Deciduous Broadleaf Trees Research Articles

Interdisciplinary approach to the landscape and firewood exploitation during the Holocene at La Garrotxa (Girona, NE Iberia)

This paper assesses the landscape and management of firewood resources during the Holocene at La Garrotxa (Girona, NE Iberia), a middle mountain region (400-1600 m a.s.l.) located within a volcanic area in the Pre-Pyrenees. Anthracological and palynological data from archaeological sites and lacustrine and peat deposits in this area have been considered in an interdisciplinary approach to the landscape and use of resources. According to Early Holocene palynological data, the landscape was characterised by the progressive expansion of forests, mainly dominated by conifers (pine and juniper) and deciduous trees (oak and hazel). The Holocene Climatic Optimum led to the culmination of forest expansion, with the dominance of dense oak forests, the landscape that the first farming societies found on arrival in this area. During the Middle to Late Holocene transition (c. 4000 cal BP), the expansion of evergreen sclerophyllous trees and the regression of broadleaf deciduous trees are recorded, in response to both climatic and anthropic causes. Deciduous Quercus and Buxus sempervirens were the most important taxa in all periods and areas, as shown in charcoal data from 26 archaeological levels. However, some other taxa had certain importance in some periods and sites. The variability observed between sites is discussed in terms of the availability of resources and the transformation of landscape evidenced in pollen records. This could explain the appearance of evergreen Quercus and other Mediterranean taxa in the Middle-Late Holocene anthracological record. The characteristics of the sites and socio-historical processes have also been considered in order to understand the use of firewood. In that sense, social necessities would have been the determining factor in planning timber and firewood procurement strategies rather than adapting to the environmental availability.

北京地区典型落叶阔叶乔木叶片含氮量和δ15N值对大气氮沉降的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 北京地区典型落叶阔叶乔木叶片含氮量和δ15N值对大气氮沉降的响应 DOI: 10.5846/stxb201511202348 作者: 作者单位: 北京林业大学,北京林业大学自然保护区学院,北京林业大学自然保护区学院,北京林业大学自然保护区学院,北京林业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 北京市优秀人才培养资助项目（2014000020124G073）；国家自然科学基金资助项目（41503077）；北京林业大学科技创新计划资助项目（BLX20120022） Responses and Indications of Foliar Nitrogen Contents and δ15N values to Atmospheric Nitrogen Deposition in Beijing, China Author: Affiliation: Beijing Forestry University,,,,Beijing Forestry University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探究植物对大气氮沉降的响应和对这部分氮素的来源指示作用，本研究通过对北京地区198个采样点，典型落叶阔叶乔木杨属（Populus）和柳属（Salix）植物叶片进行采样，测定其叶片样品含氮量和δ15 N值。结果表明：北京地区杨属植物叶片含氮量为16.5-38.6 g/kg，平均（24.0±4.0）g/kg；柳属植物叶片含氮量为17.2-36.2 g/kg，平均（25.9±4.1）g/kg。研究区域范围内杨属、柳属植物叶片的含氮量均呈现出西北低、东南高的对角线型分布，与该区域大气氮沉降的空间变异相吻合。由于研究区域范围内气候因子无明显的变异，植物叶片的含氮量变化反应了大气氮沉降对植物元素化学计量特征的影响和植物对大气氮沉降的响应。北京地区杨属植物叶片δ15N值为-3.95‰-8.10‰，平均（1.15±2.48）‰；柳属植物叶片δ15N值为-3.04‰-9.73‰，平均（2.31±2.60）‰。杨属和柳属植物叶片的δ15N值均呈现出西北高、中部高、东南低的空间分布，与叶片含氮量空间分布趋势相反。中部城区较高的δ15N值反应了交通污染对大气含氮化合物增加的影响；西北部较高的δ15N值反应了该区域受人为活动排放源的影响较少，自然的氮循环是其较高δ15N值的主要原因；东南部较低的δ15N值则有可能是由农业活动和交通共同作用的结果。 Abstract:With 60% of the total area located in the North China Plain, Beijing suffered with very high atmospheric nitrogen (N) deposition in the south part, which was as high as 100 kg hm-2 a-1 including both organic and inorganic nitrogenous species from both wet and dry deposition. To test the responses of foliar N contents of plants, a collection of deciduous broadleaf tree leaves was conducted across Beijing areas. Typical deciduous broadleaf trees, Populus and Salix were selected at 189 sites, which were firstly designed at 5-decimal minute in latitude and longitude grid resolution and then excluded sites without Populus or Salix species. Leaf sampling collection was carried out in the end of August corresponding to annual peak-standing biomass in late summer. Five trees of every species at each site were selected, and five mature leaves of every tree were collected. All the leaf samples were over-dried at 105℃ for 10 minutes and then 65℃ for 48 hours to constant mass. Samples of each species at each site were put together and grounded with a mill to pass 1-mm sieve for N contents analysis. Foliar N was determined following Kjeldehl digestion and δ15N values were determined by continuous flow isotope-ratio mass spectrometer. The foliar N contents were (24.0±4.0) g/kg and (25.9±4.1) g/kg on average for Populus and Salix, respectively. Spatial variations of both the two genus showed similar trends, with higher foliar N contents in the southeast and lower foliar N contents in the northwest, consisting with the spatial variation of atmospheric N deposition in Beijing area. The foliar δ15N values were (1.15±2.48)‰ and (2.31±2.60)‰ on average for Populus and Salix, respectively. However, the spatial variation trends of δ15N values were contrary with the foliar N contents. Higher δ15N values were found in the city center and northwest, while lower δ15N values were found in the southeast. With the different δ15N values of potential sources, the higher δ15N values in the city center indicated the traffic emission sources, the higher δ15N values in the northwest indicated the natural N cycling, while the lower δ15N values indicated both the agricultural and traffic pollution. 参考文献 相似文献 引证文献

Diversity of leaf litter leachates from temperate forest trees and its consequences for soil microbial activity

Leaching of water-soluble compounds is a dominant process during the first stages of litter decomposition, providing the microorganisms in the underlying soil with an important source of labile carbon and nutrients. Leachate composition (quantity and quality) can vary considerably among different plant species, but its consequences for soil microbially-driven processes remains largely unexplored. Here, we evaluated the differences in leachate quantity and quality from freshly fallen leaf litter of widely distributed coniferous and deciduous broadleaf tree species of European temperate forests, and their effects on soil microbial responses in a microcosm experiment under controlled conditions. Leachates of broadleaf litter contained higher amounts of carbon and nitrogen available for microbes, but with substantially higher aromaticity than leachates from coniferous litter. A one-time leachate addition to soils immediately increased soil microbial respiration with longer lasting effects of deciduous broadleaf compared to coniferous litter leachates leading to a microbial community with an apparently more efficient use of carbon. When leachates of different species were mixed, the observed microbial responses differed in some cases from that expected based on soils to which leachates from single species were added. These non-additive effects were partly explained by the functional dissimilarity of leachate traits, suggesting complementary resources for microorganisms when leachates of different species are available. Our data show that species-specific litter-derived leachates of varying quantity and quality and their mixtures distinctly affect soil microorganisms. In forest ecosystems with recurrent leaf litter inputs from the same species, such leachate effects may determine soil processes also in the longer term, controlling biogeochemical cycling to an important degree.

Improved representation of plant functional types and physiology in the Joint UK Land Environment Simulator (JULES v4.2) using plant trait information

Abstract. Dynamic global vegetation models are used to predict the response of vegetation to climate change. They are essential for planning ecosystem management, understanding carbon cycle–climate feedbacks, and evaluating the potential impacts of climate change on global ecosystems. JULES (the Joint UK Land Environment Simulator) represents terrestrial processes in the UK Hadley Centre family of models and in the first generation UK Earth System Model. Previously, JULES represented five plant functional types (PFTs): broadleaf trees, needle-leaf trees, C3 and C4 grasses, and shrubs. This study addresses three developments in JULES. First, trees and shrubs were split into deciduous and evergreen PFTs to better represent the range of leaf life spans and metabolic capacities that exists in nature. Second, we distinguished between temperate and tropical broadleaf evergreen trees. These first two changes result in a new set of nine PFTs: tropical and temperate broadleaf evergreen trees, broadleaf deciduous trees, needle-leaf evergreen and deciduous trees, C3 and C4 grasses, and evergreen and deciduous shrubs. Third, using data from the TRY database, we updated the relationship between leaf nitrogen and the maximum rate of carboxylation of Rubisco (Vcmax), and updated the leaf turnover and growth rates to include a trade-off between leaf life span and leaf mass per unit area.Overall, the simulation of gross and net primary productivity (GPP and NPP, respectively) is improved with the nine PFTs when compared to FLUXNET sites, a global GPP data set based on FLUXNET, and MODIS NPP. Compared to the standard five PFTs, the new nine PFTs simulate a higher GPP and NPP, with the exception of C3 grasses in cold environments and C4 grasses that were previously over-productive. On a biome scale, GPP is improved for all eight biomes evaluated and NPP is improved for most biomes – the exceptions being the tropical forests, savannahs, and extratropical mixed forests where simulated NPP is too high. With the new PFTs, the global present-day GPP and NPP are 128 and 62 Pg C year−1, respectively. We conclude that the inclusion of trait-based data and the evergreen/deciduous distinction has substantially improved productivity fluxes in JULES, in particular the representation of GPP. These developments increase the realism of JULES, enabling higher confidence in simulations of vegetation dynamics and carbon storage.

Site-level importance of broadleaf deciduous trees outweighs the legacy of high nitrogen (N) deposition on ecosystem N status of Central Appalachian red spruce forests

Atmospheric nitrogen (N) deposition can influence forest ecosystem N status, and the resilience of forests to the effects of N deposition depends on a number of co-occurring environmental factors that regulate N retention or loss. In this study, we test the idea that N deposition may have important and long-lasting impacts on patterns of N cycling by using field and laboratory techniques to assess N status in seven high-elevation Central Appalachian red spruce (Picea rubens Sarg.) forests located at sites that historically received moderate to high inputs of N atmospheric deposition. During 2011 and 2012, we measured multiple indices of N availability (e.g. foliar/soil C:N and δ15N, resin ion-exchange, and N transformation rates) that integrate N cycling over seasonal to decadal time scales. Using a model selection approach, we compared the strength of the association between various environmental factors and temporally-integrated indices of N status in a series of regression models. Site-level differences in the relative importance value of broadleaf deciduous (BD) trees consistently explained most of the observed variation in N status. Soil C:N was significantly lower for sites with greater BD importance (R 2 = 0.67–0.77), and there was a strong positive relationship between BD importance and soil δ15N content (R 2 = 0.64–0.85). Despite a four-fold difference in historic deposition across the seven forest sites, we did not observe any significant relationships between site N status and N deposition. These findings suggest that potential legacy effects of N deposition were obscured by the influence of BD importance on N status at these sites. Our results add strong support to the idea that predicting the resilience of forests to the effects of N deposition requires detailed knowledge on the contribution of tree species composition to soil N cycling and retention.

Implementation of a Marauding Insect Module (MIM, version 1.0) in the Integrated BIosphere Simulator (IBIS, version 2.6b4) dynamic vegetation–land surface model

Abstract. Insects defoliate and kill plants in many ecosystems worldwide. The consequences of these natural processes on terrestrial ecology and nutrient cycling are well established, and their potential climatic effects resulting from modified land–atmosphere exchanges of carbon, energy, and water are increasingly being recognized. We developed a Marauding Insect Module (MIM) to quantify, in the Integrated BIosphere Simulator (IBIS), the consequences of insect activity on biogeochemical and biogeophysical fluxes, also accounting for the effects of altered vegetation dynamics. MIM can simulate damage from three different insect functional types: (1) defoliators on broadleaf deciduous trees, (2) defoliators on needleleaf evergreen trees, and (3) bark beetles on needleleaf evergreen trees, with the resulting impacts being estimated by IBIS based on the new, insect-modified state of the vegetation. MIM further accounts for the physical presence and gradual fall of insect-killed dead standing trees. The design of MIM should facilitate the addition of other insect types besides the ones already included and could guide the development of similar modules for other process-based vegetation models. After describing IBIS–MIM, we illustrate the usefulness of the model by presenting results spanning daily to centennial timescales for vegetation dynamics and cycling of carbon, energy, and water in a simplified setting and for bark beetles only. More precisely, we simulated 100 % mortality events from the mountain pine beetle for three locations in western Canada. We then show that these simulated impacts agree with many previous studies based on field measurements, satellite data, or modelling. MIM and similar tools should therefore be of great value in assessing the wide array of impacts resulting from insect-induced plant damage in the Earth system.

Study on <i>Panax notoginseng</i> F.H.Chen Cultivation Under Forest

To overcome the Panax notoginseng F.H.Chen facility cultivation high cost and the consecutive monoculture problems of cultivated land, to satisfy the market demand, to save the production cost, improve the utilization rate of forest land, increase the income of forest farmers, protect the ecological environment, we has been used Yunnan wenshan Panax notoginseng F.H.Chen high quality seedlings for carring out cultivation technology research under forests, according to plant spacing 25 cm ×30 cm to planting, used randomized block design, repeated three times. We choice the Nut forest and China fir forest that the altitude is above 1000m and forests canopy density pond are 0.8 in shuping township Hongjiang, Gracp forest and Kiwi fruit forest that the altitude is 900m and forest canopy density of 0.6 and 0.5 respectively in tangwan township. The test results in 4 forests showed that cultivation growth of nut forest cultivation of Panax notoginseng F.H.Chen, crown diameter, survival rate, three years raw tuber weight were higher than the other three kinds of forests land, China fir forest is better than that of grape and Kiwi fruit forest, grapes forest is higher than the kiwi fruit forest at crown diameter and survival rate, but high growth and tuber weight below the kiwi fruit forest. when we cultivated Panax notoginseng F.H.Chen for scale cultivation under forests, Research results show that we should preference chioce Nut forest in Nut forest, China fir forest, Gracp forest and Kiwi fruit forest at Panax notoginseng F.H. Chen cultivation. because the nut are broadleaf deciduous tree species, lots of fallen leaves decomposed by decaing, increased the soil humus content that makes more loose fertile soil, better permeability, and damp, cool, more diffuse light and scattered light under forests. It is comformed to Panax notoginseng F.H.Chen ecological habit and the rule of the growth and development, and the Panax notoginseng F.H.Chen liked cloudy, joied the cool shade under forests, avoid direct light, liked oblique or scattered light. The Panax notoginseng F.H.Chen large scale cultivations undergrowth can overcome the facility cultivation cost high, production input more, technology is difficulty disadvantages such as, it’s can save the production cost, improve the utilization efficiency of forest land and increase the income of forest farmers, drive to get rich of local forest farmers, protect the ecological environment, promote the sustainable development of Panax notoginseng F.H.Chen industry.

Light compensation points in shade-grown seedlings of deciduous broadleaf tree species with different successional traits raised under elevated CO2.

We measured leaf photosynthetic traits in shade-grown seedlings of four tree species native to northern Japan, raised under an elevated CO2 condition, to investigate the effects of elevated CO2 on shade tolerance of deciduous broadleaf tree species with different successional traits. We considered Betula platyphylla var. japonica and Betula maximowicziana as pioneer species, Quercus mongolica var. crispula as a mid-successional species, and Acer mono as a climax species. The plants were grown under shade conditions (10% of full sunlight) in a CO2 -regulated phytotron. Light compensation points (LCPs) decreased in all tree species when grown under elevated CO2 (720 μmol·mol(-1) ), which were accompanied by higher apparent quantum yields but no photosynthetic down-regulation. LCPs in Q. mongolica and A. mono grown under elevated CO2 were lower than those in the two pioneer birch species. The LCP in Q. mongolica seedlings was not different from that of A. mono in each CO2 treatment. However, lower dark respiration rates were observed in A. mono than in Q. mongolica, suggesting higher shade tolerance in A. mono as a climax species in relation to carbon loss at night. Thus, elevated CO2 may have enhanced shade tolerance by lowering LCPs in all species, but the ranking of shade tolerance related to successional traits did not change among species under elevated CO2 , i.e. the highest shade tolerance was observed in the climax species (A. mono), followed by a gap-dependent species (Q. mongolica), while lower shade tolerance was observed in the pioneer species (B. platyphylla and B. maximowicziana).

New patterns of establishment and growth of Picea, Abies and Betula tree species in subalpine forest gaps of Jiuzhaigou National Nature Reserve, Sichuan, southwestern China in a changing environment

Temperature increase in the southeastern Tibetan Plateau in the past thirty years is high but its effects on tree dynamics of subalpine coniferous forests are not well understood. This study focuses on tree establishment and growth in 26 subalpine forest gaps between 2900m and 3200m in Jiuzhaigou National Nature Reserve, Sichuan, China. Normally Abies faxoniana and Picea purpurea dominate the canopy of subalpine forests in the reserve. Our study examined tree species establishment and growth, environmental conditions in these gaps, and the potential future changes in forest composition in the reserve. Seedlings, saplings and mature trees were counted, measured and cored to assess species’ numbers, age, and growth parameters. Root structure was also studied. Gap environmental conditions were recorded and climate changes examined. For a wide range of differently aged gaps, numerous seedlings, saplings and even mature canopy trees of Betula albo-sinensis, a deciduous broadleaf tree, were observed. B. albo-sinensis was most abundant in gaps with the following characteristics: (1) steep slopes (>30°), (2) areas with thin soil (<5cm depth) or (3) large areas (>600m2) with deep soil (>15cm depth). In contrast, the site characteristics required for successful establishment of the two evergreen conifers A. faxoniana and P. purpurea are soil >9cm deep and slopes <30°. B. albo-sinensis has shallower roots with smaller root:shoot ratio than the conifer species. Increasing temperature, declining cloud cover and increasing high rainfall incidences are increasing habitats that favor establishment and growth of B. albo-sinensis and inhibit the establishment and growth of A. faxoniana and P. purpurea in subalpine areas of Jiuzhaigou, southwestern China.

서울 도심 가로수 및 가로녹지의 기온 저감 효과와 기능 향상 연구

본 연구는 도시 내 가로수 및 가로녹지의 수종, 식재유형, 가로녹지 구조, 녹량(녹지용적)에 따른 기온 변화량을 규명하고자 하였다. 수종별 비교 가능한 3종 이상의 가로수가 식재된 유형은 교목 1열+관목이었으며, 보차간 기온차이 평균값 간 분석에서 소나무 <TEX>$1.35^{\circ}C$</TEX>, 느티나무 <TEX>$1.84^{\circ}C$</TEX>, 은행나무 <TEX>$2.00^{\circ}C$</TEX>, 양버즘나무 <TEX>$2.57^{\circ}C$</TEX>이었다. 규격이 크고 수관폭이 넓은 수종은 가로변에 그늘을 제공하여 기온 저감에 상당한 영향을 주는 것으로 분석되었다. 가로수 식재유형과 기온과의 관계 분석결과는 교목 1열 유형은 평균기온 차이 <TEX>$1.80^{\circ}C$</TEX>, 교목 2열 유형은 평균기온 차이 <TEX>$2.15^{\circ}C$</TEX>로 교목 열수 증가에 따라 보차간 기온차이 평균값이 큰 것을 알 수 있었다. 가로녹지 구조별 기온 저감 효과 분석결과는 교목 유형 <TEX>$1.94^{\circ}C$</TEX>, 교목+관목 유형 <TEX>$2.49^{\circ}C$</TEX>, 교목+아교목+관목 유형 <TEX>$2.57^{\circ}C$</TEX>이었으며, 기온저감은 단층구조보다 다층구조에서 효과적이었다. 녹량(녹지용적량)과 기온저감량과의 관계 분석에서는 녹량이 많을수록 기온저감 효과가 커지는 것으로 분석되었다. 연구 결과 수관용적이 크고 교목층의 열수가 많으며, 다층구조인 식재형태는 가로 내 녹량과 관계가 있음을 의미하였다. 본 결과를 바탕으로 기온 저감 효과와 기능 강화를 위한 가로녹지 조성 기준을 제안하였다. 보도폭 3m 이하인 경우에는 수관용적이 작은 낙엽활엽수와 최대 1m의 띠녹지 조성을 통한 교목+관목의 구조를 제시하였다. 보도폭 3m 이상인 경우에는 수관용적이 큰 낙엽활엽수 다열 식재 및 1m 이상의 띠녹지 조성, 교목과 관목뿐만 아니라, 아교목 성상의 수목 식재를 통한 다층구조 녹지조성이 가능할 것으로 판단되었다. The goal of this research is to examine air temperature changes according to tree type, plantation type, roadside green area structure, and green volume of street green area within a city. The plantation type that could be analyzed for comparison by tree type with over 3 species was 1 rows of tree+shrubs. The results of analysis of average air temperature difference between pedestrian and car streets vis-a-vis 1 row of tree+shrub in high air temperature areas were: Pinus densiflora, <TEX>$1.35^{\circ}C$</TEX>; Zelkova serrata, <TEX>$1.84^{\circ}C$</TEX>; Ginkgo biloba, <TEX>$2.00^{\circ}C$</TEX>; Platanus occidentalis, <TEX>$2.57^{\circ}C$</TEX>. This standard large wide canopy species was analyzed by the roadside to provide shade to have a significant impact on air temperature reduction. In terms of analysis of the relationship between plantation type of roadside trees and air temperature, the average air temperature difference for 1 row of tree type was <TEX>$1.80^{\circ}C$</TEX>; for 2 rows of trees it was <TEX>$2.15^{\circ}C$</TEX>. In terms of analysis of the relationship between the roadside green area structure and air temperature, for tree type, average air temperature <TEX>$1.94^{\circ}C$</TEX>: for tree+shrub type, average air temperature <TEX>$2.49^{\circ}C$</TEX>; for tree+mid-size tree+shrub type, average air temperature <TEX>$2.57^{\circ}C$</TEX>. That is, air temperature reduction was more effective in a multi-layer structure than a single layer structure. In the relationship analysis of green volume and air temperature reduction, the air temperature reduction effect was enlarged as there was a large amount of green volume. There was a relationship with the green volume of the road, the size of the tree and number of tree layers and a multi-layer structured form of planting. The canopy volume was large and there were a great number of rows of the tree layer and the plantation type of multi-layer structure, which is what is meant through a relationship with the green volume along the roadside. Green composition standards for air temperature reduction effects and functional improvement were proposed based on the result. For a pedestrian street width of 3m or less in the field being ideal, deciduous broadleaf trees in which the canopy volume is small and the structure of the tree+shrub type through the greatest 1m green bend were proposed. For a pedestrian street width of over 3m, deciduous broadleaf trees in which the canopy volume is large and is multi-layer planted with green bend over 1m, tree+mid-size tree+shrub type was proposed.

Variations of leaf inclination angle distribution with height over the growing season and light exposure for eight broadleaf tree species

Leaf inclination angles are of critical importance in determining the transmission of radiation by vegetation canopies. In this short communication we address the seasonal and vertical changes in leaf inclination angles for eight deciduous broadleaf tree species common to temperate and hemiboreal ecoclimatic regions. The greatest changes in leaf inclination angles are observed in spring at the top of the canopy. Tree species with more vertical leaf inclination angles are more sensitive to light exposure than tree species with more horizontal inclination angles. We also test the sensitivity to user subjectivity of the leveled digital camera method for measuring leaf inclination angles and show that the method provides comparable results irrespective of the user.

New flux based dose–response relationships for ozone for European forest tree species

To derive O3 dose–response relationships (DRR) for five European forest trees species and broadleaf deciduous and needleleaf tree plant functional types (PFTs), phytotoxic O3 doses (PODy) were related to biomass reductions. PODy was calculated using a stomatal flux model with a range of cut-off thresholds (y) indicative of varying detoxification capacities. Linear regression analysis showed that DRR for PFT and individual tree species differed in their robustness. A simplified parameterisation of the flux model was tested and showed that for most non-Mediterranean tree species, this simplified model led to similarly robust DRR as compared to a species- and climate region-specific parameterisation. Experimentally induced soil water stress was not found to substantially reduce PODy, mainly due to the short duration of soil water stress periods. This study validates the stomatal O3 flux concept and represents a step forward in predicting O3 damage to forests in a spatially and temporally varying climate.

The longevity of broadleaf deciduous trees in Northern Hemisphere temperate forests: insights from tree-ring series

Understanding the factors controlling the expression of longevity in trees is still an outstanding challenge for tree biologists and forest ecologists. We gathered tree-ring data and literature for broadleaf deciduous (BD) temperate trees growing in closed-canopy old-growth forests in the Northern Hemisphere to explore the role of geographic patterns, climate variability, and growth rates on longevity. Our pan-continental analysis, covering 32 species from 12 genera, showed that 300-400 years can be considered a baseline threshold for maximum tree lifespan in many temperate deciduous forests. Maximum age varies greatly in relation to environmental features, even within the same species. Tree longevity is generally promoted by reduced growth rates across large genetic differences and environmental gradients. We argue that slower growth rates, and the associated smaller size, provide trees with an advantage against biotic and abiotic disturbance agents, supporting the idea that size, not age, is the main constraint to tree longevity. The oldest trees were living most of their life in subordinate canopy conditions and/or within primary forests in cool temperate environments and outside major storm tracks. Very old trees are thus characterized by slow growth and often live in forests with harsh site conditions and infrequent disturbance events that kill much of the trees. Temperature inversely controls the expression of longevity in mesophilous species (Fagus spp.), but its role in Quercus spp. is more complex and warrants further research in disturbance ecology. Biological, ecological and historical drivers must be considered to understand the constraints imposed to longevity within different forest landscapes.

Carbon gain optimization in five broadleaf deciduous trees in response to light variation within the crown: correlations among morphological, anatomical and physiological leaf traits

AbstractLeaf trait variations in five deciduous species (Quercus robur, Corylus avellana, Populus alba, Acer campestre, Robinia pseudoacacia) growing in an old broadleaf deciduous forest in response to light variation within the tree crown was analyzed. Net photosynthetic rate (PN), leaf respiration rate (R) and the photosynthetic nitrogen use efficiency were, on average, more than 100% higher in sun than in shade leaves. A. campestre and C. avellana sun leaves had the highest specific leaf area (SLA, 156.0 ± 17.9 cm2 g-1) and the lowest total leaf thickness (L, 101.9 ± 8.8 μm) underlining their shade-tolerance. Among the shade-intolerant species (Q. robur, P. alba and R. pseudoacacia), Q. robur had the lowest SLA and the highest L in sun leaves (130.6 ± 10.0 cm2 g-1 and 160.8 ± 9.6 μm, respectively) since shade-intolerant species typically have thicker leaves. The higher PN decrease in respect to R decrease from sun to shade leaves attested the higher sensitivity of PN than R to light variations within the crown. This determined a 69% lower R/PN in sun than in shade leaves. This result is further attested by the significant correlation between PN and the relative photosynthetic photon flux density. The shade-tolerant species have a 76% higher R/PN ratio than the shade-intolerant ones. The measured leaf phenotypic plasticity (PI = 0.35) was in the range of broadleaf deciduous species. Plasticity is a key trait useful to quantify plant response to environmental stimuli. It is defined as the ability of a genotype to produce different phenotypes depending on the environment. Among the considered species, Q. robur showed the highest PI (0.39) and P. alba the lowest (0.29). Knowledge on phenotypic plasticity is important in making hypotheses about the dynamics of the studied forest in consideration of environmental stress factors, including invasive species competition and global climate change.

Future changes of the terrestrial ecosystem based on a dynamic vegetation model driven with RCP8.5 climate projections from 19 GCMs

Future changes of terrestrial ecosystems due to changes in atmospheric CO2 concentration and climate are subject to a large degree of uncertainty, especially for vegetation in the Tropics. Here, we evaluate the natural vegetation response to projected future changes using an improved version of a dynamic vegetation model (CLM-CN-DV) driven with climate change projections from 19 global climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). The simulated equilibrium vegetation distribution under historical climate (1981–2000) has been compared with that under the projected future climate (2081–2100) scenario for Representative Concentration Pathway 8.5 (RCP8.5) to qualitatively assess how natural potential vegetation might change in the future. With one outlier excluded, the ensemble average of vegetation changes corresponding to climates of 18 GCMs shows a poleward shift of forests in northern Eurasia and North America, which is consistent with findings from previous studies. It also shows a general “upgrade” of vegetation type in the Tropics and most of the temperate zones, in the form of deciduous trees and shrubs taking over C3 grass in Europe and broadleaf deciduous trees taking over C4 grasses in Central Africa and the Amazon. LAI and NPP are projected to increase in the high latitudes, southeastern Asia, southeastern North America, and Central Africa. This results from CO2 fertilization, enhanced water use efficiency, and in the extra-tropics warming. However, both LAI and NPP are projected to decrease in the Amazon due to drought. The competing impacts of climate change and CO2 fertilization lead to large uncertainties in the projection of future vegetation changes in the Tropics.

Isolation and characterization of 12 microsatellite loci from Maackia fauriei (Fabaceae), a large tree endemic to Jeju Island

The high endemism and unique vegetation of Jeju Island are threatened by anthropogenic disturbances and climate change. Restricted to Jeju Island, the deciduous broadleaf tree, Maackia fauriei is an endemic, vulnerable species. We developed 12 microsatellite markers as an effective molecular tool in assessing genetic diversity and tested them in 33 individuals from a local population. Loci had 3–20 alleles each, with observed and expected heterozygosities ranging from 0.394 to 0.909 and from 0.621 to 0.903, respectively. These markers will be valuable for establishing conservation strategies for M. fauriei on Jeju Island.

Biophysical forcings of land‐use changes from potential forestry activities in North America

Land‐use changes through forestry and other activities alter not just carbon storage, but biophysical properties, including albedo, surface roughness, and canopy conductance, all of which affect temperature. This study assessed the biophysical forcings and climatic impact of vegetation replacement across North America by comparing satellite‐derived albedo, land surface temperature (LST), and evapotranspiration (ET) between adjacent vegetation types. We calculated radiative forcings (RF) for potential local conversions from croplands (CRO) or grasslands (GRA) to evergreen needleleaf (ENF) or deciduous broadleaf (DBF) forests. Forests generally had lower albedo than adjacent grasslands or croplands, particularly in locations with snow. They also had warmer nighttime LST, cooler daily and daytime LST in warm seasons, and smaller daily LST ranges. Darker forest surfaces induced positive RFs, dampening the cooling effect of carbon sequestration. The mean (±SD) albedo‐induced RFs for each land conversion were equivalent to carbon emissions of 2.2 ± 0.7 kg C/m2 (GRA–ENF), 2.0 ± 0.6 kg C/m2 (CRO–ENF), 0.90 ± 0.50 kg C/m2 (CRO–DBF), and 0.73 ± 0.22 kg C/m2 (GRA–DBF), suggesting that, given the same carbon sequestration potential, a larger net cooling (integrated globally) is expected for planting DBF than ENF. Both changes in LST and ET induce longwave RFs that sometimes had values comparable to or even larger than albedo‐induced shortwave RFs. Sensible heat flux, on average, increased when replacing CRO with ENF, but decreased for conversions to DBF, suggesting that DBF tends to cool near‐surface air locally while ENF tends to warm it. This local temperature effect showed some seasonal variation and spatial dependence, but did not differ strongly by latitude. Overall, our results show that a carbon‐centric accounting is, in many cases, insufficient for climate mitigation policies. Where afforestation or reforestation occurs, however, deciduous broadleaf trees are likely to produce stronger cooling benefits than evergreen needleleaf trees provide.

Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

AbstractRed alder (Alnus rubra), a nitrogen(N)‐fixing deciduous broadleaf tree, can strongly influence N concentrations in western Oregon and Washington. We compiled a database of stream N and GIS‐derived landscape characteristics in order to examine geographic variation in N across the Oregon Coast Range. Basal area of alder, expressed as a percent of watershed area, accounted for 37% and 38% of the variation in summer nitrate and total N (TN) concentrations, respectively. Relationships between alder and nitrate were strongest in winter when streamflow and landscape connections are highest. Distance to the coast and latitude, potential surrogates for sea salt inputs, and watershed area were also related to nitrate concentrations in an all‐subsets regression analysis, which accounted for 46% of the variation in summer nitrate concentrations. The model with the lowest Akaike's Information Criterion did not include developed or agricultural land cover, probably because few watersheds in our database had substantial levels of these land cover classes. Our results provide evidence, at a regional scale, that background sources and processes cause many Coast Range streams to exceed proposed nutrient criteria, and that the prevalence of a single tree species (N‐fixing red alder) exerts a dominant control over stream N concentrations across this region.

Chronic water stress reduces tree growth and the carbon sink of deciduous hardwood forests

Predicted decreases in water availability across the temperate forest biome have the potential to offset gains in carbon (C) uptake from phenology trends, rising atmospheric CO2 , and nitrogen deposition. While it is well established that severe droughts reduce the C sink of forests by inducing tree mortality, the impacts of mild but chronic water stress on forest phenology and physiology are largely unknown. We quantified the C consequences of chronic water stress using a 13-year record of tree growth (n = 200 trees), soil moisture, and ecosystem C balance at the Morgan-Monroe State Forest (MMSF) in Indiana, and a regional 11-year record of tree growth (n > 300 000 trees) and water availability for the 20 most dominant deciduous broadleaf tree species across the eastern and midwestern USA. We show that despite ~26 more days of C assimilation by trees at the MMSF, increasing water stress decreased the number of days of wood production by ~42 days over the same period, reducing the annual accrual of C in woody biomass by 41%. Across the deciduous forest region, water stress induced similar declines in tree growth, particularly for water-demanding 'mesophytic' tree species. Given the current replacement of water-stress adapted 'xerophytic' tree species by mesophytic tree species, we estimate that chronic water stress has the potential to decrease the C sink of deciduous forests by up to 17% (0.04 Pg C yr(-1) ) in the coming decades. This reduction in the C sink due to mesophication and chronic water stress is equivalent to an additional 1-3 days of global C emissions from fossil fuel burning each year. Collectively, our results indicate that regional declines in water availability may offset the growth-enhancing effects of other global changes and reduce the extent to which forests ameliorate climate warming.

Historical range of fire frequency is not the Achilles' heel of the Corsican black pine ecosystem

Summary This study investigated the fire‐vegetation relationship by reconstructing the long‐term fire and vegetation dynamics around a small lake in the Mediterranean montane belt on Corsica Island. The vegetation is characterised by forests dominated by Pinus nigra ssp. laricio, an endemic subspecies that is currently threatened. Populations of this taxon are geographically restricted, and their ranges are decreasing, possibly because of disturbance, that is, fire and logging. Here, we examine the role of fire in vegetation dynamics and its effect on diversity since the lateglacial at a montane site using sedimentary plant macrofossils and charcoal to reconstruct local vegetation and fire frequency, respectively. Macrofossils of P. laricio provide evidence for its growth around the Lac de Creno since 13 200 cal. years bp, which is consistent with its natural origin in Corsica. The onset of the Holocene (~11 700 cal. years bp) was marked by a rapid shift in the treeline, the establishment of P. laricio‐dominated woodlands with low species turnover, and a long‐term increase in taxa richness as a result of successive expansions of broadleaved deciduous trees. In spite of fire‐return intervals (FRIs) fluctuating between 30 and 490 years during the Holocene, P. laricio‐dominated woodlands persisted for several millennia, and fires likely played an ecological role in the functioning of these woodlands. The 12 000 year record of mean FRI (80 years between fires; i.e. frequency of 12.5 fires 1000 year−1) can be used to define a baseline for the management and conservation of P. laricio montane forests. Our findings demonstrate that P. laricio has a long history, a natural origin in Corsica, and that Corsican pine forests have survived to a wide range of burning conditions over the last 13 200 years. Synthesis: We present multimillennial fire and vegetation histories of a Mediterranean montane site. Pinus nigra ssp. laricio has been present near the study site since approximately 13 200 cal. years bp, demonstrating that this pine was present on the island prior to the arrival of pre‐historic humans. The long‐term records also show that P. laricio woodlands were mixed with deciduous broadleaf trees (Betula sp. and Fagus sylvatica), and other needleleaf trees (Abies alba), at least, and were not influenced by changes in fire frequency. We conclude that (i) fire is a natural component of the ecosystem and (ii) fires likely played an important ecological role in the functioning of the Corsican black pine woodland ecosystem.