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To better understand the effect of the Paleocene‐Eocene Thermal Maximum (PETM) on continental ecosystems, we studied 40 new palynological samples from the Bighorn Basin (BHB), northwestern Wyoming, USA. We see palm and fern abundances increase in the last 20–40 ka of the Paleocene, then dramatically with the onset of the carbon isotope excursion (CIE) defining the base of the PETM. Palynomorphs of plant groups with modern temperate climate distributions are absent from the CIE body, and this is when tropical plants are most diverse and abundant. During the CIE recovery, pollen of mesophytic/wetland plants become more common while tropical taxa persist. In the post‐CIE early Eocene tropical taxa are rare and temperate forms abundant, similar to the late but not latest Paleocene. Changes in the palynoflora are more easily detected if reworked palynomorphs are removed from analyses. We interpret palynofloral changes to indicate warming in the latest Paleocene, rapid warming and drying with the CIE onset, dry tropical climates through the CIE body, a return to wetter floodplains during a very warm CIE recovery, and cooler wet conditions in the post‐PETM early Eocene. These inferences are consistent with geochemical and paleobotanical proxies. Strikingly similar patterns in the palynoflora and megaflora suggest changes in vegetation were a basin‐wide phenomenon. These rapid, climatically forced changes in floral composition occurred without major extinction, perhaps indicating nearby refugia in which plants adapted to cooler and wetter climates persisted through the PETM. Key Points: Bighorn Basin palynofloras began shifting toward hot/dry tolerant plants during the latest Paleocene "pre‐onset" carbon isotope excursionsPalynofloras from early in the carbon isotope excursion (CIE)‐body were dominated by ferns and palms indicating disturbance, then later by dry tropical lineagesWetland taxa regained abundance during the CIE recovery, indicating climate‐forced changes in plant distributions without major extinction [ABSTRACT FROM AUTHOR]

Premise: Understanding establishment and spread of non‐native plants is important in the face of a homogenizing global flora. While many studies focus on successful, invasive species, fewer have studied failed plant introductions. Until the early 1900s, large quantities of ship ballast, often containing foreign plant propagules, were deposited in New Jersey (USA). The resulting ballast flora is documented in extensive herbarium records, providing us a unique opportunity to analyze successes and failures of novel plant species introductions. Methods: We used digitized specimens from 75 herbaria to study 264 non‐native species introduced into New Jersey through 19th century ballast deposition. We used spatial (density‐based clustering; HDBSCAN) and temporal analyses of species retention and geographic spread to quantify disappearance rate, survival, and dispersion through time and define trajectory groups. Results: Four distinct trajectory groups were identified: waif (only present during import; 32% of species), short‐term (disappeared quickly; 20%), established–limited spread (survives locally, 30%), and established–widespread (widespread, 18%). Species disappearance rate was highest during ballast deposition and decreased soon after deposition stopped around 1900. Spatial patterns showed a strong association with 19th century railroads for inland dispersal from ports. The disappearance rate and spatial analyses are robust to herbarium collection bias. Conclusions: This study using New Jersey as a model is one of the few documenting multispecies successes and failures in inadvertent plant introductions. Results reveal distinct trends in species establishment and geographic spread and highlight the utility of herbarium specimens in answering questions that span large time scales. [ABSTRACT FROM AUTHOR]

The aim of this study is to analyze the floristic changes occurred between 1991 and 2018 in the "Pineto Urban Regional Park" (Rome) as a result of a land-use change that in mid-90s led to the abandonment of traditional pasture practices and a shift to a more intense frequentation for recreational purposes. About 25 years after the change in management the area has a similar floristic richness, but it is characterized by a high turnover rate, a significant homogenization of the flora and a change in the community structure with a higher level of dominance. The removal of the pasture, which has favoured an increasing frequentation by people, seems to be the main driver of these changes. We suggest that a more active management, with the reintroduction of a sustainable grazing and a limitation of the fruition in marginal areas close to the urban matrix, could restore an higher diversity and reverse the homogenization processes detected in this study and at the same time ensure the citizen fruition. [ABSTRACT FROM AUTHOR]

Abstract Background Local floristic diversity has massively decreased during the twentieth century in Central Europe even though in the 1990s diversity began increasing again in several regions. However, little is known whether this increase is equally distributed among plant groups with different reproductive traits. Methods Our study is based on data of the Swiss Biodiversity Monitoring Program. In this program, plant species occurrence is recorded since 2001 in 450 regularly distributed 1 km2 study sites. For all 1774 plant species registered in the study, we researched data on flower/pseudanthium type and colour, reproductive system, and groups of flower visitors. We then tested whether temporal changes in species frequency were equally distributed among species with different trait states. Results Species richness and functional richness significantly increased in the study sites while functional evenness decreased. The frequency of wind-pollinated species increased more strongly than that of insect-pollinated species. Further, the frequency of species with simple, open insect-pollinated flowers and pseudanthia visited by generalist groups of insects increased slightly more strongly than the frequency of species with complex flowers visited by more specialized groups of flower visitors. Additionally, the frequency of self-compatible species increased significantly more than that of self-incompatible species. Thus, the overall increase in local plant species richness in Switzerland is mostly driven by wind- and generalist insect-pollinated, self-compatible species. In contrast, species with complex flowers, which are essential for specialized groups of flower visitors and species with self-incompatible reproductive systems profited less. Conclusions Our study thus emphasizes the need to consider functional traits in the planning and monitoring of conservation activities, and calls for a special focus on plant species with specialized reproductive traits.

A flora of the vascular plants of the Greater Mount Holyoke Range (GMHR) in Hampshire County, Massachusetts, was published in 2008. Brief, informal updates have been issued since then, but with the continued discovery of additional species, the impetus for a comprehensive update became apparent. This article reports all known changes since 2008 and discusses some of the factors contributing to these changes. The update added a net of 51 taxa to the current flora, including three new state-listed species, a county record, a species listed as historic in Massachusetts, and two taxa known from specimens but not found in the original survey. Five historical records were found. The updates came from new field collections, observations, redetermination of existing specimens, and historical records discovered subsequent to the 2008 flora. The current flora is now 878 taxa, of which 19% are considered nonnative or otherwise introduced to the GMHR. The combined current and historical flora is 918 taxa. [ABSTRACT FROM AUTHOR]

The distribution of Cypripedium macranthos and C. × ventricosum in Eastern Europe is described in the literature controversially. At the same time, Cypripedium species are legally protected plants of the highest conservational importance, and detailed knowledge about their historic and current distribution is essential for correct setting of conservation priorities. In the present article, we have assembled primary information about localities of C. macranthos and C. × ventricosum in Russia and Ukraine by referring to the original information sources, mostly to old herbaria and literature. As a result, 19 localities have been estimated as incorrect, 11 as doubtful and only 12 as reliable. Historical absence of C. macranthos and C. × ventricosum in the Republic of Chechnya, Republic of Mari El, Ulyanovsk Region and Kursk Region has been confirmed, whereas its presence in the Republic of Udmurtia, Nizhniy Novgorod Region, Vologda Region, Yaroslavl Region, Republic of Komi, and Voronezh/Lipetsk Regions is questioned. Original herbarium specimens confirming its locality in the Samara Region have been found in the herbarium. The existence of the species in Ukraine is being discussed in view of the information published by V.G. Sobko in 1989, but omitted in later publications. A sharp decrease in the number of localities has been proven. The only extant locality of C. macranthos is situated in the Republic of Chuvashia, and that of C. × ventricosum (1–4 subpopulations) in the Bryansk Region. The amount of hybridisation between C. macranthos and C. calceolus in Eastern Europe was previously underestimated. In the part of the species' distribution centered in Bryansk Region, only hybrids have been recorded since 1903. This fact determines the need for corresponding changes in floristic data and in documents which establish local plant protection.

We examined historical changes and patterns in the nonnative flora of Franklin County in western Massachusetts. The historical flora was documented by examining more than 16,000 herbarium specimens and additional records from the literature. We characterized the recent flora during 10 years of field work from 2010 to 2019. Temporal changes and distributions of nonnative species were examined at the town level. Among all species recorded in the county, nonnatives comprised 27.4%, or 34.8% if waifs and species persisting from cultivation with little spread are included. Nonnative species as a group increased dramatically over time relative to native species, and those nonnatives considered invasive increased more than other nonnative species. Reported frequencies of several species increased from 0 to 2 towns in the historical flora (1800–2009) to most of the 26 towns in the county today. The proportion of nonnative species in a town's flora was correlated with the human population density, but different regions of the county did not differ significantly in the proportion of nonnative species. Species from eastern Asia showed greater increases in frequencies than species from Eurasia and parts of North America outside New England, and the Asian species had later average arrival dates in the county. Species with bird-dispersed seeds were better represented among taxa showing the greatest increases than were species dispersed by wind or other means. Nonnative species with a history of herbal or culinary use increased much less than those with other patterns of human use, presumably reflecting less emphasis on some such species in local gardens. As a group, the agricultural weeds did not show patterns of change different from other species, perhaps reflecting the continued importance of agriculture in parts of the county. [ABSTRACT FROM AUTHOR]

We examined changes in the native vascular flora of Franklin County, Massachusetts, a largely rural county with a long history of botanical investigation. The historical flora was documented using herbarium specimens and literature records, and the current flora was assessed in 10 years of field work starting in 2010. The county contains 26 towns, and apparent changes were based on town-level presence/absence. In total, 1205 species were recorded. Apparent losses from the historical flora totaled 5.6% of species, and apparent gains totaled 4.2%. Several families exhibited greater declines than the flora as a whole, including the Orchidaceae, Ophioglossaceae, Ranunculaceae, and Violaceae. Species dependent on fungi during at least part of their life cycle declined relative to other species, but were concentrated in a small group of families, including the Orchidaceae and Ophioglossaceae. Species with fleshy fruits increased relative to those with ant-dispersed seeds. Annuals increased relative to biennials and perennials, probably due to the increasing extent of ruderal habitats. Graminoids showed greater apparent increases than forbs, which may reflect undercollecting of the former taxa during the historical period. Species changes were related to habitat, with marked increases in plants of ruderal habitats, but other apparent changes may reflect sampling biases. Northern taxa appear to be declining relative to other species, particularly in towns at lower elevations. This study is one of several that have examined floristic changes in the northeastern United States and is part of a nascent literature suggesting that climate changes have altered the southern New England flora in the past century. Additional documentation of regional floras is needed to facilitate assessments of future floristic changes. [ABSTRACT FROM AUTHOR]

There are very few long-term studies on Antarctic vegetation available, and very little is known of plant community changes over time in the Antarctic Peninsula area, an area itself subject to considerable change in recent decades. The vegetation of the South Bay area near the Spanish Station Juan Carlos I on Livingston island (South Shetland Islands) was extensively surveyed in the 1980s, and this study reports comparison of that survey with a new extensive survey carried out in the 2018/19 austral summer. A total of 38 species was found in the survey, an overall decrease in diversity, with eight previously recorded species not relocated including all representatives of the families Encalyptaceae (two species) and Hypnaceae (two species). One previously unrecorded species was found. Descriptions and discussion of each taxon recorded are provided, along with consideration of the possible causes of the changes observed. [ABSTRACT FROM AUTHOR]

Yunnan in southwestern China is renowned for its high plant diversity. To understand how this modern botanical richness formed, it is critical to investigate the past biodiversity throughout the geological time. In this review, we present a summary on plant diversity, floristics and climates in the Cenozoic of Yunnan and document their changes, by compiling published palaeobotanical sources. Our review demonstrates that thus far a total of 386 fossil species of ferns, gymnosperms and angiosperms belonging to 170 genera within 66 families have been reported from the Cenozoic, particularly the Neogene, of Yunnan. Angiosperms display the highest richness represented by 353 species grouped into 155 genera within 60 families, with Fagaceae, Fabaceae, Lauraceae and Juglandaceae being the most diversified. Most of the families and genera recorded as fossils still occur in Yunnan, but seven genera have disappeared, including Berryophyllum, Cedrelospermum, Cedrus, Palaeocarya, Podocarpium, Sequoia and Wataria. The regional extinction of these genera is commonly referred to an aridification of the dry season associated with Asian monsoon development. Floristic analyses indicate that in the late Miocene, Yunnan had three floristic regions: a northern subtropical floristic region in the northeast, a subtropical floristic region in the east, and a tropical floristic region in the southwest. In the late Pliocene, Yunnan saw two kinds of floristic regions: a subalpine floristic region in the northwest, and two subtropical floristic regions separately in the southwest and the eastern center. These floristic concepts are verified by results from our areal type analyses which suggest that in the Miocene southwestern Yunnan supported the most Pantropic elements, while in the Pliocene southwestern Yunnan had abundant Tropical Asia (Indo–Malaysia) type and East Asia and North America disjunct type that were absent from northwestern Yunnan. From the late Miocene to late Pliocene through to the present, floristic composition and vegetation types changed markedly, presumably in response to altitude changes and coeval global cooling. An integration of palaeoclimate data suggests that during the Neogene Yunnan was warmer and wetter than today. Moreover, northern Yunnan witnessed a pronounced temperature decline, while southern Yunnan experienced only moderate temperature changes. Summer precipitation was consistently higher than winter precipitation, suggesting a rainfall seasonality. This summary on palaeoclimates helps us to understand under what conditions plant diversity occurred and evolved in Yunnan throughout the Cenozoic.

Highlights • Floristic composition tends to recover to a pre-logging status after 25 years. • Shifts in floristic composition mainly driven by sharp increase in pioneer species. • Little or no change in abundance of late-successional and non-exploited species. • Forest ability to recover following low to moderate levels of disturbance (<65 m3). • Tropical forests under selective logging retain important environmental value. Abstract Selective logging is one of the most prominent land uses in tropical forests and although it involves harvesting a limited number of trees, the impact on forest structure, composition and aboveground biomass can be significant. Although these impacts are well documented, what is little known is the extent to which selective logging affects tree floristic composition and its recovery process. Understanding how floristic composition is affected by logging activities is essential for determining subsequent cutting cycles, for the maintenance of carbon stocks and for biodiversity conservation. This research investigates the effect of logging on long-term trends on the recovery of species composition in a tropical forest using a unique logging experiment where measurements have been taken annually over a period of 25 years. Changes in 12 long-term 1-hectare (ha) permanent plots were assessed where different selective logging intensities occurred. In the first years after logging, floristic composition differed widely between intact and selectively logged forests, with exploited areas deviating from pre-logged composition. Over time, exploited areas shifted towards the original composition, with more pronounced changes in this trend after ∼13 years. Shifts in floristic composition were caused mainly by a significant increase in light-demanding fast-growing pioneer species and their subsequent continuous high mortality rates after 13 years of the recovery process. In contrast, the control plots showed similar shifts in composition over time, suggesting external factors such as long-term climate changes may be driving these shifts. The results suggest that 25 years after an experimental selective logging has taken place, floristic composition tends to recover closer to the pre-logged status. Thus, in the absence of further human disturbances, experimental selectively logged forests in low to moderate intensities are compatible with biodiversity conservation, at least during the first cycle of exploitation. Reconciling conservation strategies with the recovery of stocks of commercial timber species would be greatly improved by using these results and lead towards more sustainable forest management plans. [ABSTRACT FROM AUTHOR]

Mega‐dams create highly fragmented archipelagos, affecting biodiversity and ecosystem functioning in remnant forest isolates. This study assessed the long‐term impact of dam‐induced fragmentation on insular tropical tree communities, with the aim of generating robust recommendations to mitigate some of the detrimental biodiversity impacts associated with future dam development.We inventoried adult and sapling trees across 89 permanent plots, located on 36 islands and in three mainland continuous forest sites in the Balbina Dam, Brazilian Amazon. We examined differences in recruitment, structure, and composition of sapling and adult tree communities, in relation to plot‐, patch‐ and landscape‐scale attributes including area, isolation, and fire severity.Islands harboured significantly lower sapling (mean ± 95% CI 48.6 ± 3.8) and adult (5 ± 0.2) tree densities per 0.01 ha, than nearby mainland continuous forest (saplings, 65.7 ± 7.5; adults, 5.6 ± 0.3). Insular sapling and adult tree communities were more dissimilar than in mainland sites, and species compositions showed a directional shift away from mainland forests, induced by fire severity, island area, and isolation.Insular sapling recruitment declined with increasing fire severity; tree communities with higher community‐weighted mean wood density showed the greatest recruitment declines. Our results suggest that insular tree communities are unstable, with rare species becoming extinction‐prone due to reduced tree recruitment and density on islands, potentially leading to future losses in biodiversity and ecosystem functioning across Balbina's >3,500 reservoir islands.Policy implications. In Balbina, fire and reduced habitat area and connectivity were drivers of tree community decay after only 28 years of insularization, despite strict protection provided by the ~940,000 ha Uatumã Biological Reserve. Given that many dams are planned for lowland, moderately undulating Amazonia, we recommend that dam development strategy explicitly considers (a) dam location, aiming to minimize creation of small (<10 ha) and isolated islands, (b) maintaining reservoir water levels during droughts to reduce fire risk, and (c) including aggregate island area in environmental impact and offset calculations. Ideally, we recommend that alternatives to hydropower be sought in lowland tropical regions, due to the far‐reaching biodiversity losses and ecosystem disruption caused by river impoundment. [ABSTRACT FROM AUTHOR]

Side-effects of intensification have raised public concerns. Declining diversity and abundance of wild species and pollution have been reported worldwide. National surveys are necessary to assess the overall effect on the wild flora of the changing management of arable land. We studied how the plant diversity in 40 fields in Denmark has changed over a period of 50 years. Three surveys of the vegetation and the viable soil seed banks were conducted at the same locations in Danish fields in 1964, 1989, and 2014. The same methods were used to estimate the soil seed bank in the ploug layer and to describe the corresponding vegetation in the three surveys. Soil samples were placed in trays in a greenhouse for nine months, and the plants from germinating seeds were identified. Significant changes were found in the viable soil seed bank and the vegetation. A drastic decline of plant species and seeds was observed after the first 25 years. The frequency of species and the number of seeds were reduced considerably from 1964 to 1989. In 2014, the number of seeds in the soil seed bank had increased to the same level as in 1964, whereas the frequency of the species in the vegetation was at about the same level as in 1989. The species in the vegetation deviated partly from those found in the viable soil seed bank as the number of species recorded in both assessments made up only about 50% in all surveys. Relatively few species dominated and have been able to adapt to modern cultivation practice. [ABSTRACT FROM AUTHOR]

Intensive agricultural practices can dramatically change the landscape, thereby increasing the concentrations and rates at which nutrients are delivered to aquatic ecosystems. In the United States, concerns about accelerating rates of lake eutrophication related to increases in nutrient loading require a method of quantifying ecological changes that have occurred since European settlement. Because the application of traditional quantitative total phosphorus transfer functions in paleolimnology has proven difficult in shallow, hypereutrophic lakes, we used several approaches in this study to assess ecosystem changes associated with eutrophication of 32 natural lakes in the state of Iowa, USA. In addition to traditional transfer function methods, we estimated changes in primary productivity from the flux of biogenic silica (BSi) and organic carbon accumulation rates (OC AR). Additionally, we compared pre-disturbance diatom communities to modern diatom communities, i.e. floristic change, using non-metric multi-dimensional scaling and square chord distance. OC AR and BSi fluxes increased over time and were positively correlated with the time period of agricultural intensification in the region (post-1940). Ninety-one percent of the lakes in this study showed evidence for eutrophication based on geochemical proxies, and 88 % of lakes showed major floristic change in the diatom community. Whereas geochemical indicators showed consistent increases in productivity across most lakes, floristic changes reflected more complex interactions between other environmental drivers. The magnitude of floristic change did not directly correlate to nutrient-driven increases in primary production, but was driven by ecological diatom assembly related to lake depth. Transfer functions consistently perform poorly, especially for shallow lakes, and other techniques that combine geochemistry and diatom ecology are recommended for reconstructions of eutrophication. [ABSTRACT FROM AUTHOR]

The influence of substrate lithology on the distribution of many vascular and nonvascular plants has long been recognized, especially in alpine, subalpine, and other rocky habitats. In particular, plants have been classified as dependent on high-calcium substrates (i.e., calcicoles) based on common restriction to habitats developed in calcareous rocks, such as limestone and marble. In a classic 1907 paper on the influence of substrate on plants, M. L. Fernald singled out a particular meadow on Mont de la Table in the Chic-Choc Mountains of Québec for its unusual co-occurrence of strict calcicole and calcifuge (i.e., acidophile) plant taxa. We re-located this site, investigated substrate factors responsible for its unusual plant diversity, and documented current plant distributions. No calcareous rocks were found on site. However, inclusions of calcareous rocks were found farther up the mountain. The highest pH and dissolved calcium concentrations in surface waters were found in a series of springs that deliver groundwater, presumably influenced by calcareous rocks up the slope. Within the habitat delineated by common occurrences of calcicole species, available soil calcium varied by a factor of five and soil pH varied by almost 1.5 units, depending on microtopography and relative connection with groundwater. Variation in hydrologic delivery of weathering products leads to large variation in chemical composition of soils and waters within calcareous-influenced habitats. Here, the fine-scale variability of habitat, rather than plasticity in the plants' tolerances, appeared to be responsible for co-occurrence of taxa considered to be strict calcicoles or calcifuges. The flora in 2005-2008 was very similar to what it was in 1906, although in-filling of woody vegetation and strong chemical gradients driven by climatically controlled hydrologic processes suggest the possibility of future vegetation changes with continued climate change. [ABSTRACT FROM AUTHOR]

Question How did frequency and local abundance of key bryophytes in Dutch fens change between 1940 and 2000? Location The Netherlands. Methods A total of 1939 vegetation relevés, objectively assigned to the class Parvocaricetea and dating from the period 1940-1999 inclusive, were extracted from a national Netherlands database. From this relevé set, two additional data sets were derived; these were syntaxonomically homogeneous at the association level. One contained 418 Scorpidio-Caricetum diandrae relevés and the other 956 Pallavicinio-Sphagnetum relevés. The following analyses were done for these three data sets: frequency and local abundance change of 13 bryophyte species over three 20-yr periods were described using logistic regression and the nonparametric Jonckheere-Terpstra test, respectively. Results Acidophytic, late-successional species, notably Sphagnum palustre and Polytrichum uliginosum, have replaced relatively early-successional species such as brown mosses, Sphagnum subnitens and Sphagnum squarrosum during the studied period. The results were mostly consistent across the three data sets. Local abundance patterns generally paralleled those of frequency, although cover trends were often less robust. Conclusions Drastic changes have taken place in the bryophyte layer of Dutch fens between 1940 and 2000. Our study has shown that acidophytic, late-successional bryophytes have replaced relatively early-successional brown moss and Sphagnum species. Both hydrological changes and nutrient shifts (in particular phosphorus enrichment and ammonium toxicity) appear to have been responsible for the observed rapid shifts in the bryophyte layer of Dutch fens. [ABSTRACT FROM AUTHOR]

Premise of the study: The fossil record provides information about the long-term response of plants to CO2-induced climate change. The Paleocene-Eocene Thermal Maximum (PETM), a 200000-yr-long period of rapid carbon release and warming that occurred ~56 million years ago, is analogous to future anthropogenic global warming. Methods: We collected plant macrofossils in the Bighorn Basin, Wyoming, United States, from a period spanning the PETM and studied changes in floristic composition. We also compiled and summarized published records of floristic change during the PETM. Key results: There was radical floristic change in the Bighorn Basin during the PETM reflecting local or regional extirpation of mesophytic plants, notably conifers, and colonization of the area by thermophilie and dry-tolerant species, especially Fabaceae. This floristic change largely reversed itself as the PETM ended, though some immigrant species persisted and some Paleocene species never returned. Less detailed records from other parts of the world show regional variation in floristic response, but are mostly consistent with the Bighorn Basin trends. Conclusions: Despite geologically rapid extirpation, colonization, and recolonization, we detected little extinction during the PETM, suggesting the rate of climate change did not exceed the dispersal capacity of terrestrial plants. Extrapolating the response of plants from the PETM to future anthropogenic climate change likely underestimates risk because rates of climate change during the PETM may have been an order of magnitude slower than current rates of change and because the abundant, widespread species common as fossils are likely resistant to extinction. [ABSTRACT FROM AUTHOR]

Aim The aim of this work was to identify the main changes in the flora and vegetation of the Iberian Peninsula over the Cenozoic Era, to record the disappearance of taxa associated with these changes and to determine the influence of climate and human activity on these events. Location The Iberian Peninsula and Balearic Islands. Methods A critical review was made of the palaeobotanical literature with the aims of detecting patterns of floristic change and extracting information on the disappearance of different taxa over the Cenozoic. These data are viewed alongside the most recent data for the climate of this period. A critical analysis is made of the role of Palaeotropical and Arctotertiary taxa in the forest communities of the Iberian Peninsula throughout the Cenozoic. Results Although the Eocene–Oligocene transition was a time when many taxa disappeared, the most outstanding events occurred between the end of the Oligocene and throughout the Miocene. Substantial floristic changes took place over this period, including the disappearance of 177 Palaeotropical taxa. This was probably related to acute cooling and aridification; no evidence exists that the Messinian Salinity Crisis had any important effect in the Iberian Peninsula. The last great disappearance of Palaeotropical taxa (36 in total) ended in the Middle–Late Piacenzian; Arctotertiary taxa were most affected during the Pleistocene. The Lower–Middle Pleistocene transition, best represented by marine isotopic stages (MIS) 36–34 and 20–18 and characterized by a change in glacial cyclicity, was the time of the last notable disappearance of taxa. Main conclusions This work provides the first chronogram of extinctions for the Iberian flora, and records the disappearance of 277 taxa during the Cenozoic. A clear relationship was detected between the main climatic events and the latest appearances of the different taxa. [ABSTRACT FROM AUTHOR]

This study was conducted in the Chiapas Highlands, a tropical mountain region where traditional agricultural practices have resulted in a mosaic landscape of forest fragments embedded in a matrix of secondary vegetation and crop fields. The question addressed was how may woody species richness be affected by forest fragment attributes derived from traditional laud-use patterus. Species inventories of total woody species, canopy and understorey trees, and shrubs were obtained in 22 forest fragments (⩾ 5 ha). Multiple regression analyses were applied to examine the effects of size, matrix, isolation and shape of the forest fragments on richness of these species guilds. Fragment size was cor- related with shape (r = 0.75) and isolation (r = -0.69), and isolation was correlated with shape (r = -0.75). Total species richness, and number of shrubs and understorey trees in fragments were related to isolation; moreover, additive effects of fragment shape were found for shrubs. The number of canopy species was not related to any fragment variable. Matrix did not help to explain species richness, possibly due to the landscape structure created by the traditional land-use patterns. In addition to size and isolation, we point out the need of considering shape and matrix as additional fragmentation attributes, along with social and economic factors, if we are ever going to be successful in our management and conservation actions. [ABSTRACT FROM AUTHOR]

Upward migration of plant species due to climate change has become evident in several European mountain ranges. It is still, however, unclear whether certain plant traits increase the probability that a species will colonize mountain summits or vanish, and whether these traits differ with elevation. Here, we used data from a repeat survey of the occurrence of plant species on 120 summits, ranging from 2449 to 3418 m asl, in south-eastern Switzerland to identify plant traits that increase the probability of colonization or extinction in the 20th century. Species numbers increased across all plant traits considered. With some traits, however, numbers increased proportionally more. The most successful colonizers seemed to prefer warmer temperatures and well-developed soils. They produced achene fruits and/or seeds with pappus appendages. Conversely, cushion plants and species with capsule fruits were less efficient as colonizers. Observed changes in traits along the elevation gradient mainly corresponded to the natural distribution of traits. Extinctions did not seem to be clearly related to any trait. Our study showed that plant traits varied along both temporal and elevational gradients. While seeds with pappus seemed to be advantageous for colonization, most of the trait changes also mirrored previous gradients of traits along elevation and hence illustrated the general upward migration of plant species. An understanding of the trait characteristics of colonizing species is crucial for predicting future changes in mountain vegetation under climate change.

1. Experiments were carried out at three sites in southern Scotland to determine the suitability of Molina grassland for sustained use in providing summer grazing for cattle, and to investigate grazing control as a tool to manipulate the species composition of hill pastures in Britain. 2. Cutting experiments showed that frequency and severity of defoliation were more important than timing in their effects on Molinia. Weights of clippings declined in successive years only in response to treatments that involved repeated within-season cutting. 3. Three years of repeated light defoliation (33% lamina length removed each June, July and August), compared with uncut controls, reduced leaf production in a fourth uninterrupted growing season by 40%, while repeated heavy defoliation (66% lamina removal) reduced it by 78%. Reductions in both the numbers and the size of tillers contributed to this result. Single annual cuts only reduced leaf production at 66% lamina removal when they took place late in the season. 4. Plots grazed by cattle at two sites for 6 years compared treatments where 66% rather than 33% of the herbage was removed by grazing. The rates of leaf extension in Molinia were reduced at the higher level of use. In comparison with areas protected from grazing during the final year of treatment only, the biomass of Molinia and other grasses in areas open to grazing showed that the taller Molinia was utilized to a much greater extent than the other grasses. After 6 years of grazing,t he biomass of Molinia at 33% utilization was reduced by 46–65% compared with ungrazed exclosures, while at 66% utilization it was reduced by 86%. 5. Basal internode size was greatly reduced in the grazed plots compared with the ungrazed exclosures, with effects on tiller base size being more important than variation in concentrations in determining amounts of starch, total water soluble carbohydrates, N, P and K on a per tiller basis. Site × management interactions for concentrations could be interpreted in terms of variations in stage of maturity, potential for growth and plant/animal nutrient cycling pathways. 6. Floristic diversity was increased and that of other broad-leaved grasses increased by grazing. At 33% utilization, the cover of Molinia appeared to be leveling off (at around 60–65% after 3–5 years) while at 66% utilization a continued downward trend was evident. Species trends were also influenced by site factors, with exclusion of grazing leading to a reduced cover of Festuca ovina only where conditions were favourable for high yields of taller grasses. 7. The responses of Molinia to defoliation are discussed in relation to its pattern of growth and low rate of leaf and tiller turnover and to its responses to soil and climatic factors. The effects of grazing on nutrient cycling and sward canopy structure, in influencing competitive relationships with other species, are considered and the wider issues relevant to management protocols are outlined. [ABSTRACT FROM AUTHOR]

Yunnan in southwestern China is renowned for its high plant diversity. To understand how this modern botanical richness formed, it is critical to investigate the past biodiversity throughout the geological time. In this review, we present a summary on plant diversity, floristics and climates in the Cenozoic of Yunnan and document their changes, by compiling published palaeobotanical sources. Our review demonstrates that thus far a total of 386 fossil species of ferns, gymnosperms and angiosperms belonging to 170 genera within 66 families have been reported from the Cenozoic, particularly the Neogene, of Yunnan. Angiosperms display the highest richness represented by 353 species grouped into 155 genera within 60 families, with Fagaceae, Fabaceae, Lauraceae and Juglandaceae being the most diversified. Most of the families and genera recorded as fossils still occur in Yunnan, but seven genera have disappeared, including Berryophyllum , Cedrelospermum , Cedrus , Palaeocarya , Podocarpium , Sequoia and Wataria . The regional extinction of these genera is commonly referred to an aridification of the dry season associated with Asian monsoon development. Floristic analyses indicate that in the late Miocene, Yunnan had three floristic regions: a northern subtropical floristic region in the northeast, a subtropical floristic region in the east, and a tropical floristic region in the southwest. In the late Pliocene, Yunnan saw two kinds of floristic regions: a subalpine floristic region in the northwest, and two subtropical floristic regions separately in the southwest and the eastern center. These floristic concepts are verified by results from our areal type analyses which suggest that in the Miocene southwestern Yunnan supported the most Pantropic elements, while in the Pliocene southwestern Yunnan had abundant Tropical Asia (Indo-Malaysia) type and East Asia and North America disjunct type that were absent from northwestern Yunnan. From the late Miocene to late Pliocene through to the present, floristic composition and vegetation types changed markedly, presumably in response to altitude changes and coeval global cooling. An integration of palaeoclimate data suggests that during the Neogene Yunnan was warmer and wetter than today. Moreover, northern Yunnan witnessed a pronounced temperature decline, while southern Yunnan experienced only moderate temperature changes. Summer precipitation was consistently higher than winter precipitation, suggesting a rainfall seasonality. This summary on palaeoclimates helps us to understand under what conditions plant diversity occurred and evolved in Yunnan throughout the Cenozoic.