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1.
《Southern Forests》2013,75(4):237-246
The relationship between root and shoot growth and how it is modified by chronic or episodic drought stress is so far not well understood. Allometric partitioning theory (APT) supposes a constant root–shoot allometry. Optimal partitioning theory (OPT) assumes that plants’ root growth is enhanced under water limitation. However, recent studies show that fine and coarse roots react differently. This paper draws attention to the root–shoot allometry of adult Monterey pines (Pinus radiata D.Don) and its dependency on site conditions in South Africa. For assessment of the root–shoot-diameter relationship as an allometric relationship in general and for comparison with APT we used a sample of nine radiata pines from Jonkershoek and three maritime pines (Pinus pinaster Aiton) from Napier. In order to test for a site-dependency of the root–shoot allometry we sampled increment cores from stem and coarse roots of 48 radiata pines along a gradient from moist to dry sites in the Western Cape province. Tree ring analysis revealed an allometric relationship between root diameter (dr) and shoot diameter (ds) (ln(dr) = a + α dr,ds × ln(ds)). Despite strong variation of the allometric exponent α dr,ds we found a systematic deviation from 1.0 as would be predicted by APT. We also found α dr,ds to decrease with drought stress, which is contradictory to both APT and OPT. However, on sites with more pronounced drought stress we detected greater allometric factors a. We hypothesise that fine root growth, and also fine root mortality, is higher on dry sites. On these sites coarse roots seem to be less necessary for matter transport compared with moist and fertile sites. On the latter, fine roots are less ephemeral and require larger coarse roots for transport. We conclude that combined root shoot tree ring analyses have the potential for improving understanding and modelling ecosystems and better assessment of forest functions such as resource use efficiency, stand stability and belowground carbon storage. 相似文献
2.
The root segments selected from dominant trees ofPopulus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion
sprout. The affecting factors of gemination rate, survival rate, and height growth for cutting wood of root sprout were comparatively
analyzed. The results showed that the best suitable substrate for burying root is pearlite, with a germination rate of 15.16%.
3–4-cm root segments has the highest rate of germination (12.4%). The mixture of sand and soil (2∶1) is the best cutting substrate,
with a survival rate of 81.3%, while as to height growth of cutting wood, the mixture of turfy and soil (1∶1) is the best.
The cutting woods selected from different positions of stem show difference in height growth. The cutting wood from top stem
is higher obviously than those from middle or low stem.
Biography: XING Ya-juan (1969-), female, assistant researcher in Forest Research Institute of Heilongjiang Province, Harbin 150040,
P. R. China.
Responsible editor: Song Funan 相似文献
3.
William L. Headlee Ronald S. Zalesny Jr. Richard B. Hall 《Journal of Sustainable Forestry》2019,38(1):18-30
In this study, we evaluated ‘Crandon’ coarse root biomass and architecture grown at different topographic positions and fertilizer rates. Complete excavations were conducted on a subset of trees after the first growing season and showed that root biomass was strongly related to stem biomass (R2 = 0.93), but not topographic position or fertilizer rate. After the third growing season, subsamples of roots were collected from another subset of trees and showed coarse root architecture variables to be strongly related to several metrics of the tree and root size (R2 = 0.61 to 0.82), while also differing by topographic position. Equations relating root biomass to stem biomass were derived from both methodologies (complete excavation v. subsampling for architecture measurements), and comparison of the equations indicated no difference in slopes (p = 0.59) or intercepts (p = 0.90), although the subsampling approach had a weaker model fit. Our results suggest ‘Crandon’ roots (i) adhere to strong allometric relationships with stem biomass, (ii) alter their architecture within the constraints of this allometric relationship according to site conditions, and (iii) can be subsampled to estimate root biomass from root architecture parameters with similar accuracy (but less precision) compared to complete excavations. 相似文献
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5.
We developed site-specific allometric models for Leucaena leucocephala × pallida var. KX2 trees in a shaded coffee agroecosystem in Hawaii to predict above- and belowground biomass and the regrowth potential
of pollarded trees. Models were used to compare tree growth rates in an experimental agroforestry system with different pollarding
frequencies and additions of tree pruning residues as mulch. For all allometric equations, a simple power model (Y = aXb) provided the optimal prediction of biomass or regrowth after pollarding. For aboveground biomass components (stem, branches,
leaves, and seed and pods), stem diameter alone was the best predictor variable. Stump diameter provided the best prediction
of coarse root biomass and aboveground regrowth after pollarding. Predictions of biomass from generalized allometric models
often fell outside the 95% confidence intervals of our site-specific models, especially as biomass increased. The combination
of pollarding trees once per year plus the addition of tree mulch resulted in the greatest aboveground regrowth rates as well
as accumulation of biomass and C in the stump plus coarse roots. Although optimal prediction required the development of site-specific
allometric relationships, a simple power model using stem or stump diameter alone can provide an accurate assessment of above-
and belowground tree biomass, as well as regrowth potential under specific management scenarios. 相似文献
6.
Belowground competition in a broad-leaved temperate mixed forest: pattern analysis and experiments in a four-species stand 总被引：1，自引：0，他引：1
We investigated fine root biomass and distribution patterns in a species-rich temperate Carpinus–Quercus–Fagus–Tilia forest and searched for experimental evidence of symmetry or asymmetry in belowground competition. We conducted extensive
root coring and applied the recently introduced in situ-root growth chamber technique for quantifying fine root growth under
experimentally altered intra- and interspecific root neighbourhoods in the intact stand. In 75% of all soil cores, fine roots
of more than two tree species were present indicating a broad overlap of the root systems of neighbouring trees. Quercus trees had more than ten times less fine root biomass in relation to aboveground biomass or productivity (stem growth) and
a much higher leaf area index/root area index ratio than Carpinus, Fagus and Tilia trees. The root growth chamber experiments indicated a high belowground competitive ability of Fagus in interspecific interactions, but a low one of Quercus. We conclude that (1) interspecific root competition is ubiquitous in this mixed stand, (2) root competition between trees
can be clearly asymmetric, and (3) tree species may be ranked according to their belowground competitive ability. Fagus was found to be the most successful species in belowground competition which matches with its superiority in aboveground
competition in this forest community. 相似文献
7.
《Scandinavian Journal of Forest Research》2012,27(6):532-544
Abstract This transect study in 41–178 year-old stands of Lodgepole pine (Pinus contorta DOUGL. ex. LOUD.) in the southern boreal forest of British Columbia, Canada, analyses how site conditions modify the coarse root–shoot dynamics of trees. The allometric relationship between diameter growth of coarse roots and trunk is scrutinised for long-term site dependence, and short-term reactions to periodic climate conditions. Along a gradient from poor to rich sites, we analysed 54 trees. The sampling scheme provided two increment cores each from the three main roots and the shoot at breast height per tree. From the year-ring series, we calculated diameter time series for each shoot and each root. With these data, we show (1) that the trees’ coarse root diameter and shoot diameter are linearly related in a double-logarithmic coordinate system, thus representing constant allometry on the long run. Statistical analysis of these long-term trajectories reveals that (2) the relative allocation to coarse roots versus shoot is much higher on poor sites compared to rich sites. A closer look at the short-term reaction to stress events in the period from 1995 to 2000, where several dry years occurred, underpins that (3) a lack of water supply triggers biomass allocation in favour of coarse roots at the expense of shoot growth most pronouncedly on poor sites. Implications of this morphological plasticity for allometric theory, method development, tree and stand dynamics and carbon storage assessment are discussed. 相似文献
8.
G. Moser C. Leuschner D. Hertel D. Hölscher M. Köhler D. Leitner B. Michalzik E. Prihastanti S. Tjitrosemito L. Schwendenmann 《Agroforestry Systems》2010,79(2):171-187
In South-east Asia, ENSO-related droughts represent irregularly occurring hazards for agroforestry systems containing cocoa
which are predicted to increase in severity with expected climate warming. To characterize the drought response of mature
cocoa trees, we conducted the Sulawesi Throughfall Displacement Experiment in a shaded (Gliricidia sepium) cocoa agroforestry system in Central Sulawesi, Indonesia. Three large sub-canopy roofs were installed to reduce throughfall
by about 80% over a 13-month period to test the hypotheses that (i) cocoa trees are sensitive to drought due to their shallow
fine root system, and (ii) bean yield is more sensitive to drought than leaf or stem growth. As 83% of fine root (diameter
<2 mm) and 86% of coarse root biomass (>2 mm) was located in the upper 40 cm of the soil, the cocoa trees examined had a very
shallow root system. Cocoa and Gliricidia differed in their vertical rooting patterns, thereby reducing competition for water. Despite being exposed for several months
to soil water contents close to the conventional wilting point, cocoa trees showed no significant decreases in leaf biomass,
stem and branch wood production or fine root biomass. Possible causes are active osmotic adjustment in roots, mitigation of
drought stress by shading from Gliricidia or other factors. By contrast, production of cocoa beans was significantly reduced in the roof plots, supporting reports
of substantial reductions in bean yields during ENSO-related drought events in the region. We conclude that cocoa possesses
traits related to drought tolerance which enable it to maintain biomass production during extended dry periods, whereas bean
yield appears to be particularly drought sensitive. 相似文献
9.
To assess the effects of seedling spacing on one-year-old seedling morphology in the nursery, seeds of three provenances of Fraxinus angustifolia were sown at five different seedling spacings within rows of two different spacings in the seedbed. Subsequent growth performance of one-year-old seedlings was assessed by planting in the forest. Within row spacings were: 4.3, 5.0, 6.3, 8.3, and 12.5 cm, and there were five rows at 20 cm apart, or three rows at 33 cm apart across the 1.2 m wide seedbeds. Both spacings within and between rows significantly affected shoot height, root collar diameter, root dry weight and shoot dry weight, but not root/shoot ratio. Wider spacings produced larger seedlings, but only the wider spacing within rows significantly increased fine and coarse root mass. Provenances showed significant differences in diameter, root/shoot ratio, and fine and coarse roots, and they also showed interactions with row spacings in height and diameter measurements. One year after outplanting, diameter growth was significantly related to provenance, and diameter growth was 88% greater for trees from 33 cm nursery row spacing than those from 20 cm nursery row spacing. 相似文献
10.
The Importance of Weed Control and the Use of Tree Shelters for Establishing Broadleaved Trees on Grass-Dominated Sites in England 总被引：1，自引：0，他引：1
The results of seven experiments are used to illustrate themechanisms of weed competition and its effects. Studies of soilmoisture tension and foliar nutrient content indicated thatcompetition was primarily for moisture and nutrients reducingthe survival and growth of young trees. These effects are greateron soils with poor moisture retention, or where the climateresults in high soil moisture deficits. To be effective, weedcontrol must eliminate root competition. This can be done bycultivation, herbicides or mulching; cutting weeds above groundlevel is ineffective. Tree shelters accelerate the height growthof young trees and protect them from mammals and herbicide drift. 相似文献
11.
Gaku Hitusma Takayuki Ota Tatsuo Kanazashi Takashi Masaki 《Journal of Forest Research》2006,11(4):281-287
We investigated changes in sapling growth and morphology of Thujopsis dolabrata var. hondai (hiba) for 7 years after release from suppressed lighting by selection cutting. We examined changes in aboveground biomass,
elongation of stems and lateral branches, and annual diameter increment at the stem base. Vertical distributions of leaves
per branch and per individual were also measured for morphological analysis. Under the suppressed condition before cutting,
the crown consisted of orthotropic lateral branches, elongating up to the top of the stem or farther, and no branch was aborted.
This crown type with large crown depth and concavity of the upper part had a bowl-like appearance. After the selection cutting,
relative light intensity on the saplings increased from 4% to 26%. The increment enhanced aboveground biomass and stem elongation
7 years after the cutting. Diameter growth at the stem base was particularly accelerated 2 years after the cutting. While
crown shape transformation of the saplings was not conspicuous at 7 years after the cutting, some released saplings showed
a superior stem elongation ratio to that of the lateral branches. Thus, the upper part of the crown of these saplings changed
from a bowl-like shape to a convex shape like that of a dome. Our study suggested that suppressed hiba saplings with the unique
bowl-shaped crown enhanced their growth rates rapidly in response to improved light conditions, but required much more than
7 years for the full process of crown transformation for us to identify future trees in this stand.
An erratum to this article is available at. 相似文献
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14.
Elevational change in woody tissue CO2 efflux in a tropical mountain rain forest in southern Ecuador
Much uncertainty exists about the magnitude of woody tissue respiration and its environmental control in highly diverse tropical moist forests. In a tropical mountain rain forest in southern Ecuador, we measured the apparent diurnal gas exchange of stems and coarse roots (diameter 1-4 cm) of trees from representative families along an elevational transect with plots at 1050, 1890 and 3050 m a.s.l. Mean air temperatures were 20.8, 17.2 and 10.6 degrees C, respectively. Stem and root CO(2) efflux of 13 to 21 trees per stand from dominant families were investigated with an open gas exchange system while stand microclimate was continuously monitored. Substantial variation in respiratory activity among and within species was found at all sites. Mean daily CO(2) release rates from stems declined 6.6-fold from 1.38 micromol m(-2) s(-1) at 1050 m to 0.21 micromol m(-2) s(-1) at 3050 m. Mean daily CO(2) release from coarse roots decreased from 0.35 to 0.20 micromol m(-2) s(-1) with altitude, but the differences were not significant. There was, thus, a remarkable shift from a high ratio of stem to coarse root respiration rates at the lowest elevation to an apparent equivalence of stem and coarse root CO(2) efflux rates at the highest elevation. We conclude that stem respiration, but not root respiration, greatly decreases with elevation in this transect, coinciding with a substantial decrease in relative stem diameter increment and a large increase in fine and coarse root biomass production with elevation. 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(4):348-357
The aim of this study was to examine the ways in which the volume, physical appearance and location of retention trees affect the scenic quality of clear-cutting areas. A total of 373 respondents rated 40 digitally edited images. If only a few retention trees remained in the cutting area, they did not seem to affect the ratings, but when 3 m3 ha?1 was retained the scenic quality of the clear-cutting area improved. The better the condition of the retention trees, the more they were appreciated. Retention trees in a poor condition did not enhance the scenic quality of clear-cutting areas. Mature retention trees were found to be more attractive than undergrowth. Even undergrowth was preferred to clear-cutting areas without any trees. Respondents also preferred retention trees standing alone to trees in groups. Forest owners provided higher overall preference scores than visitors. The scenic quality of clear-cutting areas can be substantially improved if there remains an adequate volume of mature retention trees that are in good condition. 相似文献
16.
Crop productivity under differently lopped canopies of multipurpose trees in Central Himalaya, India 总被引：3，自引：1，他引：3
Ficus species are multipurpose trees well known by rural populations in Sahelian and Sudanian zones of Africa. Their uses are well documented but their amenability for vegetative propagation has not been extensively studied. This paper compares the rooting ability of stem and aerial root cuttings from thirteen Ficus species found in West Africa. It highlights the differences between species belonging to the sub-genera Sycomorus and Urostigma. The former show no capacity to propagate from cuttings whereas the latter, with epiphytic development, can be propagated by cuttings, although this capacity varies among species. Thus, F. thonningii, F. leprieurii and F. ovata are easily propagated, while F. platyphylla and F. elasticoides are propagated with difficulty. The rooting capacity also varies depending on the cutting material used. It decreases in the following order: long leafless hardwood cuttings (pole) > nodal cuttings > apical cuttings. Rooting potential increases when the cuttings are harvested towards the end of the dry season(March to May). Aerial root can be used for cuttings in all species of the sub-genus Urostigma. The capacity of root cuttings to regenerate is greatest when cuttings are collected at the beginning of the dry season (November). In this case, wound-induced adventitious roots arise at the basal end of the cutting while de novo buds are developed from the cambium at the distal end. The subsequent morphological development is identical to that of a stem cutting. These results clarify and allow the optimal use of the knowledge and methods developed by the indigenous people of the Sahel and could assist and promote fig tree (Ficus sp.) domestication in the dry tropics.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
17.
《Scandinavian Journal of Forest Research》2012,27(5):419-430
Abstract Typically, in forest inventory the volume of tally trees is predicted with a volume model estimated at national level. Such a global model is not unbiased regionally if there is spatial variation in the tree form due to one or more unknown predictors. This regional bias could be reduced or removed if the models were localized to each region or subarea. The localization is easiest if the area can be divided into homogeneous areas with respect to stem form. This study tested whether the localization results depend on the way the division is made and on the size of the subareas. The study area was divided spatially into homogeneous subareas with residuals of the global model or with the local spatial index, G i *, or both with classification and regression trees, the leaves of which formed the subareas. In addition, two other spatial divisions were created: an administrative forest centre and spatially equal-sized subarea divisions. The localized models were compared with the global model. The root mean squared errors (RMSEs) of localized models were smaller in median and in mean, but maximum values exceeded the overall global model RMSE. The localization reduced local RMSEs on average by 1–6%. The differences between the spatial divisions were small, although the aggregate standard errors and RMSEs were slightly smaller in regression trees. Only 50 ± 8% of the subareas were spatially homogeneous in regression tree divisions, which suggests that either the division criteria or the division method were inadequate. 相似文献
18.
不同间伐强度对人工阔叶红松林生长的影响 总被引：10，自引：0，他引：10
文章针对不同间伐强度对人工阔叶红松林生长的影响进行了调查研究。结果表明:阔叶树胸径生长和蓄积增长率随间伐强度加大而增加,但对树高的影响较小;间伐强度的增大会明显促进红松胸径和树高的生长,但是首次抚育间伐会使当年的树高生长量显著降低,以后随林龄的增加树高生长量会逐渐恢复正常生长;中度间伐措施对阔叶树和红松的生长均比较有利,10a生的阔叶红松林实施上层抚育的适宜间伐强度为45%左右;中度间伐的林分由于资源水平适中(主要是光资源),因而有利于林下植被均匀度和多样性的提高。 相似文献
19.
A study of an agrisilviculture system comprising Gmelina arborea and soybean (Glycine max) was conducted in the subhumid region of Central India. Above- and below-ground biomass production and distribution of coarse and fine roots were studied in 4-year-old G. arborea, planted at a spacing of 2 × 2 m, 2 × 3 m, 2 × 4 m and 2 × 5 m. The total biomass varied from 10.89 Mg ha–1 to 3.65 Mg ha–1 depending on the tree density. Among the different tree components, stemwood contributed maximum biomass (54.3–79.4%), followed by branches and leaves. Root distribution pattern showed that most of the coarse roots were distributed in the top 40 cm of soil, whereas fine roots were concentrated in the top 20 cm. Coarse root biomass decreased with an increase in spacing. The spread of roots was asymmetrical in trees planted at 2 × 2 m and 2 × 3 m spacings, while it was symmetrical in trees planted at wide spacings. No significant difference was observed in the fine root biomass in different stands. The root:shoot ratio increased with an increase in spacing. Crop (soybean) growth and productivity varied significantly and it increased with a decrease in tree density. Soybean yield varied between 1.5 Mg ha–1 to 2.1 Mg ha–1. The role of root architecture of G. arborea trees on productivity of crops under agri-silviculture system is discussed. 相似文献
20.
Shoot anatomical features viz., number of vessel elements, width and length of vessel and fibre elements were studied in relation
to juvenility/maturity of teak (Tectona grandis Linn. f.). The findings show significant differences in these features, which indicates that variation in shoot anatomy can
be used as a reliable indicator of juvenility/maturity in teak. The effect of age of donor plants and application of auxins
on adventitious root formation in single noded leafy stem cuttings of teak was also investigated. Aging of donor trees suppressed
rooting and sprouting of cuttings, but increased callus formation at the base of cuttings. Per cent rooting and per cent sprouting
in cuttings decreased as age of donor plants increased from 2-months to 15-years and up to 30-years. IBA treatment promoted
per cent rooting as well as per cent sprouting, NAA promoted only rooting and it suppressed sprouting. The effect of auxin
treatment on rooting and sprouting of teak stem cuttings varied with the age of donor plants. Auxin and its concentration,
which suppressed rooting and sprouting in cuttings of younger donor plants, actually promoted rooting when cuttings were taken
from more mature donor plants. It appears that the auxin requirement for causing and promoting rooting in teak cuttings increased
with increasing age of donor plants. The higher auxin requirement for causing and promoting rooting in cuttings of older trees
may be due to a decrease in the content on endogenous auxins or decreased sensitivity of aging tissues to rooting promoters
and /or accumulation of inhibitory substances which inhibit rooting. 相似文献