚期优势种具有更高的单位面积叶片构建成本、叶片撕裂力以及穿透力,但其叶片最大光合速率较低;同时,单位面积叶片构建成本与机械抗性呈显著正相关关系,而叶片角质层厚度、比叶重等结构性状也与叶片构建成本、机械抗性均呈显著正相关。因此,从叶片能量投资策略上反映了南亚热带森林演替进程中叶片构建成本与机械抗性的协同关系。     

Plant growth-form alters the relationship between foliar morphology and species shade-tolerance ranking in temperate woody taxa

Variation in leaf size (area per leaf) and leaf dry weight per area (LWA) in relation to species shade- and drought-tolerance, characterised by Ellenberg's light (ELD) and water demand (EWD) values, respectively, were examined in 60 temperate woody taxa at constant relative irradiance. LWA was independent of plant size, but leaf size increased with total plant height at constant ELD. Canopy position also affected leaf morphology: leaves from the upper crown third had higher LWA and were larger than leaves from the lower third. Leaf size and LWA were negatively correlated, and leaf size decreased and LWA increased with decreasing species shade-tolerance. Mean LWA was similar for trees and shrubs, but trees had larger leaves than shrubs. Furthermore, all relationships were altered by plant growth-form: none of the qualitative tendencies was significant for trees. This implies the considerably lower plasticity of foliar parameters in trees than those in shrubs. Accordingly, shade-tolerance of trees, having relatively constant leaf structure, may be most affected by the variability in biomass partitioning and crown geometry which influence foliage distribution and spacing and finally determine canopy light absorptance. Alteration of leaf form and investment pattern for construction of unit foliar surface area which change the efficiency of light interception per unit biomass investment in leaves, is a competitive strategy inherent to shrubs. EWD as well as wood anatomy did not control LWA and leaf size, though there was a trend of ring-porous tree species to be more shade-tolerant than diffuse-porous trees. Since ring-porous species are more vulnerable to cavitation than diffuse-porous species, they may be constrained to environments where irradiances and consequently evaporative demand is lower.     

Leaf strategies and soil N across a regional humidity gradient in Patagonia

We analyzed leaf traits related to carbon-fixation, nutrient conservation strategies, and decomposability and their relationships with potential N-mineralization and microbial N in soil in 19 species of 5 dominant life forms growing in 40 sites across a regional humidity gradient in northern Patagonia. We hypothesized that (1) the shifting of species and life forms across the humidity gradient is related to a shifting in traits of green and senesced leaves with some overlapping among life forms, and (2) leaf traits associated with litter decomposition are related to the potential dynamics of soil-N across the humidity gradient. LMA in green leaves and P-resorption efficiency decreased with humidity while concentrations of lignin and total phenolics in green and senesced leaves and P concentration in senesced leaves increased with humidity. Soil C and N concentrations were positively correlated to humidity. Increasing soil N concentration was related to increasing rates of absolute (per unit soil mass) potential net N-mineralization and microbial-N flush. Relative (per unit N mass) potential net N-mineralization and microbial-N flush decreased with soil N and were inversely correlated to lignin concentration and C/N ratio in senesced leaves. We found overlapping in N concentration and C/N ratio in green and senesced leaves, P concentration in green leaves, and N resorption among species and life forms across the humidity gradient. We concluded that (1) leaf traits related to carbon fixation and the decomposition pathway significantly varied with humidity and were not overlapped between plant life forms from dry and humid habitats, (2) the largest overlapping among species and plant life forms across the gradient occurred in those leaf traits related to N conservation in the plant, and (3) life forms from humid habitats produce more recalcitrant litter that induce lower rates of relative potential net N mineralization (per unit N) than those of dry habitats.     

浙江省箬寮岘自然保护区木本植物区系研究

通过对浙江省箬寮岘自然保护区木本植物资源的实地考察,结果表明,箬寮岘自然保护区植物资源十分丰富,共有木本植物89科292属738种,地理成分复杂,温带性质属种略多于热带分布的属种,有许多古老的科属和孑遗种,木本植物区系过渡性特征明显。并就该保护区木本植物资源的保护提出了建议。     

海防林叶片形态、光合特征和枝条抗性对长期风胁迫的响应

为了解长期风胁迫对海防林的影响,对沿海6种林龄为8～10 a的防护林树种的叶片形态、光合特征及枝条抗性对长期风胁迫的响应特征进行了研究.结果表明,与未受风胁迫海防林相比,长期风胁迫显著降低了女贞(Ligustrum lucidum)、无患子(Sapindus mukorossi)、红楠(Machilus thunber...     

Genetic variation in leaf pigment,optical and photosynthetic function among diverse phenotypes of <Emphasis Type="Italic">Metrosideros polymorpha</Emphasis> grown in a common garden

Coordinated variation has been reported for leaf structure, composition and function, across and within species, and theoretically should occur across populations of a species that span an extensive environmental range. We focused on Hawaiian keystone tree species Metrosideros polymorpha, specifically, 13-year old trees grown (2–4 m tall) in a common garden (approximately 1 ha field with 2–3 m between trees) from seeds collected from 14 populations along an altitude–soil age gradient. We determined the genetic component of relationships among specific leaf area (SLA), the concentrations of nitrogen (N) and pigments (chlorophylls, carotenoids, and anthocyanins), and photosynthetic light-use efficiency. These traits showed strong ecotypic variation; SLA declined 35% with increasing source elevation, and area-based concentrations of N, Chl a + b and Car increased by 50, 109 and 96%, respectively. Concentrations expressed on a mass basis were not well related to source elevation. Pigment ratios expressed covariation that suggested an increased capacity for light harvesting at higher source elevation; Chl/N and Car/Chl increased with source elevation, whereas Chl a/b declined; Chl a/b was higher for populations on younger soil, suggesting optimization for low N supply. Parallel trends were found for the photosynthetic reactions; light-saturated quantum yield of photosystem II (Φ _PSII) and electron transport rate (ETR) increased with source elevation. Correlations of the concentrations of photosynthetic pigments, pigment ratios, and photosynthetic function across the ecotypes indicated a stoichiometric coordination of the components of the light-harvesting antennae and reaction centers. The constellation of coordinated morphological, biochemical and physiological properties was expressed in the leaf reflectance and transmittance properties in the visible and near-infrared wavelength region (400–950 nm), providing an integrated metric of leaf status among and between plant phenotypes.     

Intraspecific Functional Trait Variation in a Tree Species (Lithocarpus dealbatus) along Latitude

We quantied intraspecic variation and covariation of leaf mass per area (LMA), leaf dry matter concentration (LD), leaf frost sensitivity (LFS) and Fv/Fm of leaves of 8 Lithocarpus dealbatus populations across the geographical distribution from north to south to determine the magnitude and whether it is related to environmental conditions, latitude and mean annual temperature. The results showed that the total variation (coefcient of variation) of LMA, LD, LFS and Fv/Fm were 160%, 177%, 211% and 401% respectively. The total intraspecic variation was contributed by the difference among populations, individuals and leaves. The difference among populations accounted for the largest total variation in LMA, LD and Fv/Fm, whereas the difference among leaves accounted for the largest total variation in LFS. On population level, LMA was significantly positive related to the latitude and Fv/Fm was significantly negative, but LD and LFS were not related to the latitude. LMA decreased while Fv/Fm increased significantly with the increase of mean annual temperature. LD was a downward quadratic variation, and LFS was upward with the increase of mean annual temperature. The principal component analysis of four functional traits showed that no population was located nearer to the origin of the first and second principal component, and populations at the edge of distribution area located at both sides of the first principal component axis. The results suggested that the environmental variation in the distribution could cause intraspecic variation of functional traits. There is no population could represent a species in functional traits. When an average trait value for species is considered and trait comparisons are done among species, intraspecific variation of traits could not be ignored.     

Consequences of the Elimination of Old Leaves upon Spring Phenological Events and the New Leaves Nutrient Concentration in a Wintergreen Woody Species in the Southern Hemisphere

Previous studies analyzed the importance of old leaves conservancy for wintergreen species plant growth only after early spring old leaves elimination. However, carbon and nutrient resources for growth could have already been translocated from old leaves to shoots during autumn. In this work, the effect of old leaves absence on the leaf mass per area (LMA, g m⁻²) and nutrient concentration of new spring leaves, shoot growth, and flowering was studied in Aristotelia chilensis, an Andean Patagonic woody wintergreen species of Argentina. Plants were studied after autumn defoliation (AD) or late winter defoliation (WD) and results were compared to those of undamaged control plants (CO). The new leaves LMA and mineral nutrient (N, P, K, and Mg) concentration values did not decrease in AD or WD compared to CO plants. Conversely, CO plants showed higher flowering intensity and shoot lengthening compared to AD or WD plants. There were not remarkable differences regarding the defoliation time, though non-flowering shoots grew in a lesser degree than the flowering shoots in WD plants. It was concluded that A. chilensis old leaves cohort is an important source to shoot growth and flowering but their absence does not affect the new leaves structure or nutritional status from early spring in either AD or in WD plants. New leaves formation probably is guaranteed by resources (carbon and nutrients) previously stored in stems or even in the buds containing the preformed leaves since March, by the end of summer. Provided the availability of complete resources for the new leaf flush independently of the old leaves A. chilensis would restore the carbon balance as soon as possible to resume the growth of heterotrophic tissues at normal rates. Endogenous response to counterbalance the old leaves absence on non-flowering shoots was more effective when there was greater lag time between defoliation and shoot growth resume. Flowering and non-flowering shoots compete for the available resources when A. chilensis have not yet expanded leaves and shoots supporting reproductive structures were stronger sinks compared to non-flowering shoots in WD plants.