Deciduous Broad-leaved Species Research Articles

Interspecific variation in the size‐dependent resprouting ability of temperate woody species and its adaptive significance

Summary Resprouting of woody species after above‐ground damage may help plants to persist longer at a given site and quickly reoccupy disturbed sites, thereby strongly influencing forest dynamics. Resprouting has been discussed from two adaptation perspectives: recovery from damage by catastrophic disturbance and survival in frequently disturbed shaded understorey. However, few studies have comprehensively dealt with both adaptation types to understand resprouting strategies. To understand the adaptive significance of resprouting, we assessed the size dependence of resprouting ability after stem clipping for 24 deciduous broad‐leaved species, including shrubs, sub‐canopy and canopy trees, in a cool‐temperate forest in Japan. The community assembly includes species adapted to past catastrophic disturbances (e.g. fire, logging) and to stable forest with intermittent treefall (currently the dominant disturbance). We correlated resprouting ability with life‐history strategies based on demographic parameters and plant functional traits, such as leaf mass per area (LMA), leaf toughness and wood density. All the studied species could resprout in juveniles, and resprouting ability increased as stump size increased. Most sub‐canopy and canopy trees lost their ability to resprout after attaining a particular stump size, whereas shrub species retained the ability to resprout throughout their lifetimes. The relative growth rate, LMA and foliar nitrogen did not greatly influence the resprouting ability of a species. In contrast, species with smaller maximum size, lower leaf toughness and lower wood density had better juvenile resprouting ability. This better resprouting ability may have evolved because these characteristics make them more vulnerable to shaded understorey. However, species with larger maximum size and lower leaf toughness retained their ability to resprout to a larger size. Synthesis. A better resprouting ability is related to the ability to survive frequent disturbances, in juveniles, which are characteristics of both forest understorey and frequent fire or drought. To retain resprouting ability until grown seems to be an adaptation to survive infrequent large disturbances. Light‐demanding species, which generally have better resprouting ability than shade‐tolerants both in juveniles and adults, are adapted to disturbances of various scale and frequency; however, shade‐tolerants could survive well in the understorey due to a combination of stronger physical defences and resprouting ability.

Foliar carbon isotope discrimination and related traits along light gradients in two different functional-type tree species

To understand how different plant functional types respond to light intensities, foliar carbon isotope discrimination (Δ13C) and related traits, i.e., specific leaf area (SLA), mass- and area-based nitrogen concentrations (Nmass and Narea), leaf dry mass content (LDMC) of two evergreen coniferous and three deciduous broad-leaved species, were measured under four light intensities. Foliar Δ13C and SLA increased significantly from full- to low-light conditions for all species. These indicate that species studied could increase their light capture capacity under low-light conditions, leading to lower water-use efficiency (higher 13C discrimination). There were significant differences in the responses of foliar Nmass or Narea to light variations in the two functional types, indicating that different functional-type tree species may have different N-use strategies to adapt to the light variations. It was found that there were large functional-type-dependent differences with regard to the relationships between foliar Δ13C and other leaf traits. Our findings suggest that all tree species could change foliar morphology to increase their light-harvesting ability under low-light conditions at the expense of decreasing their water-use efficiency. However, large differences in N-use strategy may exist between deciduous and evergreen species, which may be vital for the survival of these two functional-type tree species in a shaded understory. More important, our findings reveal that changes in Δ13C are not directly related to foliar N if N investment does not proportionally increase the photosynthetic capacity; this should be considered when exploring the relationships of nitrogen concentrations with Δ13C.

Foliar symptoms triggered by ozone stress in irrigated holm oaks from the city of Madrid, Spain.

BackgroundDespite abatement programs of precursors implemented in many industrialized countries, ozone remains the principal air pollutant throughout the northern hemisphere with background concentrations increasing as a consequence of economic development in former or still emerging countries and present climate change. Some of the highest ozone concentrations are measured in regions with a Mediterranean climate but the effect on the natural vegetation is alleviated by low stomatal uptake and frequent leaf xeromorphy in response to summer drought episodes characteristic of this climate. However, there is a lack of understanding of the respective role of the foliage physiology and leaf xeromorphy on the mechanistic effects of ozone in Mediterranean species. Particularly, evidence about morphological and structural changes in evergreens in response to ozone stress is missing.ResultsOur study was started after observing ozone -like injury in foliage of holm oak during the assessment of air pollution mitigation by urban trees throughout the Madrid conurbation. Our objectives were to confirm the diagnosis, investigate the extent of symptoms and analyze the ecological factors contributing to ozone injury, particularly, the site water supply. Symptoms consisted of adaxial and intercostal stippling increasing with leaf age. Underlying stippling, cells in the upper mesophyll showed HR-like reactions typical of ozone stress. The surrounding cells showed further oxidative stress markers. These morphological and micromorphological markers of ozone stress were similar to those recorded in deciduous broadleaved species. However, stippling became obvious already at an AOT40 of 21 ppm•h and was primarily found at irrigated sites. Subsequent analyses showed that irrigated trees had their stomatal conductance increased and leaf life -span reduced whereas the leaf xeromorphy remained unchanged. These findings suggest a central role of water availability versus leaf xeromorphy for ozone symptom expression by cell injury in holm oak.

温带12个树种新老树枝非结构性碳水化合物浓度比较

Non-structural carbohydrates( NSC) are important carbon reserves in trees,which vary seasonally due to changes in the strength of carbon sink or source. Seasonal fluctuations of NSC in branches are influenced by multiple factors such as leaf phenology,shoot extension,and radial growth,but it is not clear which factor plays the key role. Here we measured the NSC concentrations in the new twigs( current year) and old branches( ≥ 1 years old,diameter 3 cm) at seven phenological stages for 12 temperate tree species in northeastern China. The objectives were to( 1) compare seasonalities of NSC concentrations in the new twigs and old branches,( 2) explore relationships between concentrations of soluble sugars and starch in these tissues,and( 3) explore factors controlling the inter-specific variations in NSC concentrations in branches. The species included three evergreen conifers[Korean pine( Pinus koraiensis),Mongolian pine( Pinus sylvestris var. mongolica) and Korean spruce( Picea koraiensis) ],one deciduous conifer[Dahurian larch( Larix gmelinii) ],and eight deciduous broadleaved species [Mongolian oak( Quercus mongolica),Japanese elm( Ulmus japonica),Manchurian ash( Fraxinus mandshurica),Manchurian walnut( Juglans mandshurica),Korean aspen( Populus davidiana),Ussuri poplar( Populus ussuriensis),white birch( Betula platyphylla),and Amur linden( Tilia amurensis) ].For each species,one branch at the mid-crown was sampled and separated into new twigs and old branches. Concentrations of soluble sugars and starch were determined with a modified phenol-sulphuric method,and expressed as a percentage of dry matter( % DM). The concentrations of NSC in new twigs and old branches showed similar seasonal patterns of NSC concentration for all the tree species except for Korean aspen and Ussuri poplar. The concentrations of NSC in the new twigs were usually higher than those in the old branches. The concentrations of TNC( total non-structural carbohydrates,sum of soluble sugars and starch) in the old branches of the evergreen species increased significantly before bud-break,declined slightly during bud-break,and kept relatively stable after leaf flushing until autumn when the concentration of NSC rebounced slightly. The concentrations of TNC in the old branches of the deciduous species decreased significantly before or during bud-break,and then progressively increased in both new twigs and old branches along the season. Meanwhile,a conversion of starch to soluble sugars was observed in October when the dormant season started. There was a significant and positive linear relationship between the concentrations of soluble sugars and starch for both new twigs and old branches when the data were pooled across all the species. The seasonal mean concentration,maximum concentration,and storage capacity of TNC in the old branches decreased significantly with the duration of shoot extension increasing for all the species except for Mongolian oak( the species with an intra-annual regrowth of branch),Korean spruce and Japanese elm( no data available). These findings suggested that the shoot growth of these temperate trees relies strongly on NSC reserves,and the duration of shoot length growth is inter-connected with TNC storage in branches. Future researches on forest carbon cycle modeling and global climate change should consider this functional inter-connection.

제주도 난대림에서 노루 뿔의 성장과정에 의한 어린나무 박피에 관한 연구

산림에서 나무껍질이 벗겨지는 피해는 노루를 비롯한 사슴과에 속하는 포유류에 의해 발생하며 먹이 부족이 주요 원인이다. 그러나 제주도에서는 뿔이 녹각으로 되는 과정에서 벨벳을 벗겨내는 행동에 의해 나무껍질이 벗겨지는 피해가 발생하여 이들을 살펴보았다. 국립산림과학원 한남시험림내의 해발 400m에서 500m 사이에 위치한 6km구간의 임도 주변 5m지역을 대상으로 2011년 9월 9일부터 10월 4일까지 맑은날을 택하여 본조사를 실시하였다. 노루가 뿔로 긁은 피해목은 총 25종, 267본이었으며 낙엽활엽수가 18종 134본, 상록활엽수가 5종 71본, 나머지 2종 62본은 침엽수였다. 뿔 긁기로 가장 선호하는 수종은 굴거리나무(Daphniphyllum macropodum), 삼나무(Cryptomeria japonica), 비목(Lindera erythrocarpa), 누리장나무(Clerodendrum trichotomum), 산초나무(Zanthoxylum schinifolium) 순이었다. 피해목은 주로 3~4년생의 어린나무이며 평균 수고는 <TEX>$120.7{\pm}42.4cm$</TEX>이었고, 지상 5cm 높이에서의 직경은 <TEX>$1.5{\pm}0.5cm$</TEX>, 피해 시작점(최저점)은 지상에서부터 평균 <TEX>$22.1{\pm}10.1cm$</TEX> 지점이었고, 피해길이는 평균 <TEX>$27.5{\pm}10.6cm$</TEX>이었다. 나무껍질이 벗겨지면 이차적으로 균류의 침입을 받게 되며 이로 인해 어린나무의 외형이 변하거나 죽게 되어 난대림의 향후 종 구성에 영향을 야기할 수 있다. 기후변화에 따른 제주도 산림의 식생변화가 예견되는 시점에서 노루의 뿔에 의한 피해는 난대림의 자연 갱신은 물론 조림과 묘목생산 그리고 지속적인 산림경영에 영향을 미칠 것으로 판단된다. Peeling damage of trees is usually caused by Cervidae such as deer, roe deer because of the lack of food in forests. However, it happens as part of the developing of antlers in Jeju Island when the roe deer try to remove the Velvet-the skin of the antlers. The research area is the Hannam experimental forest (400 m up to 500 m above sea level) of Korea Forest Research Institute in Jeju Island, and the survey was carried out along the 6 km long of forest road with 5 m width on both sides. Twenty five tree species (total 267 stands) are damaged by peeling; 18 (134 stands) deciduous broad-leaved species, 5 (71 stands) in evergreen broad-leaved species, 2 (62 stands) coniferous species. The most common damaged species are in order of Daphniphyllum macropodum, Cryptomeria japonica, Lindera erythrocarpa, Clerodendrum trichotomum, Zanthoxylum schinifolium. Mainly damaged trees are approximately 3~4 years old saplings, and they show the mean height <TEX>$120.7{\pm}42.4cm$</TEX>, diameter measured at 5 cm height <TEX>$1.5{\pm}0.5cm$</TEX>. The Lowest peeling beginning height is <TEX>$22.1{\pm}10.1cm$</TEX>, and the mean length of peeling is <TEX>$27.5{\pm}10.6cm$</TEX>. Once the peeling damage happens, the saplings are infected by fungi secondly, and are distorted or dead, therefore the future structure of warm-temperate forests could be in influenced in species. Warm-temperate forest landscape and species change related to the climate change is a rising issue in Jeju Island. However the changes caused by peeling damage also could be an important issue in the natural process of forest environment, afforestation, local nursery and sustainable forest management of Jeju Island.

Climate Model Comparisons

Ecology![Figure][1] CREDIT: CHRISTIAN R. LINDER Predicting the effects of climate change on the future distributions of species is an inherently uncertain exercise. There are uncertainties in climate models themselves and also in the models of species' response to climate change. To address this problem, Cheaib et al. compared the predictions of eight different species' response models for five dominant tree species in the flora of France, representative of the range of forest communities from Mediterranean in the south to more temperate in the north. For the two evergreen species considered, there was generally good agreement between models. Holm oak, the dominant Mediterranean species, substantially increases its range under all model scenarios; the range of Scots pine, a species of cooler and mountainous regions, was predicted to contract under most models. However, models agreed relatively poorly in their predictions of range shifts of three temperate broad-leaved deciduous species. A principal source of uncertainty is the current limits to understanding the effects of increasing CO2 concentrations on the physiology of these species. Such comparisons not only help foresters and conservation managers judge the probability of success (or otherwise) of management alternatives, but also help to focus future research on the areas of greatest uncertainty Ecol. Lett. 15 , 10.1111/j.1461-0248.2012.01764.x (2012). [1]: pending:yes

Responses of leaf structure and photosynthetic properties to intra-canopy light gradients: a common garden test with four broadleaf deciduous angiosperm and seven evergreen conifer tree species.

Spectra of leaf traits in northern temperate forest canopies reflect major differences in leaf longevity between evergreen conifers and deciduous broadleaf angiosperms, as well as plastic modifications caused by within-crown shading. We investigated (1) whether long-lived conifer leaves exhibit similar intra-canopy plasticity as short-lived broadleaves, and (2) whether global interspecific relationships between photosynthesis, nitrogen, and leaf structure identified for sun leaves adequately describe leaves differentiated in response to light gradients. We studied structural and photosynthetic properties of intra-tree sun and shade foliage in adult trees of seven conifer and four broadleaf angiosperm species in a common garden in Poland. Shade leaves exhibited lower leaf mass-per-area (LMA) than sun leaves; however, the relative difference was smaller in conifers than in broadleaves. In broadleaves, LMA was correlated with lamina thickness and tissue density, while in conifers, it was correlated with thickness but not density. In broadleaves, but not in conifers, reduction of lamina thickness was correlated with a thinner palisade layer. The more conservative adjustment of conifer leaves could result from a combination of phylogenetic constraints, contrasting leaf anatomies and shoot geometries, but also from functional requirements of long-lived foliage. Mass-based nitrogen concentration (Nmass) was similar between sun and shade leaves, and was lower in conifers than in deciduous broadleaved species. Given this, the smaller LMA in shade corresponded with a lower area-based N concentration (Narea). In evergreen conifers, LMA and Narea were less powerful predictors of area-based photosynthetic rate (A max(area)) in comparison with deciduous broadleaved angiosperms. Multiple regression for sun and shade leaves showed that, in each group, A max(mass) was related to Nmass but not to LMA, whereas LMA became a significant codeterminant of A max(mass) in analysis combining both groups. Thus, a fundamental mass-based relationship between photosynthesis, nitrogen, and leaf structure reported previously also exists in a dataset combining within-crown and across-functional type variation.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-012-2279-y) contains supplementary material, which is available to authorized users.

Investigation on pistachio distribution in the mountain regions of northeast Iran by ALOS

Iran supports five different vegetation zones. One of those is the Irano-Touranian zone that is located in the northeast of Iran. This vegetation zone includes arid and semi-arid lands, and its area is about 3.5 million hm2. It supports growth of pistachio (Pistacia vera), a deciduous-broadleaved species, which is one of the ecologically and economically most important native species. In this study, we analyzed three images acquired by ALOS satellite, including 10m resolution multispectral band (AVNIR-2), 2.5 m resolution “Backward” PRISM image, and 2.5 m resolution “Nadir” PRISM image, based on a provided rational polynomial coefficient (RPC). Using the “Backward” and “Nadir” images, a 2.5 m resolution digital elevation model (DEM) was produced. Four methods with AVNIR-2 and PRISM data were used to produce pan-sharpening images and conduct an object-based feature extraction process. Normalized Difference Vegetation Index (NDVI) was used to determine the maximum distribution of pistachio in related elevation. The accuracy of the DEM was tested on 28 ground control points in the pair image as tie points, with the value of parallax error of 0.9027 m. The created elevation map indicated that pistachio trees grow up at 650m above sea level (a.s.l.). The result from NDVI in the related elevation showed the maximum density of pistachio at 800m a.s.l. In addition, the result of feature extraction in the forest showed the area of each target element calculated. The results of this research will improve decision-making and lead to sustainable management in general.

Within-twig Biomass Allocation in Evergreen and Deciduous Broad-leaved Species:Allometric Scaling Analyses

Biomass allocation in current-year shoots(twigs) is an important parameter categorizing plant life history strategies,and it is an important driving factor for plant net carbon obtaining.In this study,the scaling relationships of biomass allocation within twigs of evergreen and deciduous species at Gongga mountain were estimated using standardized major axis estimation(SMA) and the phylogenetically independent contrast analysis(PIC) methods.The results indicated:Isometric relationships were found between twig mass and stem mass,leaf mass and lamina mass,as well as between stem mass and leaf mass,suggesting that the biomass allocation to either leaves or laminas were independent of twig mass;allometric relationships were found between petiole mass and leaf mass,as well as between petiole mass and twig mass,indicating the importance of leaf petioles to the within-twig biomass allocation;evergreen species tended to have a greater petiole mass at a given twig or lamina mass than deciduous species.Our results indicate that petioles serve as an adverse forcing on the maximization of lamina biomass and the allometric relationship between lamina and lamina support varies with species type.

Ancient Subalpine Clonal Spruces (&lt;i&gt;Picea abies&lt;/i&gt;): Sources of Postglacial Vegetation History in the Swedish Scandes

This study addresses the long-standing issue of postglacial immigration of Picea abies (Norway spruce) into Scandinavia. The main methodological focus is on using megafossil tree remains (wood and cones) of spruce and other species retrieved from the treeline ecotone of the Swedish Scandes as a tool for vegetation reconstruction. The core data come from radiocarbon dating of megafossils preserved in the soil underneath clonal groups of Picea abies , formed by rooting of branches that over time give rise to new upright stems. At high elevations, we found living spruce clones, which in some cases may be part of a continuous clonal series dating back to the early Holocene (9500 cal. yr BP). The presence of Picea in the Swedish Scandes at this early stage concurs with previous megafossil inferences. This date, which places the arrival of Picea very soon after regional deglaciation, is several millennia earlier than the arrival date inferred from pollen data. The persistence of some individual Picea clones from the early Holocene thermal optimum to the present implies that permanently open or semi-open spots existed in the high-mountain landscape even during periods when treelines in general were much higher than at present. Initially, Picea clones appear to have existed in a regional no-analogue vegetation matrix of widely scattered pine ( Pinus sylvestris ), mountain birch ( Betula pubescens ssp. czerepanovii ), Siberian larch ( Larix sibirica ) and thermophilic broadleaved deciduous species. In response to subsequent neoglacial cooling, the alpine character of the landscape has been enhanced through a lowered pine treeline and the disappearance of larch and thermophiles. The endurance of spruces, which escaped fire and other calamities, is due to their inherent phenotypic plasticity. Increasing climatic harshness throughout the Holocene conserved them as crippled krummholz, protected from winter stress by almost complete snow coverage. The appearance of Picea abies exclusively in western Scandinavia shortly after the deglaciation could suggest that the species immigrated from “cryptic” ice age refugia much closer to Scandinavia than conventionally thought.

Variation of δ13C of wood and foliage with canopy height differs between evergreen and deciduous species in a temperate forest

We investigated post-photosynthetic fractionation and carbon transfer mechanisms of different plant functional types growing under the same climatic conditions in North-eastern China. The variations in δ13C of trunk and branches were compared with leaf δ13C at different canopy heights of Pinus koraiensis (evergreen coniferous species), Larix gmelinii (deciduous coniferous species) and Quercus mongolica (deciduous broad-leaved species). Results showed that δ13C of leaves increased (became more enriched) with increasing canopy height for both coniferous species (P. koraiensis, L. gmelinii) but not for Q. mongolica (a deciduous broad-leaved species). δ13C of both trunk and branches also increased with sampling height for the evergreen conifer P. koraiensis but did not significantly vary for either of the deciduous species (L. gmelinii or Q. mongolica), except a significant increase in branch δ13C for L. gmelinii. Similarly, δ13C of trunk and branches were strongly correlated with leaf δ13C only in the evergreen conifer, P. koraiensis. 13C was consistently more enriched in trunk, branches, and roots compared to leaves in all three species. Our findings suggest that, even under the same climatic conditions, different plant functional types may exhibit different carbon transfer mechanisms. This is contrary to the previous hypothesis that different carbon transfer mechanisms operate in forests of different climatic zones, especially in tropical and temperate forests. Particularly, the differences occur predominantly between evergreen and deciduous trees rather than between coniferous and broad-leaved trees. The significant difference in δ13C between leaves and wood tissues confirms a previous post-photosynthetic isotope fractionation in temperate forests.

Cambial growth dynamics and climatic control of different tree life forms in tropical mountain forest in Ethiopia

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.

The leaf size-twig size spectrum in evergreen broad-leaved forest of subtropical China.

Plant twig characters for 82 woody species including individual leaf and total leaf mass, stem mass, individual leaf area, total leaf area and stem cross-sectional area were investigated at the twig level in different altitudes and life forms on Meihuashan Mountain in Southeastern China. The results showed that twig cross-sectional area of plant twigs were found to allometrically scale to individual leaf area and total leaf area that the twig supported, all with the common SMA (standardized major axis) slope being significantly larger than 1.0. However, the spectrum of twig leaf mass–stem mass was found to be mostly isometric and the slope had no significant deviation from 1.0, the same as the spectrum of twig total leaf area–twig leaf mass. The allometric constants (y-intercepts) of the relationships between the stem cross-sectional area and leaf area (both total leaf area and individual leaf area) were found to decrease significantly along the altitudinal gradient. Compared to deciduous broad-leaved species, the evergreen broad-leaved species were smaller in total leaf area for a given cross-sectional area or stem mass. This suggests that the species would support less leaf area at a given twig cross-sectional area with increasing environmental stress. And the life form can modify leaf-stem scaling relationship because of the difference of function.

Oak Conservation and Restoration on Private Forestlands: Negotiating a Social-Ecological Landscape

In the midwestern United States, oak (Quercus spp.) forests are considered critical habitat for conserving biodiversity and are a declining resource. Ecological conditions, such as deer herbivory and competition from more mesic broad-leaved deciduous species, have been linked to poor oak regeneration. In the Midwest, where up to 90% of forestland is privately owned, a greater understanding of social dimensions of oak regeneration success is especially critical to designing effective restoration strategies. We sought to determine factors that serve as direct and indirect constraints to oak restoration and identify policy mechanisms that could improve the likelihood for restoration success. We conducted in-depth qualitative interviews with 32 natural resource professionals working in the Midwest Driftless Area. We found that most professionals anticipate that oak will remain only a component of the future forest. Furthermore, they identified the general unwillingness of landowners to adopt oak restoration practices as a primary driving force of regional forest change. The professionals pointed to interdependent ecological and social factors, occurring at various scales (e.g., economic cost of management, deer herbivory, and exurban residential development) as influencing landowner oak restoration decisions. Professionals emphasized the importance of government cost-share programs and long-term personal relationships to securing landowner acceptance of oak restoration practices. However, given finite societal resources, ecologically- and socially-targeted approaches were viewed as potential ways to optimize regional success.

Relationships between leaf life span, leaf mass per area, and leaf nitrogen cause different altitudinal changes in leaf δ13C between deciduous and evergreen species

We examined the variability in stable carbon isotope ratio (δ13C) in leaves of two deciduous broad-leaved species and two evergreen conifer species along an altitudinal gradient in central Japan. The δ13C of the two deciduous species decreased with altitude, except near the upper distribution limit. The two evergreen species, however, showed no clear altitudinal trends for δ13C. The δ13C of the two deciduous species was positively correlated with leaf mass per area (LMA), indicating that the altitudinal variation in δ13C was controlled by LMA. Leaf nitrogen per mass (as a proxy of assimilation capacity, Nmass) was negatively correlated with LMA for the two deciduous species, while it was not correlated with LMA for the two evergreen species. Leaf life span of the two deciduous species decreased with altitude, whereas that of the two evergreen species increased. Thus, the two deciduous species had shorter-lived thinner leaves with higher Nmass at higher altitudes, and the two evergreen species had longer-lived leaves. These changes contribute to the positive carbon balance at higher altitudes. Therefore, the different changes in δ13C with altitude between the deciduous and evergreen species are ascribed to the different altitudinal changes in the leaf traits for carbon balance.

Plant limiting nutrients in Andean-Patagonian woody species: Effects of interannual rainfall variation, soil fertility and mycorrhizal infection

Andean-Patagonian forests are especially interesting for the study of N and P limitation because they receive minimal atmospheric pollution, have little influence of vascular N-fixing species, and grow on volcanic soils that retain P. In a previous study of 10 woody species (four broad-leaved deciduous species, three broad-leaved evergreens and three conifers) conducted during an exceptionally dry year in NW Patagonia, and on the basis of nutrient resorption efficiency and proficiency, we suggested that N was the most limiting nutrient except for the broad-leaved evergreen Lomatia hirsuta. In the present work, we compared patterns of nutrient limitation during a dry and a wet year, quantified the percentage of mycorrhizal infection, and related mycorrhizal behavior and nutrient limitation to soil fertility. We used N and P concentrations in green leaves as indicators of nutrient requirements, and N and P concentrations in senescent leaves (resorption proficiency) and the N/P ratio in green leaves as indicators of nutrient limitation. We also determined leaf mass area (LMA) and lignin concentration as indicators of structural and chemical defences. From previous works, the following soil fertility indicators were included: pH, organic C, total N, exchangeable cations, Olsen-P, potential N mineralization (pNmin) and N retained in microbial biomass (N-MB). Nitrogen, P and lignin concentrations in green and senescent leaves did not differ significantly between the dry and the wet year either by species or by functional groups. Most species behaved as N-proficient and P-non-proficient; this together with values of foliar N/P ratios lower than 14–16 confirmed N limitation in these forests. The only species limited by P but not by N was L. hirsuta (1.0–1.1% N in senescent leaves, N/P ratio = 21–23), a non-mycorrhizal species with cluster roots. The lack of P limitation in the other species was probably related to the high percentages of infection with arbuscular mycorrhizae (80–90% in Maytenus boaria and the conifers Araucaria araucana, Austrocedrus chilensis and Fitzroya cupressoides), and ectomycorrhizae (73–79% in five Nothofagus species). Nitrogen and P requirements were positively correlated among themselves and negatively with lignin and LMA. Soil fertility was positively correlated with nutrient requirements and negatively with lignin and LMA. Conifers had lower N and P requirements, higher LMA, lower foliar N/P ratio and grew on soils of lower soil N dynamics (lower pNmin and N-MB) than ectomycorrhizae-associated species.

Tree species diversity affects canopy leaf temperatures in a mature temperate forest

Forest canopies play a major role in biosphere—atmosphere interaction. Their actual temperature may deviate substantially from ambient atmospheric conditions as reported by weather stations. While there is a long tradition of false-colour imagery, new digital technologies in combination with IR transmission lenses and autocalibration routines permit unprecedented insight into the actual temperature regimes in canopies. We report canopy leaf temperature distribution over space and time assessed over a 35 m tall mixed deciduous forest in NW Switzerland by means of a construction crane and a high resolution thermal camera. At an air temperature of 25 ° C, conifers ( Picea abies, Pinus sylverstris and Larix decidua) and deciduous broad-leaved trees with exceptionally high transpiration ( Quercus petraea) or very open, low density canopies ( Prunus avium) exhibited mean canopy leaf temperatures close to air temperature (0.3–2.7 K above ambient) and the maximum amplitude within a given crown reached 6–9 K. In contrast, broad-leaved deciduous species with dense canopies ( Fagus sylvatica, Carpinus betulus and Tilia platyphyllos) were 4.5–5 K warmer than air temperature and showed within canopy temperature amplitudes of 10–12 K. Calculated leaf boundary resistance was clearly lower for conifers (3–24 m s −1) than for broad-leaved trees (33–64 m s −1). The study illustrates that mean leaf temperatures in forest trees are not adequately explained by either stomatal conductance or leaf dimensions, but strongly depend on canopy architecture (leaf area density, branching habits) in combination with leaf traits. Aerodynamic leaf and canopy characteristics lead to strongly enhanced vapour pressure gradients (evaporative forcing) and leaf temperatures vary enormously over short distances, calling for statistical temperature models (frequency distribution) rather than the use of means in any flux calculations. The presence/absence of certain tree taxa plays a key role in forest surface temperature.

Spatial pattern dynamics over 10 years in a conifer/broadleaved forest, northern Japan

The present study investigated stand dynamics during 10-year period in a conifer/broadleaved mixed forest in Hokkaido, northern Japan, focusing on spatially dependent recruitment, mortality and growth of two growth-form groups, deciduous broadleaved species and the dominant evergreen conifer Abies sachalinensis. The stand-level basal area was maintained over the 10-year period, while a compositional equilibrium at the individual species level was not confirmed. Univariate and bivariate spatial analyses revealed clustering of many of the constituent species. The absence of single-species patches suggested an ambiguous mosaic formed by co-occurrence of Abies and broadleaved trees. The trend towards an aggregated distribution of Abies and broadleaved trees was caused by spatially dependent recruitment rather than mortality. New recruits of broadleaved species were spatially associated with surviving broadleaved trees, while this was not the case for Abies. The degree of competitive effects on growth was not consistent over the 10-year period. Abies showed between-groups competition, but not within-group competition. In contrast, we found asymmetric competitions between the broadleaved trees. Our results suggest that Abies is not sufficiently competitively dominant to exclude broadleaved trees, and that the co-occurrence of the two growth-form groups might be maintained.

Spatial pattern and regeneration dynamics in a temperate Abies—Tsuga forest in southwestern Japan

This article reports the regeneration dynamics of a temperate Abies—Tsuga forest in Kirishima Yaku National Park, southwestern Japan, and examines the influence of species coexistence mediated by gap disturbances on biomass production. All trees taller than 2m in a 1-ha plot were monitored over four growing seasons. Three growth-form groups occupied different vertical layers. Evergreen conifers and deciduous broad-leaved trees tended to be spatially segregated from evergreen broad-leaved trees, which formed thickets in the understorey. The regeneration of understorey evergreen broad-leaved trees was affected by canopy gaps. The recruitment of conifers and deciduous broad-leaved species was not observed during the four growing seasons. This suggests that regeneration is sporadic and the present environmental conditions are not favorable for these canopy species. The mortality and unsuccessful recruitment of conifers and deciduous trees appeared to cause fluctuations in the productivity of the stand. However, an abundance of canopy gaps accelerates the regrowth of shorter species, and the fluctuation of productivity resulting from the population dynamics of canopy species would be partly mitigated by the regeneration of evergreen understorey species. The horizontal and vertical heterogeneity of the temperate mixed forest was a result of the patch structures of the three growth-form groups. The different regeneration patterns among the three groups, which were driven by interactions of species-specific regeneration niches and disturbance regimes, might be an important factor in maintaining the aboveground productivity in a transitional mixed forest between warm-temperate and cool-temperate zones.

Carbon assimilation, nitrogen, and photochemical efficiency of different Himalayan tree species along an altitudinal gradient

In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (Psat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, Psat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest Psat at saturating irradiance and the highest leaf N content. This N content was higher and Psat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, Psat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by δ13C, showed the same range reported for temperate tree species. The ranking of δ13C values for the different tree types was conifers < evergreen broadleaved<deciduous, suggesting tighter stomatal closure and higher water use efficiency for the evergreen types, confirming trends found elsewhere. No relevant differences of δ13C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (δF/Fm’), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .δF/Fm’ along the altitudinal gradient correlated well with the reported altitudinal distribution of the species.