木炭遗存揭示藏东南过去2700年人类生存环境及木材利用策略

木材是早期人类在青藏高原高海拔区域生存所需的关键性资源之一, 对木材的利用是人类适应极端环境的策略之一。本研究通过对青藏高原东南部8处考古遗址出土木炭的系统分析, 重建了遗址周边的木材资源, 发现过去2700年以来, 在木材资源丰富的藏东南, 先民采集的木材种类多样, 只在少数遗址显示出对特定木材的选择偏好; 波堆藏布流域人群利用的主要木材为当地的果树光核桃(Prunus mira), 其他区域则以川滇高山栎(Quercus semecarpifolia)和高山松(Pinus densata)为主, 显示出木材利用策略具有明显的空间差异; 研究还发现, 在气候变化影响下, 高山松在先民日常生活中的比重逐渐降低, 而川滇高山栎等灌木逐渐增加。本研究第一次对藏东南区域木材利用历史进行了重建, 为探讨人类对藏东南的行为适应提供了新的视角。

     

甘肃小陇山锐齿栎群落生物量特征分析

对甘肃小陇山锐齿栎群落乔木层生物量进行大量的野外调查和分析,结果表明:1.锐齿栎单一优势种混交群落生物量最大,其次为锐齿栎-鹅耳枥等小乔木混交群落,而锐齿栎单一优势种群落(纯林)生物量相对较小,杂木林群落生物量最小,其生物量比锐齿栎单一优势种混交群落低34.27%;2.锐齿栎群落乔木层的生物量增长规律为在群落发育成熟(80林龄左右)之前生物量在一直增加,到形成稳定的群落结构(成熟林),生物量趋于稳定(200 t/hm2),随群落发育进入末期,生物量有可能稍有降低;3.锐齿栎群落乔木层生物量在阴、阳坡都随海拔梯度先升高,后降低,呈典型的“中间膨胀”模式。     

Hydrogeomorphic control on tree growth responses in the Elton area of the Cheshire Saltfield, UK

Increment cores were sampled from oak (Quercus robur) and ash (Fraxinus excelsior) growing at Elton, an area of the Cheshire Saltfield that has experienced significant subsidence and damage to the natural and built environments in the latter part of the twentieth century. Ring-width measurements for Elton trees permitted the construction of one main site chronology (Elton) and four sub chronologies (Elton A, Elton B, Elton C, Elton ASH). Ring-width difference between these and a control chronology identified periods of sustained growth reduction in oak trees commencing in AD 1859/1861, 1886 and 1934. Growth reductions after 1934 are related to watertable draw down caused by brine pumping from a concentration of nine boreholes at Elton, up to 2 km from tree sampling locations. Growth reductions in 1859/1861 and 1886 are likely to be the result of earlier phases of brine pumping in the Wheelock Valley, up to 5 km to the east of Elton, and these reductions correlate well with historic records of subsidence and pumping activity. Cessation of pumping in 1977 led to a lagged growth recovery in oak trees between 1981 and 1986, indicating that an artificial drought had been imposed on the Elton area for a period in excess off 100-y. This research demonstrates a hydrological separation of surface water and groundwater in an area where salt beds are overlain by till and that ring-width records of Q. robur can be used to reconstruct watertable variability and also the spatial impact of solution mining.     

Quercus yangyiensis sp.nov.from the Late Pliocene of Baoshan,Yunnan and Its Paleoclimatic Significance

A new Quercus （Fagaceae） morphospecies is described based on well-preserved fossil leaves.The fossils were collected from Yangyi Formation of the Upper Pliocene at the Yangyi coalmine,Baoshan,western Yunnan,China.Details of the microstructure of mesophyll tissue are preserved because lithification of the fossils was not complete.The fossil laminas possess typical characteristics of Quercus sect.Heterobalanus：quite thick and coriaceous cuticle; secondary veins bifurcating near the margin in the middle and top of the leaf; and upper epidermis with adaxial hypodermis.Based on a detailed morphological and anatomical comparison with all living and fossil species of Quercus sect.Heterobalanus,the fossil leaves prove to be different in their sparse and garland-shaped multicellular trichomes on the lower epidermis,and so it is described as a new species Quercus yangyiensis He,Li et Sun sp.nov.The much sparser trichomes of our fossils compare well with those of living Quercus sect.Heterobalanus and indicate a more humid climate during the deposition of the Yangyi Formation in the Late Pliocene.     

Influence of species and rain event characteristics on stemflow volume in a temperate mixed oak–beech stand

This study aimed at analysing the effects of biological and meteorological factors on stemflow generation in a temperate mixed oak (Quercus petraea Liebl.) and beech (Fagus sylvatica L.) stand. A statistical model was developed to predict single‐event individual stemflow volume from trunk circumference and rainfall depth allowing mechanistic stemflow parameters to be deduced from the model, namely stemflow rates (SF_rate), storage of water on tree organs (S_t) and rainfall thresholds for stemflow (RF_min). SF_rate and S_t increased with increasing trunk circumference while RF_min was not significantly influenced by tree size. RF_min and, for a given tree size, S_t were higher for oak than for beech, and inversely for SF_rate. For each species, RF_min was higher for the leaved season than for the leafless period, while the opposite was found for SF_rate, and S_t was not significantly affected by the season. Increasing wind speed during rain increased SF_rate, lowered RF_min and did not influence S_t. In contrast, S_t and RF_min tended, respectively, to decrease and to increase with increasing values of the ratio between the cumulated potential evaporation during the dry period preceding the rain event and the volume of the preceding rainfall (Eva p_ADP/R_previous). Stemflow volume, which results from the combined effects of the previous parameters, was higher for beech than for oak and also higher during the leafless period than during the leaved period; these differences were large for the smallest events but decreased rapidly as rainfall depth increased. In addition, an enhancing and a depressing effect on stemflow volume were shown for the average wind speed during rain and for the ratio Eva p_ADP/R_previous, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Impact of interacting bark structure and rainfall conditions on stemflow variability in a temperate beech-oak forest,central Germany

ABSTRACT

Trees concentrate rainfall to near-stem soils via stemflow. When canopy structures are organized appropriately, stemflow can even induce preferential flow through soils, transporting nutrients to biogeochemically active areas. Bark structure significantly affects stemflow, yet bark-stemflow studies are primarily qualitative. We used a LaserBark to compute bark microrelief (MR), ridge-to-furrow amplitude (R) and slope (S) metrics per American Society of Mechanical Engineering standards (ASME-B46.1–2009) for two morphologically contrasting species (Fagus sylvatica L. (European beech), Quercus robur L. (pendunculate oak)) under storm conditions with strong bark water storage capacity (BWSC) influence in central Germany. Smaller R and S for F. sylvatica significantly lowered BWSC, which strongly and inversely correlated to maximum funnelling ratios and permitted stemflow generation at lower rain magnitudes. Larger R and S values in Q. robur reduced funnelling, diminishing stemflow drainage for larger storms. Quercus robur funnelling and stemflow was more reliant on intermediate rain intensities and intermittency to maintain bark channel-dependent drainage pathways. Shelter provided by Q. robur’s ridged bark also appears to protect entrained water, lengthening mean intrastorm dry periods necessary to affect stemflow. Storm conditions where BWSC plays a major role in stemflow accounted for much of 2013’s rainfall at the nearest meteorological station (Wulferstedt).

Editor M.C. Acreman; Associate editor not assigned     

浙东新近纪一种栎属植物化石微细特征及其古环境指示

归于壳斗科栎属的一种植物化石黄毛青冈(亲缘种)Quercusaff.delavayi Franch采于浙江天台中新统下南山组。该化石不仅具有与现生黄毛青冈Quercus delavayi Franch相似的叶形态结构,而且两者表皮微细构造亦颇为一致,宏观和微观特征表明,当前材料与现生黄毛青冈具有一定的亲缘关系。通过研究不同时间、不同地点现生黄毛青冈的表皮微细特征,发现黄毛青冈毛基的个体发育重演了青冈亚属毛基的系统演化。进一步比较化石与现生材料的毛基参数及其他表皮特征,推论浙江天台中新世的古气候较现在温暖湿润,根据现生与化石黄毛青冈气孔比率计算出浙江天台中新世古大气CO2体积分数为(395.22±5.61)×10-6。     

Species differences in stomatal control of water loss at the canopy scale in a mature bottomland deciduous forest

In order to evaluate factors controlling transpiration of six common eastern deciduous species in North America, a model describing responses of canopy stomatal conductance (G_S) to net radiation (R_N), vapor pressure deficit (D) and relative extractable soil water (REW) was parameterized from sap flux data. Sap flux was measured in 24 mature trees consisting of the species Carya tomentosa, Quercus alba, Q. rubra, Fraxinus americana, Liriodendron tulipifera, and Liquidambar styraciflua in a bottomland oak-hickory forest in the Duke Forest, NC. Species differences in model coefficients were found during the 1997 growing season. All species showed a reduction in G_S with increasing D. R_N influenced G_S in the overstory shade intolerant L. styraciflua to a larger extent than the other species measured. In addition, despite a severe drought during the study period, only L. tulipifera showed a decline in G_S with decreasing REW. The primary effect of the drought for the other species appeared to be early autumn leaf senescence and abscission. As a result, despite the drought in this bottomland forest accustomed to ample water supply, maximum daily transpiration (1.6 mm) and growing season transpiration (264 mm) were similar to a nearby upland forest measured during a year of above average precipitation. These results may aid in assessing differences in water use and the ability of bottomland deciduous species to tolerate alterations in the frequency or amount of precipitation. Results also suggest little variation in water use among forests of similar composition and structure growing in different positions in the landscape and subjected to large interannual variation in water supply.     

A map of autumn precipitation for the third millennium BP in the Eastern Iberian Peninsula from charcoal carbon isotopes

Carbon isotope composition (δ¹³C) in tree-rings has become routinely used in palaeoclimatic research for the assessment of changes in plant water availability in seasonally dry climates. However, the distribution of long tree-ring records around the world is very limited. Alternatively, the original climate signal of wood δ¹³C is well preserved in fossil charcoal and, accordingly, charcoal δ¹³C can be used to quantify past changes in water availability (e.g. precipitation). We report a case study on spatial palaeoclimate reconstruction which aims to characterize the transition between Bronze and Iron Ages, the so-called Iron Age Cold Epoch (ca. 900–300 BCE), using charcoals of Quercus ilex/coccifera from a set of 11 contemporary archaeological sites of eastern Spain. Climatic inferences were obtained after calibrating a linear model predicting seasonal precipitation from δ¹³C of Q. ilex wood samples obtained across a rainfall gradient. The best regression model corresponded to September–December (autumn) precipitation (P_aut), in agreement with the fact that Q. ilex is able to exploit previous-year water reserves thanks to very effective water uptake. Subsequently, we estimated P_aut from the δ¹³C of fossil charcoal to infer spatial patterns in water availability. Overall, estimated past P_aut was about 19% higher (296 mm) than present-time values averaged across archaeological sites (249 mm). However, a clear geographic pattern of differences in precipitation could be observed in which the inner continental regions of eastern Spain were characterized by more humid conditions in the past, whereas the coastal strip of the Mediterranean Sea barely differed in past and present P_aut values. The quite uniform distribution of archaeological sites over eastern Spain allowed development of contour maps of absolute and relative (to present) past P_aut using gridded interpolation methods implemented in a GIS, highlighting the potential of this approach for reconstructing high-resolution spatial patterns of past climate.     

乌冈栎的地理分布

利用植物地理学分布区理论与地理信息系统技术,整合相关标本信息和文献,对乌冈栎地理分布区进行研究。结果表明:1)乌冈栎水平地理分布以亚热带为主,水平分布范围在中国(23°―34°N,100°―120°E)和日本(26°―37°N,128°―140°E);垂直分布大多在海拔500m以上,少数地区可降至海拔200m,日本分布区海拔要低于中国。2)乌冈栎现代分布区可分为中国东部分布区、中国南部分布区、中国西部分布区、中国西南部分布区和日本分布区,而中国东部分布区是目前的分布中心。3)利用壳斗科化石资料,对乌冈栎起源演化及散布途径作了推断,对其起源时间、传播路线等进行了讨论。4)第三纪及第四纪气候的演变对乌冈栎现代地理分布格局有着重大影响,为适应气候变化,其形态特征与常绿硬叶栎类中的高山栎类植物有一定差别,并逐渐退出了高山分布的地理位置。乌冈栎是否传统观点认为的冬青栎东亚替代种还有待于进一步商榷。