Ecological conditions and the distribution of alpine juniper (<Emphasis Type="Italic">Juniperus communis</Emphasis> subsp. <Emphasis Type="Italic">alpina</Emphasis>) in the Hrubý Jeseník Mts

In the Hruby Jeseník Mts of the Czech Republic, research was carried out from 2001–2005 aimed at completing an up-to-date census of alpine juniper [Juniperus communis subsp. alpine (Smith) Čelakovsky] and an evaluation of the overall health status of the populations, and at investigating the impacts of the main environmental factors on the viability of this species. 13 sites were identified with 283 individuals in total, but the sites differed dramatically in the number of recorded individuals. Comparisons with historical literature sources show that the species has been in decline. The main reasons for this decline include: a lack of suitable sites for colonization connected with a lack of adequate disturbance factors, competition from shading trees, and the presumed high age of the juniper populations combined with zero generative reproduction. More than two thirds of the individuals showed slight damage to their assimilation system. A health status of bad or very bad was determined for 5 % of the alpine juniper individuals. These trees in the Hruby Jeseník Mts are also exposed to pressure from some herbivore insects and mammals. The populations are not yet in a literally critical state, but considering the range of impacts affecting them, it will be necessary to pay significant attention to their conservation strategies. Some recommendations for future management are suggested.     

Upper Holocene dry land vegetation in the Moravian–Slovakian borderland (Czech and Slovak Republics)

Five pollen diagrams representing the upper Holocene vegetation and its anthropogenic changes are presented and evaluated. They come from small spring fens in the Czech (Moravian) and Slovak borderland. The northern part of the region (the Beskydy Mts) had natural, precultural forests with either coniferous trees (Picea abies and Abies alba) or mixed with Fagus sylvatica. In the southern part of the region (the Bílé Karpaty Mts) forests dominated by Fagus mixed with Acer, Fraxinus and Ulmus prevailed, whereas conifers were almost absent, although in a central, transitional region (northern Bílé Karpaty Mts) Abies was locally abundant in relatively humid places. Medieval colonisation deforested their lower areas and foothills in the course of the 11th–13th centuries and transformed the original mixed oak forests into fields and meadows, but the mountain forests were little affected. In the Beskydy Mts in the north, the Walachian colonisation of the 16th and 17th centuries transformed parts of the mountain forests into meadows, pasture and farmlands. Most remaining woodlands were transformed during the last two centuries into spruce plantations. In the Bílé Karpaty Mts in the south, the Walachian transformation of mountain forests had already started by the 15th century. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

New,rare and noteworthy lichens in the Giant Mountains

A commented list of 19 particularly interesting and noteworthy lichen species collected recently in the Giant Mts (Karkonosze, Krkonoše) is given. Most of them were found on the basalt outcrop in the western wall of the Mały Śnieżny Kocioł cirque (germ. Kleine Schneegrube), which is the most valuable and most conserved area in this mountain range. Two species are new to Poland: Lecanora gangaleoides and Lecidea praenubila. Umbilicaria cinereorufescens is reported for the first time from the Sudety Mts as a whole. Three species are new for the Giant Mts: Buellia ocellata, Diplotomma lutosum and Fuscidea praeruptorum. Eight species: Aspicilia microlepis, Belonia russula, Caloplaca crenularia, C. nivalis, Gyalecta biformis, Koerberiella wimmeriana, Miriquidica complanata and Polyblastia cruenta were re-discovered after over 100 years on the historical locality in the Mały Śnieżny Kocioł cirque.     

Pollen and macroscopic analyses of sediments from two lakes in the High Tatra mountains, Slovakia

The paper presents the results of investigations concerning the accumulation processes, sediment composition, pollen and macroscopic analyses of sediments from the lakes Popradské pleso (1513 m) and Štrbské pleso (1345 m) in the High Tatra mountains, western Carpathians, Slovakia. While Popradské pleso is undoubtedly of glacial origin with silts in the Lateglacial layers and algal gyttja in the Holocene layers, Štrbské pleso or its greater part originated recently between the 16th and the beginning of the 18th centuries when the previous bog of Atlantic or early Subboreal age was flooded with water after the dispersed outflow from the bog depression was blocked. Our pollen and macrofossil analyses indicate mountain tundra in the Lateglacial and a continuous presence of coniferous forest with Picea abies with admixture of Pinus cembra, Larix decidua, Juniperus communis and Pinus cf. mugo in the uppermost elevations at the alpine forest limit since the very beginning of the Holocene. No noticeable oscillation of the forest line can be interpreted from our pollen analyses. It seems probable that its position was controlled by geomorphological and edaphic conditions rather than by the Holocene climatic changes. Spruce forests dominated at elevations between ca. 1000–1400 m during the whole Holocene.     

Palaeogeobotanical evaluation of the Holocene profile from the Řežabinec fish-pond

Stratigraphic, pollen and macroscopic analyses of the Holocene limnic and peat sediments from the ?e?abinec fish-pond (southern Bohemia, Czechoslovakia) are presented and evaluated. New information on the sedimentary processes (especially the middle Holocene stratigraphic anomaly), the development of aquatic and mire vegetation, the character of the forest cover and human activity in the ?e?abinec area during the Preboreal, Boreal, Subboreal and Subatlantic has been obtained.     

Cytotype distribution inEmpetrum (Ericaceae) at various spatial scales in the Czech Republic

Ploidy levels inEmpetrum (crowberry) from the Czech Republic and from one adjacent locality in Poland were estimated by flow cytometry to examine cytotype distribution patterns at large (within the country), medium (within mountain ranges) and small (within particular localities) spatial scales. Diploid, triploid, and tetraploid individuals were found. Triploids are reported from Central Europe for the first time; they occurred in the Krkono?e Mts. Exclusively diploid plants were observed in three mountain ranges (the Kru?né hory Mts., Labské pískovce Mts., Adr?pa?sko-Teplické skály Mts.), exclusively tetraploids were observed in the Jeseníky Mts., and both cytotypes were observed in the ?umava Mts., Jizerské hory Mts. and Krkono?e Mts. Except for the latter mountain range, diploids and tetraploids were always found in different habitats. Spatial isolation is supposed to be the main barrier preventing cytotype mating. A mosaic-like sympatric occurrence of different cytotypes was demonstrated in the Krkono?e Mts., where peat bogs and rocky places were not spatially separated. Eight of 11 localities studied there were inhabited by diploids and tetraploids (five localities), diploids and triploids (one locality) or all three ploidy levels (two localities). Diploid and triploid plants occasionally intermingled at 0.3 × 0.3 m. Flower sex in crowberries was strongly associated with ploidy level: diploids usually had unisexual flowers, the tetraploids bore exclusively bisexual flowers. However, a few diploid plants with hermaphrodite flowers occurred in one population in the Krkono?e Mts.     

Thecamoebians from the small streams of the Boubín area (Šumava Mts,Czech Republic)

From 1999–2005, seventy-eight samples were collected from the small streams in the area of the Boubín Mountain including also the natural preserve “Boubínsky prales” (Boubín primeval forest) (Šumava Mts, Czech Republic). Nineteen species of thecamoebians were identified in the samples; the most abundant species were Centropyxis orbicularis, Pontigulasia compressa, Centropyxis aculeata, Difflugia oblonga and Centropyxis arcula. Species composition of assemblages as well as ecological affinities of the most common taxa are comparable with data from the previously analysed streams in the Šumava Mts. This correlation improves the quality of data for environmental preferences of thecamoebian assemblages contained in the streams and these can be used for interpretation of ancient environments. Though species composition of assemblages changes gradually, two end-member assemblages can be defined. For both assemblages, environmental conditions were defined: Lower-diversity assemblages dominated by centropyxids originated mainly from standing water with low content of organic debris. Relative abundances of C. orbicularis showed negative correlations with abundances of other Centropyxis spp. which may indicate different ecological affinities of this species. Centropyxis orbicularis may tolerate higher levels of fine organic debris in stream sediments. Assemblages with common to abundant occurrences of P. compressa and/or D. oblonga prefer running water. Difflugia oblonga dominated in samples with higher content of fine organic debris. Relation between test size of D. oblonga and flow rate was recorded: large D. oblonga prevailed in standing water while small specimens dominated in fast streams.     

Sex-based differences in vigor and site preferences of Juniperus communis subsp. nana

Dioecious alpine juniper has been influenced by human impacts, management and climate changes; hence, its present populations are remnant fragments of its former distribution in central Europe. Complex environmental shifts have had fatal consequences for growth, reproduction and health of juniper and hence for its population structure. We asked the questions: 1) what was the population size structure, the sex ratio and the health status of individuals? 2) How were the population parameters linked with the environmental conditions and surrounding vegetation? The study area was close and above the upper forest limit in central Europe, the Hrubý Jeseník Mts. The parameters of each juniper individual and its environmental conditions were obtained, Ellenberg's indicator values and habitat categories were also determined. Proportions of sex categories, shrub size and environmental conditions were investigated to assess relationships between the population categories and environmental factors. We revealed linkage among the shrub size, health vigor, vegetation cover, a habitat and environmental factors. While there was equal ratio of females and males (1:1), small individuals of undetermined sex predominated that reducing the effective population size. Juniper health vigor was associated with surrounding vegetation cover. Individuals of undetermined sex were smaller than those of remaining sex categories and prefer specific habitats at higher elevation, underlining the effect of abiotic conditions on sex performance and ratio. The observed pattern, which was attributed to shift in land-use practices in the middle of 20th century and climate changes, could be improved by management. We recommended experimental local grazing and mowing accompanying by profound and continuing assessment of interaction among environmental factors and juniper performance.     

Zur Langzeit?kologie des L?rchen-Arvengürtels in den südlichen Walliser Alpen

Kaltenrieder P., Tinner W. and Ammann B. 2005. Long-term vegetation history at timberline in the Swiss Alps (Alpe d’Essertse, VS). Bot. Helv. 115: 137–154. Palaeoecological studies in the “Alpe d’Essertse” area have provided much information about vegetation changes and timberline fluctuations during the Holocene. In this study we repeated previous biostratigraphic investigations using plant macrofossils to improve their temporal and taxonomic resolution and to test their reliability. By analyzing 0.5-cm layers of a lake sediment we reached a temporal resolution of 44 years, and we were able to reconstruct vegetation changes in the surrounding area at species level. The sedimentary record analyzed extends from the Late-Glacial to the late Holocene. Alpine grasslands (12’000–11’000 cal. BP) were afforested by Larix decidua, Juniperus nana, and Pinus cembra (11,000–9’600 cal. B.P.). Stable subalpine larch-stone pine-forests (9’600–4’900 cal. BP) were followed by shrublands and meadows as a consequence of the climatically and anthropogenically induced destruction of forest vegetation (4’900–2’600 cal. BP). Changes in the abundance of P. cembra and L. decidua needles as well as changes of the other taxa were consistent with those found in previous studies from the same lake. Our results demonstrate that plant-macrofossil records can be reproduced spatially and temporally on separate cores with independent ¹⁴C chronologies.

Manuskript angenommen am 24. Juli 2005     

贡嘎山雅家埂峨眉冷杉林线种群的时空动态

通过对贡嘎山雅家埂峨眉冷杉种群林线附近6个3000 m2样地(阴阳坡各3个)中峨眉冷杉(Abies fabri Craib)种群的定位调查,分析了过去100a间该区峨眉冷杉种群的时间-空间动态。结果表明:1)雅家埂林线附近峨眉冷杉种群密度在过去100 a(主要是近50 a)有显著的升高,但树线的海拔位置并无明显的爬升;2)阴阳坡林线格局存在显著的坡向分异:阴坡林线和树线的海拔高度显著高于阳坡(分别比阳坡高152.5 m和135.8 m),阳坡林线附近峨眉冷杉早期的生长速率在大于阴坡,但后期的生长速率却低于阴坡;3)热量(温度)控制假说不能完全解释雅家埂目前的树线格局,除气候因素之外,其它因素也限制了雅家梗地区树线位置的变化。     

Macroscopic indicators for the retrospective assessment of Norway spruce crown response to stress in the Krkonoše Mountains

The synergistic effect of a number of natural and anthropogenic stress factors is probably responsible for forest decline in Central Europe. The macroscopic indicators of Norway spruce crown status, as well as branch structure transformation, were proposed to reconstruct the retrospective stress response of a tree to stress conditions over a 30-year period. Based on crown defoliation and the proportion of secondary shoots, five categories of tree response to stress factors were introduced: resistant trees (crown defoliation ≤35%, secondary shoots ≤65%); resilient trees (crown defoliation ≤35%, secondary shoots >65%); susceptible moderately transformed trees (crown defoliation >35%, secondary shoots ≤65%); susceptible strongly transformed trees (crown defoliation >35%, 65% < secondary shoots ≤90%); and exhausted trees to the environment (crown defoliation >35%, secondary shoots >90%). These stress response categories are discussed assuming a sink/source relationship on carbohydrate allocation. The relationship between stress response categories and current regenerative processes in the crown, assessed by macroscopic markers on bud development and shoot growth, is outlined. The research has been carried out mainly in three permanent research plots of old autochthonous Norway spruce forest stands in the Krkonoše Mts. (Czech Republic) under different historical stress loads.     

干扰对高山林线再形成过程的影响

高山林线是一类典型的生态交错带,因其特殊的结构和功能以及对外界环境的高度敏感性而成为全球气候变化研究的热点之一.本文简要介绍了高山林线的相关概念及其界定,从高山林线海拔位置波动、植被格局变化、生态交错带物种组成变化及其生理生态特征变化等几个方面阐述了干扰对高山林线再形成过程的不同影响,总结了高山林线物种对干扰的两种基本响应方式,即退行和入侵.认为人为干扰在一定程度上弱化了当前气候变暖对高山林线波动的影响,因而在不同地区必须紧密结合当地可能的干扰来讨论高山林线的波动,否则结果有可能因误差较大而失去应有的价值.指出该研究在高海拔地区进行植被恢复的指导意义.     

高山林线交错带高山杜鹃的凋落物分解

凋落物分解是维持生态系统生产力、养分循环、土壤有机质形成的关键生态过程。高山林线交错带是陆地生态系统中对气候变化响应的敏感区域。季节变化和海拔梯度上的植被类型差异可能会影响该区域凋落物的分解,进而对高山生态系统的碳氮循环产生重要影响。采用凋落物分解袋的方法,研究了川西高山林线交错带优势种高山杜鹃(Rhododendron lapponicum)凋落叶在雪被期和生长季的分解特征。结果显示:(1)季节变化和植被类型对高山杜鹃凋落物的分解均具有显著影响(P0.05),凋落叶的质量损失主要发生在生长季且在高山林线最大,暗针叶林中雪被期的质量损失略高于生长季,但差异不显著;(2)林线交错带上高山杜鹃凋落叶分解缓慢,一年干物质失重率为9.62%,拟合分解系数k为0.145;(3)高山杜鹃凋落叶的质量变化主要体现在纤维素降解显著且集中在雪被期,木质素无明显降解,在高山林线上C/N、C/P、木质素/N变化幅度较小且C、N、P的释放表现得稳定而持续。结果表明,季节性雪被对林线交错带内高山杜鹃分解的影响不仅局限在雪被期内,雪被融化期间频繁的冻融作用和雪融水淋洗作用可能会促进高山杜鹃凋落物在生长季初期的分解。总的来看,在气候变暖的情景下,雪被的缩减、生长季的延长和高山杜鹃群落的扩张可能加速高山林线交错带高山杜鹃凋落物的分解。     

Syntaxonomy and ecology of plant communities of the Carici rupestris-Kobresietea bellardii in the western carpathians

We present a syntaxonomic account of the communities of the alliances of Oxytropido-Elynion Br.-Bl. 1949 and Festucion versicoloris Krajina 1933 from Western Carpathians. Both alliances comprise naked-rush, cushion form and dwarf-shrub heath communities typical of wind-exposed habitats occurring at the highest altitudes of the Tatra Mts. They represent a relic vegetation of the cold stages of the Pleistocene (probably Late Glacial Maximum) and they can be classified within the class of Carici rupestris-Kobresietea bellardii Ohba 1974. A set of relevés was subject to numerical-classification analysis. Floristics and ecology of the communities were characterised and the relationships to similar syntaxa were discussed. The Oxytropido-Elynion is restricted to the extreme ridge positions in the highest altitudes of the Belianske Tatry Mts. Five associations were distinguished, such as the Pyrolo carpaticae-Salicetum reticulatae, the Festuco versicoloris-Oreochloetum distichae, the Festucetum versicoloris, the Oxytropido carpaticae-Elynetum myosuroides and the Drabo siliquosae-Festucetum versicoloris. The Festucion versicoloris is limited to the mylonite zone of the alpine and subnival belt of the Vysoké Tatry and Západné Tatry Mts (and found as rare in the Nízke Tatry Mts). The stands of these communities prefer terraces of steep rocky faces and cliffs and stabilised small-grained screes below the cliffs. Within this alliance, three associations were described, including the Agrostio alpinae-Festucetum versicoloris, the Silenetum acaulis and the Salicetum kitaibelianae.     

Fagus silvatica L. und das aceri-fagetum an der alpinen Waldgrenze in Mitteleuropäischen gebirgen

Summary In the Central Europaean mountain ranges, the alpine timberline is usually formed by Picea abies or by other conifers (Larix decidua, Pinus mugo, Pinus cembra). Unlike in the East Europaean mountains, the Balkan Peninsula, the Europaean Mediterranean and Les Vosges, Fagus silvatica occurs sporadically on the alpine timberline in this area where it forms very specific woods.This type of the alpine timberline is bound to the association Aceri-Fagetum (Bartsch 1940, Moor 1952). This association is found on the highest sites of the Fagion alliance in the subalpine vegetation zone. Within this zone, the association is bound to localities with heavy snowfall and a submaritime climat. It occupies larger areas in the Swiss Jura and in Les Vosges. In other Central Europaean mountains (the Alps, Schwarzwald, Krkonoe etc.) it occus in isolated areas only.Many trunk deformations and bush forms are found with Fagus on a large scale in the snow impacted localities (steep slopes, periphery of corries, avalanche slopes etc.). Crawling and sliding snow causes these growth deformations in the Fagus seedlings since their first year.The general increase of the vegetative propagation is a remarkable and exceptional response of Fagus in adapting to these extreme growth conditions. Under alpine timberline conditions, the generative propagation is very limited.The vegetative shoots with adventitious root systems are formed mainly from branches layering in the humus. The typical monocormonal tree-form of Fagus from lower altitudes turns in this way into a polycormon. From an evolutionary point of view, it is a suitable substitution; but from the ecological viewpoint, however, it is a sturdy growth form. In its typical form, the polycormon is formed by a number of vegetative shoots, which may be deformed but are very elastic and resistent. The number of shoots in a polycormon varies from 3–5 below, and up to 40–50 at and above the timberline. They are formed by shoots of a number of filial successions. The decay of a polycormon results from decreasing vitality of single shoots or, very often, it is caused by the impact of snow and ice. Considering, however, the fact that single shoots have a sufficient adventitious root system and are thus physiologically independent, the dying of the other shoots does not mean a danger for the existence of the remaining part of the polycormon. The age of a polycormon as a whole is difficult to determine. Fagus polycormons can be considered as a typical growthform of the highest sites of the association Aceri-Fagetum. No other tree species is able to form close stands under these conditions. This phenomenon is of primary importance for the existence of this plant community.The unusual character of the structure and dynamics of the highest Aceri-Fagetum stands gives rise to a special type of the alpine timberline which should be understood not as a line but as a transitional zone between the closed stands and the hon-wooded plant communities of the subalpine vegetation zone. The dynamic succession of the Fagus polycormons guarantees the stability of the Fagus stands forming the alpine timberline.

---

Fagus silvatica L. und das aceri-fagetum an der alpinen Waldgrenze in Mitteleuropäischen gebirgen

     

Towards the reconstruction of the Holocene vegetation history of Lower Provence: two new pollen profiles from Marais des Baux

Two new¹⁴C-dated Holocene pollen profiles from Marais des Baux, Bouches-du-Rhône, France, are presented. The record begins in the Younger Dryas, when the vegetation consisted mainly of grasses and mugwort (Artemisia). The Preboreal was marked by a transitory expansion of pine forests and was followed by the establishment of a rich deciduous oak-forest that included hazel (Corylus) and elm (Ulmus). During the Boreal, hazel played a dominant role within the oak-forest. The oak forests, which includedQuercus ilex, achieved a major expansion during the Atlantic period. The Subboreal was characterised by the regional establishment of, firstly, fir (Abies) and then beech (Fagus). The spread and expansion of beech coincides with the first clear evidence for farming. Agricultural activities brought about the decline of deciduous oak-forest. During the Subatlantic, forests in the vicinity of Marais des Baux were cleared for farming. Cereal growing, which included rye cultivation, was of considerable importance. Three noteworthy characteristics that serve to differentiate the Holocene vegetation history of the low-lying Provence region from other French regions are as follows: 1) the early establishment (from the onset of Preboreal) of low altitude mixed forest; 2) the expansion during the Subboreal of fir and beech in low altitude areas with a Mediterranean climate and, 3) the exceptional taxonomic richness of the pollen assemblages (120 identified taxa) and the presence of borealalpine and Euro-Siberian taxa that no longer exist in Lower Provence.     

山西五台山高山林线的植被景观

 过草本植物群落的分类和排序,结合对乔木和灌木分布的分析,确定了五台山高山林线的几条植被界线以及五台山森林上限附近植被的性质。结果表明：1）阳坡林线的海拔范围为2 605～2 790 m,阴坡林线的海拔范围为2 810～3 015 m;2）草本植物群落随海拔高度的变化比较明显,阴坡和阳坡从郁闭林到山顶均依次分布林下草本层、林缘草甸、亚高山灌丛草甸、高山草甸,草本植物的分布很好地体现了林线内部景观的差异性;3）海拔高度是高山林线附近草本植物群落空间分异的决定性因素。     

Long-term vegetation dynamics in the Šumava Mts. natural spruce-fir-beech forests

In 1972(74)–1996(98), repeated phytocoenological surveys of natural mixed forest remainders were made on permanent plots in the Šumava Mts. in the south-western part of the Czech Republic. The surveys were made in localities with subsoils poor in nutrients (Boubín-Milešice—27 plots) and in a locality with nutrient-rich subsoil (Stožec—15 plots). Vegetation dynamics were studied according to the year of measurement and the nutrient capacity of the geological bedrock. We used the indices of floristic similarity, the calculation of plant communities’ characteristics (Shannon–Wiener’s index, equitability index), the calculation of taxa characteristics (fidelity, average cover, constancy) and multivariate ordination analyses—indirect (DCA) and direct (CCA). Changes in environmental conditions were studied between the years of measurement and between the localities using bioindication—by the calculation of Ellenberg indicator values (EIV) for plant communities. Over 24 years both the nutrient-poor site and the nutrient-rich site showed a considerable reduction in the tree layer cover and conversely the advancement of shrub layers. The coverage degree of dominants in the main tree layer (Fagus sylvatica, Picea abies and Abies alba) markedly decreased. Abies alba also exhibited a pronounced drop in constancy. On the other hand, the lower tree layer and shrub layers in Boubín-Milešice exhibited a distinctive invasion of Fagus sylvatica. An increase in the frequency of Sorbus aucuparia and a decrease in the frequency of Ulmus glabra were determined too. Herb layer changes were highly significant between the 1970s and the 1990s with qualitative changes being greater than quantitative changes. The number of species and Shannon–Wiener’s index increased. A significant difference was recorded between the nutrient-poor and the nutrient-rich sites in the values of the quantitative similarity of relevés with other differences being insignificant. The nutrient-poor sites exhibited herb layer homogenisation. A significant increase of EIV for light was found on both site types. The changes in phytocoenoses were interpreted partly as developmental trends (caused by indirect impact of man—e.g. fluctuations in game populations since the 18th century, the impact of air pollution); partly as cyclical changes connected with the developmental cycle of the natural temperate forest.     

The Sibyla model and development of beech forests affected by air pollution

The paper deals with the health status, production and structure of autochthonous beech stands in the eastern part of the Krkonoše Mts. (Czech Republic). The region was affected by increased air pollution load due to long-range SO₂ transmission from the late 1970s to the early 1990s. In 1980, five research plots were established in long unmanaged beech stands at an optimum stage. Tree coordinates and initial biometrical measurements were made in 1980 and repeated in 2005. The defoliation of individual trees was monitored every year (ICP Forests principles). The actual stand development is compared with the model development worked out by the Sibyla growth simulator in variants with a model of natural mortality and with entering a real mortality of trees. Differences between the stand characteristics of actual and simulated development of forest stands suggest some production losses. The reason to the losses can be seen in the long-term impact of air pollution in the first decade of monitoring and its after-effects on soil quality and worsening health condition of stands. The anticipated acceleration in the onset of the phase of stand disintegration under the influence of air pollution load was not demonstrated.     

The Holocene treeline in the northern Andes (Ecuador): First evidence from soil charcoal

Indications for the speed and timing of past altitudinal treeline shifts are often contradictory. Partly, this may be due to interpretation difficulties of pollen records, which are generally regional rather than local proxies. We used pedoanthracology, the identification and dating of macroscopic soil charcoal, to study vegetation history around the treeline in the northern Ecuadorian Andes. Pedoanthracology offers a complementary method to pollen-based vegetation reconstructions by providing records with high spatial detail on a local scale. The modern vegetation is tussock grass páramo (tropical alpine vegetation) and upper montane cloud forest, and the treeline is located at ca. 3600 m. Charcoal was collected from soils in the páramo (at 3890 and 3810 m) and in the forest (at 3540 m), and represents a sequence for the entire Holocene.The presence of páramo taxa throughout all three soil profiles, especially in combination with the absence of forest taxa, shows that the treeline in the study area has moved up to its present position only late in the Holocene (after ca. 5850 cal years BP). The treeline may have been situated between 3600 m and 3800 m at some time after ca. 4900 cal years BP, or it may never have been higher than it is today. The presence of charcoal throughout the profiles also shows that fires have occurred in this area at least since the beginning of the Holocene.These results contradict interpretations of palaeological data from Colombia, which suggest a rapid treeline rise at the Pleistocene–Holocene transition. They also contradict the hypothesis that man-made fires have destroyed large extents of forest above the modern treeline. Instead, páramo fires have probably contributed to the slowness of treeline rise during the Holocene.