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1.
Effects of microsite light availability on the growth and survival of transplantedQuercus serrata Thunb. seedlings in aMiscanthus sinensis Anderss. grass canopy were investigated by a “plant's eye view” approach. Diffuse site factors, i.e., the fractional transmissions
of diffuse photosynthetic photon flux density, were estimated at 15 cm aboveground in 108 microsites where the seedlings grew.
Microsite diffuse site factors were significantly different between surviving and dead seedlings during the experiment period
from April to October (F[1,14]=10.9, P<0.01). Relative growth rate of dry weight for individual seedlings positively depended on the diffuse site factors
(r2=0.482, P<0.001 in May; r2=0.312, P<0.001 in October). Only 16 seedlings produced their second stem flush within the grass canopy. The ratio of height
to dry weight of the second stem flush was significantly higher for the seedlings grew in shady microsites than for those
in less shady microsites (r2=0,471, P<0.01 in May). This study suggests that the microsite heterogeneity of light availability is one of the important
factors affecting the establishment of tree seedlings in patchy grasslands. 相似文献
2.
Fluctuation of photosynthetic photon flux density within aMiscanthus sinensis canopy 总被引:2,自引:0,他引:2
Detailed measurements of diurnal variations in photosynthetic photon flux density (PPFD) were made at seven locations within
the canopy of aMiscanthus sinensis grassland to evaluate the light conditions of microsites for heliophilic tree seedlings. Multiple regression analysis revealed
that the short-term light fluctuation on a clear day was highly dependent on the wind speed and solar elevation angle, whereas
on a cloudy day it was mainly determined by the PPFD incident from above the canopy.
The relative PPFD at 40 cm aboveground varied from 0.065 to 0.252, depending on sky conditions and the sensor's position in
relation to clumped patches ofM. sinensis. On a clear day, the proportion of PPFD readings above 100 μmol·m−2·s−1 contributed by sunflecks ranged between 25.4% and 82.0%. Computer simulation showed that the contribution of sunflecks to
the daily carbon gain ofQuercus serrata seedlings may range from 11% to 65%.
The mean relative PPFD measured under diffuse light conditions was linearly related to the daily total PPFD and the daily
carbon gain by single leaves ofQ. serrata seedlings. This suggests that the relative PPFD under diffuse light conditions provides an appropriate measure of site-specific
light availability within a grass canopy. 相似文献
3.
Summary Factors affecting seedling Virola surinamensis (Myristicaceae) survival and growth were investigated on Barro Colorado Island, Panama. Seedlings planted 3 months after germination were monitored in treefall gaps and understory using 2.25 ha irrigated and control plots through the first dry season. During the dry season, irrigated plants in gaps increased total leaf area significantly more than did irrigated plants in the shaded understory. Over the same dry season, control plants in gaps and in the shaded understory lost similar amounts of leaf area. Seedlings in understory were suppressed in stem height and biomass in both irrigated and control plots; these measures were greater in gaps and greatest in irrigated gaps (height). Roots were similar in length in all treatments, but greater in biomass in gaps than understory due to greater proliferation of secondary roots in control and irrigated gaps than in control and irrigated understory. This experiment demonstrates both water and light limitation during the first dry season after germination. V. surinamensis seedlings are capable of survival and modest growth of leaf area in the deep shade of the understory in moist locations; they are severely disadvantaged in shaded understory subject to drought, where most seeds fall and most seedlings establish. The broken canopy of a gap allows shoot and consequently root growth that permits seedlings to survive seasonal drought. 相似文献
4.
Three deciduous broad-leaved trees, Quercus serrata, Castanea crenata and Carpinus laxiflora, were the main constituents of a coppice forest in central Japan. The shoot elongation and leaf emergence modes of both saplings
and the canopy of the three species were investigated. The shoot elongation modes of Q. serrata and C. crenata were the same in saplings and the upper layer of the canopy. The second shoots of these two species were formed after the
first shoots were elongated. C. laxiflora was different between saplings and the upper layer of the canopy. In saplings, only the first shoots took a long time to
elongate. In the upper canopy layer, higher order shoots were formed in the same way as in the other two species. In the lower
layer of the canopy, all three species showed the same shoot elongation mode, in which only the first shoot and its duration
of elongation was short. Leaf longevity, individual leaf area, leaf mass per unit leaf area and the stem mass per unit stem
length of C. laxiflora were significantly shorter or significantly smaller than those of Q. serrata and C. crenata. The length of the stem per unit leaf area of C. laxiflora was three times that of Q. serrata and five times that of C. crenata. The elongation growth of C. laxiflora was highly efficient as it occurred with a small leaf area. The shoot dynamics and the shoot structure of C. laxiflora are more suitable for elongation growth than in Q. serrata and C. crenata. Furthermore, the shoot structures of the three species were compared and ecological characteristics of the three species
are discussed.
Received: 29 September 1998 / Accepted: 17 September 1999 相似文献
5.
Akio Takenaka 《Ecological Research》1986,1(2):129-140
Ecophysiological comparisons were made of the growth and photosynthetic characteristics between seedlings of deciduousQuercus serrata and evergreenQuercus myrsinaefolia. Q. myrsinaefolia seedlings naturally occurring in secondary coppice forests showed exponential-like growth in height with age, while sympatricQ. serrata seedlings were considerably smaller in height, their growth being limited by shortage of light. The photosynthetic characteristics
measured under laboratory conditions showed no bases for the differences in growth between the two species on the forest floor:
Light compensation points of the seedlings raised under 5% daylight were almost identical for the two species, being about
6.0 μE·m−2·s−1. Growth analysis of seedlings planted in a coppice forest showed that bothQ. serrata andQ. myrsinaefolia could hardly grow during the summer under the shrub layer, when relative photon flux density (RPFD) was 0.9±0.5%. In the
winter, when RPFD under the leafless canopy increased to 29.3±2.7%, the dry matter production of the evergreen seedlings ofQ. myrsinaefolia was much improved. Current-year seedlings of the species showed NAR of 0.102±0.021 g·dm−2·mo−1 during the winter. Temperature dependency of photosynthesis and increment of leaf temperature by direct solar beam also indicated
active photosynthesis ofQ. myrsinaefolia on the forest floor during the winter. 相似文献
6.
Akifumi Makita Yasuo Konno Noboru Fujita Ken′ichi Takada Etsuji Hamabata 《Ecological Research》1993,8(2):215-224
The recovery process of aSasa tsuboiana population after a mass flowering and death in 1977 was investigated by 15 years of observation in the Hira Mountains, Kinki
district, western Japan. Seed production was high (6600–13 800 seeds m−2 inSasa plots and 3900 seeds m−2 in a forest plot) but emergent seedling density was low (14–21 seedlings m−2), probably because of seed predation byMicrotus montebelli occurring between seed shedding and the next spring. The seedling density had decreased further by the next year and theS. tsuboiana population recovered from only a limited number of seedlings. In spite of such a low initial density, theS. tsuboiana population was able to regenerate successfully and attained the previous full stand height in 7–16 years.Miscantbus sinensis invaded and delayed the recovery ofS. tsuboiana in one plot, butS. tsuboiana became dominant as it caught up with the height ofM. sinensis. Seedling growth patterns, such as frequent tillering, the onset of rhizome extension in the early stage of seedling growth
and frequent culm production from rhizomes, played important roles in the successful regeneration ofS. tsuboiana. 相似文献
7.
Takahide Kurosawa 《Journal of plant research》1995,108(3):277-281
Resource allocation and the seasonal change of stem length inEuphorbia lasiocaula Boiss. andE. sinanensis (Hurusawa) T. Kurosawa et H. Ohashi were examined in 10 populations on hills in Miyagi Prefecture, northern Japan. Differences
were found in the diameter of stem, stem/leaf ratio of dry weight, vegetative dry weight/leaf area, and the beginning, end
and duration of stem growth.Euphorbia lasiocaula has a thicker stem, a larger stem/ leaf ratio, a larger vegetative dry weight/leaf area, a later beginning and end of stem
growth and a longer period of stem growth thanE. sinanensis. These differences support the relationships among plant height, resource allocation and phenology predicted by the mathematical
models of Givnish (1982) and Sakai (1991, 1994). The tall and thick stems ofE. lasiocaula are considered to be favorable for capturing sunlight in grassy places, causing it to allocate much of its resources to the
stems. On the other hand,E. sinanensis is considered to be adapted to deciduous forest floors or forest margins because it completes growing before it is shaded
by canopy trees or by tall herbs, which is enabled by the larger allocation of resources to the leaves. 相似文献
8.
Mamoru Kanzaki 《Journal of plant research》1984,97(3):297-311
The regeneration process of a subalpine coniferous forest, a mixed forest ofTsuga diversifolia (dominant species),Abies veitchii, Abies mariessi, andPicea jezoensis var.hondoensis, was studied on the basis of annual ring data. The age class distribution was discontinuous and four age groups occurred
in the study plot (30m×30m). The canopy layer was a mosaic of patches (83.8–133.7 m2 patch area), which had different mean ages. The recruitment of canopy trees was carried out only by advance regeneration
in the plot. The diameter growth ofAbies andPicea exceeded diameter growth ofTsuga in the gap.Abies lived for 200–300 years and their trunks were susceptible to heart rot.Picea lived for 300–400 years andTsuga for more than 400 years. The regeneration process derived from the analysis of the plot consisted of three phases leading
to the development of a even-aged patch; (1) the establishment of saplings before a gap opening, (2) the opening of a gap
in the canopy and repair of the canopy by advance regenerated saplings dominated by rapid growth species,Abies andPicea, and (3) the dying off of canopy trees as each species reached the end of its life-span, resulting in pure patches of long-livedTsuga. 相似文献
9.
Livestock grazing represents a major human disturbance to grasslands throughout the world. We evaluated the effects of long-term
grazing (>20 years) on a dominant perennial grass species, Leymus chinensis (Trin.) Tzvel., in the semiarid grassland of Inner Mongolia, China, in terms of its morphological and functional responses.
L. chinensis, one of the most abundant species in semiarid grassland, had significantly smaller leaf area, fewer vegetative tillers and
shorter shoot internodes length, but significantly greater specific leaf area for the individuals in the grazing plot than
those in the exclosure (grazing-free) plot. Long-term grazing also altered the relative distribution of biomass to leaves,
roots and rhizomes. The biomass, coverage and the number of species were lower in the grazing plot by 50–70% in comparison
with those in the grazing-free plot. In addition, the long-term grazing substantively decreased the physiological capacities
of this grass species, including significantly lower net photosynthetic rate, apparent quantum efficiency, photochemical efficiency
of PSII and water use efficiency. Significantly higher stable oxygen isotope ratios (δ
18O) of the soil water in the grazing plot than those in the grazing-free plot indicated a much higher soil evaporation in the
grazing plot because of less litter coverage. Seasonal patterns in the δ
18O values of the stem water of L. chinensis and three other common species in the grazing and grazing-free plots indicated that plants in the grazing and grazing-free
plots might shift their water sources differently from a dry month (June) to a wet month (August). This study illustrated
the importance of using different approaches to study the possible responses of grass species in arid regions to human disturbances,
such as long-term grazing. 相似文献
10.
Josef Urban F. Tatarinov N. Nadezhdina J. Čermák R. Ceulemans 《Trees - Structure and Function》2009,23(2):391-399
A detailed biometrical study of the exotic understorey invader Prunus serotina (Ehrh.) was carried out in a mixed coniferous forest stand in northern Belgium. Based on detailed destructive measurements
of eight selected model trees, allometric relations of tree height, crown projected area, woody and leaf dry mass and leaf
area on tree diameter at breast height (DBH) were derived. The scaling-up procedure from the tree to the stand level was done
using the frequency distribution of DBH obtained at the selected experimental plot. The vertical and radial distributions
of the tree foliage were estimated by the “cloud” technique. The vertical profile of leaf area showed a bimodal distribution
pattern with maxima at heights of 4 and 6 m above the ground. The leaf area index (LAI) of the understorey Prunus serotina as estimated by the described up-scaling procedure (5.1) was significantly higher than the LAI (2.6) as measured by a plant
canopy analyser and was also significantly higher than the LAI of the overstorey species Scots pine (1.5–3.0). The LAI of
a neighbouring Rhododendron understorey reached only 1.25. This study emphasises the importance of an exotic understorey species in the total leaf area
of mixed coniferous forests which might have important implications for the energy and mass exchanges of the entire forest. 相似文献
11.
高寒草甸高原早熟禾个体性状对放牧与围封的响应 总被引:1,自引:0,他引:1
植物对放牧的响应是植物在响应过程中为生存和繁殖所形成的适应策略,研究植物表型反应对揭示草原生态系统的放牧响应机制具有重要意义。以青藏高原高寒草甸主要植物高原早熟禾(Poa alpigena)为研究对象,通过放牧和围封试验,研究其个体性状对放牧与围封的响应,旨在为草原生态系统放牧机制提供理论依据。结果表明:1)在长期放牧干扰下,除叶片数和根重外,其他性状株高、分枝数、叶长、叶宽、叶面积、茎粗、茎长、根长、根粗、穗长、总叶质量、单叶质量、茎重、穗重、全株重均出现显著变小的特征(P0.05);而短期围封对于高原早熟禾叶长、叶宽、总叶质量、单叶质量、茎重、穗重、根重等功能性状的恢复效果并不显著(P0.05),表明放牧退化草原植物性状具有保守性;2)通过构建高原早熟禾性状可塑性变化谱,发现穗重、茎重、全株重、分蘖数、茎长、株高等可塑性幅度较大,为放牧响应的敏感指标,叶片数、叶宽、茎粗、根粗的可塑性变化幅度较小,为惰性性状。 相似文献
12.
Akira Haraguchi 《Journal of plant research》1993,106(1):31-35
Phenotypic and phenological properties ofMenyanthes trifoliata L. were investigated within and outside of aPhragmites australis (Cav.) Trin. ex. Steud. canopy in a floating peat mat in Mizorogaike Pond, Central Japan. Under theP. australis canopy,M. trifoliata adjusted its phenotypic properties to the conditions of decreased light by increasing leaf blade area, decreasing leaf blade
thickness and elongating petioles. The earlier expansion of leaves ofM. trifoliata within theP. australis community than outside the community was advantageous in terms of allowing the plant in the mixed community to produce as
much dry matter as possible before the foliage ofP. australis could overgrow it. Despite the harmful effect ofP. australis onM. trifoliata's vegetative growth and reproduction, the latter species can persist in aP. australis community by changing its phenotypic and phenological properties. 相似文献
13.
To examine the small-scale variations in light and space availability, photon flux density (PFD) at 20 cm aboveground was
measured at 2 cm intervals along each of four 160 cm horizontal transects under an overcast sky condition in aMiscanthus sinensis Anderss grass canopy. Two characteristics were identified for the variation patterns of PFD penetration along transects;
the predominant variations of PFD penetration prevailed at the scales usually larger than 10 cm, and the point-to-point fluctuations
occurred everywhere. Spatial autocorrelation coefficients of PFD penetration along transects were highly positive (>0.5) over
the lag distances from 2 to 6 cm, while those of the point-to-point fluctuations exhibited a random series. Spectrum analysis
showed a higher spectrum density at the lower frequency, that is, at the higher periodicity, which indicated that the variation
of PFD penetration was mainly due to the patchy distribution of grass canopy. PFD-available spans along the transects and
contour maps were examined to evaluate the microsites fulfilling both PFD and space requirements in the growth ofQuercus serrata Thunb. seedlings. More than 75% of the spans with PFD penetration constantly exceeding 0.04 were shorter than 8 cm, which
suggests that a large proportion of high PFD spots may not be used byQ. serrata seedlings in the grass canopy because of the limitation of availability in space. The spatial heterogeneity of PFD at small
scales may be of great importance in the succession ofM. sinensis grass communities. 相似文献
14.
Chun-Wang Xiao Osbert J. Sun Guang-Sheng Zhou Jing-Zhu Zhao Gang Wu 《Trees - Structure and Function》2005,19(6):712-721
We studied the responses of leaf water potential (Ψw), morphology, biomass accumulation and allocation, and canopy productivity index (CPI) to the combined effects of elevated
CO2 and drought stress in Caragana intermedia seedlings. Seedlings were grown at two CO2 concentrations (350 and 700 μmol mol−1) interacted with three water regimes (60–70%, 45–55%, and 30–40% of field capacity of soil). Elevated CO2 significantly increased Ψw, decreased specific leaf area (SLA) and leaf area ratio (LAR) of drought-stressed seedlings, and increased tree height, basal
diameter, shoot biomass, root biomass as well as total biomass under the all the three water regimes. Growth responses to
elevated CO2 were greater in well-watered seedlings than in drought-stressed seedlings. CPI was significantly increased by elevated CO2, and the increase in CPI became stronger as the level of drought stress increased. There were significant interactions between
elevated CO2 and drought stress on leaf water potential, basal diameter, leaf area, and biomass accumulation. Our results suggest that
elevated CO2 may enhance drought avoidance and improved water relations, thus weakening the effect of drought stress on growth of C. intermedia seedings. 相似文献
15.
Summary Water willow and grey alder were grown on a raised sphagnum bog in central Sweden. The stands were intensively treated by daily irrigation and fertilization during the growing period in order to improve site fertility. After a 2-year establishment period high production rates were achieved in willow stands, 0.8 kg stem dry weight m–2 year–1 on current plus one (C+1) year old shoots. In these stands the canopy was closed with a leaf area index (LAI) that peaked at approximately 7. The canopy in the alder stand did not close during the initial 3 years of growth and the measured production rate was relatively low, at approximately 0.4 kg dry weight m–2 year –1 in the last year. The leaf nitrogen content was 3%–4% of dry weight during the summer and the other studied mineral elements were in almost optimal proportion to nitrogen. This was considered to be an effect of the intensive fertilization regime. Above-ground production close to maximum yield was attained in the prevailing conditions of soil, climate and biomass partitioning. 相似文献
16.
The behaviour and distribution of adultCoccinella septempunctata L. (Coleoptera: Coccinellidae) were recorded in two plots of winter wheat infested with the cereal aphidsSitobion avenae (F.) andMetopolophium dirhodum (Walk.) (Homoptera: Aphididae). One plot was sprayed with the pyrethroid insecticide deltamethrin at a rate of 6.25 g a.i./ha
and the other was left unsprayed. Single ladybird beetles were released sequentially on the ground at the centre of the sprayed
and unsprayed plots and their behaviour and position in the crop canopy were recorded at 30 second intervals for a total of
15 min per beetle. Assessments, with fresh beetles, continued for four days after spray application with a total of eighty
ladybird beetles observed. The 15 min period was selected to avoid lethal effects and no ladybird beetles were killed or knocked
down as a result of exposure to deltamethrin residues during this period. Significant differences were found between the overall
behaviour patterns ofC. septempunctata in the untreated and deltamethrin treated plots up to three days after the spray application. Ladybird beetles exposed to
deltamethrin residues were observed to walk and groom significantly more frequently and to rest significantly less frequently
than those in the unsprayed plot. Significant differences were also found between the observed distribution of ladybird beetles
in the sprayed and unsprayed crop canopies, with higher numbers of observations towards the bottom of the crop canopy and
on the ground in the deltamethrin treated plot than in the untreated plot during the first two days after deltamethrin application.
Upon the foliage itself, ladybird beetles were observed significantly more frequently on the abaxial leaf surface in the deltamethrin
treated crop compared with the untreated crop. The results are discussed in terms of possible evidence for the repellency
of deltamethrin toC. septempunctata and also the implications for integrated pest management of changes in predator behaviour and crop distribution resulting
from sub-lethal uptake of insecticides. 相似文献
17.
Every other week over their second growing season, stem height, collar diameter, shoot and root dry masses, number of lateral roots and length of the tap root were measured on nursery grown seedlings ofAbies balsamea L. Mill.,Pinus banksiana Lamb.,Pinus resinosa Ait.,Picea mariana Mill. BSP andPicea glauca Moench Voss. Root elongation, branching and mycorrhizal development were also recorded.Given species showed distinct seasonal growth patterns. The rate and timing of maximum root growth (mg/dry weight/week) differed markedly between species.Except for the increase in height ofPinus banksiana, root and shoot growth were not negatively correlated.The results are discussed in relation to the performance of tree seedlings in the nursery. 相似文献
18.
Yasuo Suto 《Mycoscience》1999,40(6):509-516
A leaf spot disease called frosty mildew was observed onChaenomeles sinensis throughout Japan. Small brown spots with white tufts occurred followed by successive defoliation. On the fallen leaves, minute
black dots are formed. The causal fungus was regarded as a new species ofMycosphaerella, M. chaenomelis, andCercosporella chaenomelis in anamorph. Pathogenicity of the fungus was confirmed only inC. sinensis by inoculation experiments. Colonies of the fungus grew well on potato sucrose agar, and grew at 10–30°C with an optimum
temperature of 25°C. The fungus overwintered on the fallen diseased leaves in the form of pseudothecia, and ascospores served
as the primary infection source from April to June. 相似文献
19.
为探究中国沙棘对土壤镉(Cd)胁迫的性别响应差异,该研究以中国沙棘2年生幼苗为材料,利用盆栽试验研究在不同浓度Cd处理下(0(CK)、25、50、100和200 mg·kg-1)雌、雄株幼苗的生长、叶片生理特性以及Cd富集特征的差异。结果表明:(1)Cd处理下中国沙棘幼苗雌、雄株的株高和基径生长以及各器官生物量均表现出低浓度(<50 mg·kg-1)促进,高浓度(> 100 mg·kg-1)抑制的现象;低浓度Cd处理下雌株的株高、基径增长率和生物量的增幅均高于雄株;高浓度Cd处理下(200 mg·kg-1)雄株株高增长率、叶生物量和总生物量分别较CK显著降低,而雌株均未显著下降。(2)随着Cd浓度升高,雌、雄株叶片光合色素含量和抗氧化酶活性呈先升后降的变化趋势,丙二醛(MDA)和渗透调节物质含量呈上升趋势;Cd浓度为50~200 mg·kg-1时,雌株叶片的光合色素含量、抗氧化酶活性和渗透调节物质含量均高于雄株,而MDA含量始终低于雄株。(3)随着Cd浓度升高,雌、... 相似文献
20.
Emiko Maruta 《Ecological Research》1994,9(2):205-213
Seedling establishment ofPolygonum cuspidatum (Seib. et Zucc.) andPolygonum weyrichii (F. Schmit) var.alpinum (Maxim.), dominant early-successional species in a volcanic gravel area on Mt Fuji, Japan, was compared for current-year
seedlings at 2500 m a.s.l. The rate of survival in the first winter after germination at 2500 m was 2% and 24% forP. cuspidatum andP. weyrichii seedlings, respectively, and correlated with the upper distribution limit of each (2500–2600 m forP. cuspidatum; 3200–3300 m forP. weyrichii). The critical size for survival was 12 mg dry weight for overwintering current-year seedlings of both species. At 2500 m,
the percentage of seedlings that attained the critical size for survival at the end of the first growing season was 19% and
85% forP. cuspidatum andP. weyrichii, respectively. Growth curves indicated that the larger-seeded characteristic ofP. weyrichii contributed to larger end-of-season size and resulted in higher rate of seedling survival at 2500 m, compared with smaller-seededP. cuspidatum. Current-year seedlings ofP. weyrichii, at least up to 3250 m, attained the first year annual growth critical for overwintering and therefore for successful seedling
establishment, due to the large-seeded characteristic. At the top (3770 m) beyond the upper distribution limit ofP. weyrichii, most seedlings raised artificially failed to attain the critical size for survival in the first growing period due to the
reduced growing period. Failure of seedling establishment would thus appear to restrict the distribution of the species at
altitudes higher than 3300 m. 相似文献