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1.
Anoplophora glabripennis (Motsch.) is a woodboring beetle that is native to China. For a long time, it caused great losses in the economy and ecology
of northwest China. Attractants are often used to control insects. The volatiles emitted from the host plant play an important
role for insects in finding their target. To explore the mechanism of selectivity to different host plants, the response of
Anoplophora glabripennis to four different host plants was investigated, which included Acer negundo L., Acer mono Maxim., Acer truncatum Bunge. and Acer platanoides L., and the compounds in the profiles of volatiles were identified from these species. The olfactory responses of Anoplophora glabripennis to the odors of different plants showed preference for certain host plants: Acer negundo, Acer mono and Acer truncatum. The attraction of Acer negundo and Acer mono was significantly different (p<0.05). The attraction of Acer negundo to the insects was stronger than to Acer mono. Acer platanoides neither attracted nor repelled the insects. Compounds in the profiles of volatiles from the above four species were identified
and quantified by gas chromatography-mass spectrometry (GC-MS) equipped with a CP-4020 termodesorption and cold trap (TCT)
device. The constituents of volatiles and the relative concentrations were different in the four host species. The amount
of ketones, alcohols and aldehydes in the four plants showed the same order: Acer negundo<Acer mono<Acer truncatum<Acer platanoides, while that of alkanes and esters was quiet different: Acer negundo L.>Acer mono Maxim.>Acer truncatum Bunge.>Acer platanoides L.. 1-penten-3-ol, ocimene and trans-Germanylacetone were repellent to Anoplophora glabripennis. 1-penten-3-ol and trans-gerranylacetone were identified in Acer platanoides, and Ocimene was the most attractive to Anoplophora glabripennis among these species. The extent of feeding damage caused by Anoplophora glabripennis differed among four species. The sequences was Acer negundo>Acer mono>Acer truncatum>Acer platanoides. The epidermal hairs of the four host plants revealed that the extent of damage was related to the physical characteristics
of the host plants.
__________
Translated from Acta Ecologica Sinica, 2006, 26(3): 870–877 [译自:生态学报] 相似文献
2.
Recent studies suggest that physiological traits can be affected by tree size due to stronger hydraulic limitation in taller
trees. As trees vary greatly in size, both within and among species, the adaptive responses to hydraulic limitation may be
different among species with different maximum sizes. To investigate this, we explored size-dependency in photosynthetic and
hydraulic parameters of three Acer species (Acer mono Maxim., Acer amoenum Carr and Acer japonicum Thunb.) using trees of various sizes under well-lit conditions. Leaf stomatal conductance of the Acer species decreased with tree size, implying that water supply to leaves decreases as trees grow. In contrast, content of nitrogen
increased with tree size, which may compensate for the decrease in stomatal conductance to maintain the photosynthetic rate.
Although the increase in nitrogen and leaf mass per area were larger in species with larger statures, the size-dependency
in stomatal conductance was not different among species, and photosynthetic rate and hydraulic conductance were maintained
in the three Acer species. Therefore, we suggest that hydraulic limitation on gas exchange does not necessarily depend on the maximum height
of the species and that maintenance of photosynthesis and hydraulic properties is a fundamental physiological process during
tree growth. 相似文献
3.
Relationships among root branch order, carbon, and nitrogen in four temperate species 总被引:19,自引:0,他引:19
The objective of this study was to examine how root length, diameter, specific root length, and root carbon and nitrogen
concentrations were related to root branching patterns. The branching root systems of two temperate tree species, Acer saccharum Marsh. and Fraxinus americana L., and two perennial herbs from horizontal rhizomes, Hydrophyllum canadense L. and Viola pubescens Ait., were quantified by dissecting entire root systems collected from the understory of an A. saccharum-Fagus grandifolia Ehrh. forest. The root systems of each species grew according to a simple branching process, with laterals emerging from
the main roots some distance behind the tip. Root systems normally consisted of only 4–6 branches (orders). Root diameter,
length, and number of branches declined with increasing order and there were significant differences among species. Specific
root length increased with order in all species. Nitrogen concentration increased with order in the trees, but remained constant
in the perennial herbs. More than 75% of the cumulative root length of tree seedling root systems was accounted for by short
(2–10 mm) lateral roots almost always <0.3 mm in diameter. Simple assumptions suggest that many tree roots normally considered
part of the dynamic fine-root pool (e.g., all roots <2.0 mm in diameter) are too large to exhibit rapid rates of production
and mortality. The smallest tree roots may be the least expensive to construct but the most expensive to maintain based on
an increase in N concentration with order.
Received: 25 November 1996 / Accepted: 27 March 1997 相似文献
4.
Long-Term Growth and Succession in Restored and Natural Mangrove Forests in Southwestern Florida 总被引:4,自引:0,他引:4
We compared colonization, growth and succession from 1989 to 2000 in a restored mangrove site and in gap and closed canopy
sites in a natural mangrove forest. The restored site was created in 1982 and planted with Rhizophora mangle (≈2 m−2) propagules. By 1989, Laguncularia racemosa, with densities up to 12.9 tree m−2, was a dominant in all plots, although densities were greater at edge plots relative to inner plots, and near open water
(west plots) relative to further inland (east plots), and in tall mangrove plots relative to scrub plots. Rhizophora mangle (1989 tree densities about 2 m−2) was a codominant in inner and scrub plots, while Avicennia germinans had the lowest densities (<1 tree m−2) in all plots. From 1989 to 2000 L. racemosa experienced reduced recruitment and apparent density-dependent mortality of canopy individuals in plots with high initial
densities. Scrub plots experienced high rates of colonization by R. mangle and L. racemosa, rapid growth in height of all species (1989–1996), followed by a dieoff of L. racemosa in later years (1997–2000) as the canopy came to resemble that of tall mangrove plots. Colonization and growth rates were
lower in gap and closed canopy regions of the natural forest relative to rates in the restored site. After 11 years, densities
of L. racemosa were 10–20× lower and R. mangle slightly less in the gap relative to densities in tall mangrove plots in the restored site at the same age. Although the
restored stand had converged with the natural forest by 2000 in terms of some factors such as species richness, vegetation
cover, litterfall, and light penetration, trees were still much smaller and stem densities much higher. Full development of
mature structure and ecological function will likely require decades more development. 相似文献
5.
Short-Term Effects of Cattle Browsing on Tree Sapling Growth in Mountain Wooded Pastures 总被引:2,自引:0,他引:2
Charlotte Vandenberghe François Freléchoux Marie-Agnès Moravie Fawziah Gadallah Alexandre Buttler 《Plant Ecology》2007,188(2):253-264
Browsing by livestock has been identified as an important factor preventing tree regeneration in wooded pastures. Two field
experiments were performed to investigate the effects of cattle browsing on tree sapling growth in a mountain-wooded pasture.
Two size classes (ca. 12–17 cm and 41–59 cm) of each of 4 species (Picea abies, Abies alba, Acer pseudoplatanus and Fagus sylvatica) were exposed to zero, low and high grazing intensities. We measured the proportion of saplings browsed and the effect of
browsing on growth. A mowing treatment within the zero grazing intensity treatment showed no significant effect on sapling
growth. One percent of the large saplings but 25% of the small saplings escaped browsing. Saplings were better protected when
surrounded by taller vegetation. The proportion of saplings browsed was not significantly different among species although
evergreen tree saplings lost a larger proportion of biomass than deciduous species when browsed. Under grazing, average current-year
shoot production and total aboveground biomass of all species were significantly reduced. Browsing effects tended to be smaller
at the lower grazing intensity. Because the deciduous species were least reduced in aboveground growth, especially under the
low grazing intensity, we conclude that at least in short-term, deciduous species are less affected by cattle browsing. 相似文献
6.
Invasive Plants can Inhibit Native Tree Seedlings: Testing Potential Allelopathic Mechanisms 总被引:3,自引:0,他引:3
The mechanisms by which invasive species affect native communities are not well resolved. For example, invasive plants may
influence other species through competition, altered ecosystem processes, or other pathways. We investigated one potential
mechanism by which invasive plants may harm native species, allelopathy. Specifically, we explored whether native tree species
respond differently to potential allelopathic effects of two invasive plant species. We assessed the separate effects of Lolium arundinaceam (tall fescue) and Elaeagnus umbellata (autumn olive) on three common successional tree species: Acer saccharinum (silver maple), Populus deltoides (eastern cottonwood), and Platanus occidentalis (sycamore). Tall fescue and autumn olive are widely planted and highly invasive or persistent throughout North America where
they often grow in forest edges, old fields, and other sites colonized by pioneering tree species. In an exploratory greenhouse
experiment, we applied aqueous extracts derived from soil, leaf litter, or live leaves to native trees. We compared these
treatments to a sterile water control and also to minced leaves leached in water, a common, but potentially less realistic
method of testing for allelopathy. For all tree species, minced leaves from tall fescue reduced the probability that seedlings
emerged, and minced leaves of autumn olive reduced the number of days to emergence. During other demographic stages, the three
native tree species diverged in their responses to the invasive plants. Platanus occidentalis exhibited the widest range of responses, with reduced root biomass due to minced tissue from both invasive species, reduced
days to emergence and marginally reduced survival from minced tall fescue, and reduced leaf biomass from tall fescue leaf
litter. Populus deltoides appeared insensitive to most extracts, although survival was marginally increased with application of minced or fresh leaf
extracts from autumn olive. In addition, minced tall fescue shortened the time to seedling emergence for Acer saccharinum, potentially a positive effect. Overall, results suggest that allelopathy may be one mechanism underlying the negative impacts
of tall fescue and autumn olive on other plant species, but that effects can depend strongly upon the source of allelochemicals
and the tree species examined. 相似文献
7.
We used clearcut logging in establishing four replicated sizes of canopy openings (0.016, 0.08, 0.4, and 2.0 ha) in a southern Appalachian hardwood forest in 1981 to examine the long-term effects of disturbance size on plant community structure, biomass accumulation, aboveground net primary productivity (NPP), and mode of recovery. The reestablishment of NPP and biomass following logging was 6–7-fold greater in large than small openings by 17 years. Total biomass in the 2.0 ha openings (127.3 Mg ha−1) recovered 59.5% as NPP (19.7 Mg ha−1 yr−1) reached 225% of precut forest levels. Biomass accumulation was 2.6–3.6-fold greater in interior than edge locations of all but the 0.016 ha gaps. The absence of significant patch size or edge vs. interior differences in tree densities suggests that growth rates of individual trees were enhanced in more insolated microenvironments. Sprouting (86–95% of tree NPP) was much more important than advance regeneration (4–10%) or seedling germination (<2%) during early recovery in all opening sizes. Canopy dominant Quercus and Carya trees exhibited limited sprouting following disturbance. Instead, shade-intolerant Robinia pseudoacacia and Liriodendron tulipifera were major sprouters that used N-fixation (Robinia) and rapid growth (Liriodendron) in attaining 7.4 and 5.9 fold greater biomass accumulation, respectively in 2.0 ha than 0.016 ha opening sizes. Seedling germination and understory production were extensive in all openings following logging, but declined rapidly as the young tree canopy began closing by 4–6 years. The relative importance of shade-intolerant tree biomass approximately doubled over 17 years as shade-tolerant tree seedlings, herbs, and shrubs gradually regained importance under the emerging canopy. Sprouting caused the persistence of a tree species composition in all openings that remained relatively similar to the precut forest. Large disturbances on mountain slopes of the southern Appalachians generally promote sprouting and rapid recovery, whereas small disturbances in low-elevation cove forests lead to a gradual recovery through seedling germination and/or advance regeneration. Continued logging in the southern Appalachians will increase the relative size and frequency of large disturbances, further the importance of sprouting of shade-intolerant species, and lead to more even-aged forest stands throughout the region. 相似文献
8.
Climate change is expected to promote migration of species. In ecotones, areas of ecological tension, disturbances may provide
opportunities for some migrating species to establish in otherwise competitive environments. The size of and time since disturbance
may determine the establishment ability of these species. We investigated gap dynamics of an old-growth red pine (Pinus resinosa Sol. ex Aiton) forest in the Great Lakes–St. Lawrence forest in northern Ontario, Canada, a transition zone between temperate
and boreal forest. We investigated the effects of gaps of different sizes and ages on tree species abundance and basal area.
Our results show that tree species from the temperate forest further south, such as red maple (Acer rubrum L.), red oak (Quercus rubra L.), and white pine (Pinus strobus L.), establish more often in large, old gaps; however, tree species that have more northern distributions, such as black
spruce (Picea mariana Mill.), paper birch (Betula papyrifera Marsh.), and red pine show no difference in establishment ability with gap size or age. These differences in composition
could not be attributed to autogenic succession. We conclude that treefall gaps in this forest facilitate the establishment
of northward migrating species, potentially providing a pathway for future forest migration in response to recent changes
in climate. 相似文献
9.
We conducted a field investigation and evaluation of 13C natural abundance to determine the growth habit and propagation strategy of Acer catalpifolium Rehd., a tree species native to China that is highly endangered. The results showed that A. catalpifolium is a K‐selected strategist and pioneer species. Its narrow ecological range limits its geographical distribution, and poor fecundity limits its population size. The analysis of 13C natural abundance showed that A. catalpifolium does not use organic matter for reproduction when its stand volume is less than 1.08 × 106 cm3 or it is less than 18.6 m tall, but it does use this strategy when it has a sufficient 1.08 × 106 cm3 stand volume or more or is taller than 18.6 m. If environmental conditions are not conducive (e.g., severe human disturbance, cliff edges, or fierce interspecific competition) to the continued growth of the tree, A. catalpifolium may allocate organic matter for reproduction. Human disturbance seems to promote the population expansion of A. catalpifolium. We provide our suggestions for the promotion and protection of A. catalpifolium as a species. 相似文献
10.
Transpiration and whole-tree conductance in ponderosa pine trees of different heights 总被引:17,自引:0,他引:17
M. G. Ryan B. J. Bond B. E. Law R. M. Hubbard D. Woodruff E. Cienciala J. Kucera 《Oecologia》2000,124(4):553-560
Changes in leaf physiology with tree age and size could alter forest growth, water yield, and carbon fluxes. We measured tree
water flux (Q) for 14 ponderosa pine trees in two size classes (12 m tall and ∼40 years old, and 36 m tall and ∼ 290 years old) to determine
if transpiration (E) and whole-tree conductance (g
t) differed between the two sizes of trees. For both size classes, E was approximately equal to Q measured 2 m above the ground: Q was most highly correlated with current, not lagged, water vapor pressure deficit, and night Q was <12% of total daily flux. E for days 165–195 and 240–260 averaged 0.97 mmol m–2 (leaf area, projected) s–1 for the 12-m trees and 0.57 mmol m–2 (leaf area) s–1 for the 36-m trees. When photosynthetically active radiation (I
P) exceeded the light saturation for photosynthesis in ponderosa pine (900 μmol m–2 (ground) s–1), differences in E were more pronounced: 2.4 mmol m–2 (leaf area) s–1 for the 12-m trees and 1.2 mmol m–2 s–1 for the 36-m trees, yielding g
t of 140 mmol m–2 (leaf area) s–1 for the 12-m trees and 72 mmol m–2 s–1 for the 36-m trees. Extrapolated to forests with leaf area index =1, the 36-m trees would transpire 117 mm between 1 June
and 31 August compared to 170 mm for the 12-m trees, a difference of 15% of average annual precipitation. Lower g
t in the taller trees also likely lowers photosynthesis during the growing season.
Received: 19 April 1999 / Accepted: 23 March 2000 相似文献
11.
Spatial and age-dependent tree-ring growth responses of Larix gmelinii to climate in northeastern China 总被引:2,自引:0,他引:2
Tree-ring width chronologies from 276 Larix gmelinii cores taken in northeastern China were used to analyze spatial and age-dependent growth–climate response relationships. Tree
radial growth from five localities showed similar patterns, while exhibiting different tree-ring growth responses to local
climate. The rotated principal component analysis (RPCA) indicated that tree age, growing season moisture conditions, and
ambient air temperature variations resulted from location differences (e.g., longitude, latitude, and altitude), which could
explain the non-stationary spatial climate–growth relations observed. The study tested the fundamental assumption that the
climate–growth of L. gmelinii was age independent after the removal of size trends and disturbance signals. The age-related climate–growth relationship
might potentially improve the veracity of past climate reconstructions. Bootstrapped correlation function analyses suggested
that the response of L. gmelinii radial growth to climate differed between trees ≥150 years old and <150 years old. Mean sensitivity and standard deviation
for trees increased with age in the <150 years old tree class; whereas trees ≥150 years old had no significant relationship
with age. These results showed that the assumption of age-independent climate–growth relationship is invalid at these sites.
Physiological processes and/or hydraulic constraints dependent on tree age, together with detrending techniques could be the
possible causal factors of clear age-dependent responses. These results suggested the importance of incorporating trees of
all ages into the chronology to recover a detailed climatic signal in a reconstruction of L. gmelinii for this region. 相似文献
12.
Stephanie Sobek Christoph Scherber Ingolf Steffan-Dewenter Teja Tscharntke 《Oecologia》2009,160(2):279-288
Tree species-rich forests are hypothesised to be less susceptible to insect herbivores, but so far herbivory–diversity relationships
have rarely been tested for tree saplings, and no such study has been published for deciduous forests in Central Europe. We
expected that diverse tree communities reduce the probability of detection of host plants and increase abundance of predators,
thereby reducing herbivory. We examined levels of herbivory suffered by beech (Fagus sylvatica L.) and maple saplings (Acer pseudoplatanus L. and Acer platanoides L.) across a tree species diversity gradient within Germany’s largest remaining deciduous forest area, and investigated whether
simple beech or mixed stands were less prone to damage caused by herbivorous insects. Leaf area loss and the frequency of
galls and mines were recorded for 1,040 saplings (>13,000 leaves) in June and August 2006. In addition, relative abundance
of predators was assessed to test for potential top-down control. Leaf area loss was generally higher in the two species of
maple compared to beech saplings, while only beech showed a decline in damage caused by leaf-chewing herbivores across the
tree diversity gradient. No significant patterns were found for galls and mines. Relative abundance of predators on beech
showed a seasonal response and increased on species-rich plots in June, suggesting higher biological control. We conclude
that, in temperate deciduous forests, herbivory–tree diversity relationships are significant, but are tree species-dependent
with bottom-up and top-down control as possible mechanisms. In contrast to maple, beech profits from growing in a neighbourhood
of higher tree richness, which implies that species identity effects may be of greater importance than tree diversity effects
per se. Hence, herbivory on beech appeared to be mediated bottom-up by resource concentration in the sampled forest stands,
as well as regulated top-down through biocontrol by natural enemies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users. 相似文献
13.
Sapling growth as a function of light and landscape-level variation in soil water and foliar nitrogen in northern Michigan 总被引:3,自引:0,他引:3
Kobe RK 《Oecologia》2006,147(1):119-133
Interspecific differences in sapling growth responses to soil resources could influence species distributions across soil
resource gradients. I calibrated models of radial growth as a function of light intensity and landscape-level variation in
soil water and foliar N for saplings of four canopy tree species, which differ in adult distributions across soil resource
gradients. Model formulations, characterizing different resource effects and modes of influencing growth, were compared based
on relative empirical support using Akaike’s Information Criterion. Contrary to expectation, the radial growth of species
associated with lower fertility (Acer rubrum and Quercus rubra) was more sensitive to variation in soil resources than the high fertility species Acer saccharum. Moreover, there was no species tradeoff between growth under high foliar N versus growth under low foliar N, which would
be expected if growth responses to foliar N mediated distributions. In general, there was functional consistency among species
in growth responses to light, foliar N, and soil water availability, respectively. Foliar N influenced primarily high-light
growth in F. grandifolia, A. rubrum, and Q. rubra (but was not significant for A. saccharum). In A. saccharum and A. rubrum, for which soil water availability was a significant predictor, soil water and light availability simultaneously limited
growth (i.e., either higher light or water increased growth). Simple resource-based models explained 0.74–0.90 of growth variance,
indicating a high degree of determinism. Results suggest that nitrogen effects on forest dynamics would be strongest in high-light
early successional communities but that water availability influences growth in both early successional and understory environments. 相似文献
14.
城市森林在吸收、滞留大气污染物,改善城市生态环境方面具有重要意义。以大庆市6种常见绿化树种为研究对象,采用水洗-滤膜法和熏气试验探究不同树种对总悬浮颗粒物(TSP)、大颗粒物(PM>10)、粗颗粒物(PM3—10)和细颗粒物(PM1—3)的滞留规律以及对大气中SO2、NO2的消减效果。研究结果表明:(1)不同树种的滞尘能力差异显著(P<0.05),对TSP的滞留量从大到小依次为:油松(3.82±0.40)g/m2>红瑞木(1.45±0.12)g/m2>紫丁香(1.22±0.17)g/m2>梣叶槭(1.21±0.13)g/m2>大叶杨(0.93±0.17)g/m2>旱柳(0.54±0.14)g/m2;(2)树种间对不同颗粒物的滞留量具有显著差异(P<0.05),供试树种对不同粒径颗粒物滞留的质量占比表现... 相似文献
15.
Jiri Dolezal Jong-Suk Song Jan Altman Stepan Janecek Tomas Cerny Miroslav Srutek Jiri Kolbek 《Ecological Research》2009,24(2):281-290
Secondary woodlands in South Korea cover most mountains from low to middle elevations. While general patterns of forest succession
are well understood, little is known about mechanisms of stand recovery after disturbance. We examined the spatio-temporal
variations in establishment, growth, size inequality, and mode of competition among trees in a 50-year-old post-logging Quercus mongolica-dominated stand. We further compared the growth and stem allometry of single trees, presumably of seed origin, with multi-stemmed
trees resprouting from stumps. Q. mongolica formed the upper canopy 16–22 m tall, 88.3% of total stand basal area, and 36.2% of total stem density, with most trees established
during the first post-logging decade (51.2% were resprouts). During the first three decades, the Q. mongolica recruits grew exponentially, and disproportionately more in diameter than few older reserved trees left after the last cutting.
This substantially decreased size inequality. The reverse trend was observed from 1994 to 2004: larger trees grow more, indicating
an increasing asymmetry of competition for light. Neighborhood analysis revealed that when target trees had more or larger
neighbors, their exponential phase of growth was reduced and maximum size was decreased. After the 50 years of stand development,
more than 70% of Q. mongolica showed growth decline as a result of competitive stress, and mortality was about 30%, concentrated in smaller size classes.
Compared to single stems, resprouts within clones do not seem to compete less asymmetric as might be expected based on studies
of clonal herbaceous plants and physiological integration within genets. As Q. mongolica was also negatively affected by competition from woody species currently prevailing in the lower tree stratum (Tilia amurensis, Acer mono, Fraxinus rhynchophylla, Acer pseudosieboldianum), we predict the stand will become increasingly dominated by these more shade-tolerant trees. 相似文献
16.
Conservation of threatened tree species requires basic information on growth rates and ages. This information is lacking for
many species, but can be obtained relatively easily from tree ring analysis. We studied four threatened Vietnamese species:
three conifers from high-elevation forests (Calocedrus macrolepis, Dacrydium elatum and Pinus
kwangtungensis) and one broad-leaved species from lowland forest (Annamocarya sinensis). We collected increment cores from remnant populations in protected areas and measured ring width. We built chronologies
and found significant correlations with rainfall (all species) and temperature (two species), indicating that rings were formed
annually. Diameter-age trajectories showed that species reached reproductive size at 60–80 years. Maximum observed ages were
128–229 years. Some species showed large variation in long-term growth rates among individuals, which was partially explained
by strong persistence of growth differences. We also assessed whether growth rates changed over time. For certain size categories
in some species, we found higher recent growth rates of juvenile trees compared to those in the distant past. This shift requires
a cautious interpretation, but is consistent with a CO2 fertilization effect. For other size categories, we found contrasting results: extant large trees had higher growth rates
as small juveniles compared to extant small trees. Such correlations, which we found for all species, suggest a ‘juvenile
selection effect’: the preferential survival of fast-growing juveniles to the canopy. Information on ages, historical growth
rates and juvenile selection effect is relevant for the planning of conservation actions. 相似文献
17.
Linking xylem diameter variations with sap flow measurements 总被引:1,自引:0,他引:1
Sanna Sevanto Eero Nikinmaa Anu Riikonen Michael Daley J. Cory Pettijohn Teis N. Mikkelsen Nathan Phillips N. Michele Holbrook 《Plant and Soil》2008,305(1-2):77-90
Measurements of variation in the diameter of tree stems provide a rapid response, high resolution tool for detecting changes
in water tension inside the xylem. Water movement inside the xylem is caused by changes in the water tension and theoretically,
the sap flow rate should be directly proportional to the water tension gradient and, therefore, also linearly linked to the
xylem diameter variations. The coefficient of proportionality describes the water conductivity and elasticity of the conducting
tissue. Xylem diameter variation measurements could thus provide an alternative approach for estimating sap flow rates, but
currently we lack means for calibration. On the other hand, xylem diameter variation measurements could also be used as a
tool for studying xylem structure and function. If we knew both the water tension in the xylem and the sap flow rate, xylem
conductivity and/or elasticity could be calculated from the slope of their relationship. In this study we measured diurnal
xylem diameter variation simultaneously with sap flow rates (Granier-type thermal method) in six deciduous species (Acer rubrum L., Alnus glutinosa Miller, Betula lenta L., Fagus Sylvatica L. Quercus rubra L., and Tilia vulgaris L.) for 7–91 day periods during summers 2003, 2005 and 2006 and analyzed the relationship between these two measurements.
We found that in all species xylem diameter variations and sap flow rate were linearly related in daily scale (daily average
R
2 = 0.61–0.87) but there was a significant variation in the daily slopes of the linear regressions. The largest variance in
the slopes, however, was found between species, which is encouraging for finding a species specific calibration method for
measuring sap flow rates using xylem diameter variations. At a daily timescale, xylem diameter variation and sap flow rate
were related to each other via a hysteresis loop. The slopes during the morning and afternoon did not differ statistically
significantly from each other, indicating no overall change in the conductivity. Because of the variance in the daily slopes,
we tested three different data averaging methods to obtain calibration coefficients. The performance of the averaging methods
depended on the source of variance in the data set and none of them performed best for all species. The best estimates of
instantaneous sap flow rates were also given by different averaging methods than the best estimates of total daily water use.
Using the linear relationship of sap flow rate and xylem diameter variations we calculated the conductance and specific conductivity
of the soil–xylem–atmosphere water pathway. The conductance were of the order of magnitude 10−5 kg s−1 MPa−1 for all species, which compares well with measured water fluxes from broadleaved forests. Interestingly, because of the large
sap wood area the conductance of Betula was approximately 10 times larger than in other species. 相似文献
18.
Interspecific and intraspecific variation in tree seedling survival: effects of allocation to roots versus carbohydrate reserves 总被引:13,自引:0,他引:13
We examined interspecific and intraspecific variation in tree seedling survival as a function of allocation to carbohydrate
reserves and structural root biomass. We predicted that allocation to carbohydrate reserves would vary as a function of the
phenology of shoot growth, because of a hypothesized tradeoff between aboveground growth and carbohydrate storage. Intraspecific
variation in levels of carbohydrate reserves was induced through experimental defoliation of naturally occurring, 2-year-old
seedlings of four northeastern tree species –Acer rubrum, A. saccharum, Quercus rubra, and Prunus serotina– with shoot growth strategies that ranged from highly determinate to indeterminate. Allocation to root structural biomass
varied among species and as a function of light, but did not respond to the defoliation treatments. Allocation to carbohydrate
reserves varied among species, and the two species with the most determinate shoot growth patterns had the highest total mass
of carbohydrate reserves, but not the highest concentrations. Both the total mass and concentrations of carbohydrate reserves
were significantly reduced by defoliation. Seedling survival during the year following the defoliation treatments did not
vary among species, but did vary dramatically in response to defoliation. In general, there was an approximately linear relationship
between carbohydrate reserves and subsequent survival, but no clear relationship between allocation to root structural biomass
and subsequent survival. Because of the disproportionate amounts of reserves stored in roots, we would have erroneously concluded
that allocation to roots was significantly and positively related to seedling survival if we had failed to distinguish between
reserves and structural biomass in roots.
Received: 14 December 1999 / Accepted: 2 June 1999 相似文献
19.
Michiel van Breugel Paulo van Breugel Patrick A. Jansen Miguel Martínez-Ramos Frans Bongers 《Plant Ecology》2012,213(1):25-34
Competition between neighboring plants plays a major role in the population dynamics of tree species in the early phases of
humid tropical forest succession. We evaluated the relative importance of above- versus below-ground competition during the
first years of old-field succession on soil with low fertility in Southern Mexico, using the premise that competition for
light is size-asymmetric, unlike competition for nutrients. Plant growth is thus expected to be disproportionally impeded
by larger neighbors. We studied how growth and survival of 3.5–5.5 m tall saplings of Cecropia peltata and Trichospermum mexicanum, two pioneer species that dominate the secondary forests in the study region, varied with the abundance and size of neighboring
trees in 1–2 year old secondary vegetation. We found that local neighborhood basal area varied 10-fold (3 to 30 cm2 m-2) and explained most of the variation in diameter and height growth of the target saplings. Most growth variables were strongly
affected by the neighbors bigger than the focal trees with no significant additive effect of the smaller neighbors, indicating
asymmetric competition. Smaller neighbors did have a small but significant additive effect on the diameter growth of Cecropia saplings and stem slenderness of Trichospermum saplings. We conclude that competition for light was more important than belowground competition in this initial phase of
moist tropical forest successional, despite the low soil fertility. 相似文献
20.
Cambial growth dynamics and climatic control of different tree life forms in tropical mountain forest in Ethiopia 总被引:1,自引:0,他引:1
Julia Krepkowski Achim Br?uning Aster Gebrekirstos Simone Strobl 《Trees - Structure and Function》2011,25(1):59-70
Munessa Forest is a mountain forest in south-eastern Ethiopia experiencing seasonal rainfall variation. We investigated seasonal
cambial activity and dormancy from increment rates of four different tree species belonging to varying life forms, namely,
evergreen native conifer (Podocarpus falcatus), evergreen introduced conifer (Pinus patula), evergreen broadleaved tree (Prunus africana) and deciduous broadleaved tree (Celtis africana). Measurements of stem radius fluctuations were registered with the help of high-resolution electronic dendrometers. Daily
amplitudes of stem diameter variations and daily and monthly net growth rates were determined and related to climatic variables
measured at local climate stations. Thin sections of wood collected with a microcorer every 3–6 weeks allowed a visual control
of newly formed wood cells during consecutive time intervals. Lack of water availability during the long dry season induced
cambial dormancy of 5–7 months depending on life forms. After the onset of the short rainy season, stem swelling started quite
synchronously with a variation of only single days in all studied species. Evergreen tree species were able to initiate wood
formation during the short rainy season, whereas growth in the deciduous broadleaved species started in the long rainy season.
The acquired data provide a basis for delineating the species-specific growth boundaries and the duration of the cambial growing
season. 相似文献