Coexistence Approach Research Articles

Palaeovegetational evolution of the Çankırı-Çorum Basin during the Mio-Pliocene (Central Anatolia) based on the IPR analysis method

Reconstruction of past vegetation and climates in the Cankiri-Corum Basin, one of the largest basins of Central Anatolia, is important for understanding the regional palaeovegetation. In this study, the palaeovegetational and palaeoclimatic proxies of the basin within the late middle Miocene and early Pleistocene interval are presented using the Integrated Plant Record (IPR) vegetation analysis and the coexistence approach (CA). The IPR analysis allows the reconstruction of six types of zonal vegetation: broad-leaved deciduous forests (BLDF), mixed mesophytic forests (MMF), broad-leaved evergreen forests (BLEF), xeric open woodlands and xeric grasslands or steppes, all identified from the microfloras of Cankiri-Corum Basin. During the late middle Miocene, warm temperate and humid climatic conditions prevailed and the palaeovegetation in the Cankiri-Corum Basin was represented by BLEF and an ecotone between MMF and BLEF. The cooling from the late middle Miocene to early late Miocene had begun as well, as low precipitation periods in the climatic conditions during the same time interval were recorded in the basin. Presumably, the proportion of broad-leaved deciduous elements remained balanced because the palaeotopography did not change significantly during the late Miocene in the Cankiri-Corum Basin. The recorded cooling could be related to a global climatic change from the middle to late Miocene. During the Tortonian to Messinian transition, the palaeovegetation type was represented by BLDF and suggests a continuous cooling trend in the basin. The palaeovegetation types of the late late Miocene comprise MMF in the northern part of the Cankiri-Corum Basin and xeric grassland or steppe in the southern part of the basin. Warm and dry climatic conditions were recorded from the Tortonian to the Messinian; these warm conditions during the Messinian could be correlated to the Messinian salinity crisis. According to the IPR analysis results, the northern part of the Cankiri-Corum Basin palaeotopography seems to be higher in altitude than the southern part. Palaeovegetation types in the latest late Miocene and early Pliocene were characterised by MMF and an ecotone between BLDF and MMF in the northern part of the Cankiri-Corum Basin and open woodland vegetation in the southern part of the basin. The percentage of the broad-leaved deciduous component from the latest late Miocene and early Pliocene decreases in the Cankiri-Corum Basin, which could be related to beginning uplift starting changes in the palaeotopography. In the early Pliocene, this uplift was continued in the basin.

Modeling and estimation of pollen-mediated gene flow at the landscape scale

Abstract Undesired pollen-mediated gene flow (PMGF) in large-scale agriculture has received considerable attention for their ability to affect biological invasions. However, it has been not yet sufficiently understood how landscape structure and large-scale anthropogenic dispersal influence the gene spreading process. To explore the possible gene flow from crop species to wild relatives, we performed a literature review in ecosystem PMGF research for four major transgenic crops (maize, rice, wheat, oilseed rape). We found that whether pollen flow results induce a high cross-pollination rate mainly depends on the types of genetically modified (GM) species and cropping practice. Interestingly, the increase in the plot size of a pollen donor can lead to the increase in PMGF under ideal field conditions. However, while in a much larger landscape, it rapidly drops due to the exponential decrease in pollen density and the relatively low out-crossing rates. In large-scale field surveys, seeds of those plants with dormancy capability amplify the occurrence of transgene invasion and can remain alive in the seedbank for several years. Furthermore, in comparison with the distance-based methods, more and more spatio-temporal simulation models have proposed that a higher up-scaling percentage of GM crops is acceptable in a coexistence area of GM and non-GM crops. This highlights that the fate of (trans)genes should be emphasized in designing coexistence approaches. These results carry implications for gene dispersal management and indicate areas for future work, such as how to incorporate the response functions of different pollination factors into simulating models.

Bio-Inspired Approach for Inter-WBAN Coexistence

When wireless body area networks (WBANs) using the same channel transmit superframes (SFs) simultaneously, they interfere with each other. To resolve this problem, we propose a co-channel inter-WBAN coexistence method adopting bio-inspired models. The proposed method avoids the inter-WBAN interference by distributing the timing at which each WBAN sends its SF in a distributed manner. We also identify the position of a contention-free period in an SF whereby the time slots in the period do not overlap with any time slots in the SFs of the coexisting WBANs. In addition, we show that the proposed method can limit the number of WBANs interfering with each other during a contention access period. Through simulation studies, we show that the proposed method can adapt to changes in the density and topology of the coexisting WBANs. We also show that in contrast to other conventional methods, our method guarantees that the data frames sent during a contention-free period in an SF are free from collisions regardless of the number of coexisting WBANs. Thus, the proposed method enhances the throughput of a WBAN by increasing the successful data frame transmission rate.

Paleogene climate dynamics in the Primorye Region, Far East of Russia, based on a Coexistence Approach analysis of palaeobotanical data

The Paleogene climate dynamics in Primorye (Far East of Russia) are studied using the Coexistence Approach, based on palaeobotanical records. Palaeobotanical data for the reconstruction comprises 54 palaeofloras covering the early Paleocene to late Oligocene, a time span of ca. 42 myr. The climate inferences obtained are consistent with independently derived global trends, demonstrating general climate cooling through the Paleogene. Cooling is most striking regarding the cold month mean temperature, while the decline of mean annual temperature was less marked. Our data indicate that the Paleogene climate of Primorye was significantly warmer than present, in general, with the warmest conditions prevailing throughout the Eocene and in the southeast of the study area. Negligible Paleogene temperature gradients over Primorye are related to the global pattern and specific regional aspects. The precipitation reconstruction points to conditions considerably wetter than at present. A distinct increase in mean annual precipitation is observed for the early Eocene and persisted throughout the Eocene and Oligocene. The regional rainfall pattern fundamentally differed from modern conditions, and this holds for all studied variables. The inland region and the south of Primorye were significantly more humid than today. The Paleogene pattern was possibly related to a monsoon-type circulation and enhanced landward flow of humid air masses, due to an overall flatter geomorphology of the East Asian coastal areas.

Joint Design of Transmit Waveforms for Object Tracking in Coexisting Multimodal Sensing Systems.

We examine a multiple object tracking problem by jointly optimizing the transmit waveforms used in a multimodal system. Coexisting sensors in this system were assumed to share the same spectrum. Depending on the application, a system can include radars tracking multiple targets or multiuser wireless communications and a radar tracking both multiple messages and a target. The proposed spectral coexistence approach was based on designing all transmit waveforms to have the same time-varying phase function while optimizing desirable performance metrics. Considering the scenario of tracking a target with a pulse–Doppler radar and multiple user messages, two signaling schemes were proposed after selecting the waveform parameters to first minimize multiple access interference. The first scheme is based on system interference minimization, whereas the second scheme explores the multiobjective optimization tradeoff between system interference and object parameter estimation error. Simulations are provided to demonstrate the performance tradeoffs due to different system requirements.

Middle Eocene East Asian monsoon prevalence over southern China: Evidence from palynological records

Abstract The initiation of Asian monsoon systems is a complex and controversial issue, and the existence of monsoon systems in the Eocene has not yet been confirmed by commonly applicable proxy data. Eocene palynological records from three basins in southern China provide an ideal opportunity to investigate the early stage of the Asian monsoon due to their unique geographical location. The palynological assemblages suggest that the middle Eocene vegetation in southern China was composed of mixed evergreen and deciduous broad-leaved forests, accompanied by abundant subtropical to tropical evergreen taxa, thus bearing strong resemblance to the modern vegetation in southern China, and indicating a warm-humid subtropical climate. By analysing the palynological data using a coexistence approach (CA), we quantitatively reconstructed seven climatic parameters, which indicate a subtropical monsoon climate with a mean annual temperature (MAT) in the range 16.5 to 23.5 °C and a mean annual precipitation (MAP) in the range 1035 to 1724 mm, similar to those of the modern subtropical monsoon climate in southern China although the MAT was surprisingly lower than present. Significant seasonal variations in precipitation and temperature and as well as the spatial distribution of MAP during the middle Eocene were most similar to those of the modern East Asia Monsoon (EAM) climate of southern China, clearly indicating that the Eocene climate of southern China was mainly influenced by the EAM, rather than the Indian monsoon (IM) or Inter-tropical Convergence Zone (ITCZ) monsoons. By combining the above results with previously published geological evidence, we infer that the EAM developed in southern China as early as the middle Eocene, albeit with an intensity that may have been weaker than present. The establishment of the middle Eocene EAM in southern China was most likely driven by the northward drift of the Indian Subcontinent and its collision with the Eurasian continent, associated with the uplift of the Central-Southern Tibetan Plateau, which enlarged the land-sea thermal contrast and deepened the low pressure over continental Asia in summer, thus greatly intensifying the East Asian subtropical summer monsoon over southern China.

Enthalpy of dissociation of methane hydrates at a wide pressure and temperature range

We present a detailed overview of the calculation of the enthalpy of dissociation of methane hydrates, focusing primarily on methods that are based on either the Clapeyron equation or the direct calculation of the enthalpies of all the components that are involved in the dissociation reaction. Molecular dynamics simulations are used extensively in order to calculate the enthalpies and molar volumes of water, methane, and sI methane hydrate (with variant degree of occupancy) at pressure and temperature conditions along the three-phase (Hydrate – Liquid water – Vapor) equilibrium line. While for temperatures lower than 304 K there is a consensus that the enthalpy of dissociation is independent of temperature, the case for temperatures higher than 304 K is not that clear, particularly for the case when the Clapeyron equation is used. Therefore, new experimental measurements are required for the higher temperatures to shed light to the problem. In addition, the aqueous solubility of methane is calculated using the phase coexistence approach, resulting in accurate predictions when using the TIP4P/Ice water model and the OPLS-UA model for methane.

The complexity of climate reconstructions using the coexistence approach on Qinghai\u2013Tibetan Plateau

Quantifying the palaeoclimates of Qinghai–Tibetan Plateau is vital for understanding the uplift history of plateau and the evolution of Asian monsoon since Cenozoic. Recently, the Coexistence Approach (CA) has been employed to reconstruct the palaeoelevation and palaeoclimate of the plateau by several studies. However, the application of CA in mountainous areas and the realism of climate reconstructions via this method are seldom discussed, although the complexity of reconstructions is speculated. Here we reevaluated the realism of climate reconstruction using the CA with modern pollen samples from the Qinghai–Tibetan Plateau, and try to explore the possible factors influencing the precipitation and temperature reconstructions by CA. We suggest that the long-distance transport pollen as a result of the Asian summer monsoon potentially significantly affects the reconstructions both for precipitation and temperature. The precipitation complexly interacting with snowmelt and permafrost thaw leads to the discrepancy between the reconstructed precipitation and the real value. The response temperature for blossoming of dwarfed plants on the plateau is mostly likely higher than the air temperature (usually measured at 1.5 m above ground) due to energy flux or morphological adaptation of inflorescences during the growing season, causing the distortion of temperature reconstructions. Precipitation reconstruction is notoriously difficult as the establishers of CA have already suggested, but reconstructing the low temperatures may be even more challenging on Qinghai–Tibetan Plateau. Though all of the explorations in current paper are in a qualitative way, it offers an inspiration of how appropriately interpret the disagreements between CA results and the observations, and of how to obtain a reasonable reconstruction of palaeoclimate of the plateau.

СО-БЫТИЙНЫЙ ПОДХОД К ВОСПИТАНИЮ ШКОЛЬНИКОВ

СО-БЫТИЙНЫЙ ПОДХОД К ВОСПИТАНИЮ ШКОЛЬНИКОВ

A Paleogene leaf flora (Profen, Sachsen-Anhalt, Germany) and its potentials for palaeoecological and palaeoclimate reconstructions

Leaves as main locations of photosynthesis show various adaptations of morphological and anatomical traits to habitat conditions. By implication, leaf traits of fossil dicotyledonous plants can be used as proxies for reconstructions of palaeoenvironmental and palaeoclimatic conditions. Herein, a Paleogene leaf flora, the Profen-Süd LC assemblage from central Germany, is introduced and its leaf traits are outlined. Based on a preliminary phytosociological analysis, a floristic evaluation with respect to modern comparative vegetation refers to azonal communities predominated by a Rhodomyrtophyllum-Steinhauera riparian association. It mirrors local rather but species-divers vegetation. Morphological (shape; margin; venation) and morphometrical (area; leaf mass per area) leaf parameters are determined on a representative subsample and applied to the Trait Combination Type (TCT) analysis for gross-morphological characterization of fossil leaf assemblages, and to quantitative methods for estimation of palaeoclimate parameters: Climate Leaf Analysis Multivariate Program, Coexistence Approach and Leaf Margin Analysis. As a result the assemblage contains only four out of 16 TCTs. Morphological diversity is assumed to be characteristically low as the TCT pattern is not fundamentally distinct from that of the coeval hinterland flora of Kučlin (Czechia). Leaf size is overwhelmingly microphyll, and leaf mass per area values are in accordance with present-day evergreen forests. Main results refer to a sclerophyllous evergreen broad-leaved forest. All palaeoclimate calculations deliver similar estimates for subtropical climate with frost-free winters and humid conditions but certain seasonality in precipitation. Results are briefly discussed in context to depositional environment and taphonomic aspects. Moreover, traces of insect herbivory on the fossil leaves are treated as additional traits beyond classical parameters. Respective patterns are briefly documented and discussed to obtain deeper insights into ecosystem structure and food webs. Finally, this case study gives rise to several open questions about reliability and meaningfulness of fossil leaf traits and the feasibility in palaeoecological investigations.

Global warming and rainfall: Lessons from an analysis of Mid-Miocene climate data

The Mid-Miocene Climatic Optimum (MMCO) has been regarded as an analog for future global warming due to its scale of warming being equivalent to the warming predicted for the next century by the International Panel on Climate Change (IPCC)'s fourth report. However, little is known about how the MMCO influenced paleoprecipitation in central China. In this study, two pollen floras from the eastern Longzhong Basin, northern central China, were quantitatively analyzed to reconstruct the climatic conditions likely during the MMCO. The paleoclimatic parameters obtained by applying the Coexistence Approach (CoA) to these two palynological assemblages showed that the mean annual temperature (MAT, 16.6 °C) for the MMCO was 5.7 °C higher than the present-day MAT (10.9 °C), and that mean annual precipitation (MAP, 955.4 mm) was 413.5 mm higher than at present (541.9 mm), indicating a much warmer and wetter climate. The higher mean temperature for the coldest month (CMT) and the minimum monthly precipitation (MiMP) values also indicate a warmer and wetter coldest and driest month, respectively, and thus suggest the prevalence of a more balanced seasonal paleoclimate in northern central China. These climatic conditions are equivalent to higher global temperatures of ~5–6 °C during the MMCO. This finding would imply that precipitation in northern central China will increase in the context of ongoing global warming.

Miocene pollen assemblages from the Zeku Basin, northeastern Tibetan Plateau, and their palaeoecological and palaeoaltimetric implications

A comprehensive understanding of the tectonic uplift history of the Tibetan Plateau (TP), a 2000 km wide region with a mean altitude of 4000–5000 m above sea level (asl), is crucial for interpreting global Cenozoic climate change, collisional tectonics and the evolution of the Asian climatic system. However, the timing, degree and extent of the uplift of the TP remain controversial. Here we report new palynological data from Early to Mid-Miocene lacustrine-swamp sediments in the Zeku Basin, northeastern TP. The palynoflora includes 68 palynotaxa at a family or genus level, comprising gymnosperms (16.2%), angiosperms (77.9%), pteridophytes (2.9%) and others (2.9%), and is suggestive of a mixed warm temperate forests of coniferous (e.g., Picea, Abies and Tsuga) and deciduous broadleaved trees (e.g., Ulmus/Zelkova, Betula and Quercus), with some subtropical elements (e.g., Carya and Liquidambar). Three periods of vegetation succession can be recognized from the Caergen Section, indicating a stepwise warming and drying trend from bottom to top. The local palaeoclimatic parameters obtained by applying the Coexistence Approach (CoA) to palynologic assemblages rendered mean annual temperature (MAT) values of 14.2–16.1 °C and mean annual precipitation (MAP) values of 797–1113 mm. This study departs from the traditional application of the CoA, relying on published determination of plant-climate relationships, rather than on data derived from the Paleoflora Database, which is currently not fully open-access. Based on the difference in temperatures between the Early to Mid-Miocene and the present day, and the temperature lapse rate, corrected to take account of Miocene global temperature differences, the estimated palaeoaltitude of the Zeku Basin during the Early to Mid-Miocene was 1200–1400 m asl. This palaeoaltitude estimate suggests that this basin has experienced about 2200–2500 m of uplift since the Early to Mid-Miocene. Findings therefore do not support previous hypotheses that the northeastern TP attained its present altitude before the Miocene.

Human–wildlife coexistence: attitudes and behavioural intentions towards predators in the Maasai Mara, Kenya

AbstractLiving alongside predators can entail substantial costs both in terms of livelihoods and personal safety. Negative interactions with predators can lead to negative attitudes and behavioural intentions such as retaliatory or pre-emptive killing. As a result, conservation strategies are increasingly adopting human–wildlife coexistence approaches aimed at minimizing the costs associated with living with predators by providing direct or indirect benefits. This is done in the hope that people will foster positive attitudes and behavioural intentions towards predators. However, people's attitudes and their behavioural intentions are not necessarily linked, and both need to be understood for conservation actions to be effective. We conducted 747 semi-structured interviews with community members in the Maasai Mara, Kenya, to determine which factors influenced people's attitudes and behavioural intentions towards predators and whether the two were linked. Most interviewees (57.52%) had a positive attitude towards predators as measured by their assertion that people, livestock and predators should coexist. Their attitude was dependent on benefits, occupation, conservancy membership and perceived community ownership of predators, but was not influenced by the costs of livestock depredation. Most respondents who were members of a conservancy had positive attitudes towards predators but this differed by conservancy, suggesting that, in addition to benefits, conservation politics could influence attitudes. In total, 10.3% of respondents said that they would kill a predator if it killed their livestock. This behavioural intention was only influenced by the respondent's attitude. Understanding the factors that influence attitudes and behavioural intentions will aid future management and coexistence strategies.

Busy tone based coexistence algorithm for WRAN and WLAN systems in TV white space

TV White Space (TVWS) refers to frequency band reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems from interference, interference among unlicensed systems is left mainly to manufacturers. Consequently, there is a need to develop new coexistence approaches between TVWS networks. Busy tone broadcasting is a coexistence method, which can be used by TVWS networks to announce the selected frequency band is occupied. In this paper, a busy tone based coexistence algorithm is proposed for IEEE 802.11af and IEEE 802.22 networks and analyzed by considering different client distributions experiencing log-normal shadowing, where the exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for different scenarios. The results show that with the proposed coexistence approach, a WLAN can reliably detect the busy tone signal to change its frequency band and can reduce interference to WRAN. Even if there is no available frequency band for the WLAN, the WRAN still maintains its enhanced successful packet transmission performance. The deployment of the proposed algorithm is important for successful coexistence between cognitive wireless networks, where interference is not regulated, such as in TVWS bands.

Oligocene climate signals and forcings in Eurasia revealed by plant macrofossil and modelling results

The Oligocene represents a transitional time period from a warm climate to a cooler climate that is more representative of the modern day; yet, a general view of continental climate pattern and forcings are still lacking. Different proxies and models show striking disparities, especially in mid-high latitudes, requiring validation of Oligocene climate reconstruction in order to understand the large-scale processes that drive the observed climate changes. Here, we compiled 149 macrofossil floras in the mid-high latitudes of Eurasia, then quantitatively reconstructed the Oligocene climate using Coexistence Approach (CA) and combined previously published paleoclimate data. During the Oligocene, Eurasian mid-high latitudes were mainly dominated by a humid subtropical climate. Mean annual temperature (MAT) ranged between 5.4 °C and 25.5 °C with mean annual precipitation (MAP) ranging from 338 to 2453 mm. Three regions (Europe, central Eurasia and eastern Asia) indicate different climatic regimes, with a generally warmer and wetter climate in Europe and a colder and drier climate in central Eurasia when compared to eastern Asia. No significant reorganization of climate was observed between the Early and Late Oligocene. The climate anomalies between the Oligocene and present indicate that geographic changes (e.g. retreat of the Paratethys Sea) played an important role in shaping the climate pattern of Eurasia. By comparing the fossil data to a range of different HadCM3L model simulations of the Oligocene with differing boundary conditions (e.g. CO2 and topography), we demonstrate similar large-scale climate spatial patterns between models and fossil data, however, models simulated much higher temperature seasonality (lower simulated winter temperatures and higher simulated summer temperatures) in Eurasia. Mean annual temperature analysis indicates that simulations with 560 and 1120 ppmv CO2 matched better with fossil data when compared to other simulations, depending on the topography. These results provide some constraints that should be considered for future paleoclimate modelling.

Massive MIMO Unlicensed: A New Approach to Dynamic Spectrum Access

Nowadays, the demand for wireless mobile services is copious and will continue increasing in the near future. Mobile cellular operators are therefore looking at the unlicensed spectrum as an economical supplement to augment the capacity of their soon-to-be overloaded networks. The same unlicensed bands are luring Internet service providers, venue owners, and authorities into autonomously setting up and managing their high-performance private networks. In light of this exciting future, enhancing the coexistence between multiple unlicensed technologies becomes a pivotal issue. In this article, we present the fundamentals and the main challenges behind massive MIMO unlicensed, a new approach for technology coexistence in the unlicensed bands, that is envisioned to boost spectrum reuse for a plethora of use cases.

Paleoelevations in the Jianchuan Basin of the southeastern Tibetan Plateau based on stable isotope and pollen grain analyses

The southeastern margin of the Tibetan Plateau (TP) is a key region for understanding the region's surface uplift mechanisms. This study focused on the Jiuziyan and Shuanghe Formations (Fms) in the Jianchuan Basin, both of which include lacustrine calcareous mudstones and marls. Ostracods of the genus Austrocypris found within the Jiuziyan and Shuanghe Fms constrain the age of strata to the Late Eocene. This study used two different proxies, i.e. fossil pollen coexistence and the δ18O (VPDB) values of carbonate (δ18Oc), to reconstruct paleoelevation and the extant paleoenvironment from lacustrine calcareous mudstones and marls preserved in the Eocene stratigraphy of the Jianchuan Basin. The coexistence approach (CA) using pollen data from the Shuanghe Fm indicates a paleoelevation of 1.3–2.6 km above sea level (asl), which would most probably have been associated with a vegetation cover consisting of tropical-subtropical, deciduous, coniferous, broadleaf forests. The reconstructed mean annual air temperature (MAAT) had a value of 16.8–21.7 °C, warmer than today's MAAT (~6 °C). Oxygen isotope results from the Jiuziyan Fm, with/without modification between Eocene and modern Myanmar sea level, suggested that the surface of the Jianchuan Basin was at a paleoelevation between 0.5+0.8–0.5 km asl and 2.5 ± 0.7 km asl (δ18Omw: −8.9 ± 1.3‰, 2σ). During the Shuanghe Fm sedimentation the paleoelevation was between 0.9 +0.7–0.7 km asl and 2.9 ± 0.6 km asl (δ18Omw: −9.5 ± 1.1‰, 2σ). Our results suggest that a stepwise uplift of Jianchuan Basin and crustal thickening initiated during the Eocene was the cause of passive surface uplift of the southeastern Tibetan Plateau (TP) rather than Miocene lower crustal flow.

Low-latitude vegetation and climate dynamics at the Paleocene-Eocene transition – A study based on multiple proxies from the Jathang section in northeastern India

We present a multi-proxy study of an upper Paleocene-lower Eocene succession from the paleo-equatorial region. The study is carried out on a coal-bearing, shallow-marine succession exposed at Jathang, east Khasi hills, Meghalaya, northeastern India. The succession was deposited in a low-energy, coastal marsh-bay complex. Dinoflagellate cyst biostratigraphy yields a late Paleocene to early Eocene age for the section. The deposits of the lower part of the succession represent a transgressive systems tract (TST) defined by seven parasequences, each starting with bay sediments deposited during transgression, followed by a shallowing-upward bay fill-marsh deposit. In the vertical succession, each parasequence acquires an increasingly marine character, culminating in a maximum flooding surface at the Paleocene-Eocene boundary. It is followed by four shallowing upward parasequences deposited in a highstand systems tract (HST). Enhanced chemical weathering and high terrestrial supply are testified by raised SiO2 and Al2O3 contents and high percentages of terrestrial palynomorphs. The pollen flora recovered from the Jathang section was used for quantitative paleoclimate and vegetation reconstructions. The Coexistence Approach was applied based on Nearest Living Relatives (NLRs) of sixty fossil species recorded at different stratigraphic levels. Seven climate variables were determined for the fossil assemblages, and, as a measure of the seasonality of climate, the number of dry months was estimated. Our study shows that during the Paleocene there existed warm, seasonally dry tropical climate conditions with mean annual temperature at ca. 24–26 °C and mean annual precipitation at ca. 700–1800 mm, and with a dry season of 5–6 months. Particularly warm and wet, perhumid climate conditions with 26–27 °C and 2200–3200 mm mean annual precipitation with a dry period of 2–3 months were reconstructed for the latest Paleocene-earliest Eocene interval. The study shows a distinct vegetational turnover from palm-dominated, seasonally dry tropical forest during the Paleocene to highly diversified dicotyledonous megathermal rainforest during the latest Paleocene-early Eocene. The present study demonstrates that the reduced duration of the dry period during the latest Paleocene-earliest Eocene, due to a more active hydrological cycle, played a major role in determining the climate and shaping the vegetation cover in the paleo-equatorial region. There is evidence from our data that seasonality of rainfall is the determining factor for the tropical forest vegetation pattern of the equatorial region rather than mean annual rainfall condition. As the main trigger for the observed step-wise changes of the hydrology along the studied succession, the fast northward movement of the Indian Plate is inferred.

Upper Eocene palynoflora from Łukowa (SE Poland) and its palaeoenvironmental context

This paper presents the results of a palynological investigation of the sands from upper Eocene (Priabonian) epicontinental marine strata at Łukowa, SE Poland. This locality represents an isolated spot of upper Eocene strata in the southern part of epicontinental Poland due to later uplift and erosion of this area. The sands studied yielded a well-preserved palynoflora, providing information about palaeovegetation and palaeoclimate after the Early Eocene Climate Optimum. During the study a total of 94 fossil species of palynomorphs were identified. The results indicate that the vicinity of the sedimentary basin was covered by vegetation with a significant portion of thermophilous taxa and containing many elements with East Asian affinities. The plant communities were composed of Platanus, Platycarya, Engelhardioideae, members of the Hamamelidaceae, Sapotaceae, Fabaceae, Oleaceae, Fagaceae (probably evergreen Quercus and Castanoideae), and Betulaceae families, as well as Salix, Carya, and others. Members of the Pinaceae family and Sciadopitys were components of coniferous or mixed forests. Taxodium, and presumably Glyptostrobus, together with Nyssa, might have covered areas with a higher groundwater level. The pollen of Milfordia and Aglaoreidia cyclops can probably be considered as representing marsh/freshwater vegetation. Cryptogams are represented mainly by ferns (including members of the Lygodiaceae and Schizaeaceae, probably as well as Gleicheniaceae and Cyatheaceae families) and Lycopodiaceae (including Lycopodiella). The presence of frequent pollen and spores of the genera presently growing under tropical and subtropical climatic conditions and the presence of several taxa characteristic for swamps indicate that the climate during deposition of the sediments studied was warm and humid. The mean annual temperature of 17.2–23.1°C was estimated on the basis of Coexistence Approach method.

Miocene vegetation shift and climate change: Evidence from the Siwalik of Nepal

Abstract We reconstruct climate and vegetation applying the Coexistence Approach (CA) methodology on two palaeofloras recovered from the Lower (middle Miocene; ~ 13–11 Ma) and Middle Siwalik (late Miocene; 9.5–6.8 Ma) sediments of Surai Khola section, Nepal. The reconstructed mean annual temperature (MAT) and cold month mean temperature (CMT) show an increasing trend, while warm month mean temperature (WMT) remains nearly the same during the period. The reconstructed precipitation data indicates that the summer monsoon precipitation was nearly the same during the middle and late Miocene, while the winter season precipitation significantly decreased in the late Miocene. The overall precipitation infers increased rainfall seasonality during the late Miocene. The vegetation during the middle Miocene was dominated by wet evergreen taxa, whereas deciduous ones increased significantly during the late Miocene. The reconstructed climate data indicates that high temperature and significantly low precipitation during the winter season (dry season) in the late Miocene might have enhanced forest fire which favoured the expansion of C4 plants over C3 plants during the period. This idea gets further support not only from a recent forest fire in northern India that was caused by the weakening of winter precipitation, but also from the burnt wood recovered from the late Miocene Siwalik sediments of northern India.