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Melvin T. Tyree - One of the best experts on this subject based on the ideXlab platform.
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natural and experimentally altered hydraulic architecture of branch junctions in Acer Saccharum marsh and quercus velutina lam trees
Trees-structure and Function, 1997Co-Authors: Roni Aloni, John D Alexander, Melvin T. TyreeAbstract:The functional xylem anatomy and the hydraulic conductivity of intact and treated branch junctions of the diffuse-porous sugar maple (Acer Saccharum Marsh.) were compared to those of the ring-porous black oak (Quercus velutina Lam.). Maple shoots possessed greater growth intensity than those of oak. The extensive growth of the maple trees resulted in about a two-fold increase in xylem production in the maple branches. Branches were altered by removing a patch of bark from the base of a branch (near a junction) leaving a bridge of bark on the upper or lower side of the branch. The experimentally treated branch junctions revealed that, in oak, most (up to 92%) of the water flows in the lower side of a branch, where most of the large vessels occurred. In maple, most of the conductive tissue was observed to form in the upper side of the branches, which was equally or more conductive than the lower side. A treatment of longitudinal, parallel scratches in the bark-bridge, which reduced earlywood vessel width, substantially decreased conductivity (to only 15%) in oak, but had no effect on conductivity in maple. In maple, such wounding stimulated more wood formation and increased conductivity. In both trees, a narrow bridge at the junction induced more wood formation and higher conductivity in the branch. The mechanisms controlling wood formation and water flow in branch junctions of ring- and diffuse-porous trees are discussed.
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root carbohydrate reserves mineral nutrient concentrations and biomass in a healthy and a declining sugar maple Acer Saccharum stand
Tree Physiology, 1997Co-Authors: Xuan Liu, Melvin T. TyreeAbstract:Soil and root characteristics were contrasted between a "declining" and a "healthy" sugar maple (Acer Saccharum Marsh.) stand in Vermont, USA. The declining stand had lower basal area increment and more crown dieback than the healthy stand. Soil pH and base cation content were lower and soil water content was higher at the site of the declining stand than at the site of the healthy stand, whereas soil temperature did not differ significantly between the sites. In live fine roots, concentrations of K and Ca were marginally (P < 0.07) lower in the declining than in the healthy stand, whereas concentrations of N, P, Mg, and Al were not significantly different (P = 0.13 to 0.87) between stands. Starch and soluble sugar concentrations of fine and coarse roots did not differ significantly between stands, indicating that crown dieback did not affect carbohydrate supply to the roots in the declining stand. Throughout the growing season, the standing live and dead root biomass were significantly higher in the declining stand than in the healthy stand, indicating that more carbon was allocated to roots and that root turnover was higher in the declining stand than in the healthy stand.
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leaf nutrition and photosynthetic performance of sugar maple Acer Saccharum in stands with contrasting health conditions
Tree Physiology, 1997Co-Authors: Xuan Liu, David S Ellsworth, Melvin T. TyreeAbstract:Leaf nutrition and photosynthetic performance of sugar maple (Acer Saccharum Marsh.) were compared between two sugar maple stands in northwestern Vermont with contrasting health conditions as indicated by annual basal area growth, degree of crown dieback, and foliar appearance. Observations made during the diurnal cycle of both stands showed no apparent leaf water stress. In both stands, leaves had similar concentrations of major non-structural carbohydrates (starch and sucrose). Over two consecutive growing seasons (1991 and 1992), we consistently observed lower leaf Ca and Mg concentrations in the declining stand than in the healthy stand. Compared with the healthy stand, lower leaf chlorophyll concentrations and apparent leaf chlorosis were observed in the declining stand, and some trees had very low foliar Ca and Mg concentrations (0.31 +/- 0.03% and 0.09 +/- 0.01%, respectively). Trees in the declining stand had lower light-saturated net photosynthetic rates on a dry mass basis at both ambient CO(2) (P(n,amb)) and saturating CO(2) (P(n,sat)) than trees in the healthy stand. There were significant linear correlations between P(n,amb) and leaf mass per unit area (LMA) and between P(n,sat) per unit leaf area and LMA. There were also linear correlations between both P(n,amb) and P(n,sat) and leaf N when expressed on an area basis in both stands, indicating that variation in LMA may have been largely responsible for the observed photosynthesis-nitrogen relationship. The values of P(n,amb) and P(n,sat) were not significantly correlated with leaf N on a mass basis but were weakly correlated with leaf Ca and Mg on a mass basis. We conclude that low leaf Ca or Mg concentrations may limit leaf CO(2) assimilation and tree carbohydrate status in the declining stand.
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hydraulic architecture of Acer Saccharum and a rubrum comparison of branches to whole trees and the contribution of leaves to hydraulic resistance
Journal of Experimental Botany, 1994Co-Authors: Shudong Yang, Melvin T. TyreeAbstract:Hydraulic resistance to water flow was measured in the xylem and leaves of above-ground portions of Acer Saccharum and Acer rubrum for trees with trunk diameters (D) ranging from 0.02 to 0.2 m. Resistance (area basis) to water flow in leaves and petioles was 24 and 13×10 3 MPa m 2 s kg -1 for A. Saccharum and A. rubrum, respectively. Leaf area of whole trees was proportional to D 1.82 . Absolute xylem resistance (MPa s kg -1 ) was proportional to D -1.64 . So xylem resistance (area basis) was proportional to D 0.2 , which was not significantly different from a zero dependence (D 0 ) for D≤0.2 m
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hydraulic resistance in Acer Saccharum shoots and its influence on leaf water potential and transpiration
Tree Physiology, 1993Co-Authors: Shudong Yang, Melvin T. TyreeAbstract:A new method is presented for measuring whole-shoot hydraulic conductance, K(T) (kg s(-1) MPa(-1)). The method was also used to determine other conductance values in maple (Acer Saccharum Marsh.) stem segments of differing diameter including: K(h) (absolute conductance or conductance per unit pressure gradient, kg s(-1) m MPa(-1)), K(s) (specific conductance or K(h) per unit wood area, kg s(-1) m(-1) MPa(-1)), and LSC (leaf specific conductance or K(h) per unit leaf area, kg s(-1) m(-1) MPa(-1)). A regression of K(T) versus stem basal diameter, D (m), gave K(T) = 5.998 x 10(-2) D(1.402) (R(2) = 0.986 for D from 0.001 to 0.1 m) and a regression for leaf area, A(L) (m(2)), gave A(L) = 4.667 x 10(3) D(2.007) (R(2) = 0.981 for D from 0.001 to 0.3 m). More than 50% of the resistance to water flow in large shoots (0.1 m in diameter and 8 to 10 m long) was contained in branches less than 0.012 m in diameter, i.e., in the distal 1.5 m of branches. We used the regressions to predict the steady state difference in pressure potential, P, between the base of a shoot of diameter D and the average pressure potential at the apices of the shoot; the relation is given by P = 7.781 x 10(4) E D(0.605), where E is the average evaporative flux density (kg s(-1) m(-2)) in the leaves attached to the shoot. After comparing the predictions of this equation to field observations of E and leaf water potential and stomatal conductance, we concluded that the hydraulic conductance of large maple shoots is sufficiently low to prevent maximum stomatal conductance in maple leaves.
Timothy J Fahey - One of the best experts on this subject based on the ideXlab platform.
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regeneration ecology of sugar maple Acer Saccharum seedling survival in relation to nutrition site factors and damage by insects and pathogens
Canadian Journal of Forest Research, 2011Co-Authors: Timothy J Fahey, John J Battles, Natalie L CleavittAbstract:The possible regeneration failure of sugar maple (Acer Saccharum Marsh.) as part of their decline has been not well explored using field studies. We sought to clarify the roles of maternal effects and dynamics of early-season survival in contributing to the previously documented pattern of larger seedlings and higher seedling densities on a Ca-treated watershed (CAL) at Hubbard Brook Experimental Forest. We used a reciprocal seed planting experiment at four sites, two sites per watershed blocked by elevation. Regardless of maternity, sugar maple seedlings planted in CAL had higher survival than seedlings in the reference watershed. However, this advantage was not as clearly linked to the Ca amendment as in our previous work, probably, in part, because Ca availability has decreased over time. Maternal effects on seed chemistry and some seedling traits were detected, but these were not strong determinants of survival. Site was a good predictor of early seedling survival with litter layer depth, pathogen pre...
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regeneration ecology of sugar maple Acer Saccharum seedling survival in relation to nutrition site factors and damage by insects and pathogens
Canadian Journal of Forest Research, 2011Co-Authors: Timothy J Fahey, John J Battles, Natalie L CleavittAbstract:The possible regeneration failure of sugar maple (Acer Saccharum Marsh.) as part of their decline has been not well explored using field studies. We sought to clarify the roles of maternal effects and dynamics of early-season survival in contributing to the previously documented pattern of larger seedlings and higher seedling densities on a Ca-treated watershed (CAL) at Hubbard Brook Experimental Forest. We used a reciprocal seed planting experiment at four sites, two sites per watershed blocked by elevation. Regardless of maternity, sugar maple seedlings planted in CAL had higher survival than seedlings in the reference watershed. However, this advantage was not as clearly linked to the Ca amendment as in our previous work, probably, in part, because Ca availability has decreased over time. Maternal effects on seed chemistry and some seedling traits were detected, but these were not strong determinants of survival. Site was a good predictor of early seedling survival with litter layer depth, pathogen pre...
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patterns of rhizosphere carbon flux in sugar maple Acer Saccharum and yellow birch betula allegheniensis saplings
Global Change Biology, 2005Co-Authors: Richard P Phillips, Timothy J FaheyAbstract:Despite its importance in the terrestrial C cycle rhizosphere carbon flux (RCF) has rarely been measured for intact root‐soil systems. We measured RCF for 8-year-old saplings of sugar maple (Acer Saccharum) and yellow birch (Betula allegheniensis) collected from the Hubbard Brook Experimental Forest (HBEF), NH and transplanted into pots with native soil horizons intact. Five saplings of each species were pulse labeled with 13 CO2 at ambient CO2 concentrations for 4‐6h, and the 13 C label was chased through rhizosphere and bulk soil pools in organic and mineral horizons for 7 days. We hypothesized yellow birch roots would supply more labile C to the rhizosphere than sugar maple roots based on the presumed greater C requirements of ectomycorrhizal roots. We observed appearance of the label in rhizosphere soil of both species within the first 24h, and a striking difference between species in the timing of 13 C release to soil. In sugar maple, peak concentration of the label appeared 1 day after labeling and declined over time whereas in birch the label increased in concentration over the 7-day chase period. The sum of root and rhizomicrobial respiration in the pots was 19% and 26% of total soil respiration in sugar maple and yellow birch, respectively. Our estimate of the total amount of RCF released by roots was 6.9‐7.1% of assimilated C in sugar maple and 11.2‐ 13.0% of assimilated C in yellow birch. These fluxes extrapolate to 55‐57 and 90‐ 104gCm � 2 yr � 1 from sugar maple and yellow birch roots, respectively. These results
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influence of nonnative earthworms on mycorrhizal colonization of sugar maple Acer Saccharum
New Phytologist, 2003Co-Authors: Beth A Lawrence, Timothy J Fahey, Esteban SuarezAbstract:Summary • Exotic earthworms can modify or eliminate surface organic (Oe/Oa) horizons in cold-temperate forest ecosystems and have profound effects on the forest soil environment, especially the rooting zone. • We examined the effects of earthworm colonization of northern hardwood forest soils on the abundance and morphology of mycorrhizal fungi associated with sugar maple ( Acer Saccharum ). We compared mycorrhizal associations of areas of earthworm invasion with those of reference (no-worm) areas in Arnot Forest, central New York, USA. • The organic horizon in reference areas had higher mycorrhizal colonization rates and higher colonized root length than did surface layers in areas with active earthworm populations. Hyphal coils were more abundant and also formed a greater proportion of total fungal colonization in reference plots. Vesicles were more abundant and were a higher contribution to total colonization in earthworm plots, indicating a possible stress response to the presence of earthworms. • By affecting mycorrhizal colonization and morphology, earthworms may influence nutrient uptake capacity of dominant forest species. Our results suggest that a profound change in the mycorrhizal system will be one component of the potential ecosystem effects of invasion of new forest habitat by nonnative earthworms.
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influence of nonnative earthworms on mycorrhizal colonization of sugar maple Acer Saccharum
New Phytologist, 2003Co-Authors: Beth A Lawrence, Timothy J Fahey, Esteban SuarezAbstract:Summary • Exotic earthworms can modify or eliminate surface organic (Oe/Oa) horizons in cold-temperate forest ecosystems and have profound effects on the forest soil environment, especially the rooting zone. • We examined the effects of earthworm colonization of northern hardwood forest soils on the abundance and morphology of mycorrhizal fungi associated with sugar maple ( Acer Saccharum ). We compared mycorrhizal associations of areas of earthworm invasion with those of reference (no-worm) areas in Arnot Forest, central New York, USA. • The organic horizon in reference areas had higher mycorrhizal colonization rates and higher colonized root length than did surface layers in areas with active earthworm populations. Hyphal coils were more abundant and also formed a greater proportion of total fungal colonization in reference plots. Vesicles were more abundant and were a higher contribution to total colonization in earthworm plots, indicating a possible stress response to the presence of earthworms. • By affecting mycorrhizal colonization and morphology, earthworms may influence nutrient uptake capacity of dominant forest species. Our results suggest that a profound change in the mycorrhizal system will be one component of the potential ecosystem effects of invasion of new forest habitat by nonnative earthworms.
Christian Messier - One of the best experts on this subject based on the ideXlab platform.
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contrasting nutritional acclimation of sugar maple Acer Saccharum marsh and red maple Acer rubrum l to increasing conifers and soil acidity as demonstrated by foliar nutrient balances
Frontiers in Ecology and Evolution, 2016Co-Authors: Alexandre Collin, Christian Messier, Benoit Cote, Mario Fontana, Nicolas BelangerAbstract:Sugar maple (Acer Saccharum Marshall, SM) is believed to be more sensitive to acidic and nutrient-poor soils associated with conifer-dominated stands than red maple (Acer rubrum L., RM). Greater foliar nutrient use efficiency (FNUE) of RM is likely the cause for this difference. In the context of climate change, this greater FNUE could be key in favouring northward migration of RM over SM. We used the concept of foliar nutrient balances to study the nutrition of SM and RM seedlings along an increasing gradient in forest floor acidity conditioned by increasing proportions of conifers (pH values ranging from 4.39 under hardwoods, to 4.29 under mixed hardwood-conifer stands and 4.05 under conifer-dominated stands). Nutrients were subjected to isometric log-ratio (ilr) transformation, which views the leaf as one closed system and considers interactions between nutrients. The ilr method eliminates numerical biases and weak statistical inferences based on raw or “operationally’’ log-transformed data. We analyzed foliar nutrients of SM and RM seedlings and found that the [Ca,Mg,K|P,N] and [Ca,Mg|K] balances of SM seedlings were significantly different among soil acidity levels, whereas they did not vary for RM seedlings. For SM seedlings, these differences among soil acidity levels were due to a significant decrease in foliar Ca and Mg concentrations with increasing forest floor acidity. Similar differences in foliar balances were also found between healthy and declining SM stands estimated from literature values. Conversely, foliar balances of RM seedlings did not differ among soil acidity levels, even though untransformed foliar nutrient concentrations were significantly different. This result highlights the importance of using ilr transformation, since it provides more sensitive results than standard testing of untransformed nutrient concentrations. The lower nutrient requirements of RM and its greater capacity to maintain nutrient equilibrium are factors that could explain its competitive success and recent northward expansion. This study underscores the importance of using nutrient balances to study the redistribution of plant species in natural ecosystems under climate change.
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host species identity site and time drive temperate tree phyllosphere bacterial community structure
Microbiome, 2016Co-Authors: Isabelle Laforestlapointe, Christian MessierAbstract:Background The increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems. Since most knowledge of tree phyllosphere bacterial communities has been gathered in tropical forests, our goal was to characterize the community structure and assembly dynamics of phyllosphere epiphytic bacterial communities in temperate forests in Quebec, Canada. We targeted five dominant tree species: Acer Saccharum, Acer rubrum, Betula papyrifera, Abies balsamea, and Picea glauca. We collected 180 samples of phyllosphere communities on these species at four natural forest sites, three times during the growing season.
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contributions of leaf photosynthetic capacity leaf angle and self shading to the maximization of net photosynthesis in Acer Saccharum a modelling assessment
Annals of Botany, 2012Co-Authors: Juan M Posada, Risto Sievanen, Christian Messier, Jari Perttunen, Eero Nikinmaa, Martin J. LechowiczAbstract:† Background and Aims Plants are expected to maximize their net photosynthetic gains and efficiently use available resources, but the fundamental principles governing trade-offs in suites of traits related to resourceuse optimization remain uncertain. This study investigated whether Acer Saccharum (sugar maple) saplings could maximize their net photosynthetic gains through a combination of crown structure and foliar characteristics that let all leaves maximize their photosynthetic light-use efficiency (1). † Methods A functional ‐structural model, LIGNUM, was used to simulate individuals of different leaf area index (LAIind) together with a genetic algorithm to find distributions of leaf angle (LA) and leaf photosynthetic capacity (Amax) that maximized net carbon gain at the whole-plant level. Saplings grown in either the open or in a forest gap were simulated with Amax either unconstrained or constrained to an upper value consistent with reported values for Amax in A. Saccharum. † Key Results It was found that total net photosynthetic gain was highest when whole-plant PPFD absorption and leaf 1 were simultaneously maximized. Maximization of 1 required simultaneous adjustments in LA and Amax along gradients of PPFD in the plants. When Amax was constrained to a maximum, plants growing in the open maximized their PPFD absorption but not 1 because PPFD incident on leaves was higher than the PPFD at which 1max was attainable. Average leaf 1 in constrained plants nonetheless improved with increasing LAIind because of an increase in self-shading. † Conclusions It is concluded that there are selective pressures for plants to simultaneously maximize both PPFD absorption at the scale of the whole individual and 1 at the scale of leaves, which requires a highly integrated response between LA, Amax and LAIind. The results also suggest that to maximize 1 plants have evolved mechanisms that co-ordinate the LA and Amax of individual leaves with PPFD availability.
Robinson W Fulweiler - One of the best experts on this subject based on the ideXlab platform.
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winter climate change and fine root biogenic silica in sugar maple trees Acer Saccharum implications for silica in the anthropocene
Journal of Geophysical Research, 2017Co-Authors: Timothy J Maguire, Pamela H Templer, John J Battles, Robinson W FulweilerAbstract:Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack, and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer Saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.
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winter climate change decreases fine root biogenic silica in sugar maple trees Acer Saccharum implications for silica export in the anthropocene
Journal of Geophysical Research, 2017Co-Authors: Timothy J Maguire, Pamela H Templer, John J Battles, Robinson W FulweilerAbstract:Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack, and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer Saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.
Martin J. Lechowicz - One of the best experts on this subject based on the ideXlab platform.
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contributions of leaf photosynthetic capacity leaf angle and self shading to the maximization of net photosynthesis in Acer Saccharum a modelling assessment
Annals of Botany, 2012Co-Authors: Juan M Posada, Risto Sievanen, Christian Messier, Jari Perttunen, Eero Nikinmaa, Martin J. LechowiczAbstract:† Background and Aims Plants are expected to maximize their net photosynthetic gains and efficiently use available resources, but the fundamental principles governing trade-offs in suites of traits related to resourceuse optimization remain uncertain. This study investigated whether Acer Saccharum (sugar maple) saplings could maximize their net photosynthetic gains through a combination of crown structure and foliar characteristics that let all leaves maximize their photosynthetic light-use efficiency (1). † Methods A functional ‐structural model, LIGNUM, was used to simulate individuals of different leaf area index (LAIind) together with a genetic algorithm to find distributions of leaf angle (LA) and leaf photosynthetic capacity (Amax) that maximized net carbon gain at the whole-plant level. Saplings grown in either the open or in a forest gap were simulated with Amax either unconstrained or constrained to an upper value consistent with reported values for Amax in A. Saccharum. † Key Results It was found that total net photosynthetic gain was highest when whole-plant PPFD absorption and leaf 1 were simultaneously maximized. Maximization of 1 required simultaneous adjustments in LA and Amax along gradients of PPFD in the plants. When Amax was constrained to a maximum, plants growing in the open maximized their PPFD absorption but not 1 because PPFD incident on leaves was higher than the PPFD at which 1max was attainable. Average leaf 1 in constrained plants nonetheless improved with increasing LAIind because of an increase in self-shading. † Conclusions It is concluded that there are selective pressures for plants to simultaneously maximize both PPFD absorption at the scale of the whole individual and 1 at the scale of leaves, which requires a highly integrated response between LA, Amax and LAIind. The results also suggest that to maximize 1 plants have evolved mechanisms that co-ordinate the LA and Amax of individual leaves with PPFD availability.
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codominance of Acer Saccharum and fagus grandifolia the role of fagus root sprouts along a slope gradient in an old growth forest
Journal of Plant Research, 2010Co-Authors: Ken Arii, Koichi Takahashi, Martin J. LechowiczAbstract:We studied how the unusual capacity of mature Fagus grandifolia to form clumps of clonal stems from root sprouts can contribute to its frequent codominance with Acer Saccharum in southern Quebec, Canada. In an old-growth forest, the degree of dominance by the two species shifted along topographic gradients spanning a few hundreds of meters, with Fagus more frequent on lower slopes and Acer on upper slopes. The frequency distribution of Fagus stem diameter had an inverse J distribution at all slope positions, which is indicative of continuous recruitment. Acer stem diameter also had an inverse J pattern, except at lower slope positions where size structure was discontinuous. For stems <2 m tall, Fagus regenerated mainly by sprouts at the upper and mid-slopes, while regeneration from seed was more pronounced on the lower slope. This change of regeneration mode affected the spatial pattern of Fagus stems. Understory trees of Fagus were positively correlated with conspecific canopy trees on upper and mid-slopes, but not on lower slopes where Fagus regenerated mainly by seedlings. Understory trees of Acer were positively correlated with conspecific canopy trees only on the mid-slope. There were many Fagus seedlings around Acer canopy trees at the lower slope, suggesting the potential replacement of Acer canopy trees by Fagus. This study suggests that the regeneration traits of the two species changed with slope position and that Fagus patches originating from root sprouts can contribute to the maintenance of Acer–Fagus codominance at the scale of local landscapes.
