Palaeobotany

Preliminary studies of the palynoflora from the Lavanttal Basin show a relatively rich assemblage of pollen and spores. The palynoflora comprises at least 17 different kinds of spores, representing the Bryophyta (Sphagnum), Lycopodiophyta (Lycopodium, Selaginella), and the Pteridophyta (Dryopteris, Osmunda, Pteris), about 20 different pollen types of conifers assignable to Cupressaceae and Pinaceae, and 130-160 different kinds of angiosperm pollen. In this study, we describe all spores together with pollen from two seed plants, i.e. Ginkgo (Ginkgophyta) and Ephedra (Gnetophyta). The fossil spores and pollen grains are preserved in phosphoritic nodules. Absence of palynomorphs characteristic of marine settings and presence of numerous freshwater algae (diatoms, dinoflagellates, and different green algae) indicate freshwater environments. This is also supported by sedimentological observations suggestive of wetland surroundings, characterised by lakes, swamps, streams, rivers and floodplain areas. The taxa reported here all seem to represent part of azonal vegetation with plants growing in swamps, on hummocks, along border of lakes or streams, on levees, or on sandy patches of floodplains. Preliminary results suggest that the vegetation thrived under a relatively warm and humid climate.

Common models for modern calcite precipitation in and around caves, soils, springs and streams involve CO2 supplied by thick, high pCO2 biogenic soils which were probably thin or non-existent before vascular plants. Indeed plant-influenced chemical weathering might have caused accelerated terrestrial carbonate production from the Devonian onwards. However terrestrial carbonates have also been documented from the Archaean, Proterozoic, Cambrian, Ordovician and Silurian. Mechanisms which could have caused non-marine carbonates to precipitate without organic-rich soils are described, and some geological events likely to have influenced non-marine carbonate precipitation up to the origin of vascular plants are highlighted. As organisms have evolved, so have the petrographic characteristics of non-marine carbonates; some examples of this are also given here .

Common models for modern calcite precipitation in and around caves, soils, springs and streams involve CO2 supplied by thick, high pCO2 biogenic soils which were probably thin or non-existent before vascular plants. Indeed plant-influenced chemical weathering might have caused accelerated terrestrial carbonate production from the Devonian onwards. However terrestrial carbonates have also been documented from the Archaean, Proterozoic, Cambrian, Ordovician and Silurian. Mechanisms which could have caused non-marine carbonates to precipitate without organic-rich soils are described, and some geological events likely to have influenced non-marine carbonate precipitation up to the origin of vascular plants are highlighted. As organisms have evolved, so have the petrographic characteristics of non-marine carbonates; some examples of this are also given here .

A palaeobotanical analysis of the Pleistocene floras and vegetation in the Iberian Peninsula shows the existence of patched landscapes with Pinus woodlands, deciduous and mixed forests, parklands (savannahlike), shrublands, steppes and grasslands. Extinctions of Arctotertiary woody taxa are recorded during the Early and Middle Pleistocene, but glacial refugia facilitated the survival of a number of temperate, Mediterranean and Ibero-North African woody angiosperms. The responses of Iberian vegetation to climatic changes during the Pleistocene have been spatially and temporarily complex, including rapid changes of vegetation in parallel to orbital and suborbital variability, and situations of multi-centennial resilience or accommodation to climatic changes. Regional characteristics emerged as soon as for the Middle Pleistocene, if not earlier: Ericaceae in the Atlantic coast indicating wetter climate, thermo-mediterranean elements in the south as currently, and broad-leaf trees in the northeastern. Overall, steppe landscapes and open Pinus woodlands prevailed over many continental regions during the cold spells of the Late Pleistocene. The maintenance of a high phytodiversity during the glacials was linked to several refuge zones in the coastal shelves of the Mediterranean and intramountainous valleys. Northern Iberia, especially on coastal areas, was also patched with populations of tree species, and this is not only documented by palaeobotanical data (pollen and charcoal) but also postulated by phylogeographical models.

—Taxonomic analysis is provided for a Middle Pennsylvanian macrofloral assemblage collected from clastic wetland deposits in Clay County, Indiana, on the eastern margin of the Illinois Basin. Adpressed plant fossils were recovered from four distinct beds in the lowermost Staunton Formation, positioned above the Minshall Coal (uppermost Brazil Formation), part of a succession deposited near the Atokan-Desmoinesian boundary. The assemblage of 22 fossil-taxa is dominated by pteridosperms (including Neuropteris flexuosa, Macroneuropteris scheuchzeri, Alethopteris densinervosa, Neuropteris ovata, Eusphenopteris neuropteroides, and Neuropteris missouriensis) with lesser cordaitaleans (Cordaites spp. indet.) and sphenopsids (particularly Sphenophyllum cuneifo-lium). Lycopsids are uncommon, and ferns are rare. In contrast, the microfloral assemblage from the Minshall Coal and overlying clastic units is dominated by lycopsid and tree fern spores. Comparisons with established biozonation schemes yield different ages depending on the regional biostratigraphic framework used: (1) latest Bolsovian (Radiizonates difformis Biozone, American microfloras); (2) latest Bolsovian or earliest Asturian ('Neuropteris' rarinervis Biozone, Appalachian Basin macrofloras); or (3) earliest Asturian (Linopteris obliqua Biozone, European macrofloras). The placement and correlation of the Bolsovian-Asturian and Atokan-Desmoinesian boundaries, which have traditionally been equated by palynology, are evaluated in the context of this discordance. Several revised stratigraphic scenarios are proposed for this interval in the Illinois Basin, which is being increasingly recognized as a time of significant environmental change throughout Euramerica. Homotaxial comparisons with European macro-floral assemblages indicate that, of the 18 biological taxa recorded, between 14 and 17 (78–94%) also are common in coeval wetland deposits in Europe. The similarities exemplify the spatial conservatism and low diversity of wetland plant communities over vast areas of tropical Euramerica, a manifestation of the intrinsically stressful conditions that characterize such habitats, and indicates that neither the Laurentian Shield nor the Appalachian-Variscan Mountains were an insurmountable barrier to plant dispersal during the Middle Pennsylvanian.

The carbon-isotope composition of fossil wood fragments, collected through a biostratigraphically well-constrained Aptian (Lower Cretaceous) shallow-marine siliciclastic succession on the Isle of Wight, southern Britain, shows distinct variations with time. The results indicate that the stratigraphic signature of δ13Cwood through the Aptian was influenced primarily by fluctuations in the isotopic composition of CO2 in the global ocean-atmosphere system, as registered in marine carbonates elsewhere, and was not governed by local paleoenvironmental and/or paleoecological factors. Negative and positive excursions in δ13Cwood through the lower Aptian occur in phase with inferred transgressions and regressions, respectively—a pattern that contrasts with that observed in many previous studies for different time intervals. The relationship between δ13C variations and relative sea-level change is tentatively interpreted as a response to various climatic and eustatic factors, relating to rapid sea-floor spreading, thermal uplift of ocean floor, emplacement of plateaus, volcanic CO2 emissions, weathering, and sedimentary rate.

The carbon-isotope composition of fossil wood fragments, collected through a biostratigraphically well-constrained Aptian (Lower Cretaceous) shallow-marine siliciclastic succession on the Isle of Wight, southern Britain, shows distinct variations with time. The results indicate that the stratigraphic signature of δ13Cwood through the Aptian was influenced primarily by fluctuations in the isotopic composition of CO2 in the global ocean-atmosphere system, as registered in marine carbonates elsewhere, and was not governed by local paleoenvironmental and/or paleoecological factors. Negative and positive excursions in δ13Cwood through the lower Aptian occur in phase with inferred transgressions and regressions, respectively—a pattern that contrasts with that observed in many previous studies for different time intervals. The relationship between δ13C variations and relative sea-level change is tentatively interpreted as a response to various climatic and eustatic factors, relating to rapid sea-floor spreading, thermal uplift of ocean floor, emplacement of plateaus, volcanic CO2 emissions, weathering, and sedimentary rate.

The Clouston Farm locality, assigned to the Lopingian Epoch and occurring within 45 the Normandien Formation of the northeastern Karoo Basin, provides evidence for a 46 community of diverse vascular plants occupying riparian woodland. The depositional 47 environment is interpreted as an abandoned trunk channel that preserved a megaflora in 48 slack-water phases punctuated by overbank deposits from rare flood events. Of 9772 49 plant specimens tabulated from an unbiased census of all fragments greater than ~ 1 cm 2 , 50 there are 51 distinct organ morphotypes, including glossopterids, sphenopsids, and ferns, 51 collectively represented as foliage, axes, fructifications, and dispersed seeds. Of the 11 52 most abundant morphotypes 10 are glossopterid morphotypes or variant subtypes, in 53 addition to a sphenopsid. Glossopterid morphotype dominance also is reflected in the 54 palynoflora. Palynological data indicate a Wuchiapingian age for the locality. A 55 specimen of the dicynodont 'Oudenodon,' found in a nearby stratigraphically equivalent 56 outcrop, is attributable to the Dicynodon Assemblage Zone, assigned a younger 57 Changhsingian age. A rich record of plant-insect associations demonstrates an elevated 58 frequency of external foliage feeding by mandibulate insects and lower incidence of 59 oviposition by palaeodictyopteroid and odonatopteroid taxa. Evidence for piercing-and-60 sucking and galling is rare. The most abundant plant taxon (glossopterid morphotype 61 C2a) is the most intensively herbivorized, overwhelmingly by external feeding and 62 ovipositing insects. Insect damage on this host is beyond that predicted by floristic 63 abundance alone. This specificity, and high herbivory levels on other glossopterid taxa, 64 demonstrates extension of the Euramerican pattern toward the preferential targeting of 65 pteridosperms. The Clouston Farm site provides a glimpse into a late Permian ecosystem 66 A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT of primary producers, herbivores, and insectivores-a prelude to the crisis that engulfed 67 life at the end of the period. 68 69

The Middle Jurassic flora of Sardinia has been studied, and 24 taxa (19 genera) belonging to horsetails, ferns (Phlebopteris, Hausmannia, Coniopteris, Todites, Cladophlebis), seed ferns (Sagenopteris, Ptilozamites), cycadophytes (Nilssonia, Pterophyllum, Cycadeospermum, Ptilophyllum, Williamsonia, Weltrichia, Taeniopteris), ginkgophytes (Czekanowskia), conifers (Geinitzia, Brachyphyllum, Elatocladus) and seeds (Carpolithes), have been identified.  The flora of Sardinia is the southernmost of all Middle Jurassic European floras.  The coeval European and North African floral assemblages (112 genera) are present in a wide variety of environments and different palaeogeographic positions, which is reflected in a wide variety of taxa. A comparison between the coeval floras of Middle Jurassic age reveals a higher degree of dissimilarity than similarity between the various assemblages, which is in disagreement with the general picture of the homogeneity in the Jurassic floras given by previous authors.

The use of fossil sediments and genetic markers has allowed reconstruction of range shifts of forest trees induced by past climatic changes. Independently, studies of the ecology and population biology of human-induced tree invasions have started to appear. Here, we review the literature on the ecology and the genetics of past and contemporary invasions of forest trees and argue that population research dealing with past (natural) or with ongoing (human-induced) invasions should be better integrated. In particular, we suggest using identical terms to describe artificial and natural invasions, as this should help integrate the two fields. We then discuss the modalities of introduction of tree species, the life history traits associated with invasiveness, the importance of long-distance seed dispersal, the establishment of small populations, the role of biotic interactions and the specific contribution of palaeoecology to the study of tree invasions. Next, we discuss genetic and evolutionary aspects, including the genetic characteristics of invasive woody species, the genetic consequences of dispersal (founder effects and admixture), shifts in dispersal-related traits and in mating system and the importance of hybridization and introgression during invasion. We then review models of the genetic consequences of tree invasions, examine the possibility for rapid adaptation of trees to new environmental conditions and discuss the relative importance of environmental versus genetic factors in controlling tree invasions. We conclude by proposing solutions for two central ''genetic paradoxes'' of invasions. The first one is the necessity for invasive species to adapt to new conditions, which seems difficult to reconcile with the expected loss of diversity through founder events. The second is the common observation of invasive species outcompeting native ones, which does not seem to fit with the belief in widespread local adaptation. #

We present fossil pollen data and discuss their climatic interpretations from a 688-cm-long sediment core from Hurleg Lake, a freshwater lake located in the Qaidam Basin on the NE Tibetan Plateau, just beyond the northern limit of the East Asian summer monsoon influence. The reconstruction of the Holocene vegetation and climate history was aided by modern surface pollen analysis. The 14000-yr chronology of the sediment core was controlled by seven AMS 14 C dates on plant macrofossils. The results of the surface pollen analysis showed that modern pollen spectra faithfully reflect the regional vegetation along a transect from alpine meadow to desert steppe and desert, so fossil pollen record can be used to reconstruct Holocene vegetation change. The pollen data showed that vegetation changed from desert before the Holocene to desert steppe dominated by Artemisia from 11.9 to 9.5 ka, desert dominated by Chenopodiaceae from 9.5 to 5.5 ka, and steppe desert dominated by Artemisia and Poaceae after 5.5 ka. This vegetation sequence indicates that climate was relatively wet before 9.5 ka, dry and variable from 9.5 to 5.5 ka, and relatively wet and stable after 5.5 ka. The climate pattern reconstructed from pollen data appears to be opposite to the paleoclimate pattern inferred at Qinghai Lake, 300 km east of our study site. That site shows a moist early Holocene during the insolation and monsoon maximum followed by a drying trend during the mid-and late Holocene. The contrast between the two sites suggests the importance of the position of the subtropical monsoon, the mid-latitude westerlies and interactions between local topography and regional climate. Our finding has important implications for understanding complex regional vegetation and climate responses to large-scale forcings in arid central Asia.

Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Nevertheless, some of their most important characteristics can be preserved in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous insects. Here, we report on an Ϸ58-my-old flora from the Cerrejó n Formation of Colombia (paleolatitude Ϸ5°N) that is the earliest megafossil record of Neotropical rainforest. The flora has abundant, diverse palms and legumes and similar family composition to extant Neotropical rainforest. Three-quarters of the leaf types are large and entiremargined, indicating rainfall >2,500 mm/year and mean annual temperature >25°C. Despite modern family composition and tropical paleoclimate, the diversity of fossil pollen and leaf samples is 60 -80% that of comparable samples from extant and Quaternary Neotropical rainforest from similar climates. Insect feeding damage on Cerrejó n fossil leaves, representing primary consumers, is abundant, but also of low diversity, and overwhelmingly made by generalist feeders rather than specialized herbivores. Cerrejó n megafossils provide strong evidence that the same Neotropical rainforest families have characterized the biome since the Paleocene, maintaining their importance through climatic phases warmer and cooler than present. The low diversity of both plants and herbivorous insects in this Paleocene Neotropical rainforest may reflect an early stage in the diversification of the lineages that inhabit this biome, and/or a long recovery period from the terminal Cretaceous extinction. diversity ͉ stability ͉ paleoclimate ͉ paleobotany ͉ Fabaceae

The Osmundales (Royal Fern order) originated in the late Paleozoic and is the most ancient surviving lineage of leptosporangiate ferns. In contrast to its low diversity today (less than 20 species in six genera), it has the richest fossil record of any extant group of ferns. The structurally preserved trunks and rhizomes alone are referable to more than 100 fossil species that are classified in up to 20 genera, four subfamilies, and two families. This diverse fossil record constitutes an exceptional source of information on the evolutionary history of the group from the Permian to the present. However, inconsistent terminology, varying formats of description, and the general lack of a uniform taxonomic concept renders this wealth of information poorly accessible. To this end, we provide a comprehensive review of the diversity of structural features of osmundalean axes under a standardized, descriptive terminology. A novel morphological character matrix with 45 anatomical characters scored for 15 extant species and for 114 fossil operational units (species or specimens) is analysed using networks in order to establish systematic relationships among fossil and extant Osmundales rooted in axis anatomy. The results lead us to propose an evolutionary classification for fossil Osmundales and a revised, standardized taxonomy for all taxa down to the rank of (sub)genus. We introduce several nomenclatural novelties: (1) a new subfamily Itopsidemoideae (Guaireaceae) is established to contain Itopsidema, Donwelliacaulis, and Tiania; (2) the thamnopteroid genera Zalesskya, Iegosigopteris, and Petcheropteris are all considered synonymous with Thamnopteris; (3) 12 species of Millerocaulis and Ashicaulis are assigned to modern genera (tribe Osmundeae); (4) the hitherto enigmatic Aurealcaulis is identified as an extinct subgenus of Plenasium; and (5) the poorly known Osmundites tuhajkulensis is assigned to Millerocaulis. In addition, we consider Millerocaulis stipabonettiorum a possible member of Palaeosmunda and Millerocaulis estipularis as probably constituting the earliest representative of the (Todea-)Leptopteris lineage (subtribe Todeinae) of modern Osmundoideae.

ABSTRACT:
This study is the first systematic comparison of the effect of acid treatment methods on the reliability of organic carbon [C] and nitrogen [N], and carbon isotope (δ13C) values on a range of terrestrial and aquatic, modern and geological environmental materials. We investigated the 3 most common methods; (i) acidification followed by sequential deionised water rinses (“rinse method”); (ii) acidification in silver capsules (“capsule method”); and (iii) acidification by exposure to an acid vapour (“fumigation method”). We also investigated the effect of sample size and capsule type (silver and tin) on C/N ratio and δ13C values. We find (i) %C, %N, C/N and δ13C showed significant within and between method variability; (ii) disproportionate and non-linear offsets of %C, %N and C/N values after acidification within and between methods and within and between sample materials; (iii) that alterations in %C did not necessarily manifest themselves in shifts in δ13C, and vice-versa; (iv) small (~ 90 μg C) sample sizes showed consistent overestimations and inaccuracies after acidification; (v) The effect of capsule type was not significant on most samples, but did show a notable effect on our aquatic materials, generally increasing %C and %N, and producing depleted δ13C values. These findings raise cause for concern on the interpretative nature of C/N ratios and their support for carbon isotope values. The comparability between laboratories (different preparation methods) and environmental settings (amount, type and nature of OM) are also likely to be problematic. We conclude that the response of C and N concentrations in organic matter to acid treatment in environmental materials is neither negligible nor systematic.

Keywords: δ13C; C/N ratio; Method comparison; Rinse method; Capsule method; Fumigation method; environmental reconstruction

ABSTRACT:
This study is the first systematic comparison of the effect of acid treatment methods on the reliability of organic carbon [C] and nitrogen [N], and carbon isotope (δ13C) values on a range of terrestrial and aquatic, modern and geological environmental materials. We investigated the 3 most common methods; (i) acidification followed by sequential deionised water rinses (“rinse method”); (ii) acidification in silver capsules (“capsule method”); and (iii) acidification by exposure to an acid vapour (“fumigation method”). We also investigated the effect of sample size and capsule type (silver and tin) on C/N ratio and δ13C values. We find (i) %C, %N, C/N and δ13C showed significant within and between method variability; (ii) disproportionate and non-linear offsets of %C, %N and C/N values after acidification within and between methods and within and between sample materials; (iii) that alterations in %C did not necessarily manifest themselves in shifts in δ13C, and vice-versa; (iv) small (~ 90 μg C) sample sizes showed consistent overestimations and inaccuracies after acidification; (v) The effect of capsule type was not significant on most samples, but did show a notable effect on our aquatic materials, generally increasing %C and %N, and producing depleted δ13C values. These findings raise cause for concern on the interpretative nature of C/N ratios and their support for carbon isotope values. The comparability between laboratories (different preparation methods) and environmental settings (amount, type and nature of OM) are also likely to be problematic. We conclude that the response of C and N concentrations in organic matter to acid treatment in environmental materials is neither negligible nor systematic.

Keywords: δ13C; C/N ratio; Method comparison; Rinse method; Capsule method; Fumigation method; environmental reconstruction

For the first time, a palynologic assemblage is described from the upper section of the Tarma Formation, Peru. It is dominated by monosaccate pollen grains with subordinate striate grains and very few spores. The abundance of Illinites unicus has allowed a revision of the systematic position of the form-genus Illinites. The assemblage is correlated with the Illinites unicus palynozone from the Amazonas Basin, and is considered to be of Westphalian C/Late Atokan age.

Fossil plant morphological traits have been used extensively as palaeoenvironment and palaeoclimate indicators. Xeromorphic features are considered to be structural adaptations that reduce water loss (e.g. thick cuticle, sunken stomata, epidermal papillae and trichomes, stomatal papillae and stomata arranged in sunken grooves), and their presence in fossil plants is often used to indicate palaeo-environmental aridity. However, in living plants, xeromorphic traits are not restricted to plants subjected to water stress and are commonly observed in plants growing in environments with high precipitation, humidity and water availability. These "xeromorphic" features often serve multiple functions such as water-repellence, defence and protection from excess light. The use of "xeromorphic" features as indicators of palaeo-environmental aridity therefore requires reinterpretation. Here we review the ecological functions of "xeromorphic" adaptations in extant plants and analyse the equivocal nature of these morphological features using the extinct Cretaceous conifer Pseudofrenelopsis parceramosa (Fontaine) Watson. We track the occurrence of stomatal papillae (waxy lobes over-hanging the stomatal pit) that are commonly considered to have an antitranspirant function, in P. parceramosa through Valanginian-Barremian sediments deposited in a fresh water lowland environment at Worbarrow Bay, Dorset, southern England. The presence/absence of stomatal papillae in P. parceramosa does not display a pattern consistent with an anti-transpirant function. In the context of supporting sedimentological, geochemical and climate modelling evidence we hypothesise that the primary function of stomatal papillae may be to repel liquid water, in addition to other functions such as providing structural support, pathogen-defence and as a response to high atmospheric particulate content caused by localised volcanism. Our review presents a new palaeo-environmental interpretation of a widespread and important mid-Cretaceous conifer but also provides an updated synthesis of palaeoenvironmental data that can be interpreted from "xeromorphic" features in fossil plants.

As vegetation evolved during the Palaeozoic Era, terrestrial landscapes were substantially transformed,
especially during the 120 million year interval from the Devonian through the Carboniferous. Early
Palaeozoic river systems were of sheet-braided style – broad, shallow, sandbed rivers with non-cohesive
and readily eroded banks. Under the influence of evolving roots and trees that stabilised banks and added
large woody debris to channels, a range of new fluvial planform and architectural styles came to
prominence, including channelled- and island-braided systems, meandering and anabranching systems,
and stable muddy floodplains. River systems co-evolved with plants and animals, generating new
ecospace that we infer would have promoted biological evolution. By the end of the Carboniferous, most
landforms characteristic of modern fluvial systems were in existence.

Wetland plant communities persisted though much of the Pennsylvanian in Euramerica and are the dominant coal forming vegetation in this region. Distribution of these floras show a dramatic decline at the end of the Carboniferous with many of the plant genera and species becoming extinct by the onset of the Permian. This has been correlated with climate change and in particular aridification associated with northwards plate motion and Euramerica moving into the doldrums, but is also associated with the Variscan orogeny and forefront destroying large areas of formerly lowland basinal settings. Other factors may include Pennsylvanian glaciations as evidenced by cyclothem and rhythmical deposition in lowlying wetland settings, and change in eustatic base level. Evidence from Euramerica demonstrates extinction of this kind of wetland biota by the earliest Permian and the development of drier floras including conifer dominated assemblages. However, new data from other parts of the world, most notably North China, confirm this model and highlight the presence of similar coal swamps ranging from the Late Pennsylvanian through the Permian. In this paper we summarise and synthesize recent taxonomic and systematic investigations undertaken on the plant fossils from the Pennsylvanian Benxi Formationthe oldest recognised wetland plant community in Chinaand the Early Permian Taiyuan Formationthe best preserved wetland plant community from China. Results indicate a remarkable similarity of the Pennsylvanian-Early Permian floras of North China with the older assemblages in the Pennsylvanian of Euramerica, and the presence of typical 'Euramerican' coal swamp plant families, genera and in some cases species in China. Conclusions include the presence of the Ameriosinian phytogeographical realm uniting Euramerica and northern Cathaysia at this time, coal swamps in the Permian of North China evolving from a 'Euramerican' origin, and the dramatic floral turnover at the end of the Carboniferous representing a regional event rather than a global extinction episode. Patterns of plant distribution through this interval have profound implications on established palaeogeographical models and support continental connection between Euramerica and Cathaysia before the end of the Carboniferous, contradicting ideas of Cathaysian island biogeography and biotic distinction. Continental connection appears to be related to glacial eustatic low-stand and previously shallow marine environments becoming vegetated. Also important is the fact that in both Euramerica and North China the pattern of floristic demise within wetland plant communities are similar to each other, implying the same causal mechanisms, with plants occupying waterlogged positions being the most severely devastated. However, ecosystem demise occurred at the end of the Carboniferous in Euramerica and in the middle Permian in North China, but in both cases the primary cause was climate change.

In the past, the phrase 'environmental allocations of water' has most often been taken to mean allocation of water to rivers. However, it is now accepted that groundwater-dependent ecosystems are an important feature of Australian landscapes and require an allocation of water to maintain their persistence in the landscape. However, moving from this theoretical realisation to the provision and implementation of a field-based management regime is extremely difficult. The following four fundamental questions are identified as being central to the effective management of groundwater-dependent ecosystems (GDEs): (1) How do we identify GDEs in the field; put another way, which species or species assemblages or habitats are reliant on a supply of groundwater for their persistence in the landscape;

Understanding seed germination biology and the dynamics of seed dormancy is essential to developing reliable germination techniques. This paper presents some new data and reviews recent findings from germination studies on Australian species, with respect to the role of temperature and moisture in the control of dormancy and germination. A seed-burial experiment was conducted over a 1-year period (January-December) with seeds of Acanthocarpus preissii Lehm., Astroloma xerophyllum (DC.) Sond., Gahnia grandis (Labill.) S.T.Blake, Goodenia scaevolina F.Muell. and Tersonia cyathiflora (Fenzl) J.W.Green to determine the fluctuations in temperature and moisture seeds naturally experience in the buried environment. All seeds became hydrated during autumn (March) while soil temperatures were >15 • C, suggestive of a period of warm stratification before the onset of cooler winter temperatures appropriate for germination. Evidence of rapid wetting and drying of seeds in the soil environment was also present. Laboratory experiments testing stratification as a means for dormancy loss showed that several weeks of warm stratification at 26/13 • C or 33/18 • C promoted germination of Lomandra preissii (Endl.) Ewart, Marianthus bicolor (Putt.) F.Muell. and Xyris lanata R.Br. seeds. X. lanata seeds also responded to several weeks of cold stratification at 5 • C. By integrating this new data with other published data on germination of Australian species, diagrammatic models of germination timing, dormancy syndromes and propagation strategies for temperate Australian species are presented as working hypotheses to help direct future research.

The cornerstone of palaeoecological research, concerned with vegetation dynamics over the recent geological past, is a good understanding of the present-day ecology and distribution of the taxa. This is particularly necessary in areas of high floral diversity such as Latin America. Vegetation reconstructions, based on numerous pollen records, now exist with respect to all major vegetation associations from Latin America. With this ever-increasing number of sedimentary records becoming available, there is a need to collate this information and to provide information concerning ecology and distribution of the taxa concerned. The existing Latin American Pollen Database (LAPD) meets the first of these needs. Information concerning the ecology and distribution of the parent taxa responsible for producing the pollen, presently lodged within the LAPD, is the focus of this paper. The 'dictionary' describes the ecology and distribution of the parent taxa responsible for producing pollen identified within sedimentary records. 0034-6667 / 02 / $^see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 3 4 -6 6 6 7 ( 0 2 ) 0 0 0 8 2 -9 These descriptions are based on a wide range of literature and extensive discussions with members of the palaeoecological community working in different parts of Latin America investigating a range of different vegetation types. ß

A review of carbon-isotope analysis (δ13C) of terrestrial organic matter indicates that this has become a valuable tool for stratigraphic correlation between marine and non-marine sequences as well as providing palaeoenvironmental information. Early Cretaceous fossil wood was collected over a 64 cm section from Flat Rocks, southeastern Australia, and analysed for carbon-isotope ratios. Three positive δ13Cplant shifts were recorded, and a similar pattern was found in the carbon/nitrogen (C/N) ratio of the plant fragments. Comparisons of δ13Cplant values and C/N ratios with sedimentolog indicate that positive shifts occur in sand-rich horizons, while negative shifts occur in mud-rich horizons. This trend most likely represents diagenetic-taphonomic changes caused by changes in the oxidation state and/or bacterial activity during deposition and fossilization of the plant matter. The application of carbon-isotope analyseson fossil plants can provide invaluable information with respect to the environment on a local, regional or global scale; however, caution must be exercised in interpreting these data accurately.

A review of carbon-isotope analysis (δ13C) of terrestrial organic matter indicates that this has become a valuable tool for stratigraphic correlation between marine and non-marine sequences as well as providing palaeoenvironmental information. Early Cretaceous fossil wood was collected over a 64 cm section from Flat Rocks, southeastern Australia, and analysed for carbon-isotope ratios. Three positive δ13Cplant shifts were recorded, and a similar pattern was found in the carbon/nitrogen (C/N) ratio of the plant fragments. Comparisons of δ13Cplant values and C/N ratios with sedimentolog indicate that positive shifts occur in sand-rich horizons, while negative shifts occur in mud-rich horizons. This trend most likely represents diagenetic-taphonomic changes caused by changes in the oxidation state and/or bacterial activity during deposition and fossilization of the plant matter. The application of carbon-isotope analyseson fossil plants can provide invaluable information with respect to the environment on a local, regional or global scale; however, caution must be exercised in interpreting these data accurately.

Various pollen morphotypes of Decodon from the Cenozoic of North America, Europe, and Asia are described for the first time, using a combination of LM and SEM. The report includes the earliest pollen record of Decodon from the Northern Hemisphere. The pollen grains were obtained from sedimentary samples using the single grain technique, allowing for a high taxonomic resolution. The fossil pollen show clear traceable changes in morphology toward the present. The apparent pollen diversity noted at the end of the Cenozoic indicates that during the Miocene, Decodon was not a monotypic genus, as at present. This is also apparent from the macrofossil record summarized here. The combined fossil record of the genus is used to evaluate the paleogeographic distribution of Decodon in time and place and to speculate about its migration across and between continents in the light of major geological events.

Investigations of geomorphology, geoarchaeology, pollen, palynofacies, and charcoal indicate the comparative scales and significance of palaeoenvironmental changes throughout the Holocene at the junction between the hyper-arid hot Wadi 'Arabah desert and the front of the Mediterranean-belt Mountains of Edom in southern Jordan through a series of climatic changes and episodes of intense mining and smelting of copper ores. Early Holocene alluviation followed the impact of Neolithic grazers but climate drove fluvial geomorphic change in the Late Holocene, with a major arid episode corresponding chronologically with the 'Little Ice Age' causing widespread alluviation. The harvesting of wood for charcoal may have been sufficiently intense and widescale to affect the capacity of intensively harvested tree species to respond to a period of greater precipitation deduced for the Roman-Byzantine period -a property that affects both taphonomic and biogeographical bases for the interpretation of palynological evidence from arid lands with substantial industrial histories. Studies of palynofacies have provided a record of human and climatic causes of soil erosion, and the changing intensity of the use of fire over time. The patterns of vegetational, climatic change and geomorphic changes are set out for this area for the last eight thousand years.

Paleocene leaf floras are rare in high latitudes of the Southern Hemisphere, where studies have shown higher taxonomic diversity compared to Northern Hemisphere equivalents. The floras provide valuable insights into biodiversity and forest communities during the Paleocene. The Antarctic Peninsula hosts a wealth of Paleocene-Eocene floras which have been used to interpret climates before, during and after one of the most abrupt and transient warming events known from the geological record. The best-preserved and most diverse Paleocene macrofossils from this region come from the Cross Valley Formation, Seymour Island Group, which have previously provided evidence for warm temperate climates prior to the PETM. Here we present the taxonomy of leaf impressions from the Paleocene Cross Valley Flora for one species and ten new leaf morphotypes of entire-margined angiosperms. The new morphotypes provide evidence of an increased angiosperm diversity within cool-temperate Gondwanan forest inhabiting the east side of the Antarctic Peninsula, which contrasts with a lower floral diversity on the west side of the Peninsula during the late Paleocene.

Plant macrofossils with epidermal features from the Lower Albian (Lower Cretaceous) Plattenkalk 2 as exposed in "Le Cavere" quarry within Pietraroja Fossil-Lagerstätte, southern Italy, include sterile foliagebearing shoots and reproductive structures of gymnosperms and possible angiosperm leaves occurring in a controversial marine depositional environment. The following taxa are recorded: Brachyphyllum sp., Frenelopsis sp., Cheirolepidiaceae gen. et sp. indet. and Nageiopsis?. Bituminous strata of the lower Plattenkalk 2 are full of plant debris composed mainly of isolated leaves and sterile axes. Taphonomic considerations suggest parautochtonous deposition for Frenelopsis while the other plant remains are allochthonous. Among the plants studied, the cheirolepidiaceous conifers have ecological significance owing to their (debated) xeromorphic foliar features. These adaptations suggest a warm and dry, or possibly coastal palaeoenvironment. Studied plant fossils together with sedimentological and palaeozoological considerations do not exclude a lagoonal hypothesis for Pietraroja sedimentary basin. This research expands the phytotaxonomic knowledge of the emergent lands within the Early Cretaceous Apenninic Carbonate Platform (ACP).

Quantitative relationships between modern pollen rain and climate are poorly studied in China, partly due to the extensive human impact on the modern vegetation. A dataset consisting of 227 modern pollen samples from forests, shrublands, meadows, steppes, and deserts in the Tibetan Plateau, the least anthropologically-disturbed region in China, provides a unique opportunity to study the quantitative relationships between modern pollen rain and climate. Pollen percentage data were calculated on a sum of 20 pollen taxa. Climatic data for each site, including mean annual precipitation (MAP), mean annual temperature (MAT), July temperature (Tjuly), and January temperature (Tjan), were derived from 214 meteorological stations in the Tibetan Plateau and adjacent areas using natural neighbor interpolation and linear interpolation methods.Canonical correspondence analysis (CCA) was used to reveal the climatic parameters that best reflect the main patterns of variation in the modern pollen rain, and to detect anomalous observations. Results of CCA indicate that MAP and Tjuly are two climatic parameters controlling the variation of modern pollen rain in the Tibetan Plateau. Pollen–climate transfer functions for MAP and Tjuly were then developed using the inverse linear regression and weighted-averaging partial least squares regression models. The functions derived from these two models are statistically significant at the 0.0000 level. A case study, in which these functions were applied to a fossil pollen record from an alpine lake in the eastern Tibetan Plateau, was conducted to show the feasibility of these functions in paleoclimate reconstruction. The results demonstrated the applicability of these pollen–climate transfer functions to fossil pollen data.