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N I Makunina - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal changes in species composition of Forests and grasslands across the North Asian Forest Steppe zone
Folia Geobotanica, 2017Co-Authors: Nikolay N. Lashchinskiy, Andrey Yu. Korolyuk, Oleg A. Anenkhonov, N I Makunina, Hongyan LiuAbstract:In the Forest-Steppe zone, the plant species composition under the Forest, especially birch, canopy can be quite similar to that of zonal grasslands. Here we synthesize, for the first time, plant compositional data for Forests and grasslands across the entire Forest-Steppe zone with the aim to address the questions how different are local species pools across different parts of the Asian Forest-Steppe zone and to what extent is the species composition of Forests and grasslands similar and whether the degree of a difference between Forests and grasslands is consistent along a large longitudinal gradient. To answer these questions, a transect of about 5,000 km was stretched from the west to the east, involving nine key areas. Based on 2,000 vegetation-plot records, we calculated Bray-Curtis Coefficients between Forests and grasslands and between the individual areas. NMDS was used to compare species pools of Forests and grasslands in the individual key areas in a gradient space. The Forest and grassland floras differed in species composition in the individual areas, but the Forests and grasslands of the same area displayed similar positions along the principal NMDS axis. We observed rather steep compositional changes along the longitudinal gradient, but quite a large set of species was shared between the key areas from the Ural Mountains to the Yenisei River. The North Asian Forest-Steppe of Western and Central Siberia can hence be considered a single entity in terms of species composition at the species pool level. Eastward from the Yenisei river, the species composition of both grasslands and Forests changed suddenly, mirroring an important biogeographical boundary. Our results suggest that the Forest-Steppe zone should be viewed as a single biome that is characterized by an alteration of two compositionally and structurally distinct habitats, Forest and grasslands, which, however, show similar patterns in terms of species pool size and local diversity.
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botanical and geographical characteristics of Forest Steppe of the altai sayan mountain region
Contemporary Problems of Ecology, 2016Co-Authors: N I MakuninaAbstract:Four types of mountain Forest Steppes have been specified in the Altai-Sayan mountain region. It has been shown that each type corresponds to a particular bioclimatic sector. The pattern of the mountain Forest-Steppe belt vegetation has been characterized for each of the types. The peculiarities of mountain Forest- Steppe vegetation changes with the increase of climate aridity conditions are described within 3 series: the primary Altaian, the primary Khakas-Tuvinian, and the secondary Khakas-Tuvinian series.
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Meadows of north Forest-Steppe and subtaiga on the Tobol and the Irtysh watershed
Vegetation of Russia, 2015Co-Authors: M. P. Tishchenko, Andrey Yu. Korolyuk, N I MakuninaAbstract:The Tobol and the Irtysh watershed occupy the western part of West-Siberian plain. Area studied covers latitudinal band between 55° and 57° n. l. It includes the southern part of subtaiga subzone and northern part of Forest-Steppe zone. This territory has been used for agriculture since XVIIth century. In the middle of XXth century the local landscapes were represented by endless arable lands alternated with tiny patches of Forests on the watersheds and swamps and solonchaks prevailing at lowlands. In the end of XXth century the large areas of arable lands, especially in northern part of mentioned area, were abandoned. Nowadays this area is covered by fallow meadows on different stages of demutation. Vegetation studies of the region have started in the end of XIXth century. One of the best scientific works on local grasslands was written by B. N. Gorodkov (1915). The spectrum of natural plant communities demonstrates some changes fr om south to north. These changes enclose both zonal and intrazonal vegetation. The southern part of the area studied belongs to Forest-Steppe zone. Its zonal vegetation is represented by small-leaved Forests, grasslands (Steppe meadows) and meadow Steppes. Zonal vegetation of northern part — subtaiga subzone — includes only small-leaved Forests. The watershed grasslands replace the cut-off Forests. Intrazonal vegetation of southern part consists of various grasslands on salty soils and swamps predominated in the northern part. The border of Forest-Steppe and subtaiga represents a combination of zonal and intrazonal communities disturbed by man. The goal of this article is to reveal the diversity of grasslands on drained soils of mentioned area. The analysis of 151 geobotanical relevйs obtained fr om subtaiga and northern Forest-Steppe of Omskaya and Tyumenskaya administrative districts has been carried out. The syntaxonomy of the Tobol-and-the Irtysh watershed grasslands is represented by 6 associations, 4 subassociations and 2 communities of 4 alliances, 4 order and 2 classes. Subtaiga and northern Forest Steppe are characterized by different spectra of grasslands. This can be explained by a presence of wide range of saline soils in Forest-Steppe and their absence in subtaiga. The floristic composition of grasslands of Forest-Steppes zone includes the plants tolerant to soil salinity such as Artemisia pontica, Galatella biflora, Plantago maxima, Eryngium planum, Saussurea amara, Limonium gmelinii. The listed species are rare in subtaiga grasslands while Festuca pratensis, Phleum pratense, Agrostis gigantea of alliance Festucion pratensis are dominated in subtaiga grassland meadows. Steppe meadows of this territory are represented by two classes. Northern Forest-Steppe subzone demonstrates the northern lim it of Festuco-Brometea (alliance Galatellion biflorae of order Festucetalia valesiacae). The associations Galatello biflorae–Calamagrostietum epigeii and Galio borealis–Artemisietum ponticae occupy the zonal positions. Their communities are characterize by high activity of meadow-Steppe mesoxerophytes that are the diagnostic of the class Festuco-Brometea. The meadow mesophytes dominate in subtaiga Steppe meadows absolutely; meadow-Steppe species are rare. They are marked with a lack of diagnostic species of alliance Galatellion biflorae. They are ascribed to the class Molinio–Arrhenatheretea, order Galietalia veri and alliance Trifolion montani as the communities Filipendula stepposa–Cenolophium denudatum and Astragalus danicus–Potentilla anserinа. Forest Steppe meadows of alliance Aconito barbati–Vicion unijugae (order Carici macrourae–Crepidetalia sibiricae, class Molinio-Arrhenatheretea) are usual for northern, subtaiga subzone of the Tobol and the Irtysh watershed. Diagnostic species list of the communities belonging to the order Carici macrourae–Crepidetalia sibiricae on West-Siberian plain is impoverished in comparison with the uplands and the mountains of South Siberia wh ere this order was described by Ermakov et al. (1999). We have revealed 2 new associations of alliance Aconito barbati–Vicion unijugae: Aegopodio podagrariae–Brachypodietum pinnati and Dracocephalo ruyschiani–Heracleetum sibiricae. In subtaiga subzone communities of these associations occupy the small well drained habitats between mesophytic Forests and arable lands. The first association unites the xerophytic Forest meadows with Aegopodium podagraria dominance, occurring only on right bank of the Ishim River. The second one includes Forest meadows of subtaiga widely spread on the Tobol and the Irtysh watershed. Association Dracocephalo ruyschiani–Heracleetum sibiricae comprises two subassociations: D. r.–H. s. typicum and D. r.–H. s.molinietosum caeruleae. One of diagnostic species of the last mentioned subassociation is Molinia caerulea that is a common species of boreal wet meadows of Europe. The eastern border of this species distribution is on the left riverside of the Ishim River. Meadows of alliance Festucion pratensis of order Arrhenatheretalia are characteristic only for subtaiga, they belong to two associations. Meadows of subassociation Cirsio setosi–Phleetum pratensis pastinacetosum sylvestris are widespread. They are wide spread over the abandoned arable lands and rather monotonous by their floristic composition. The floristic peculiarity of plant communities is abundance of diagnostic species of classes Artemisietea и Chenopodietea. Meadows of Agrostio tenuis–Festucetum pratensis Yamalov 2005 occur on sandy soils; they present one of the first stages of pine Forest demutation. Some of species are not characteristic for typical subassociation described by S. M. Yamalov (2005), therefore the meadows of this association on the Tobol and the Irtysh watershed are referred to a new subassociation A. t.–F. p. senecionetosum jacobaea.
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Mountain Forest-Steppe of South-East Altai and South-West Tuva
Vegetation of Russia, 2014Co-Authors: N I MakuninaAbstract:Some geobotanists, who studied arid mountain Steppe landscapes in South-East Altai and South-West Tuva, mentioned the existing of small isolated larch Forest areas at the height 2100–2400 m above sea level (Kuminova, 1960; Il’inskaya, 1980). We have made a special investigation of the vegetation of this rather peculiar Forest-Steppe. It can be called “high-mountain Forest-Steppe” by the altitudinal position and “cold Forest-Steppe” by the level of the heat. Such Forest-Steppe areas are found only in certain orographic conditions: they are confined to the slopes of rivers’ valleys. The foots of these slopes are situated at an altitude 1900–2000 m a. s. l. and the flat tops of the mountains – at 2400–2500 m a. s. l. Light slopes of the mountains are occupied by bunchgrass Steppes, larch Forests and meadow Steppes are located on the shady slopes. Forest-Steppe landscapesare confined to thealtitudinal rangeof the Steppe belt, whichis divided intotwosubbelts: the lower with bunchgrass(moderately dry) Steppes and theupper with cryophytic Steppes. The boundaries betweensub-belts are at differentaltitudes in the SoutheastAltai andSouthwestTuva. In South-Eastern Altai bunchgrassSteppes are replaced by cryophytic ones at the height 2400–2500m a. s. l., so Forest-Steppes are completely included in bunchgrass Steppe subbelt. In SouthwesternTuva this boundary is at 2200–2300 m a. s. l., so the lower parts of the light slopes are covered by bunchgrass Steppes and the upper parts — by cryophytic Steppes. The Steppes in mountain Forest-Steppe of South-East Altai belong to alliance Helictotrichion schelliani, the Tuvinian ones — to alliance Festucion tschujensis. These two alliances are from order Helictotrichetalia shelliani, class Cleistogenetea squarrosae.Alliance Helictotrichion schelliani includes mountain Steppes that mostly occur in semiarid bioclimatic regions of South Siberia and North Mongolia; Forest-Steppe plant communities of arid South-East Altai represent the “cold branch” of this alliance. The bunchgrass Steppes belong to new association Potentillo sericeae–Agropyretum cristati,the meadow Steppes — to new association Sileno repentis–Caricetum pediformis. In mountain Forest-Steppe of South-West Tuva 3 associations present alliance Festucion tschujensis which combines Steppe communities with participation of cryopetrophytic species. Bunchgrass Steppes are described as new association Oxytropido macrosemae–Agropyretum cristatae, cryophitic Steppes – as new association Oxytropido eriocarpae–Poetum attenuatae, meadow Steppes are included in association Artemisio phaeolepidis–Kobresietum myosuroidis. The larch Forests belong to alliance Pachypleuro alpini–Laricion sibiricae (order Festuco ovinae–Laricetalia sibiricae, class Rhytidio rugosi–Laricetea sibiricae). Forests of association Swertio obtusae–Laricetum sibiricae are characteristic of South-East Altai, Forests of association Artemisio rupestris–Laricetum sibiricae are common in South-West Tuva, Forests of association Kobresio myosuroides–Laricetum sibiricae are recorded in both regions.
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The vegetation of Steppe and Forest-Steppe belts of the Central Altai
Vegetation of Russia, 2013Co-Authors: N I MakuninaAbstract:Steppe and Forest-Steppe belts in Central Altai occupy the bottoms of inter-mountain basins, expanded river valleys and surrounding mountains. The studied 4 Steppe sites give sublatitudinal discontinuous range. The Kanskaya basin is rounded, the Ursulskaya one and the Chuya river (lower reaches) valleys are elongated from the east to the west while the Steppe site of the Katun river valley — from the south to the north. The Kanskaya basin has a rounded shape while the Ursulskaya basin and the Chuya river valley (lower reaches) are elongated in the latitudinal direction, the Steppe site of the Katun river valley — in longitudinal one. The configuration of the surrounding mountains is different: Kanskaya basin is surrounded by gradual mountain ridges with rare outcrops while valley boards of Katun and Chuya rivers are steep and rocky. Steppe belt ((600) 800–1100 m above s. l.) occupies the bottoms of the basins (expanded river valleys) and sun exposed adjoining slopes. Forest-Steppe belt (1100–1400 m) occurs on the boards of the basins and includes 2 subbelts: the transitional lower (1100–1200 m) and the main upper (1200–1400 m) ones. It is continuous in the Kanskaya and the Ursulskaya basins and fragmented on the slopes of the Katun and Chuya river valleys. The plant cover structure of each belt is determined by altitudinal types of communities as well as by stands of rocky sites (so called petrophytic Steppes). Studied Steppes belong to classes Festuco-Brometea (FB) — order Stipetalia sibiricae and Cleistogenetea squarrosae (Cs) — orders Helictotrichetalia schelliani and Stipetalia krylovii. The Forest vegetation within the Forest-Steppe belt goes to Rhytidio-Laricetea (RL) and Brachypodio–Betuletea (BB)and Steppe meadows — to Molinio-Arrhenatheretea (MA) — order Carici macrouri–Crepidetalia sibiricae. The phytocoenotic spectra of altitudinal and petrophytic types of communities in Steppe and in the upper part of Forest-Steppe belts are similar in all four sites. The key association in Steppe belt is Fragario viridis–Stipetum capillatae (FB). These in the Forest-Steppe belt are larch herb Forests of the ass. Anemonoido caeruleae–Pinetum sylvestris laricetosum (BB), Steppe meadows of the ass. Cruciato krylovii–Poetum sibiricae (MA) and the meadow Steppes of two vicarious associations — Violo dissectae–Achnatheretum sibiricae (FB) in the Kanskaya basin and Cruciato krylovii–Caricetum pediformis (FB) in three other sites. The petrophytic Steppes belong to two associations: Kitagawio baicalensis–Cleistogenetum squarrosae (Cs) on the sun exposed slopes and Galio paniculati–Caraganetum arborescentis (FB) on shadow ones within the Steppe belt, and to subass. Carici pediformis–Spiraetum trilobatae schizonepetosum multifidae (FB) that occurs only on sun exposed slopes within the Forest-Steppe belt. The differences of phytocoenotic spectra of studied sites are determined by the vegetation of the transitional stripe. Forest communities of the ass. Primulo cortusoidis–Laricetum sibiricae (RL) cover the gentle slopes of the Kanskaya and Ursulskaya basins, petrophytic stands of the ass. Carici pediformis–Spiraetum trilobatae schizonepetosum multifidae (FB) occupy rocky sites. Forest communities of the ass. Galio paniculati–Laricetum sibiricae (RL) are commonon the steep slopes of the Katun and Chuya river valleys and petrophytic stands belong to the ass. Kitagawio baicalensis–Cleistogenetum squarrosae (Cs). The bottom of the Katun river valley with the very specific mesoclimate is occupied by Steppe ass. Artemisio frigidae–Stipetum krylovii (Cs) that in general is not typical for the studied area.
Hongyan Liu - One of the best experts on this subject based on the ideXlab platform.
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Climate-Driven Holocene Migration of Forest-Steppe Ecotone in the Tien Mountains
Forests, 2020Co-Authors: Ying Cheng, Hongyan Liu, Qian Hao, Hongya Wang, Yue Han, Keqin Duan, Zhibao DongAbstract:Climate change poses a considerable threat to the Forest-Steppe ecotone in arid mountain areas. However, it remains unclear how the Forest-Steppe ecotone responds to climate change due to the limitation of the traditional pollen assemblages, which greatly limits the understanding of the history of the Forest-Steppe ecotone. Here, we examined the Tien Mountains, the largest mountain system in the world’s arid regions, as a case study to explore the migration of the Forest-Steppe ecotone using the pollen taxa diversity, by combining modern vegetation surveys, surface pollen and two fossil pollen sequences—in the mid-elevation Forest belt (Sayram Lake) and in the low-elevation desert belt (Aibi Lake). We found that the Forest-Steppe migration followed Holocene climate change. Specifically, the Forest belt where Picea schrenkiana Fisch. & C.A.Mey. dominates has a very low pollen taxa diversity, characterized by high richness and low evenness, which plays a key role in mountainous diversity. By detecting the diversity change of the deposition sites, we found that in coping with the warm and wet middle Holocene, the Forest belt expanded and widened as the observed diversities around the two lakes were very low, thus the Forest-Steppe ecotone moved downward accordingly. During the early and late Holocene, the Forest belt and the Forest-Steppe ecotone moved upward under a warm and dry climate, and downward under a cold and wet climate, as there was a reduced Forest belt effect on, or contribution to, the sites, and the observed diversities were high. Moisture loss may pose the greatest threat to the narrow Forest-Steppe ecotone, considering the climatic niche space and the limited living space for humidity-sensitive taxa. This study highlights that temperature and moisture co-influence the Forest belt change, which further determines the position migration of the Forest-Steppe ecotone.
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Divergent Hydraulic Strategies Explain the Interspecific Associations of Co-Occurring Trees in Forest–Steppe Ecotone
Forests, 2020Co-Authors: Jingyu Dai, Hongyan Liu, Xinrong Zhu, Mei Zhou, Bingbing LiuAbstract:Research Highlights: Answering how tree hydraulic strategies explain the interspecific associations of co-occurring trees in Forest–Steppe ecotone is an approach to link plant physiology to Forest dynamics, and is helpful to predict Forest composition and function changes with climate change. Background and Objectives: The Forest–Steppe ecotone—the driest edges of Forest distribution—is continuously threatened by climate change. To predict the Forest dynamics here, it is crucial to document the interspecific associations among existing trees and their potential physiological drivers. Materials and Methods: Forest–Steppe ecotone is composed of Forest and grassland patches in a mosaic pattern. We executed two years of complete quadrat surveys in a permanent Forest plot in the ecotone in northern China, calculated the interspecific association among five main tree species and analyzed their hydraulic strategies, which are presented by combining leaf-specific hydraulic conductivity (Kl) and important thresholds on the stem-vulnerability curves. Results: No intensive competition was suggested among the co-occurring species, which can be explained by their divergent hydraulic strategies. The negative associations among Populus davidiana Dode and Betula platyphylla Suk., and P. davidiana and Betula dahurica Pall. can be explained as the result of their similar hydraulic strategies. Tilia mongolica Maxim. got a strong population development with its effective and safe hydraulic strategy. Generally, hydraulic-strategy differences can explain about 40% variations in interspecific association of species pairs. Oppositely, species sensitivity to early stages of drought is convergent in the Forest. Conclusions: The divergent hydraulic strategies can partly explain the interspecific associations among tree species in Forest–Steppe ecotone and may be an important key for semiarid Forests to keep stable. The convergent sensitivity to early stages of drought and the suckering regeneration strategy are also important for trees to survival. Our work revealing the physiological mechanism of Forest compositions is a timely supplement to Forest–Steppe ecotone vegetation prediction.
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East Asian summer monsoon and topography co-determine the Holocene migration of Forest-Steppe ecotone in northern China
Global and Planetary Change, 2020Co-Authors: Ying Cheng, Hongyan Liu, Hongya Wang, Keqin Duan, Zhibao Dong, Yue HanAbstract:Abstract Forest-Steppe ecotones are generally regarded as very sensitive to climate change. However, it is still unclear whether they can be used to track past climate changes due to the combined effects of climate forcing and topographic factors. We first explored shifts of the whole Forest-Steppe ecotone in northern China during the Holocene by collecting 383 topsoil pollen samples to establish discriminant functions representative of Forest, Forest-Steppe ecotone, and temperate Steppe. The discriminant functions were applied to 39 fossil pollen sites to reconstruct the range of the Forest-Steppe ecotone during the Holocene. Our results showed that the shift of the Forest-Steppe ecotone exhibited a generally consistent trend with the intensity of the EASM, which was characterized by southward retreat during the early Holocene from 12,000 to 8000 cal. yr BP, northward expansion during the middle Holocene from 8000 to 4000 cal. yr BP, and southward retreat during the late Holocene from 4000 to 0 cal. yr BP, suggesting a dominant role of precipitation provided by the EASM. However, some sites in mountainous regions still indicated Forest group membership within the ecotone, implying possible vertical Forest migration. We stress that EASM and topography co-determine the shift of the Forest-Steppe ecotone in northern China, and mountainous terrain differences also benefit the vertical Forest migrations when threatened by the dry climate. Our study implies that future climate change may cause three-dimensional changes in vegetation, which should be considered in climate change mitigation.
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Longitudinal changes in species composition of Forests and grasslands across the North Asian Forest Steppe zone
Folia Geobotanica, 2017Co-Authors: Nikolay N. Lashchinskiy, Andrey Yu. Korolyuk, Oleg A. Anenkhonov, N I Makunina, Hongyan LiuAbstract:In the Forest-Steppe zone, the plant species composition under the Forest, especially birch, canopy can be quite similar to that of zonal grasslands. Here we synthesize, for the first time, plant compositional data for Forests and grasslands across the entire Forest-Steppe zone with the aim to address the questions how different are local species pools across different parts of the Asian Forest-Steppe zone and to what extent is the species composition of Forests and grasslands similar and whether the degree of a difference between Forests and grasslands is consistent along a large longitudinal gradient. To answer these questions, a transect of about 5,000 km was stretched from the west to the east, involving nine key areas. Based on 2,000 vegetation-plot records, we calculated Bray-Curtis Coefficients between Forests and grasslands and between the individual areas. NMDS was used to compare species pools of Forests and grasslands in the individual key areas in a gradient space. The Forest and grassland floras differed in species composition in the individual areas, but the Forests and grasslands of the same area displayed similar positions along the principal NMDS axis. We observed rather steep compositional changes along the longitudinal gradient, but quite a large set of species was shared between the key areas from the Ural Mountains to the Yenisei River. The North Asian Forest-Steppe of Western and Central Siberia can hence be considered a single entity in terms of species composition at the species pool level. Eastward from the Yenisei river, the species composition of both grasslands and Forests changed suddenly, mirroring an important biogeographical boundary. Our results suggest that the Forest-Steppe zone should be viewed as a single biome that is characterized by an alteration of two compositionally and structurally distinct habitats, Forest and grasslands, which, however, show similar patterns in terms of species pool size and local diversity.
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China Forest-Steppe Ecotone Database
Biodiversity & Ecology, 2012Co-Authors: Fengjun Zhao, Hongyan LiuAbstract:The China Forest Steppe Ecotone Database (GIVD ID AS-CN-001) contains releves of the Forest-Steppe ecotone, typical Steppe and desert Steppe in central part of Inner Mongolia, China as well as of the Zamin Ude region in Mongolia. Releves of the Forest-Steppe ecotone were recorded during the 1990s. The communities in the Forest-Steppe ecotone are classified in a phytocoenological way. 12 major types of Forest, shrubland, meadow, fen, open woodland and Steppe are differentiated and described according to 133 releves. Due to limited releves, the plant communities are named by their dominant species: 1. Quercus mongolicawoodland; 2. Betula platyphylla-woodland; 3. Betula dahurica-woodland; 4. Populus davidiana-woodland; 5. Picea meyeri-woodland; 6. Pinus tabulaeformis-woodland; 7. Ostryopsis davidiana-shrubland; 8. Polygonum viviparum-meadow; 9. Ranunculus japonica-fen; 10. Stipa baicalensis-Steppe; 11. Leymus chinensis-Steppe; 12. Ulmus pumila-open woodland. Other plant community types with less than 5 releves are Larix principis-ruprechtii-woodland, Pinus Betula fruticosa-scrub, Stipa krylovii-Steppe, Filifolium sibiricumSteppe and Thymus serphyllum-Steppe. During the 2000s, we extended our survey further to the dryer region, including typical Steppes and desert Steppes in central Inner Mongolia of China, including the huge sandy sheets, Otindag and Mu Us. Besides releve records, we systematically collected 344 soil profiles, with C, N content measured for most of the profiles, as well as grain sizes for all the profiles.
Thomas Giesecke - One of the best experts on this subject based on the ideXlab platform.
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Long-term dynamics of the East European Forest-Steppe ecotone
Journal of Vegetation Science, 2017Co-Authors: Lyudmila S. Shumilovskikh, Elena Novenko, Thomas GieseckeAbstract:Question: The European Forest-Steppe ecotone extends over 6,000 km from the Carpathian to the Ural Mountains. It is extensively used for agriculture with very few patches of semi-natural vegetation. Little is known about the history of the Forest-Steppe ecotone in Eastern Europe and here we examine its Holocene dynamics and stability and investigate when it was transformed to the modern agro-pastoral landscapes. Location: Mid-Russian Upland. Methods: We summarize the information from five pollen diagrams for the last 7,000 years and estimate Forest cover using the best modern analogue technique. We use the PCA and principal curve analysis to evaluate compositional changes. Results: The pollen data suggest that the East European Forest-Steppe boundary was located 50–70 km further northwest from the presumed present position during the period 7,000–4,500 cal yr BP. After 4,500 cal year BP, it moved approximately 100–130 km to the southeast. Since 2,000 cal year BP land use affected the boundary, while a total Forest clearance and transformation to agricultural landscapes took place in the last 400 years. Pollen data indicate a NW–SE direction of the Forest-Steppe vegetation gradient. Prior to clearance, open lime–pedunculate oak Forests existed in the NW, while the south was characterized by pine woodlands with an admixture of oak and lime with 20%–40% Forest cover. Conclusions: The East European Forest-Steppe ecotone is sensitive to climate change. The Late Holocene expansion of Forest cover is in agreement with evidence suggesting an increase in moisture availability during this time. The rapid recovery to a similar composition after human disturbance indicates a high resilience of woodland in the ecotone, which may be connected to a naturally high disturbance regime, possibly through fire. The information revealed on the position of the gradient and natural composition of the Forest is currently not depicted in maps of the potential natural vegetation.
Delphine Derrien - One of the best experts on this subject based on the ideXlab platform.
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Soil evaporation and organic matter turnover in the Sub-Taiga and Forest-Steppe of southwest Siberia.
Scientific Reports, 2018Co-Authors: Zachary E. Kayler, Félix Brédoire, Helene Mcmillan, Pavel A. Barsukov, Olga Rusalimova, Polina Nikitich, Mark R. Bakker, Bernd Zeller, Sébastien Fontaine, Delphine DerrienAbstract:Southwest Siberia encompasses the Forest-Steppe and sub-taiga climatic zones and has historically been utilized for agriculture. Coinciding with predicted changes in climate for the region is the pressure of agricultural development; however, a characterization of the soil water and carbon dynamics is lacking. We assessed current soil water properties and soil organic carbon turnover in Forests and grasslands for two sites that span the Forest Steppe and sub-taiga bioclimatic zones. Soil evaporation was 0.62 ± 0.17 mm d−1 (mean ± standard error) in grasslands and 0.45 ± 0.08 mm d−1 in the Forests of the Forest-Steppe site. Evaporation at the sub-taiga site was 1.80 ± 1.70 mm d−1 in grasslands and 0.96 ± 0.05 mm d−1 in Forest plots. Evaporation was significantly greater at the sub-taiga site than the Forest-Steppe site. The density of fine roots explained the soil water isotopic patterns between vegetation types and sites. We found soil organic matter turnover to be three times faster in the sub-taiga site than in the Forest-Steppe site. Our results show that while climate factors, in particular snow levels, between the two sites are drivers for water and carbon cycles, site level hydrology, soil characteristics, and vegetation directly interact to influence the water and carbon dynamics.
Yue Han - One of the best experts on this subject based on the ideXlab platform.
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Climate-Driven Holocene Migration of Forest-Steppe Ecotone in the Tien Mountains
Forests, 2020Co-Authors: Ying Cheng, Hongyan Liu, Qian Hao, Hongya Wang, Yue Han, Keqin Duan, Zhibao DongAbstract:Climate change poses a considerable threat to the Forest-Steppe ecotone in arid mountain areas. However, it remains unclear how the Forest-Steppe ecotone responds to climate change due to the limitation of the traditional pollen assemblages, which greatly limits the understanding of the history of the Forest-Steppe ecotone. Here, we examined the Tien Mountains, the largest mountain system in the world’s arid regions, as a case study to explore the migration of the Forest-Steppe ecotone using the pollen taxa diversity, by combining modern vegetation surveys, surface pollen and two fossil pollen sequences—in the mid-elevation Forest belt (Sayram Lake) and in the low-elevation desert belt (Aibi Lake). We found that the Forest-Steppe migration followed Holocene climate change. Specifically, the Forest belt where Picea schrenkiana Fisch. & C.A.Mey. dominates has a very low pollen taxa diversity, characterized by high richness and low evenness, which plays a key role in mountainous diversity. By detecting the diversity change of the deposition sites, we found that in coping with the warm and wet middle Holocene, the Forest belt expanded and widened as the observed diversities around the two lakes were very low, thus the Forest-Steppe ecotone moved downward accordingly. During the early and late Holocene, the Forest belt and the Forest-Steppe ecotone moved upward under a warm and dry climate, and downward under a cold and wet climate, as there was a reduced Forest belt effect on, or contribution to, the sites, and the observed diversities were high. Moisture loss may pose the greatest threat to the narrow Forest-Steppe ecotone, considering the climatic niche space and the limited living space for humidity-sensitive taxa. This study highlights that temperature and moisture co-influence the Forest belt change, which further determines the position migration of the Forest-Steppe ecotone.
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East Asian summer monsoon and topography co-determine the Holocene migration of Forest-Steppe ecotone in northern China
Global and Planetary Change, 2020Co-Authors: Ying Cheng, Hongyan Liu, Hongya Wang, Keqin Duan, Zhibao Dong, Yue HanAbstract:Abstract Forest-Steppe ecotones are generally regarded as very sensitive to climate change. However, it is still unclear whether they can be used to track past climate changes due to the combined effects of climate forcing and topographic factors. We first explored shifts of the whole Forest-Steppe ecotone in northern China during the Holocene by collecting 383 topsoil pollen samples to establish discriminant functions representative of Forest, Forest-Steppe ecotone, and temperate Steppe. The discriminant functions were applied to 39 fossil pollen sites to reconstruct the range of the Forest-Steppe ecotone during the Holocene. Our results showed that the shift of the Forest-Steppe ecotone exhibited a generally consistent trend with the intensity of the EASM, which was characterized by southward retreat during the early Holocene from 12,000 to 8000 cal. yr BP, northward expansion during the middle Holocene from 8000 to 4000 cal. yr BP, and southward retreat during the late Holocene from 4000 to 0 cal. yr BP, suggesting a dominant role of precipitation provided by the EASM. However, some sites in mountainous regions still indicated Forest group membership within the ecotone, implying possible vertical Forest migration. We stress that EASM and topography co-determine the shift of the Forest-Steppe ecotone in northern China, and mountainous terrain differences also benefit the vertical Forest migrations when threatened by the dry climate. Our study implies that future climate change may cause three-dimensional changes in vegetation, which should be considered in climate change mitigation.