竹类结构植物学研究进展

本文从竹秆、节部、叶、根、地下轴系统、胚胎等几个方面 ,对竹类结构植物学的研究进行了回顾 ,并对以后的工作进行展望。     

唐家河自然保护区连香树种群结构与数量动态

以种群静态生命表及生存分析理论为基础,以林木径级结构代表年龄结构,利用生存函数分析等方法,对唐家河自然保护区连香树种群的结构及数量动态特征进行了研究。结果表明:(1)研究区域内连香树种群结构基本呈金字塔型,其种群内幼苗较少,中老龄个体较多;(2)种群死亡率和消失率曲线变化趋势基本一致,在第Ⅱ龄级出现峰值,即幼苗死亡率较高;种群存活曲线趋于Deevey-Ⅱ型;(3) 4个生存函数曲线表明,连香树种群具有前期锐减、中后期相对稳定和末期逐渐衰退的特点,目前种群已处于衰退的早期。     

濒危植物水青树结实特性研究

对四川美姑大风顶自然保护区水青树(Tetracentronsinense Oliv.)种群的结实特性进行了分析研究.该种群果穗长度平均为13.988 cm,果穗产果量平均为104.86 g,产种量平均为1 182.5 g,表明水青树单株结实率较高;单因素方差分析表明,不同植株产果量和产种量差异显著,采自不同母树的水青树种子的重量差异达极显著水平.该种群果穗主要分布在树冠中部,果穗在阴阳面的分布没有明显的差异;果穗中以中部的产果量和产种量比率最高,而与其他乔木树种不一致.水青树胸径和冠幅都与产种量呈明显正相关,表明其营养生长与生殖生长关系密切.     

野生大熊猫采食对峨热竹粗灰分和干物质含量的影响

通过对大熊猫采食后峨热竹粗灰分和干物质含量进行观测,探讨峨热竹粗灰分和干物质含量的变异规律,及其受野生大熊猫采食的影响机制。结果表明:相同竹龄条件下,采食样方同一构件的粗灰分含量显著高于对照样方(P0.05),干物质的含量总体高于对照样方(P0.05);枝叶粗灰分的含量显著高于竹秆(P0.05),而干物质的含量总体低于竹秆。随着竹龄的增加,不同竹龄粗灰分的含量大致呈逐年上升的趋势,而干物质的含量总体上呈下降趋势。大熊猫采食对于峨热竹粗灰分和干物质的积累没有明显的影响,粗灰分和干物质不会影响野生大雄猫对峨热竹的可持续利用,有利于大熊猫放归基地栗子坪自然保护区内的大雄猫生存繁衍。     

四川5种丛生竹的秆形特征比较

为四川乡土丛生竹资源的开发、栽培和利用提供理论依据,采用随机取样方法对四川常见的5种大径丛生竹的秆型特征进行对比研究。结果表明,5种丛生竹竹秆鲜重均随胸径的增加而增大,同一胸径下慈竹的竹秆鲜重相对较小,硬头黄的竹秆鲜重相对较大。随相对高度的增加,5种丛生竹的相对直径均呈下降趋势,其中梁山慈和慈竹下降最快,其尖削度相对较大。相对壁厚随高度的变化呈逐渐减小趋势,其中硬头黄竹的相对壁厚的变化幅度最大。节间长度均随节位的增加呈先增加后逐渐减小趋势。相对慈竹而言,梁山慈在竹材质量和生物产量方面具有优势,粉单竹和料慈竹在板材加工利用方面具有优势,硬头黄竹在竹材质量、生物产量和板材加工利用方面均不具优势。     

水青树不同径级个体构件水平上的生殖配置研究

[目的]通过对濒危植物水青树的生殖配置进行研究,探讨其生殖与生存之间的权衡关系,揭示其生活史对策及其濒危机制。[方法]对固定样地内的不同径级水青树个体的标准生殖枝生物量进行观测,对不同径级个体的差异采用多重比较分析,对生殖配置(RA)、生殖构件与营养构件生物量采用相关性分析和线性回归分析,对种子数量与千粒质量进行相关性分析。[结果](1)随径级的增大,水青树的生殖和营养投入呈现同增同减的趋势,没有明显的权衡关系;(2)水青树的生殖分配(RA)随径级的变化呈现先上升后下降的趋势;(3)水青树的生殖投入与营养投入、叶生物量之间呈显著正相关,而其RA与营养投入、叶生物量之间呈显著负相关;(4)生殖构件各组分中,种子生物量所占比重均为最小,且远远低于生殖的附属结构(果序轴和果皮);种子数与种子大小之间存在权衡关系。[结论]在构件水平上,水青树的营养投入对生殖投入具有促进作用;其生殖期可划分为生殖初始期、生殖增长期、生殖高峰期和生殖衰退期等4个时期;其种子特征在生殖不同时期分别采取不同的生活史对策,可能是水青树在长期演化发展过程中形成的生殖适应性对策。     

实心狭叶方竹种群的生物量结构与地下茎生长规律研究

依据Harper的构件生物结构理论和种群生态学方法,对实心狭叶方竹种群的生物量结构和地下茎生长规律进行了研究.结果表明:(1)实心狭叶方竹种群各构件单位的生物量配置为:秆(36.30%)>叶(21.13%)>枝(17.82%)>篼(13.43%)>鞭(10.18%)>根(1.14%).其中地上部分生物量占75.25%,主要集中在1～3龄;不同年龄地上部分各构件单位的生物量分配有较大差异.秆、枝、叶的含水率均以1年生新竹最高,并随年龄的增长而逐渐减小.(2)实心狭叶方竹秆基、秆柄和竹鞭等地下茎各构件较小;秆基和竹鞭上萌芽转化为壮芽的成功率较低;竹鞭主要生长在0～15 cm的土层,幼壮龄鞭有趋浅的动态,不利于其无性系种群的克隆生长,可能是导致其种源稀少的原因之一.     

Effects of slope on soil properties and post construction desertification of highway embankments in an Alpine Meadow region北大核心CSCD

This research investigated effect of slope on the performance of highway embankment soil properties post construction, as there is a demand for technical data of this nature to underpin the design of highway revetment work in alpine meadow regions of China. A section of national road G248 in Northwest Sichuan Alpine Grassland, built 10 years ago, was identified as a study site and plots were marked out for sampling on five slope classes: gentle slope, 6°-15° (GS); moderate slope, 16°-25° (MS); steep slope, 26°-35° (SS); very steep slope, 36°-45° (VS); extreme slope, >45° (ES). Undisturbed flat natural grassland >10 m distant from the roadbed was used as the control (CK). Measurements conducted included determination of particle size composition, physical and chemical parameters of the soils, vegetation cover and the proportion of the plot area exhibiting degradation or desertification. The relative reduction rate of organic matter and total nitrogen was also determined, and differences in soil water content and fertilizer retention capacity were assessed. It was anticipated these data would provide a basis for the construction of ecologically sound slope protection structures in alpine regions. It was found that: 1) Increased slope significantly decreased the proportion of clay and silt particles and increased the proportion of coarse sand and small stones (P<0.05). The greater the slope, the greater the soil bulk density and pH value, and the lower the soil water content. 2) Slope facilitated leaching of soil carbon fractions with the leaching intensity of the fractions ranking soil organic matter (SOM)>total carbon (TC)>inorganic carbon (IC)>dissolved organic carbon (DOC). For example, SOM levels were, respectively, 115, 92, 72, 30, 9 and 3 mg·kg−1 for CK, GS, MS, SS, VS, and ES slope classes while DOC levels ranged from 35.4 mg·kg−1 in CK to 9.2 mg·kg−1 in ES. 3) The ranking for the effects of slope on various soil fertility measures was: effective N>alkali-hydrolysable N>total N>available K> available P>total K>total P. Thus, available N was more easily lost than total N and alkali-hydrolysable N. Available N levels declined progressively across slope classes from 236 mg·kg−1 in CK to 6.3 mg·kg−1 in ES, while total N and alkali-hydrolysable N showed marked loss between GS and VS slope classes. A slope threshold for sharp increase in loss of total P and available P was observed between GS and MS slope classes. With increase in slope gradient, the total K increased, while the available K content decreased. 4) With respect to the influence of slope on the degree of desertification: for CK and GS >90% of the plot area was classed as non-desertified; for GS 79% of the plot area was moderately or severely desertified; for SS, VS and ES, 79, 86 and 94%, respectively, of the plot area was severely or extremely severely desertified. The proportion of severe desertification increased markedly at > 15° slope (i. e. MS) and the proportion of extremely severe desertification increased markedly at >25° slope (i. e. SS). 5) When the slope effects were expressed in relative terms, the relative increase in desertification was high and changed little at slopes >15°, while the relative decreases in organic matter and total nitrogen were high and changed little once slope exceeded 25°. As slope angle increased, relatively low rate of total coverage percentage and powder particles <0.02 mm and the relative increase rate of sand particles >0.05 mm increase significantly. In summary, as slope of the study plots increased, fine sand, silt and clay particles were progressively lost, soil fertility progressively declined, and the degree of desertification increased markedly. Therefore, the technical plan for ecologically sound slope protection in highway construction should be formulated according to the steepness of the slope. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

基于水青树叶表型性状的核心种质资源库构建策略

[目的]为了更好地构建水青树核心种质资源库,本文以161个水青树种质为试材,利用叶表型性状的遗传变异数据,对其构建方法进行了探索。[方法]首先,采用欧氏距离和瓦尔德法对所有个体进行逐步聚类;然后,设定10个取样比例(10%、15%、20%、25%、30%、35%、40%、45%、50%、55%),分别用随机取样策略、偏离度取样策略和位点优先取样策略筛选出与之对应的核心种质资源库。将这3种不同取样策略构建的核心种质资源库进行比较,从而筛选出最适种质资源。[结果](1)三种取样策略中,位点优先取样法明显提高了其种质资源库的方差差异百分率(VD)、变异系数变化率(VR)和极差符合率(CR),且45%是最适合构建水青树核心种质资源库的比例;(2)对种质资源核心库不同数量性状进行t检验,其累计贡献率达到82%以上。[结论]在欧氏距离结合瓦尔德法聚类条件下,位点优先取样策略是构建水青树种质资源核心库的最佳方法。     

峨热竹无性系种群地上部分生物量结构与模型研究

通过对四川省石棉县栗子坪自然保护区峨热竹分株地上部分基径、枝下高、全高及分株各构件生物量进行调查和测量,研究了其地上部分生物量分配结构和形态可塑性,构建了地上部分生物量模型。研究表明：峨热竹各分株含水率随年龄增长呈下降趋势,同一龄级分株构件含水率高低表现为叶〉枝〉秆;峨热竹分株总生物量表现出多年生〉2年生〉1年生的分配特征,而同一分株各构件间则表现出秆〉枝〉叶的生物量分配格局;基径分别与各龄级秆生物量和总生物量具有显著相关性,而全高与2年生及多年生枝叶生物量具有显著相关性;以基径和全高为自变量分别建立的线性模型可为相似区域峨热竹不同龄级分株秆和枝叶构件生物量的估测提供借鉴。