Swamp Vegetation Research Articles

Dynamics and evolution of Turgay‐type vegetation in Western Siberia throughout the early Oligocene to earliest Miocene—a study based on diversity of plant functional types in the carpological record

AbstractBased on ecospectra of 66 published carpofloras we study dynamics and evolution of Turgay vegetation in Western Siberia during the early Oligocene to earliest Miocene. The ecospectra are obtained using a Plant Functional Type (PFT) classification system comprising 26 herbaceous to arboreal PFTs. The carpofloras originate from seven floristic levels covering the time‐span from the Rupelian to early Aquitanian. Key elements of these levels are documented based on original collection materials. Although impacted by local edaphic conditions, the ecospectra can be interpreted in terms of changing vegetation. Our data show that warm temperate mesophytic, mixed conifer‐broad‐leaved deciduous forest assemblages persisted throughout the Oligocene and earliest Miocene in this core area of Turgai type vegetation. This is in line with comparatively stable climate conditions persisting in the studied time‐span, showing a minor temperature decline and coeval moderate increase in seasonality and precipitation. Concurrently, the reconstructed ecospectra contradict significant continental drying throughout the Oligocene and earliest Miocene. Spatial variability of the proportions of PFTs within the single floristic horizons primarily reflects local edaphic conditions. High diversities of PFTs characteristic for swamp vegetation are mainly confined to the early Oligocene and have a regional focus. Our results indicate that taxonomical diversity, particularly concerning mesic herbs and deciduous shrubs and trees, increased towards the end of the Oligocene. This increase in biodiversity probably can be attributed to an increase in rainfall and extension of terrestrial habitats after the final retreat of the Paratethys.

Первая экспедиция Л. Г. Раменского и ее значение в его творческой биографии

Первая экспедиция Л. Г. Раменского и ее значение в его творческой биографии

Particularities of the swamp vegetation from "Iron Gate" Natura 200 site, Romania

Particularities of the swamp vegetation from "Iron Gate" Natura 200 site, Romania

Blackwater in South African estuaries with emphasis on the Mgobezeleni Estuary in northern KwaZulu-Natal

The blackwater Mgobezeleni Estuary is a small system below a peat swamp. From the air the estuary is completely black, but the water revealed only a light tea colouration with a Secchi reading of >1.7 m. The sediment is covered with black low-density fragments overlying light coloured sand. When the estuary is open the colouration of the sea is blacker than might be expected from the light tea-coloured estuary water. The results of X-ray spectroscopy showed the black fragments have a high carbon content that is most likely peat. The dissolved organic carbon content of the Mgobezeleni Estuary water is lower than that in Swartvlei in the South Western Cape, which has very dark water. The presence of very large deposits of peat at the head of the estuary together with spectroscopy data indicate that the colouration of the water emanates from leached leaves of swamp vegetation. The penetration of light through the water is not reflected from the light sand due to the peat covering, giving the appearance of very dark water. The literature suggests that the cause of blackwater is due to humic acids, peat and tannins leached from fallen leaves. The results of this study point to peat fragments not reflecting sunlight rather than peat extract and humic acids as the main cause. The slight colouration of the water is likely due to the small amount of fresh leaf litter in the catchment for the release of tannins that colour the Mgobezeleni Estuary water.

High-resolution mapping of upland swamp vegetation using an unmanned aerial vehicle-hyperspectral system

Mapping of vegetation species and communities in sensitive ecosystems is essential for identification and management of anthropogenic impacts. Unmanned aerial vehicle (UAV)-hyperspectral systems are among the latest technologies in remote sensing that hold a potential for obtaining unprecedented quality of remote sensing data for vegetation mapping and health status monitoring applications. In this study, high-resolution (1–1.5 cm) spectral imaging data (15 bands) from a tunable spectrometer is used to map five species of vegetation in a complex upland swamp environment. The overall accuracy of classification was found to be 88.9% with a kappa coefficient of 0.83. Three classes (bare earth, sedgeland grass and black sheoak) have achieved higher accuracy (above 78%) and one class (bracken fern) has lower accuracy (58%). UAV-hyperspectral technology is, therefore, an effective tool to identify and map sensitive swamp vegetation. The technology can be potentially applied to determine the health status of the species.

BIOEKOLOGI AGROFORESTRY KOPI: TUTUPAN VEGETASI DAN POLA TUMBUHAN PENYUSUN AGROFORESTRY KOPI (Coffea sp.) DI KECAMATAN PENGARON KABUPATEN BANJAR KALIMANTAN SELATAN

Coffee agroforestry is a pattern of coffee cultivation mixed with other crops of one and two species, as well as more plant species. The objective of this research is to characterize vegetation cover type around coffee agroforestry and plant pattern of coffee agroforestry. The method used in data collection is by design of field observation and focal plant species for data collection about vegetation from coffee agroforestry. Data were analyzed by the descriptive method through narration from the result of data interpretation in tabulation matrix. There are 5 types of vegetation cover in the study sites: rubber plantation, mixed garden/yard garden, open field and shrubs, rice fields and cultivation fields, natural vegetation in riparian and swamp. Coffee crops are widely grown in the form of agroforestry mixed garden and yard garden. Some fruits planted with coffee are dominated by langsat (Lansium domesticum), cempedak (Artocarpus champeden), coconut (Cocos nucifera), and banana (Musa spp.). Based on the bioecological perspective, the diversity of flora contained in coffee agroforestry is very important in maintaining the stability of ecosystems, soil and water conservation, the conservation of animals on the surface and underground of the soil.

Assessment of geostatistical features for object-based image classification of contrasted landscape vegetation cover

Accurate mapping and monitoring of savanna and semiarid woodland biomes are needed to support the selection of areas of conservation, to provide sustainable land use, and to improve the understanding of vegetation. The potential of geostatistical features, derived from medium spatial resolution satellite imagery, to characterize contrasted landscape vegetation cover and improve object-based image classification is studied. The study site in Brazil includes cerrado sensu stricto, deciduous forest, and palm swamp vegetation cover. Sentinel 2 and Landsat 8 images were acquired and divided into objects, for each of which a semivariogram was calculated using near-infrared (NIR) and normalized difference vegetation index (NDVI) to extract the set of geostatistical features. The features selected by principal component analysis were used as input data to train a random forest algorithm. Tests were conducted, combining spectral and geostatistical features. Change detection evaluation was performed using a confusion matrix and its accuracies. The semivariogram curves were efficient to characterize spatial heterogeneity, with similar results using NIR and NDVI from Sentinel 2 and Landsat 8. Accuracy was significantly greater when combining geostatistical features with spectral data, suggesting that this method can improve image classification results.

Detecting state changes for ecosystem conservation with long-term monitoring of species composition.

Effective conservation requires an understanding not only of contemporary vegetation distributions in the landscape, but also cognizance of vegetation transitions over time with the goal of maintaining persistence of all states within the landscape. Using a state and transition model framework, we investigated temporal transitions over 31years in species composition among five upland swamp vegetation communities in southeastern Australia. We applied fuzzy clustering to document transitions across communities; evaluated the resilience and resistance of communities to change; and explored the relationship between ecosystem states and major environmental factors posited to structure the system. We also evaluated the predictive ability of an established vegetation dynamics model. We found that community composition remained stable or underwent reversible or directional transitions depending on the vegetation type. Wetter communities (Ti-tree thicket and Cyperoid heath) were more stable (i.e., resistant) while drier communities showed a greater propensity to transition (i.e., had lower resistance) under the observed disturbance regime (low variance fire intervals). The resilience of drier communities differed under this regime, with Banksia thicket showing reversible compositional change, while Restioid heath and Sedgeland showed directional change. In accord with an established conceptual model, we found that communities were distributed along a hydrological gradient. In addition, vegetation structure, along with light penetration to ground level, differentiated communities. However, internal dynamics of drier communities were complex: differences in fire regime (penultimate fire interval in 2014 and number of fires since 1965) were unable to predict differences in community membership among sites. Aspects of the fire regime are expected to be more important predictors if fire intervals vary more strongly among sites in the future. Fuzzy clustering of compositional data allows managers to track community transitions over time and facilitates planned interventions for conservation purposes.

Community-weighted mean traits but not functional diversity determine the changes in soil properties during wetland drying on the Tibetan Plateau

Abstract. Climate change and human activities have caused a shift in vegetation composition and soil biogeochemical cycles of alpine wetlands on the Tibetan Plateau. The primary goal of this study was to test for associations between community-weighted mean (CWM) traits, functional diversity, and soil properties during wetland drying. We collected soil samples and investigated the aboveground vegetation in swamp, swamp meadow, and typical meadow environments. Four CWM trait values (specific leaf area is SLA, leaf dry matter content is LDMC, leaf area is LA, and mature plant height is MPH) for 42 common species were measured across the three habitats; three components of functional diversity (functional richness, functional evenness, and functional divergence) were also quantified at these sites. Our results showed that the drying of the wetland dramatically altered plant community and soil properties. There was a significant correlation between CWM of traits and soil properties, but not a significant correlation between functional diversity and soil properties. Our results further showed that CWM-LA, CWM-SLA, and CWM-LDMC had positive correlations with soil readily available nutrients (available nitrogen, AN; available phosphorus, AP), but negative correlations with total soil nutrients (soil organic carbon is SOC, total nitrogen is TN, and total phosphorus is TP). Our study demonstrated that simple, quantitative plant functional traits, but not functional diversity, are directly related to soil C and N properties, and they likely play an important role in plant–soil interactions. Our results also suggest that functional identity of species may be more important than functional diversity in influencing ecosystem processes during wetland drying.

Прибрежная травяная растительность пойм рек Вычегда и Печора. Класс Phragmito–Magno-Caricetea Klika in Klika et Novák 1941

The present study continues a series of publications by the authors on the diversity of the herb vegetation in the floodplains of the Vychegda and Pechora rivers and their tributaries (Komi Republic). The floristic classification of the orders Molinietalia Koch 1926 and Arrhenatheretalia R. Tx. 1931 was published earlier (Shushpannikova, Yamalov, 2013, 2014). The results of classification of communities belonging to the class Phragmito–Magno-Caricetea Klika in Klika et Novák 1941 are discussed in this paper in accordance with principles of the Braun-Blanquet approach (Braun-Blanquet, 1964; Mirkin, Naumova, 1998). Analysis was based on 268 relevés made in 1981–2016. The assessment of environmental parameters was performed by ecological methods by L. G. Ramensky (Ramensky et al., 1956). Syntaxonomic diversity of the vegetation of the class Phragmito–Magno-Caricetea in the floodplain of rivers Vychegda and Pechora is presented by 3 orders (Phragmitetalia W. Koch 1926, Oenanthetalia aquaticae Hejny in Kopecky et Hejny 1965 and Magno-Caricetalia Pignatti 1953), 4 alliances (Phragmition communis W. Koch 1926, Nardosmion laevigatae Klotz et Köck 1986, Equisetion arvensis Mirkin. et Naumova in Kononov et al. 1989 emend. Taran 1995 and Magnocaricion elatae Koch 1926) and 13 associations. The communities of the class Phragmito–Magno-Caricetea, as well as the order Molinietalia of Molinio–Arrhenatheretea, are located at all levels of the floodplains and are characterized by a variety of humidification conditions. However, the communities of the class Phragmito–Magno-Caricetea are characterized by higher humidification indices (72.2–86.3) compared to meadow vegetation the order Molinietalia of the class Molinio-Arrhenatheretea of (68.8–74.4). A lot of associations, heterogeneous in their floristic composition, can be divided into 9 subassociations and 10 variants. New 4 subassociations (caricetosum vesicariae, equisetosum fluviatilis, persicaretosum amphibiae and lysimachetosum vulgaris), are included into ass. Caricetum gracilis Savich 1926. The peculiarities of the floristic composition of the above mentioned associations, as well as their distribution and ecology are discussed. The distinguished associations are well differentiated by their elevation position on the floodplains. The communities of the ass. Caricetum gracilis are located at all levels of the floodplainons; these of Agrostio stoloniferae–Equisetetum arvensis — on the highest ones; Equisetetum fluviatilis — on the lowest part of the floodplains in the riparian zone. The described communities are located on the soils with various ecological indi­cators. The distinguished associations are differentiated by the levels of humidification (65.9–89.9), mean figures — 70.3–86.3. The communities of the ass. Agrostio stoloniferae–Equisetetum arvensis occupy the driest sites (65.9–72.9); these of associations ­Equisetetum fluviatilis and Nardosmietum laevigatae — the wettest ones (80.7–87.8). The ass. Caricetum aquatilis has a wide range of humidification (72.7–89.9). The variability of humidification varies from alternating to high values (6.4–12.0). The ­greatest differences in humidification are experienced by the communities of the ass. Caricetum gracilis (5.5–12.0). Тhe communities of the ass. Agrostio stoloniferae–Equisetetum arvensis occupy the richest (10.5–15.0) and alluvial soils (4.0–5.0). They are located on the low level in the riverine and middle zone of the floodplain and are formed by annual flooding on alluvial deposits. The distinguished associations are differentiated by pH (3.0–8.0), mean figures — 4.5–7.0. The communities of the associations Caricetum juncellae, Caricetum gracilis and Caricetum acutae–rostratae are located on the most acidic soil; these of the ass. Equisetetum fluviatilis — on the neutral ones. The associations are distributed by the scale of pasture digression in range 2.5–4.5, mean figures — 3.0–3.9. The communities are used for hay-making. The question of the boundary between the meadow vegetation, lowland swamp and semi-aquatic vegetation remains unsolved. The communities of the class Phragmito–Magno-Caricetea described in this paper belongs to meadows. Ass. Nardosmietum laevigatae (previously referred to the class Galio-Urticetea Pass. 1967) is included into the order Phragmitetalia W. Koch 1926. The communities of the ass. Agrostio stoloniferae–Equisetetum arvensis have a mesophilic species composition and low moisture values, so they represent a transition between the class Molinio-Arrhenatheretea order Molinietalia and class Phragmito–Magno-Caricetea. A comparison of species composition of the syntaxa in Komi Republic and that in other regions of the Eastern Europe and the Asian part of Russia showed that the semiaquatic communities of the Komi Republic have low species diversity. It is less than 16 species on sample plot. The richest are communities of the associations Caricetum gracilis and Carici acutae–Phalaroidetum arundinaceae. 101 vascular plant species are recorded in 268 geobotanical relevés of the class Phragmito–Magno-Caricetea. The aboveground phytomass varies from 30–80 g/m2 (Agrostio stoloniferae–Equisetetum arvensis) to 420 г/м2 (Phalaroidetum arundinaceae).

Late Pleistocene to Holocene evolution of the Emba Delta, Kazakhstan, and coastline of the north-eastern Caspian Sea: Sediment, ostracods, pollen and dinoflagellate cyst records

Six cores, each approximately 10m long, of late Pleistocene to Holocene age were studied from the Emba Delta region in the north-eastern Caspian Sea. Radiocarbon dates provide ages within the range of 47,820 to 12,020calBP for the middle sections, and for post-1950 close to surface. The ages fall within Marine Isotope Stage (MIS) 3, MIS 2 and MIS 1 (with MIS 4 also inferred). Four lithological units are present, each separated by an erosional contact. Unit 4 is equated with MIS 4 and consists of over-consolidated, east-west trending aeolian sands deposited during the late Pleistocene Atelian lowstand. Unit 3 is equated with MIS 3 and is a low-energy, shallow open water or lagoonal deposit based on ostracod faunas. Pollen from mesophilic trees is common, confirming warm climatic conditions. Floristic elements such as Engelhardia and Carya were shared with East Asia. Frequent Taxodiaceae pollen occurs, derived from Glyptostrobus pensilis, a seasonal freshwater swamp tree, now found naturally only in isolated relict stands in East Asia. This suggests that the north-eastern Caspian region was a ‘refugium’ supporting Glyptostrobus swamp vegetation during MIS 3. There is no evidence to indicate that these are reworked occurrences. Unit 2 consists of early Khvalynian transgressive barrier sands and Unit 1 of shoreface sands and muds of Holocene age. The late Khvalynian highstand and the Last Glacial Maximum (LGM) record are eroded by the Mangyshlak unconformity after ca. 12,500calBP. The Holocene interval contains frequent foraminifera and dinoflagellate cysts (dinocysts) of restricted ‘marine’ affinity (e.g. Lingulodinium machaerophorum). The dinocysts Pterocysta cruciformis and Impagidinium inaequalis are found commonly in the Caspian Sea for the first time. Results are compared with palynological and ostracod assemblages in surface samples from the eastern Caspian Sea coastal region.

Dynamics of the macrophyte vegetation of the Mgobezeleni floodplain and estuary, Northern KwaZulu-Natal

This empirical study describes the vegetation responses to natural and artificial perturbations that have affected the Mgobezeleni Estuary and floodplain in recent decades. Typically the floodplain and estuary are affected by the changing morphology of the beach berm and the constancy of groundwater-fed baseflow entering the estuary from the catchment. Over the past several decades there have been two major perturbations to the mangroves. A road-bridge was built across the estuary in the early 1970s that raised the water level in the mangrove area. This killed many of the mangroves before the bridge was demolished and then rebuilt to rectify the situation. The second event occurred in 2007 when extremely high seas flushed saline marine water into the lower portion of the estuarine floodplain. This killed swamp vegetation that was unable to tolerate the saline water. Decaying vegetation was flushed into the main part of the estuary and the ensuing de-oxygenated water flooded the remaining living mangroves killing all except for a handful. There has been a slow and constant expansion of Ficus trichopoda dominated swamp forest into the estuarine floodplain, displacing sedge swamp. This study highlights the importance of the hydrological regime and alerts us to the sensitivity of this system to future recruitment of mangroves after an extreme perturbation.

Detection of Ground Water Availability at Buhias Island, Sitaro Regency

The study aims to detect ground water availability at Buhias Island, Siau Timur Selatan District, Sitaro Regency. The research method used the survey method by geoelectrical instrument based on subsurface rock resistivity as a geophysical exploration results with geoelectrical method of Wenner-Schlumberger configuration. Resistivity geoelectrical method is done by injecting a flow into the earth surface, then it is measured the potential difference. This study consists of 4 tracks in which each track is made the stretch model of soil layer on subsurface of ground. Then, the exploration results were processed using software RES2DINV to look at the data of soil layer based on the value of resistivity (2D). Interpretation result of the track 1 to 4 concluded that there is a layer of ground water. State of dominant ground water contains the saline (brackish). Location of trajectory in the basin to the lowland areas is mostly mangrove swamp vegetation. That location is the junction between the results of the runoff of rainfall water that falls down from the hills with sea water. Bedrock as a constituent of rock layer formed from marine sediments that carry minerals salts.

Vegetation change and conservation status of Coastal Upland Swamps

SummaryCoastal Upland Swamp communities are characterized by high biodiversity and provide habitat for a range of threatened flora and fauna. In this research project, we are monitoring swamp vegetation dynamics over decadal timescales and relating observed changes to environmental factors. We have also modelled potential effects of climate change on swamp distributions. We found that swamp communities are spatially dynamic, both internally and in relation to the woodland matrix. Transitions between communities depended on initial states. In addition, these water‐dependent communities appeared highly sensitive to projected climate change and their ‘Endangered’ status makes their active management a high priority. Improved understanding of dynamics at the community and landscape scale facilitates horizon scanning and improves our capacity to plan effective management interventions now and under future management and climate change scenarios.

Middle Miocene (Badenian) vegetation and climate dynamics in Bulgaria and Poland based on pollen data

The Miocene represents a time in Eurasia when evergreen and thermophilous dominated Paleogene vegetation was replaced by deciduous and temperate plants. Climatically, it is the transition from a greenhouse to an icehouse world, with the middle Miocene Climatic Optimum as the last warm episode of Earth history. Processes of plant evolution, transformation of vegetation and coenotic structure were significantly forced by both, changes in the global climate system, and also by significant palaeogeographic reorganizations. To give new insight in the middle Miocene evolution of European ecosystems and climate dynamics, we compared plant assemblages from northern Bulgaria and southern Poland (southern Paratethyan and Polish Lowlands realms).Based on palaeoecological analysis the main palaeocommunities are distinguished in hygro–hydrophytic herbaceous palaeocoenoses (reed marshes), hygrophytic forest palaeocoenoses (swamp forest and bush swamp), riparian forests, and mixed mesophytic forests. Despite some differences in taxonomic composition of these fossil floras and the proportion of individual taxa the vegetation shows similar composition and trends through time. The main trend in the vegetation dynamics is a general decrease in the abundance of palaeotropic and thermophilous elements of semi-evergreen forests. Together with these changes is a corresponding increase in the role of arctotertiary species in plant communities, and these plants became dominant in the mesophytic forests. Changes in swamp vegetation are climatically related too, but these reflect mainly local environmental dynamics and changes in inundation of the basin. Climate data from Bulgaria and Poland lack significant latitudinal climate gradient, thus confirming more or less homogenous climatic conditions within Europe in the middle Miocene.

Early Holocene hydrology and environments of the Ner River (Poland)

The Ner River valley (central Poland) underwent substantial transformation during the Weichselian–Holocene transition as a result of fluvial processes and climate changes, resulting in the establishment of its present shape in the Holocene. A multiproxy study based on organic deposits from a palaeochannel fill (Lutomiersk–Koziówki) shows that after the channel was cut off during the late glacial termination, it became a shallow oxbow, fed by local springs. In the Boreal period, the oxbow lake was also fed by precipitation and became a telmatic environment overgrown by rush and swamp vegetation. Finally, it was covered by overbank deposits. The first flooding phase (9900–9600cal. BP) was followed by the accumulation of overbank sediments (after 9500cal. BP) and flooding increased after ca. 9300–9000cal. BP. Pollen data provide information on the regional vegetation context for local and regional changes. In the Atlantic period, an increase in both summer and winter temperatures is inferred from the pollen data, corresponding to an expansion of thermophilous deciduous forests. While in general, flooding phases of the Early Holocene are poorly recognised in Eastern Europe, the Lutomiersk–Koziówki site may be considered as one of the reference points for this phenomenon in the region.

祁连山不同植被类型的物候变化及其对气候的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 祁连山不同植被类型的物候变化及其对气候的响应 DOI: 10.5846/stxb201510092039 作者: 作者单位: 西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（41161017） Phenological variation in different vegetation types and their response to climate change in the Qilian Mountains, China, 1982-2014 Author: Affiliation: northwest normal university,northwest normal 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:基于1982-2006年GIMMS NDVI和2000-2014年MODIS NDVI遥感数据，利用double logistic拟合方法提取了1982-2014年祁连山区不同植被的生长季始期、生长季末期和生长季长度3个重要的物候参数，分析了不同植被物候期的时间变化趋势、空间分异特征及对气候因子的响应。结果表明：（1）祁连山区不同植被的生长季始期和生长季末期随年际变化表现出波动提前或推迟，其中沼泽植被的变化波动最大；草甸植被、灌丛植被、阔叶林植被和栽培植被生长季长度出现延长趋势；（2）祁连山区植被生长季始期集中在5月初，其中阔叶林植被生长季开始最早，荒漠植被生长季开始最晚，植被生长季末期集中在9月，栽培植被生长季结束较早，荒漠植被、沼泽植被生长季结束较晚，植被生长季长度集中在110-140 d，其中阔叶林植被、针叶林植被生长季长度较长，而荒漠植被、高山植被生长季长度较短；（3）祁连山植被物候期变化趋势的空间分布表明植被生长季始期、生长季末期主要表现为提前不明显和推迟不明显，生长季长度主要表现为缩短不明显和延长不明显；（4）物候要素与气候要素相关性表明前期温度的积累有利于植被的开始生长，但当年3月的降水量对植被生长季始期同样有重要作用，不同植被生长季末期与8月、9月温度相关性较大，而与10月、11月降水的相关性较大。 Abstract:Vegetation phenology is used in the study of climate change because of stable distribution, and ease of observation and interpretation. In this study, a 15-day time series of averaged normalized difference vegetation indices (NDVI) derived from the daily Global Inventory Modeling and Mapping Studies (GIMMS) NDVI dataset and 16-day averaged NDVI values derived from the daily Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI dataset were used to analyze trends in vegetation phenology. Firstly, using the ENVI tool to cut remote sensing data, NDVI time series data for the study area from 1982 to 2014 were obtained. Secondly, using a Savitzky-Golay filter, noise contamination caused by random factors was reduced by producing a smooth NDVI curve. Thirdly, using double logistic fitting, three important phenological parameters, including the start of growing season (SOS), the end of growing season (EOS), and the length of growing season (LOS) were extracted for different vegetation types. Temporal change trends, as well as its spatial distribution characteristics, of the nine major vegetation types in the Qilian Mountains were analyzed. These types included meadow, steppe, desert vegetation, shrub vegetation, alpine vegetation, coniferous forest, broad-leaved forest, cultivated vegetation, and swamp vegetation. In addition, the effects of climatic factors on phenology were analyzed by correlation analysis. The results showed that:(1) The annual variation of SOS and EOS of different vegetation types in the Qilian Mountains fluctuated in its advance or or delay; the maximum variation was observed in the swamp vegetation. The LOS of meadow, shrub, coniferous forest, and cultivated vegetation was longer, but the LOS of desert vegetation shortened. (2) The SOS of vegetation was primarily in May; the growing season of the broad-leaved forests began the earliest and desert vegetation began the latest. The EOS of vegetation occurred primarily in September; the growing season of cultivated vegetation ended earlier, whereas the growing season of the desert and swamp vegetation ended later. The LOS of vegetation was from 110 days to 140 days, among which the LOS of broad-leaved and coniferous forests was longer, whereas the LOS of desert and alpine vegetation was shorter. (3) The spatial distribution of variation trends for vegetation phenology indicated that SOS and LOS were advanced or delayed but not substantially, and the LOS was primarily shortened or prolonged, but not substantially. (4) The correlation of phenological metrics and climatic factors indicated that the accumulation of early stage temperature was beneficial to the growth of vegetation, but the amount of precipitation in March was also important to the SOS of vegetation. The EOS of different vegetation types was related with temperature in August and September, and correlated with precipitation in October and November, but the correlation was not significant. At different altitudes, the phenological parameters were different. In particular, the LOS appeared to shorten with increasing elevation, which is consistent with the spatial distribution of phenological parameters. These results explain the relationship between climate change and phenological phases. Climate change has an obvious effect on vegetation phenological parameters, and the phenological period can explicitly indicate the climate change. 参考文献 相似文献 引证文献

INFLUENCE OF GRAZING INTENSITY ON SWAMP PLANT COMMUNITIES IN THE TROPICAL MONTANE WETLAND ECOSYSTEMS, NILGIRIS, SOUTHERN INDIA

Livestock grazing is a major anthropogenic impact influencing both grasslands and wetlands of the world which often results in the alteration of the structure, diversity and functioning of the plant communities. Here, we seek to understand how grazing intensity influences swamp vegetation, with an emphasis on their diversity, structure and function. Six swamps were selected, two each in high, moderate and low intensity grazing sites, from the tropical montane swamps of the Upper Nilgiri Mountains, southern India. We recorded a total of 78 species belonging to 63 genera and 31 families. Our results showed that species richness, abundance and species composition differed significantly across grazing treatments. Moreover, mean vegetation cover and mean height differed significantly across grazing treatments, indicating that grazing significantly affected the vegetation structure and growth of swamp plant communities. Species compositional patterns showed that moderately grazed plant communities were significantly different from low and high grazing sites. In summary, grazing intensity influenced swamp species richness, abundance, and swamp plant communities. Specifically, high grazing pressure reduced vegetation cover causing changes in swamp community structure leading to the gradual conversion of the swamp habitat into grasslands.

Miocene climate and vegetation changes in the Cape Peninsula, South Africa: Evidence from biogeochemistry and palynology

Organic material from the Noordhoek area on the western margin of the Cape Peninsula, South Africa, was obtained from a ~50m-long drill-core dominated by fluvio-lacustrine siliciclastic sediments. The aim of this study is to constrain fluctuations in climate and the decline of tropical vegetation elements along the southwestern coast and the Cape Peninsula of South Africa, during the Late Cenozoic phase, when the Benguela upwelling system was established. The approach was to combine palynological, biogeochemical (tetraether lipids) and stable isotope (C, N) studies of the organic-bearing record from the Noordhoek area on the western margin of the Cape Peninsula. Bulk C and N isotope data of sediment organic matter, point to a predominantly C3 higher plant source vegetation. Mean annual air temperature (MAT) from the analyses of tetraether lipids (MBT′–CBT index) was compared with palynomorphs from partly unpublished data of a previously drilled core adjacent to the study site. The palynomorphs are of subtropical affinities, and suggest that an open riparian forest would have existed in the early to middle Miocene of the southwestern coast of South Africa. Together these data sources allow vegetation and climate reconstructions of subtropical conditions during the early to middle Miocene, which comprised fluctuating open riparian forest and swamp vegetation. Temperatures rose in the middle Miocene and were higher than those of the present day.

8000 years of vegetation dynamics and environmental changes of a unique inland peat ecosystem of the Jambi Province in Central Sumatra, Indonesia

Despite their importance as global carbon sinks, peatlands of Southeast Asia have been rarely studied and our current knowledge of the dynamics and ecology of these ecosystems remains incomplete. Paleoecological and palynological multi-proxy analyses including analysis of pollen, spores, charcoal, testate amoebae and sediments were carried out on a 733cm-long core taken from the Air Hitam peatland in the Jambi Province, Central Sumatra, Indonesia. The radiocarbon chronology reveals that peat formation started ca. 7800years ago. The site was covered by dipterocarp-swamp mixed rainforest during the first 2000years, after which freshwater swamp taxa became more important, in particular Durio trees. This lasted until ca. 4500years ago, when the swamp vegetation shifted to a pole forest with abundant Pandanus thickets in response to a system change from minerotrophic to ombrotrophic conditions. For this period, macro-charcoal analysis reveals that fire frequency increased, possibly as a consequence of climate change linked to the onset of the modern El Niño Southern Oscillation (ENSO) in the late Holocene. The ombrogenous Pandanus-pole forest phases were characterized by lower water table fluctuations and higher peat accumulation rates. The area of Air Hitam has been for thousands of years a highly effective carbon sequestering peatland. Natural climate variability in the past did not affect the carbon storage function as suggested by the general increase in peat accumulation during relatively drier phases and increasing ENSO variability in the late Holocene. However, the recent changes caused by selective logging, drainage and conversion to oil palm plantations, have caused a decline in the peat swamp forest communities changing the ecological functions of the peatland. It is likely that the accumulated carbon will be released in the atmosphere due to exposure to aerobic conditions and its function will be lost unless a better management of the watershed is applied.