Earth's Vegetation Research Articles

Distribution of Xylotrophic Macromycetes in Recreational Forests

Changes in soil properties under the influence of recreational use of natural forests are observed at considerable depths and can be significant for the entire biogeocenosis. These changes have a significant impact on the earth's vegetation, soil fauna and mycocenosis, disturbing the habitat of creatures here. Therefore, using indicators of biological properties of soils as a criterion of the degree of recreational degradation of soils, it is expedient to study its regularities, to study the recreational stability of biogeocenoses, to determine the possibilities and terms of restoration of areas disturbed from the point of view of recreation. The forest community is a self-regulating "organism", including both autotrophs, generating and maintaining biomass, and various heterotrophs, breaking it down. It was found that the balance of biomass produced by autotrophs and decomposing heterotrophs is crucial for the sustainability of forest communities. Xylotrophic basidiomycetes are an integral component affecting the sustainability and productivity of forest ecosystems. Xylotrophs break down woody debris and other wastes, ensuring the sustainability of the whole process. This group of organisms is very sensitive to climate change and anthropogenic factors. Therefore, the numerical composition and species diversity of xylotrophic fungi can be used as an indicator of recreational impact. Thus, intensive and long-term anthropogenic impact on forests of natural areas has led to degradation of mycobiota. As a result, species richness and diversity have been significantly reduced, generative and competitive activity has been extremely weakened. In the mountain and plain forests of Talysh, where we conducted our research, the species diversity of fungi differed in species and abundance in different biotopes.

USLE modelling of soil loss in a Brazilian cerrado catchment

Soil is a fundamental resource that supports much of the Earth's vegetation cover and is indispensable for societies. However, the types of use, changes in cover and inadequate management can cause erosion, with negative results for the economy, for the quality of life of the populations and for an ecologically balanced development. This study aimed to evaluate soil erosion in the Verdinho River Basin, located in Southwestern Goiás, in the Brazilian Cerrado, using geotechnology products and tools, in order to provide qualitative and quantitative results to support the planning and management of the river basin effectively and efficiently. The study uses Universal Soil Loss Equation (USLE) as a modelling tool. The study area is characterized by high rainfall erosivity, medium soil erodability. Potential erosion ranged from weak to very strong. The results on the integration of natural physical aspects with land use (anthropic action) resulted in soil loss corresponding to the category from slight (0–2.5 t ha−1.year−1) to extremely high (>100 t ha−1.year−1). The highest soil losses are observed in the areas of cultivated land, pasture and exposed soil associated with environments with greater natural potential for erosive processes. Inter-rill, rill erosion, as well as inter rill, rill and gully are the recognized soil erosion types gully erosion were observed, indicating which areas in the river basin are exposed to risk of soil erosion at severe level and the need to implement actions of recovery of degraded areas, as well as appropriate soil management and conservation practices.

Slowdown of the greening trend in natural vegetation with further rise in atmospheric CO<sub>2</sub>

Abstract. Satellite data reveal widespread changes in Earth's vegetation cover. Regions intensively attended to by humans are mostly greening due to land management. Natural vegetation, on the other hand, is exhibiting patterns of both greening and browning in all continents. Factors linked to anthropogenic carbon emissions, such as CO2 fertilization, climate change, and consequent disturbances such as fires and droughts, are hypothesized to be key drivers of changes in natural vegetation. A rigorous regional attribution at the biome level that can be scaled to a global picture of what is behind the observed changes is currently lacking. Here we analyze different datasets of decades-long satellite observations of global leaf area index (LAI, 1981–2017) as well as other proxies for vegetation changes and identify several clusters of significant long-term changes. Using process-based model simulations (Earth system and land surface models), we disentangle the effects of anthropogenic carbon emissions on LAI in a probabilistic setting applying causal counterfactual theory. The analysis prominently indicates the effects of climate change on many biomes – warming in northern ecosystems (greening) and rainfall anomalies in tropical biomes (browning). The probabilistic attribution method clearly identifies the CO2 fertilization effect as the dominant driver in only two biomes, the temperate forests and cool grasslands, challenging the view of a dominant global-scale effect. Altogether, our analysis reveals a slowing down of greening and strengthening of browning trends, particularly in the last 2 decades. Most models substantially underestimate the emerging vegetation browning, especially in the tropical rainforests. Leaf area loss in these productive ecosystems could be an early indicator of a slowdown in the terrestrial carbon sink. Models need to account for this effect to realize plausible climate projections of the 21st century.

Long-term, medium spatial resolution annual land surface phenology with a Bayesian hierarchical model

Land surface phenology (LSP) is a consistent and sensitive indicator of climate change effects on Earth's vegetation. Existing methods of estimating LSP require time series densities that, until recently, have only been available from coarse spatial resolution imagery such as MODIS (500 m) and AVHRR (1 km). LSP products from these datasets have improved our understanding of phenological change at the global scale, especially over the MODIS era (2001-present). Nevertheless, these products may obscure important finer scale spatial patterns and longer-term changes. Therefore, we have developed a Bayesian hierarchical model to retrieve complete annual sequences of LSP from Landsat imagery (1984-present), which has medium spatial resolution (30 m) but relatively sparse temporal frequency. Our approach uses Markov Chain Monte Carlo (MCMC) sampling to quantify individual phenometric uncertainty, which is especially important when considering long time series with variable observation quality and density, but has rarely been demonstrated. The estimated spring LSP had strong agreement with ground phenology records at Harvard Forest (R2 = 0.87) and Hubbard Brook Experimental Forest (R2 = 0.67). The estimated LSP were consistent with the recently released 30 m LSP product, MSLSP30NA, in its time period of 2016 to 2018 (R2 of 0.86 and 0.73 for spring and autumn phenology, respectively). Our Bayesian hierarchical model is an important step forward in extending medium resolution LSP records back in time as it accomplishes both critical goals of retrieving annual LSP from sparse time series and accurately estimating uncertainty.

A trait‐based approach to assessing resistance and resilience to wildfire in two iconic North American conifers

Abstract Ongoing changes in fire regimes have the potential to drive widespread shifts in Earth's vegetation. Plant traits and vital rates provide insight into vulnerability to fire‐driven vegetation shifts because they can be indicators of the ability of individuals to survive fire (resistance) and populations to persist (resilience) following fire. In 15 study sites spanning climatic gradients in the southern Rocky Mountains, USA, we quantified variation in key traits and vital rates of two co‐occurring, widely distributed conifers (Pinus ponderosa Douglas ex. P. Lawson & C. Lawson and Pseudotsuga menziesii (Mirb.) Franco). We used mixed‐effects models to explain inter‐ and intraspecific variation in tree growth, survival, bark thickness and seed cone production, as a function of species, tree life stage (i.e. diameter, height and age), average climate, local competition and site conditions. Pinus ponderosa was predicted to survive low‐severity fire at a 23% earlier age than P. menziesii. Pinus ponderosa had thicker bark and more rapid juvenile height growth, traits conferring greater fire resistance. In contrast, P. menziesii was predicted to produce seed cones at a 28% earlier age than P. ponderosa. For both species, larger individuals were more likely to survive fire and to produce cones. For P. ponderosa, cone production increased where average actual evapotranspiration (AET) was higher and local competition was lower. More frequent cone production on productive sites with higher AET is an important and underappreciated mechanism that may help to explain greater resilience to fire in these areas. Synthesis. Our analyses indicated that many plant traits and vital rates related to fire differed between Pinus ponderosa and Pseudotsuga menziesii, with trade‐offs between investment in traits that promote individual defence to fire and those that promote recolonization of disturbed sites. Future changes in fire regimes will act as a filter throughout North American forests, with our findings helping to infer which individuals and populations of two iconic species are most vulnerable to future change and offering a framework for future inquiry in other forests facing an uncertain future.

La piel humana en la narrativa corta tradicional

Como atributo del ser humano, la piel es polivalente; da origen a creencias acerca de la inmortalidad, del temperamento del sujeto y de la invulnerabilidad del guerrero. Son estas creencias a su vez fuente de relatos tradicionales. La percepción de la vegetación y de la piel de los reptiles cada año renovadas es sugestiva para el narrador primitivo: el macrocosmos también tendrá su piel. De todo esto resulta un amplio abanico de cuentos y leyendas, ya faceciosos, ya ilustrativos de potencias demoníacas.

Normalized difference vegetation change index: A technique for detecting vegetation changes using Landsat imagery

Vegetation indices have been developed to characterize and extract the Earth's vegetation cover from space using satellite images. For detection of vegetation changes, temporal images are usually independently analyzed or vegetation index differencing is implemented. In this study, a vegetation change index, named normalized difference vegetation change index (NDVCI), was developed to directly detect vegetation changes between two different time images with improved accuracy. The effectiveness of the proposed method to detect vegetation changes was evaluated in comparison with that of enhanced vegetation index (EVI) differencing and normalized difference vegetation index (NDVI) differencing methods at seven test sites under different environmental conditions in Iran, Malaysia, and Italy. Landsat imagery as one of the most widely used sources of data in remote sensing was used for this purpose. Overall accuracy, kappa coefficient, and omission and commission errors were calculated to assess the accuracy of the resulting change maps. The results demonstrated superiority and higher performance of NDVCI compared to EVI and NDVI differencing for detection of vegetation changes. In five out of the seven test sites, the classification accuracy of NDVCI was higher compared to that of the other methods. In contrast, the results revealed lower accuracy of EVI differencing for vegetation change detection at all the test sites, while NDVI differencing was superior at two of the test sites. In conclusion, the study demonstrated great performance of NDVCI for monitoring vegetation changes at different environmental conditions. Accordingly, this technique may improve the vegetation change detection in future studies.

Comparison of Small- and Large-Footprint Lidar Characterization of Tropical Forest Aboveground Structure and Biomass: A Case Study From Central Gabon

NASA's Global Ecosystem Dynamic Investigation (GEDI) mission has been designed to measure forest structure using lidar waveforms to sample the earth's vegetation while in orbit aboard the International Space Station. In this paper, we used airborne large-footprint (LF) lidar measurements to simulate GEDI observations from which we retrieved ground elevation, vegetation height, and aboveground biomass (AGB). GEDI-like product accuracy was then assessed by comparing them to similar products derived from airborne small-footprint (SF) lidar measurements. The study focused on tropical forests and used data collected during the NASA and European Space Agency (ESA) AfriSAR ground and airborne campaigns in the Lope National Park in Central Gabon. The measurements covered a gradient of successional stages of forest development with different height, canopy density, and topography. The comparison of the two sensors shows that LF lidar waveforms and simulated waveforms from SF lidar are equivalent in their ability to estimate ground elevation (RMSE = 0.5 m, bias = 0.29 m) and maximum forest height (RMSE = 2.99 m, bias = 0.24 m) over the study area. The difference in the AGB estimated from both lidar instruments at the 1-ha spatial scale is small over the entire study area (RMSE = 6.34 Mg·ha −1, bias = 11.27 Mg·ha−1) and the bias is attributed to the impact of ground slopes greater than 10–20° on the LF lidar measurements of forest height. Our results support the ability of GEDILF lidar to measure the complex structure of humid tropical forests and provide AGB estimates comparable to SF-derived ones.

Lasers, penguins, and polar bears: Novel outreach and education approaches for NASA's ICESat-2 mission

NASA's Ice, Cloud, and land Elevation Satellite (ICESat-2), to be launched in 2018, will measure the height of Earth from space using lasers, collecting the most precise and detailed account yet of our planet's elevation. The mission will allow scientists to investigate how global warming is changing the planet's icy polar regions and to take stock of Earth's vegetation. ICESat-2's emphasis on polar ice, as well as its unique measurement approach, will provide an intriguing and accessible focus for the mission's education and outreach programs. Sea ice and land ice are areas that have experienced significant change in recent years. It is key to communicate why we are measuring these areas and their importance. ICESat-2 science data will provide much-needed answers to climate change questions such as, “Is the ice really melting in the polar regions?” and “What does studying Earth's frozen regions tell us about our changing climate?” In this paper, lessons-learned and novel techniques for engaging and educating all audiences in the mission will be discussed, such as including results of a unique collaboration with art design school the Savannah College of Art Design (SCAD) to create fun and exciting products such as animated characters and interactive stories. Future collaborations with wildlife researchers, a new citizen science program in collaboration with GLOBE, and evidence from other STEAM (Science, Technology, Engineering, Arts, Math) education approaches will also be detailed in this paper.

Mapping of forest alliances with simulated multi-seasonal hyperspectral satellite imagery

A consistent and hierarchical classification of vegetation, such as the U.S. National Vegetation Classification (NVC) system, supports comprehensive conservation and management of natural ecosystems. At a detailed level, the NVC alliance is defined by diagnostic species and composition. Maps at this level of classification are often produced at local to regional scales (areas <25,000 km2) with costly manual to semi-automated interpretation of high resolution imagery. The main objective of this study was to assess the effectiveness of machine learning for automated, per-pixel (30 m) mapping of forest alliances with multi-seasonal hyperspectral imagery from a future satellite mission (HyspIRI), as simulated from Airborne Visible/Infrared Imaging Spectrometer Classic (AVIRIS-C) data. The study area was the San Francisco (S.F.) Bay Area, California, where we mapped forest alliances at regional and county scales. We implemented the Support Vector Machine (SVM) classifier in a two-stage approach, first mapping regional land cover followed by forest alliances in closed-canopy tree pixels. Predictor variables were reflectance bands and hyperspectral metrics based on indices, derivatives and absorption-fitting techniques applied to reflectance spectra, with data grouped into summer and three-season (spring, summer, fall) sets. For forest alliances, hyperspectral metrics improved overall accuracy of classifications by 2.9 to 6.4% relative to classifications based on the original reflectance bands. Multi-seasonal data improved overall accuracy by 1.3 to 6.2% relative to summer-only data. Using multi-seasonal metrics, the S.F. Bay Area regional classification with 21 alliances had an overall accuracy of 65.7% (Kappa 0.63), while the Sonoma County classification with 16 alliances had an accuracy of 75.9% (Kappa 0.72). Most forest alliances had internal variation in lifeform, species and structural properties that increased within-class spectral-temporal variation and complicated discrimination. Despite this challenge, classification accuracies were similar to regional NVC alliance reference data. We conclude that a hyperspectral satellite, with its repeat and global image acquisitions, has strong potential for accurate and economical mapping and monitoring the Earth's vegetation communities.

Peatlands and Global Change: Response and Resilience

Peatlands are wetland ecosystems that accumulate dead organic matter (i.e., peat) when plant litter production outpaces peat decay, usually under conditions of frequent or continuous waterlogging. Collectively, global peatlands store vast amounts of carbon (C), equaling if not exceeding the amount of C in the Earth's vegetation; they also encompass a remarkable diversity of forms, from the frozen palsa mires of the northern subarctic to the lush swamp forests of the tropics, each with their own characteristic range of fauna and flora. In this review we explain what peatlands are, how they form, and the contribution that peatland science can make to our understanding of global change. We explore the variety in formation, shape, vegetation type, and chemistry of peatlands across the globe and stress the fundamental features that are common to all peat-forming ecosystems. We consider the impacts that past, present, and future environmental changes, including anthropogenic disturbances, have had and will have on peatland systems, particularly in terms of their important roles in C storage and the provision of ecosystem services. The most widespread uses of peatlands today are for forestry and agriculture, both of which require drainage that results in globally significant emissions of carbon dioxide (CO2), a greenhouse gas (GHG). Climatic drying and drainage also increase the risk of peat fires, which are a further source of GHG emissions [CO2 and methane (CH4)] to the atmosphere, as well as causing negative human health and socioeconomic impacts. We conclude our review by explaining the roles that paleoecological, experimental, and modeling studies can play in allowing us to build a more secure understanding of how peatlands function, how they will respond to future climate- and land-management-related disturbances, and how best we can improve their resilience in a changing world.

Modeling plant–water interactions: an ecohydrological overview from the cell to the global scale

Vegetation and the water cycles are inherently coupled across a wide range of spatial and temporal scales. Water availability interacts with plant ecophysiology and controls vegetation functioning. Concurrently, vegetation has direct and indirect effects on energy, water, carbon, and nutrient cycles. To better understand and model plant–water interactions, highly interdisciplinary approaches are required. We present an overview of the main processes and relevant interactions between water and plants across a range of spatial scales, from the cell level of leaves, where stomatal controls occur, to drought stress at the level of a single tree, to the integrating scales of a watershed, region, and the globe. A review of process representations in models at different scales is presented. More specifically, three main model families are identified: (1) models of plant hydraulics that mechanistically simulate stomatal controls and/or water transport at the tree level; (2) ecohydrological models that simulate plot‐ to catchment‐scale water, energy, and carbon fluxes; and (3) terrestrial biosphere models that simulate carbon, water, and nutrient dynamics at the regional and global scales and address feedback between Earth's vegetation and the climate system. We identify special features and similarities across the model families. Examples of where plant–water interactions are especially important and have led to key scientific findings are also highlighted. Finally, we discuss the various data sources that are currently available to force and validate existing models, and we present perspectives on the evolution of the field. WIREs Water 2016, 3:327–368. doi: 10.1002/wat2.1125This article is categorized under: Water and Life &gt; Nature of Freshwater Ecosystems Science of Water &gt; Hydrological Processes

Human impacts drive a global topographic signature in tree cover

The Anthropocene is a geological epoch marked by major human influences on processes in the atmosphere, biosphere, hydrosphere and geosphere. One of the most dramatic features of the Anthropocene is the massive alteration of the Earth's vegetation, including forests. Here we investigate the role of topography in shaping human impacts on tree cover from local to global scales. We show that human impacts have resulted in a global tendency for tree cover to be constrained to sloped terrain and losses to be concentrated on flat terrain. This effect increases in strength with increasing human pressure and is most pronounced in countries with rapidly growing economies, limited human population stress and highly effective governments. These patterns likely reflect the relative inaccessibility of sloped topography and have important implications for conservation and modelling of future tree cover.

Global change and the terrestrial biosphere: achievements and challenges

Preface. 1 Climatic change: ecology's big question. 1.1 Early environmental biogeography: from mapping plant species distributions to mapping vegetation. 1.2 Global distributions of vegetation. 1.3 Formation or biome interactions with climate. 1.4 Concluding comments. References and notes. 2 The kaleidoscope of past vegetation patterns. 2.1 Vegetation in past climates: Quaternary palaeoecology. 2.2 Challenges for environmental change studies from Quaternary palaeoecology. 2.3 Concluding comments. References and notes. 3 The complication of time and space scales. 3.1 The ecosystem concept and scale. 3.2 Scale and the global dynamics of carbon. 3.3 Formulation of ecological models. 3.4 Interactive mosaic models. 3.5 Concluding comments. References and notes. 4 Meeting the climate change challenge. 4.1 Historical roots of the 'greenhouse warming' concept. 4.2 Climate and vegetation: the challenge of prediction. 4.3 What is the signifi cance of global climate change on Earth's vegetation? 4.4 Mosaic landscape models. 4.5 Homogeneous landscape models and climate change. 4.6 Interactive global mosaic models. 4.7 Concluding comments. References and notes. 5 Dynamic vegetation modelling using individual-based models. 5.1 Gap models: structure and model development. 5.2 History of gap model development. 5.3 Global climate change assessment applications of gap models. 5.4 Theoretical implications for global change ecology from gap models. 5.5 Concluding comments. References and notes. 6 Vegetation futures and the rise of dynamic global vegetation models. 6.1 Including the effects of land surface attributes and dynamics in climate models. 6.2 Dynamic global vegetation models. 6.3 The development of dynamic global vegetation models. 6.4 Investigating differences in dynamic global vegetation model simulations. 6.5 Vegetation feedbacks on climate. 6.6 Observations of recent vegetation change. 6.7 Concluding comments. References and notes. 7 Climate-changed futures - how different will they be? 7.1 The future view from the Intergovernmental Panel on Climate Change. 7.2 Carrying on from where the world was before now. 7.3 Carrying on from where the world is now. 7.4 Future realizations. 7.5 Concluding considerations. References and notes. 8 Climate change and global plant diversity. 8.1 Making future predictions of diversity. 8.2 Getting at the mechanisms that control species diversity. 8.3 Simulating the impact of changing climate and CO2 on future diversity. 8.4 The naturalization of invasive species. 8.5 Concluding remarks. References and notes. 9 Epilogue. References and notes. Index.

Danger of Deploying Weapons and Nuclear Power in Space

Danger of Deploying Weapons and Nuclear Power in Space

A mid-Cretaceous flora from the Kachaike Formation, Patagonia, Argentina

An overview of a new mid-Cretaceous flora from Bajo Comisión, southern Patagonia, is presented. The flora was collected from previously studied deposits of the late Albian–Cenomanian Kachaike Formation in Santa Cruz Province, Argentina. The fossil assemblage consists of about 20 species mostly of pteridophytes, pteridosperms and conifers but it also includes fronds of uncertain affinity. Bryophytes, bennettites and ginkgophytes are subordinate components. The presence of angiosperm leaves is noteworthy. This flora is from a critical time interval between the earliest Cretaceous assemblages of the Springhill Formation and Baqueró Group and the younger Late Cretaceous assemblage of the Mata Amarilla Formation in southern South America. During this period of time, profound changes were taking place in the Earth's vegetation with the radiation and diversification of angiosperms. Comparisons with other Jurassic and Cretaceous assemblages indicate links with southern and eastern Gondwanan floras. Among them, the flora of the Triton Point Formation of Alexander Island (Antarctica) is most similar to that of the Kachaike Formation. Both share the presence of Athrotaxis ungeri (= Athrotaxites ungeri), taxa at generic level including Phyllopteroides, Aculea, Ptilophyllum and Ginkgoites, a similar matoniaceous species, and a relatively diverse angiosperm record.

Pollen and spores: Microscopic keys to understanding the earth's biodiversity

The most distinctive feature of planet Earth is that, unlike any other world in this solar system, it is rich in biodiversity. Our own species, which evolved as part of the biosphere that sustains us, has the intelligence and curiosity to explore the world around us and to understand its complexity. Given the environmental challenges that lie ahead we have much to learn by exploring all aspects of biodiversity. One astonishingly informative field of investigation is palynology, the study of the pollen grains and spores of plants. These microscopic, self-contained biological units are surrounded by chemically resistant cell walls with distinctive structures and symmetry. They can provide insights into such fundamental questions as how and when plants first colonised the land or how the earth's vegetation has developed through geological time and on finer time scales. They provide phylogenetic evidence important in plant systematics and model systems for understanding plant development at the cellular level. This short voyage through the microscopic world of pollen grains and spores is a personal account of the interest and importance of these microscopic keys to understanding the earth's biodiversity.

Vegetation's Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants

Earth's deciduous plants have a sharp order-of-magnitude increase in leaf reflectance between approximately 700 and 750 nm wavelength. This strong reflectance of Earth's vegetation suggests that surface biosignatures with sharp spectral features might be detectable in the spectrum of scattered light from a spatially unresolved extrasolar terrestrial planet. We assess the potential of Earth's step-function-like spectroscopic feature, referred to as the "red edge," as a tool for astrobiology. We review the basic characteristics and physical origin of the red edge and summarize its use in astronomy: early spectroscopic efforts to search for vegetation on Mars and recent reports of detection of the red edge in the spectrum of Earthshine (i.e., the spatially integrated scattered light spectrum of Earth). We present Earthshine observations from Apache Point Observatory (New Mexico) to emphasize that time variability is key to detecting weak surface biosignatures such as the vegetation red edge. We briefly discuss the evolutionary advantages of vegetation's red edge reflectance, and speculate that while extraterrestrial "light-harvesting organisms" have no compelling reason to display the exact same red edge feature as terrestrial vegetation, they might have similar spectroscopic features at different wavelengths than terrestrial vegetation. This implies that future terrestrial-planet-characterizing space missions should obtain data that allow time-varying, sharp spectral features at unknown wavelengths to be identified. We caution that some mineral reflectance edges are similar in slope and strength to vegetation's red edge (albeit at different wavelengths); if an extrasolar planet reflectance edge is detected care must be taken with its interpretation.

Terrestrial vegetation and water balance—hydrological evaluation of a dynamic global vegetation model

Earth's vegetation plays a pivotal role in the global water balance. Hence, there is a need to model dynamic interactions and feedbacks between the terrestrial biosphere and the water cycle. Here, the hydrological performance of the Lund–Potsdam–Jena model (LPJ), a prominent dynamic global vegetation model, is evaluated. Models of this type simulate the coupled terrestrial carbon and water cycle, thus they are well suited for investigating biosphere–hydrosphere interactions over large domains. We demonstrate that runoff and evapotranspiration computed by LPJ agree well with respective results from state-of-the-art global hydrological models, while in some regions, runoff is significantly over- or underestimated compared to observations. The direction and magnitude of these biases is largely similar to those from other macro-scale models, rather than specific to LPJ. They are attributable primarily to uncertainties in the climate input data, and to human interventions not considered by the model (e.g. water withdrawal, land cover conversions). Additional model development is required to perform integrated assessments of water exchanges among the biosphere, the hydrosphere, and the anthroposphere. Yet, the LPJ model can now be used to study inter-relations between the world's major vegetation types and the terrestrial water balance. As an example, it is shown that a doubling of atmospheric CO 2 content alone would result in pronounced changes in evapotranspiration and runoff for many parts of the world. Although significant, these changes would remain unseen by stand-alone hydrological models, thereby emphasizing the importance of simulating the coupled carbon and water cycle.

Genesis of phenotypic and genotypic diversity in land plants: The present as the key to the past

The evolutionary history of vascular plants is reviewed by extrapolation back through time from a wide range of data recently derived from the present flora, using as the central theme evolutionary inferences gained from phylogenies reconstructed as cladograms. Any region of the genome can be used to infer relationships, but only a combination of knowledge of morphology and the developmental genes that underpin morphology can allow evolutionary interpretation of macroevolutionary transitions; this in turn is necessary to identify bona fide evolutionary radiations and any putative causal key innovations. Such studies require clades to be delimited not by the inclusion of particular extant ‘crown’ species but rather by specific apo‐morphies, thereby giving important phylogenetic roles to extinct as well as extant species. Dating phylogenetic divergences via molecular clocks remains seriously inaccurate, and ultimately relies primarily on fossil benchmarks. First principles suggest that evolution of most regions of the genome is fundamentally gradual, whereas evolution of regions especially prone to strong selection pressure, and of the many facets of the phenotype, is punctuational, being characterized through time dominantly by stasis. Sequence data have proved valuable for inferring monophyletic groups, but within the now widely accepted context of monophyly the taxonomic hierarchy should primarily reflect degrees of morphological rather than molecular divergence. Incongruence among contrasting data sets is best explained by understanding the biological constraints operating on each type of phylogenetic information. The conventional ‘uniformitarian’ view of evolution has only limited applicability as one traces the history of land plants through time. Diversity increased in stepwise fashion, reflecting either attainments of complexity and/or fitness thresholds by the lineage (intrinsic) or the availability of unusually permissive environments, often following major perturbations (extrinsic). The Quaternary period demonstrates especially well the resilience, and ease of migration, of the Earth's vegetation. A higher frequency of generation of novel phenotypes in the deep past is possible, but a far higher frequency of their establishment is certain; together, these factors generate an evolutionary pattern of nested radiations that is fractal, as saturation of the resource space rendered the environment decreasingly permissive through time. In the immediate future, evolutionary‐developmental genetics will have increasing value for testing homology, interpreting homoplasy and elucidating evolutionary constraints, and will become easier to pursue as whole‐genome sequences of additional ‘model’ species further invigorate comparative genomics. Complexity of gene regulation, both by other genes and by the cellular and extra‐cellular environment, appears a particularly fruitful area for further research. Nonetheless, environmental filtering of evolutionary novelties (whether instantaneously isolated mutant ‘prospecies’ or classic neoDarwinian ‘selfish genes’ selectively spreading through panmictic populations) can only be effectively understood by longer term monitoring of populations in the wild, to better capture rare evolutionary and ecological events and to better assess the efficacy of traditional microevolutionary processes. We believe that the resulting renaissance in macroevolutionary studies will encourage a broader systematic perspective ‐ one that better encompasses the remarkable diversity of evolutionary processes that together generated the present diversity of life.