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1.
调查分析了黄土丘陵区5种人工乔灌林小叶杨(Populus simonii)林,山杏(Prunus armeniaca)林,山桃(Prunus davidiana)林,沙棘(Hippophae reamnoides)林,柠条(Caragana korshinskii)林下草本层植物的物种组成、结构特征及其差异。结果表明:5种人工乔灌林下共有37种草本植物,各人工林林下物种组成数量在17~25之间变化,其中以杏树林最多;5种人工林下草本层平均盖度、平均高度、平均生物量存在较大差异,但多样性指数相差不显著。总体来说,黄土丘陵区人工乔灌林下草本植物物种组成较少,物种多样性指数较低,结构参数较小,说明该地区人工林林下环境条件较差,严重影响草本植物个体的生长发育和群落结构。综合分析表明,具有较低林分密度和林冠郁闭度的山杏林是恢复状况相对最好的人工林,揭示了保持合理的林分密度,同时采取疏伐、修枝等管理措施是促进人工林生长发育以及林下草本植物物种多样性和片层结构改善的关键。 相似文献
2.
金沙江干热河谷尽管分布区域不大,但对金沙江流域的生态环境质量具有十分重要的影响,是金沙江水土保持生态环境建设的核心区。由于其异常干热的气候特点,使得人工生态林建设更为艰难。在干热河谷典型地段——元谋的试验观测表明:现有人工乔木生态林的林分微环境较差,赤桉林Fan林内光辐射仅比林外空旷地减小了20.7％;Fan的日平均气温（27.37℃）和地表土壤温度的日平均值（32.54℃）分别比林外只低0.14和3.31℃;林分F1、F2和F3春季0～100cm土层内平均含水率分别为6.84％、5.83％和9.16％,林分Fan也只有9.83％,相比之下,以扭黄茅群落为主的自然草坡这一季节的土壤水分则可高达13.20％。由此而导致林木生长缓慢,对于10年生赤桉林,F1的平均树高和平均胸径分别为9.46m和8.68cm;F3的平均树高只有7.22m,平均胸径更小（3.97cm）,表现出明显的生长不正常。高密度的人工乔木生态林在干热河谷地区不能形成合理的林分结构,低密度的稀树或零星分布的散生木生长良好。 相似文献
3.
[目的]探明科尔沁沙地南缘的奈曼旗沙区小叶杨(Populus simonii)防护林造林密度对林下植被的影响，提出适宜植被群落多样性恢复与稳定性发展的造林密度。[方法]以自然恢复状态下，林龄相近的3种典型造林密度类型(867～1 022株/hm2,1 444～1 667株/hm2,2 177～2 322株/hm2)的小叶杨防护林为研究对象，开展每木检尺、物种组成与多样性、植被群落结构等调查，对野外采集数据进行统计分析。[结果]造林可以显著提高植被恢复与演替速度，造林密度的大小对林下植被多样性与群落稳定有显著影响，随着造林密度的减小，林下草本生物量、物种组成丰富度、物种多样性指数增大，植物恢复程度、群落稳定性上升；造林密度与林下物种多样性指数、物种数量、林下植被盖度、林下草本生物量等植被特征指标均呈现极显著负相关关系(p<0.01)。[结论]当小叶杨防护林造林密度为867～1 022株/hm2时，群落与未经开垦的草地样地的群落相似性最高，植被群落演替逐渐向地带性植被发展，与其他造林密度相比更有利... 相似文献
4.
研究林下植被对不同密度林地土壤水分环境的指示作用,可以为造林营林中的密度调控、提高林分生产力和林分稳定性等,提供理论根据。为此,对山西黄土丘陵沟壑区的14年生人工刺槐(Robiniapseudoacacia)林6种造林密度(1.5m×2m、1.5m×3m、1.5m×4m、1.5m×5m、1.5m×6m、1.5m×7m)林分的土壤水分、林下光照强度等环境因子进行观测,同时,采用样方调查法,对不同密度林内的树木生长情况和林下植物的类型、数量、分布及发育状况进行了研究。结果表明:密度小的林分内,各小环境指标均优于密度大的林分,其中土壤水分、光照强度有显著的随林分密度增大而减小的趋势,刺槐林地内随着林分密度的增大,渐渐出现干旱、半干旱地区成龄人工林土壤干化的现象,林下植被的种类和数量相应减少,物种丰富度和物种多样性指数也降低,且逐步由以鹅观草(Roegneriakamoji),小菅草(Themedaminor)为典型的中生植物,向以角蒿(Incarvilleasinensis),灰绿藜(Chenopodiumglaucum)为典型的旱生植物过渡,反映出林分内的小环境条件随林分密度变化的特征。因此,在半干旱区造林和营林中,密度不可过大,以便提高林分生产力和林分稳定性。 相似文献
5.
水土保持生态自我修复中的植物多样性恢复研究 总被引：1，自引：2，他引：1
以植物群落调查样地为基础,从物种多样性指数、生态优势度、群落均匀度和林下植被生物量,对辽东地区水土保持生态修复区的几种典型土地利用方式下植物多样性恢复效应研究表明:天然次生生态系统(天然栎林与撂荒地)的植物多样性和林下植被生物量均表现为随着修复时间的延长而增加,人工针叶林生态系统与之相反,表现为下降趋势。不同土地利用方式下,植物群落的物种多样性表现为:天然次生栎林>撂荒地>落叶松人工林>红松人工林,其中,退耕落叶松人工林的植物多样性指数高于连植落叶松人工林。 相似文献
6.
对黄土丘陵沟壑区不同密度的刺槐林、榆树林、油松林、侧柏林、油松刺槐混交林等林下草本层物种组成及多样性进行了研究,目的是为人工林生态功能恢复评价和植被建设提供理论依据。研究结果表明,该区林下草本植物共有36种,多以阳性植物为主;由于林分树种组成和密度不同,林下草本物种差异较大;林下植被演替大多处于植被演替初级阶段,针阔混交林在物种数量和建种群落上表现最好,其次是油松纯林和刺槐纯林,榆树纯林生境条件最差;无论是丰富度指数还是多样性和均匀度指数,针阔混交林表现最好,其次为刺槐、油松纯林,表现最差的为榆树、侧柏纯林。 相似文献
7.
泰山罗汉崖林场林下植被物种组成及生物多样性 总被引：1，自引：0，他引：1
通过对泰山罗汉崖林场9种人工林林下植被种类、盖度、密度的调查,采用丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数、Pielou均匀度指数,研究9个人工森林群落林下植被的物种组成和生物多样性.结果表明:1)草本层相对灌木层较为发达,草本植物的物种以禾本科的植物为最多,其次为菊科,人工林林下植... 相似文献
8.
北川河流域森林冠层结构对林下植被多样性的影响 总被引：1，自引：0，他引：1
通过在青海省西宁市大通县宝库林场设置样地,研究5种主要林分森林冠层结构对林下植被的影响。选取沙棘林、白桦林、青海云杉林、华北落叶松林和青海云杉落叶松混交林这5种主要林分,每种林分设置6个样地,在样方4角及中心设置灌木和草本样方,共设置30个乔木样方,150个灌木和草本样方,进行样地调查,并且利用鱼眼镜头相机在样方内对冠层进行拍照,获得冠层结构(林隙分数、叶面积指数、叶倾角)和林下光照(冠下直射光量子通量密度PPFD、冠下散射PPFD、冠下总辐射PPFD)。结果表明:1)各林分灌草层在物种丰富度、多样性、均匀度方面具有一定差异,其中:在物种丰富度方面,5种林分草本层都要高于灌木层,且通过单因素方差分析发现个别林分之间存在极显著差异;在物种多样性方面,除白桦林外,其他几种林分草本层均优于灌木层;在物种均匀度方面,沙棘林灌木层最低,青海云杉林在草本层中最低;青海云杉落叶松混交林在物种多样性各指标方面要高于单纯的青海云杉林和落叶松林。2)通过典型分析发现,冠层结构和林下光照之间有显著性关系,且林隙分数和林下总光照在冠层结构和林下光照2组变量中权重最高;林隙分数与灌木层物种多样性指数和均匀度指数之间呈极显著负相关,与灌木层物种丰富度之间相关关系不显著;林隙分数与草本层各多样性指标均呈不显著负相关;冠下总辐射与草本层各多样性指数之间呈显著性正相关。3)光照对草本层生长发育的作用显著高于冠层结构;而冠层结构特别是林隙分数影响着灌木层的形成,因灌木层对光照的需求低于草本层。 相似文献
9.
对福建省华安县公路建设项目植被现状进行调查,结果表明:现状植被生态类型除农田耕地、茶园、竹林、果林和杉木林、巨尾桉林外,余为次生杂生性灌草植被,植物区系成分和群落类型均属广布性的种类与群落类型。根据调查,果林、竹林、杉木、巨尾桉植物群落结构简单,林下植物较少,一般灌木层较为稀疏。物种多样性指数表明,评价范围内乔木层和灌木层的多样性指数较低。 相似文献
10.
晋西黄土区刺槐林种植密度对植被生长状况的影响 总被引：4，自引：0，他引：4
通过对山西省方山县土桥沟流域刺槐人工林植被生长指标的比较研究,分析了不同密度刺槐人工林的生长状况,以期为该区刺槐人工林的经营管理提供理论依据和技术支持.研究结果表明,同是林龄为20 a的刺槐人工林,高密度林分内林木的树高、冠幅等生长指标值,均比低密度林分内的低,但郁闭度要比低密度林分高;密度大的林分胸径普遍较小,随着林分密度的降低,胸径逐渐增大.刺槐林下灌木层和草本层植被的平均高度、盖度、生物量、物种丰富度都随着林分密度的降低而升高;各林分林下植被层的含水量也存在着随林分密度的降低而升高的趋势.从人工林的生长状况来看,晋西半干旱黄土丘陵沟壑区刺槐人工林的适宜密度为1667株/hm2. 相似文献
11.
Xiaoming Zou 《Biology and Fertility of Soils》1993,15(1):35-38
Summary Tree species differ in the quantity and quality of litter produced, and these differences may significantly affect ecosystem structure and function. I examined the importance of tree species in determining earthworm densities in replicated stands of Eucalyptus saligna Sm. and Albizia falcataria (L.) Fosberg, and in mixed stands (25% albizia and 75% eucalyptus). Mean earthworm densities ranged from 92 m-2 in the pure eucalyptus, to 281 m-2 in the mixture, and a maximum of 469 m-2 in the pure albizia stands. Only two earthworm species were present, Pontoscolex corethrurus and Amynthas gracilis. Leaf biomass on the forest floor was highest in the pure eucalyptus and lowest in the pure albizia stands, whereas the annual fine litterfall production was lowest in the pure eucalyptus and highest in the albizia stands. The N content of fine litterfall was correlated positively with earthworm density, and the fine litterfall biomass: N ratio was correlated negatively with earthworm density. Greater leaf biomass on the forest floor under eucalyptus stands despite lower rates of litterfall suggests that litter quality, rather than litter quantity, was primarily responsible for the greater earthworm density in the albizia stands. Some biogeochemical effects of tree species in the tropics may be mediated through effects on earthworm populations. 相似文献
12.
K. R. Islam M. Kamaluddin M. K. Bhuiyan Abu Badruddin 《Land Degradation \u0026amp; Development》1999,10(3):241-249
Exotic Acacia arabica, Acacia Auriculiformis, Eucalyptus camaldulensis, and Pinus caribaea, and indigenous Albizia lebbek, Cassia siamea, Chikrassia Tabularis, and Derris robusta were reforested in tropical semievergreen degraded forest lands to evaluate their capability of survival, growth, and biomass production in energy plantations. Three years after reforestation, significant variations in growth and biomass yield production were observed within each category of forest species. Both exotic and indigenous forest species had shown similar capability in the biomass production. Plant height was found a better predictor of biomass production than diameter at breast height. There have been improvements in soil properties under reforestation. Among the forest species, indigenous Cassia siamea and Derris robusta, and exotic Acacia auriculiformis were found highly adaptable, fast-growing, productive, and site improving, suitable for reforestation of degraded lands. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
13.
《Soil Science and Plant Nutrition》2013,59(1):132-141
Abstract The present study described the relationship between growth and soil physico-chemical properties in Eucalyptus camaldulensis (Myrtaceae) and Pinus caribaea (Pinaceae), two important species in Nigerian forest recovery programs. The study sites were located in a 17-year-old plantation in a Northern Nigeria forest reserve. The soils at the study sites were nutrient poor compared with other plantations. Growth of E. camaldulensis was positively correlated with exchangeable K content in soils 0–20 cm deep, and negatively correlated with total N and exchangeable Na in soils 20–150 cm deep. Growth of P. caribaea was positively correlated with available P in soils 0–20 cm deep, and volumetric water content in soils 20–150 cm deep. Soils in the top layers were very hard and plinthite layers were well developed at shallow soil depths at most sites. E. camaldulensis exhibited a comparatively high survival rate, and its growth was comparable to that in other plantations. However, the survival rates of P. caribaea were low and its growth was lower than that in other plantations. The survival rate of E. camaldulensis was lower at sites where plinthite layers were found within 50.8 cm of the surface. These results indicated that E. camaldulensis is suitable for afforestation in Northern Nigeria. However, it is not recommended for sites where the plinthite layer occurs at shallow soil depths. 相似文献
14.
Plant canopy effects on litter accumulation and soil microbial biomass in two temperate forests 总被引：2，自引：0，他引：2
The objective of this study was to determine whether differences in canopy structure and litter composition affect soil characteristics
and microbial activity in oak versus mixed fir-beech stands. Mean litter biomass was greater in mixed fir-beech stands (51.9t
ha−1) compared to oak stands (15.7t ha−1). Canopy leaf area was also significantly larger in mixed stands (1.96m2 m−2) than in oak stands (1.73m2 m−2). Soil organic carbon (C
org) and moisture were greater in mixed fir-beech stands, probably as a result of increased cover. Soil microbial biomass carbon
(C
mic), nitrogen (N
mic), and total soil nitrogen (N
tot) increased slightly in the mixed stand, although this difference was not significant. Overall, mixed stands showed a higher
mean C
org/N
tot ratio (22.73) compared to oak stands (16.39), indicating relatively low rate of carbon mineralization. In addition, the percentage
of organic C present as C
mic in the surface soil decreased from 3.17% in the oak stand to 2.26% in the mixed stand, suggesting that fir-beech litter may
be less suitable as a microbial substrate than oak litter. 相似文献
15.
S. M. Reichman N. W. Menzies C. J. Asher D. R. Mulligan 《Journal of plant nutrition》2013,36(6):1127-1141
ABSTRACT In Australia, metal-contaminated sites, including those with elevated levels of copper (Cu), are frequently revegetated with endemic plants. Little is known about the responses of Australian plants to excess Cu. Acacia holosericea, Eucalyptus crebra, Eucalyptus camaldulensis, and Melaleuca leucadendra were grown in solution culture with six Cu treatments (0.1 to 40 μ M). While A. holosericea was the most tolerant to excess Cu, all of the species tested were sensitive to excess Cu when compared with exotic tree and agricultural species. The critical external concentrations for toxicity were < 0.7 μM for all species tested. There was little differentiation between shoot-tissue Cu concentrations in normal versus treated plants, thus, the derivation of critical shoot concentrations was possible only for the most tolerant species, A. holosericea. Critical root Cu concentrations were approximately 210 μg g?1 (A. holosericea), 150 μ g g?1 (E. crebra), 25 μ g g?1 (E. camaldulensis), and 165 μ g g?1 (M. leucadendra). These results provide the first comprehensive combination of growth responses, critical concentrations, and toxicity symptoms for three important Australian genera for use in the management of Cu-contaminated sites. 相似文献
16.
高寒沙区人工沙棘对风沙危害的生态响应 总被引：1，自引：0，他引：1
[目的]沙棘(Hippophae rhamnoides)是高寒沙区典型的优良治沙物种,其风沙危害的抗逆性研究对沙棘生态适应性机理及高寒沙区生物治沙工作具有重大的探究与指导意义。[方法]对不同类型沙丘不同林龄的人工沙棘林进行了样方调查和风沙活动监测。[结果]沙棘群落特征与地表风蚀强度变化具有时空同步性。轻度风蚀与中轻度沙埋现象有助于沙棘的生长与群落的发展,固定与半固定沙丘人工沙棘的株高冠幅均为流动型沙丘沙棘的3~6倍;沙棘各生长指标与株下蚀积深度具有显著的二次函数拟合关系,8年生沙棘生长的最佳沙埋深度在30—40cm。2008—2016年,各沙丘沙棘群落特征与局地输沙率、粗糙度、蚀积深度等风沙活动特征分别表现出显著的指数递减、多函数递增和二次函数先增后加减的变化规律。[结论]高寒沙区沙棘对风沙危害的响应特征反映了沙棘良好的风沙适应能力,也指示沙棘造林技术需要注重立地条件选取、造林结构改进与多物种配置,保障沙棘的稳定生长势态与良好的生态修复效益。 相似文献
17.
Seasonal distribution of Xenylla brevispina (Collembola) in the canopy and soil habitat of a Cryptomeria japonica plantation 总被引：1，自引：0，他引：1
We investigated the life cycle and habitat use of an arboreal collembolan species, Xenylla brevispina, in the canopy and soil of a conifer (Cryptomeria japonica D. Don) plantation. The adaptive significance of migration between arboreal and soil habitats in the maintenance of its population in relation to the vertical structure of the forest is discussed. We sampled dead branches with foliage in the canopy (canopy litter) and on the forest-floor (soil litter). X. brevispina had one generation a year throughout the 3 years of the study. The mean densities of X. brevispina were similar in the canopy litter (0.06 to 14.57 g−1 dry weight) and the soil litter (0.44 to 18.99 g−1 dry weight). Seasonal patterns of density and relative abundance indicate that individuals of X. brevispina in the canopy were closely associated with those in the soil. These results suggest that vertical migration between the canopy and the soil might be a strategy allowing X. brevispina to be a predominant collembolan species in this forest. 相似文献
18.
Growth and soil N supply in young Eucalyptus tereticornis stands at two sites in Kerala, India, were examined in response to cover cropping with three legume species (Pueraria phaseoloides, Stylosanthes hamata, and Mucuna bracteata). The effects of legume residues on soil N supply were investigated in a long-term (392 day) laboratory incubation using leaching micro-lysimeters. Residues from the eucalypt and legume species had different rates of net N release during the laboratory incubation. Net N release was significantly related to residue N concentration (R2 =0.94), the C:N ratio (R2 =0.91), the lignin:N ratio (R2 =0.83), and the (lignin + soluble polyphenol):N ratio (R2 =0.95). Nitrogen release rates declined in the order Mucuna > Pueraria > Eucalyptus > Stylosanthes. There was no net N release from Stylosanthes residues during the 392-day laboratory incubation, whereas Mucuna and Pueraria released N throughout the incubation period. Net N release from mixtures of legume and eucalypt residues was not additive in the early phase of the incubation, probably because eucalypt residues initially immobilized a portion of the legume-derived N in addition to the soil-derived N. Legume establishment had no significant effect on tree growth at one site (Kayampoovam), but resulted in depressed tree growth at the lower rainfall site (Punnala) at 18 months. There were no significant treatment effects on growth at Punnala after that time. Cover cropping with legumes during the early phase of forest plantation growth may be a useful mechanism to enhance soil N supply and optimize the synchrony between N supply and tree N uptake. Although these effects did not translate into improved plantation growth in the 3 years of this study, improved soil organic matter and N fertility may help ensure sustainable productivity over several rotations in the future. This study showed that the effect of legumes on N dynamics varies markedly with legume species. This, together with other factors (e.g. competition with trees, N fixation capacity), will be important in selecting suitable species for cover cropping in forest plantations. 相似文献