Understanding plant physiological response to a rising atmospheric CO2 concentration (ca) is key in predicting Earth system plant–climate feedbacks; however, the effects of long-term rising ca on plant gas-exchange characteristics in the tropics are largely unknown. Studying this long-term trend using herbarium records is challenging due to specimen trait variation. We assessed the impact of a ca rise of ~95 ppm (1927–2015) on the intrinsic water-use efficiency (iWUE) and maximum stomatal conductance (gsmax) of five tropical tree species in Fiji using the isotopic composition and stomatal traits of herbarium leaves. Empirical results were compared with simulated values using models that uniquely incorporated the variation in the empirical gsmax responses and species-specific parameterisation. The magnitude of the empirical iWUE and gsmax response was species-specific, ranging from strong to negligible. Stomatal density was more influential than the pore size in determining the gsmax response to ca. While our simulation results indicated that photosynthesis is the main factor contributing to the iWUE gain, stomata were driving the iWUE trend across the tree species. Generally, a stronger increase in the iWUE was accompanied by a stronger decline in stomatal response. This study demonstrates that the incorporation of variation in the gsmax in simulations is necessary for assessing an individual species’ iWUE response to changing ca.

Plants in the understory experience climatic conditions affected by the overstory canopy that influence physiological and biochemical processes. Here, we investigate the relationships of leaf lipid molecular abundances to leaf water content, transmitted irradiance, and free-air temperature (Tair) from deciduous angiosperm (Quercus buckleyi) and evergreen gymnosperm (Juniperus ashei) understory trees across an elevation gradient in a central Texas (USA) woodland. Monthly sampling from 04/2019 to 01/2020 revealed that long-chain leaf waxes (≥ C27) accumulated with leaf water deficit over the growing season for both tree species. Higher transmitted light during the hottest, driest months was due to a decreased leaf area index (LAI) in the canopy as leaf shedding is a common drought response. Isoprenoids (sesqui-, di-terpenoids, phytosterols) in leaves changed by month with changing LAI and transmittance associated with monthly Tair changes. The chain length of n-alkanols in Q. buckleyi shifted with seasonal LAI at different topographic positions. The unsaturation of fatty acids in both tree species decreased with increased seasonal Tair but showed topography sensitivity. Leaf-level metabolites responded to understory microclimatic variables that were influenced by seasonality and topography.

Universal coverage systems with a single primary insurer" include the "insurance" systems of Australia and Canada as well as the "service" systems of Sweden and the U.K.* "Universal coverage systems with multiple primary insurers but no choice" have multiple insurers within a geographic area but people assigned to an insurer according to some demographic trait -mainly occupation.This describes France and Japan in which neighbors in Paris or Tokyo could have different coverage based on their employment.* "Universal coverage systems with competing primary insurers," allow most people to choose an insurer -as in Germany, the Netherlands, or Switzerland.* "Systems without universal coverage," means the United States, which is unique in many ways but he sees partial coverage as the most fundamental.In Chapter 2 Rice then defines "key system components," or variables, that following chapters describe for each of the ten countries.These include: * Governance, such as the extent to which government agencies or private actors make key decisions or the extent to which central or subnational governments take the lead.* Financing, which includes sources of revenue, the progressivity or regressivity of those sources, and so both horizontal and vertical equity.* Coverage, which he very nicely defines in terms of breadth (across the population), scope (which benefits are covered), and depth (what proportion of the cost for a service is covered -i.e.cost-sharing issues).* The role of voluntary private insurance as a supplement to the primary coverage (so U.S. employer-sponsored coverage doesn't count).* Choice both of insurer and care provider, which varies mostly in the use of forms of gatekeeping.

A minuscule fraction of the Earth's paleobiological diversity is preserved in the geological record as fossils. What plant remnants have withstood taphonomic filtering, fragmentation, and alteration in their journey to become part of the fossil record provide unique information on how plants functioned in paleo-ecosystems through their traits. Plant traits are measurable morphological, anatomical, physiological, biochemical, or phenological characteristics that potentially affect their environment and fitness. Here, we review the rich literature of paleobotany, through the lens of contemporary trait-based ecology, to evaluate which well-established extant plant traits hold the greatest promise for application to fossils. In particular, we focus on fossil plant functional traits, those measurable properties of leaf, stem, reproductive, or whole plant fossils that offer insights into the functioning of the plant when alive. The limitations of a trait-based approach in paleobotany are considerable. However, in our critical assessment of over 30 extant traits we present an initial, semi-quantitative ranking of 26 paleo-functional traits based on taphonomic and methodological criteria on the potential of those traits to impact Earth system processes, and for that impact to be quantifiable. We demonstrate how valuable inferences on paleo-ecosystem processes (pollination biology, herbivory), past nutrient cycles, paleobiogeography, paleo-demography (life history), and Earth system history can be derived through the application of paleo-functional traits to fossil plants.

The Cretaceous is characterized as a greenhouse climate from elevated atmospheric carbon dioxide concentrations, transgressive seas, and temperate ecosystems at polar paleolatitudes. Here we test the hypothesis that the early Cretaceous was a cold climate state with a new Aptian atmospheric carbon dioxide record from the C3 plant proxy and early Cretaceous sea level curve from stable oxygen isotopes of belemnites and benthic foraminifera. Results show that carbon dioxide concentrations were persistently below 840 ppm during the Aptian, validating recent General Circulation Model simulations of ice sheets on Antarctica at those concentrations. In addition, sea level was estimated to be within the ice sheet window for much of the early Cretaceous prior to the Albian. This background state appears to have been episodically interrupted by Large Igneous Province volcanism followed by long-term carbon burial from weathering. We hypothesize that the early Cretaceous was largely an icehouse punctuated by warm snaps. Atmospheric carbon dioxide concentrations remained below 840 parts per million and polar regions were glaciated throughout much of the Early Cretaceous except during episodic volcanism, according to an analysis of stable isotope composition of plants and biogenic carbonate data.

Grassy ecosystems cover more than 40% of the world's terrestrial surface, supporting crucial ecosystem services and unique biodiversity. These ecosystems have experienced major losses from conversion to agriculture with the remaining fragments threatened by global change. Woody plant encroachment, the increase in woody cover threatening grassy ecosystems, is a major global change symptom, shifting the composition, structure, and function of plant communities with concomitant effects on all biodiversity. To identify generalisable impacts of encroachment on biodiversity, we urgently need broad-scale studies on how species respond to woody cover change. Here, we make use of bird atlas, woody cover change data (between 2007 and 2016) and species traits, to assess: (1) population trends and woody cover responses using dynamic occupancy models; (2) how outcomes relate to habitat, diet and nesting traits; and (3) predictions of future occupancy trends, for 191 abundant, southern African bird species. We found that: (1) 63% (121) of species showed a decline in occupancy, with 18% (34) of species' declines correlated with increasing woody cover (i.e. losers). Only 2% (4) of species showed increasing population trends linked with increased woody cover (i.e. winners); (2) Open habitat specialist, invertivorous, ground nesting birds were the most frequent losers, however, we found no definitive evidence that the selected traits could predict outcomes; and (3) We predict open habitat loser species will take on average 52 years to experience 50% population declines with current rates of encroachment. Our results bring attention to concerning region-wide declining bird population trends and highlight woody plant encroachment as an important driver of bird population dynamics. Importantly, these findings should encourage improved management and restoration of our remaining grassy ecosystems. Furthermore, our findings show the importance of lands beyond protected areas for biodiversity, and the urgent need to mitigate the impacts of woody plant encroachment on bird biodiversity.

Forest canopy structure is a fundamental ecosystem attribute affecting regional and global climate through primary production by CO2 drawdown and evapotranspirative feedback. Environmental changes in temperature and light affect leaf physiology and thus canopy functioning. Leaf physiological changes may be reflected in expressed chemical compounds (e.g., leaf lipid biomarkers), that offer opportunities to characterize and quantify climatic effects on plant canopies in the present and the past. To assess this possibility, we systematically investigated the lipids from leaves of deciduous angiosperm (Quercus buckleyi, April-October 2019) and evergreen gymnosperm (Juniperus ashei, April-October 2019 and January 2020) tree species at monthly sampling intervals over one growing season in a natural sub-humid ecosystem of central Texas. Fatty acid unsaturation in Q. buckleyi and J. ashei leaves was negatively correlated with air temperature. The average chain lengths of leaf wax n-alkanols of Q. buckleyi were strongly correlated with leaf area index (LAI) and absorbed photosynthetically active radiation (APAR) (r(2) > 0.5). The stigmasterol/beta-sitosterol ratio was correlated with light transmittance in the canopy of Q. buckleyi, with values of the sterol ratio three-fold higher in shaded leaves than in sparse canopies. The observed seasonal changes in leaf lipid molecular composition and chain-lengths might be related to their biosynthetic responses to temperature and light stresses. Finally, we developed multi-lipid regression models resolving seasonal differences in temperature, LAI, and APAR. We posit that the specific lipid biosynthetic responses to variations in temperature and light are a basis for reconstructing terrestrial paleoenvironmental changes.

Streambank erosion processes influence the amount of soil material contributed to rivers and sedimentation rates in receiving reservoirs. However, the amount of data on bank erosion rates is limited both in range and extent affecting planning for mitigation and watershed management. Dendrogeomorphology is used to determine the date of wood anatomy changes in annual growth increments of roots exposed by erosion of stream banks that when coupled with measurement of the distance of roots to the channel side can be used to calculate the bank retreat rate. Erosion rates derived from dendrogeomorphology are important because these provide erosion data over longer time scales (decades). Here, we use this method to quantify erosion for three different sized watersheds (4 to 3781 km2) located in the water-scarce southern U.S. prairies that are heavily reliant on surface water and reservoir storage. From 49 roots from the two smaller drainages, erosion ranged from 1.5 to 25.4. For 19 roots collected from the larger subbasin erosion rates were larger ranging from 7.4 to 325.0 cm/years with the larger values and variance associated with two high-flow events that occurred a year before sampling. We also found differences in straight and meandering portions of the streams where the distance to bank was strongly and positively correlated with the years since root exposure in straight sections. In contrast, meandering bends also showed a positive but low correlation for root exposure date and distance collected. We attribute this difference to erosional processes (i.e., scour and mass wasting) occurring at these channel locations. When compared with other erosion studies across the southern U.S. prairie, our values were similar in magnitude but with low correlation to drainage area indicating site specificity of erosion mechanisms, and watershed landcover influence for different drainages, despite being in the same ecological region.

Terrestrial plants have transformed Earth's surface environments by altering water, energy, and biogeochemical cycles. Studying vegetation-climate interaction in deep time has necessarily relied on modern-plant analogs to represent paleo-ecosystems—as methods for reconstructing paleo- and, in particular, extinct-plant function were lacking. This approach is potentially compromised given that plant physiology has evolved through time, and some paleo-plants have no clear modern analog. Advancements in the quantitative reconstruction of whole-plant function provide new opportunities to replace modern-plant analogs and capture age-specific vegetation-climate interactions. Here, we review recent investigations of paleo-plant performance through the integration of fossil and geologic data with process-based ecosystem- to Earth system–scale models to explore how early vascular plants responded to and influenced climate. First, we present an argument for characterizing extinct plants in terms of ecological and evolutionary theory to provide a framework for advancing reconstructed vegetation-climate interactions in deep time. We discuss the novel mechanistic understanding provided by applying these approaches to plants of the late Paleozoic ever-wet tropics and at higher latitudes. Finally, we discuss preliminary applications to paleo-plants in a state-of-the-art Earth system model to highlight the potential implications of different plant functional strategies on our understanding of vegetation-climate interactions in deep time. ▪ For hundreds of millions of years, plants have been a keystone in maintaining the status of Earth's atmosphere, oceans, and climate. ▪ Extinct plants have functioned differently across time, limiting our understanding of how processes on Earth interact to produce climate. ▪ New methods, reviewed here, allow quantitative reconstruction of extinct-plant function based on the fossil record. ▪ Integrating extinct plants into ecosystem and climate models will expand our understanding of vegetation's role in past environmental change.

Environmental restriction of forest distribution may be specific to the eco-physiological limits of era-appropriate plants. Accounting for major limiting factors in deep time will improve understanding of ecosystems dominated by extinct plants, surface processes, and Earth System function. Major plant taxa associated with Earth’s penultimate icehouse (the late Paleozoic ice age [LPIA]) are thought to have been limited by moisture seasonality based on evidence from fossil and geological records. We apply recently described methodologies­—climate modeling and ecosystem-process modeling—to simulate global arboreal vegetation in the late Paleozoic ice age. We will compare the intensity of modeled moisture seasonality with plant performance of major late Paleozoic plant taxa. Using National Center for Atmospheric Research’s Community Earth System Model version 1.2 (CESM) simulations, varying pCO2, pO2, and ice extent for the Pennsylvanian, and fossil-derived leaf C:N, maximum stomatal conductance, specific conductivity, and stem physiological limitations for several major Carboniferous plant groups, we will simulate global ecosystem processes at a 2-degree resolution with Paleo-BGC. We hypothesize that moisture seasonality patterns across Pangea will interact with modeled era-appropriate taxa—based on stem hydraulic hysteresis and leaf water limitations—to impact arboreal plant growth and forest cover. The simulated function of era-appropriate stem and leaf trait combinations may provide a mechanistic link to drought-tolerance evolution in lineages like the coniferophytes that persist across global ecological upheavals.

Whereas carbon isotope ratios of marine carbonates are well characterized through the Phanerozoic, the carbon isotope ratios of terrestrial plant organic matter (delta C-13(p)) are less so due to the variety of plant parts and materials in which carbon is preserved and the challenges involved in interpreting carbon isotope fractionation in deep time. In 2016, an initial effort to compile published terrestrial organic carbon isotope data for the Phanerozoic (delta C-13(p); ISOORG16; Nordt et al. 2016) was accomplished, consisting of 6888 delta C-13(p) estimates derived from ten organic matter sources. Here, we present an updated version of the Cenozoic and Mesozoic portions of that database (ISOORG23), consisting of 20,334 data points with an expanded 12 groups of organic material (i.e., amber, biomarkers, bulk sediment, coal, copal, leaves, n-alkanes, n-alkanoic acids, paleosol organic matter, peat, wood, and other plant parts). In addition, the entire database was updated to align with the 2020 Geologic Timescale (GTS-2020), with most delta C-13(p) data points (19,313) placed in 5 Myr bins and hypothetical numerical ages assigned to the subset of 12,828 data points where dating methods were available. Not surprisingly, we found that most published data are from Cenozoic age materials. Mean delta C-13(p) values for plant material (excluding amber and C3 plants) showed overall depletion in delta C-13(p) from the Mesozoic ( 24.4 +/- 0.02%; n = 7895) to Cenozoic ( 25.9 +/- 0.02% n = 10,230). Among the different organic materials analyzed in ISOORG23, amber showed the highest delta C-13(p) values ( 23.1%), compared to sub-modern peat and copal with the lowest values ( -26.8 and - 27.5%, respectively). LOESS analyses of the ISOORG23 database with assigned numerical ages were compared to similar analyses performed on a compilation of carbon isotopes of marine calcium carbonate (delta C-13(carb)) included in GTS-2020, as well as earlier compilations of atmospheric CO2 delta C-13 (delta C-13(CO2)) for the Cenozoic and the Cretaceous portion of the Mesozoic. Those comparisons reveal both periods of correspondence and divergence between delta C-13(p) and delta C-13(CO2) and delta C-13(carb) values, potentially indicating that major carbon cycle and/or climatic events are present in the delta C-13(p) data, though interpretation is affected by low data density during specific periods. A key finding is a consistently increased discrimination in both delta C-13(p) and delta C-13(CO2) records that begins at the Miocene Climatic Optimum and continues to the present. However, from the combined Cenozoic and Mesozoic data, that decline in delta C-13(p) began as early as 135 Ma.

As plant species expand their upper limits of distribution under current warming, some retain both traditional climate space and biotic environment while others encounter novel conditions. The latter is the case for Rhododendron campanulatum, a woody shrub that grows both above and below treeline at our study site in the Eastern Himalayas where a very conspicuous, stable treeline was defined by a nearly contiguous canopy of tall Abies spectabilis trees, many of which are over a century old. Prior work showed that treeline had remained static in this region while R. campanulatum expanded its elevational range limit. We tested local adaptation of R. campanulatum by performing reciprocal transplants between the species' current elevational range limit (4023 m above sea level [asl]) and just above treeline (3876 m asl). Contrary to expectation, the coldest temperatures of late winter and early mid-spring were experienced by plants at the lower elevation: R. campanulatum at species' limit (upper site) were covered by snow for a longer period (40 more days) and escaped the coldest temperatures suffered by conspecifics at treeline (lower site). The harsher spring conditions at treeline likely explain why leaves were smaller at treeline (15.3 cm(2)) than at species limit (21.3 cm(2)). Contrary to results from equivalent studies in other regions, survival was reduced more by downslope than by upslope movement, again potentially due to extreme cold temperatures observed at treeline in spring. Upslope transplantation had no effect on mortality, but mortality of species limit saplings transplanted downslope was three times higher than that of residents at both sites. A general expectation is that locals should survive better than foreign transplants, but survival of locals and immigrants at our species limit site was identical. However, those species limit saplings that survived the transplant to treeline grew faster than both locals at treeline and the transplants at species limit. Overall, we found asymmetric adaptation: Compared with treeline saplings, those at species limit (147 m above treeline) were more tolerant of extremes in the growing season but less tolerant of extremes in winter and early mid-spring, displaying local adaptation in a more complex manner than simply home advantage, and complicating predictions about impacts of future regional climate change.

Streambank erosion impacts rivers and reservoirs due to bank erosion. However, little information of stream bank is available due to the need for advanced planning. Dendrogeomorphology offers a post-hoc method to calculate streambank erosion providing information about past erosion events and processes. Bank retreat can be calculated by dendrogeomorphology where the distance from a channel bank of an exposed live root shows anatomical changes that are dated from the root’s growth rings. We estimated bank erosion for three different sized southern U.S. watersheds ranging in area from 4 to 3781 km using dendrogeomorphology compared to modeled erosion based on critical velocity required for sediment transport. Erosion values ranging from 3.8 to 13.5 cm/yr for the smaller drainages with no difference found between root and modeled erosion rates. The large sub-basin had erosion ranging from 33.6 to 196.4 cm/yr with high variance associated with two prior 2-year flow events with significant differences found between root and modeled values. We also found distance to bank strongly and positively correlated with root exposure in straight sections of the channel in contrast to roots collected in meander bends attributed to erosion processes (i.e., scour, mass wasting) occurring at these locations. When compared with other erosion studies across the southern U.S. prairie, our values were similar in magnitude but with low correlation to drainage area indicating site specificity of erosion mechanisms. We confirm dendrogeomorphology provides reasonable estimate of bank erosion across multiple spatial scales, important for watershed management in areas lacking intentional and persistent monitoring.

Grasslands were often viewed as successional vegetation, a precursor to a possible forest, and were thought to have low diversity.However, a growing number of research projects have shown that these ecosystems boast high biodiversity and massive carbon storing potential, and require at least a century to recover after agricultural ploughing which severely disrupts the environment and consequently lowers plant diversity and carbon stocks.Conserving natural grasslands should be prioritised, as they provide us with important ecosystem services beneficial to not only natural systems, but also the longevity of humans through food security and buffering of the effects of climate change.

SUMMARY1) Research Aims —Loudetia simplexis a common and dominant species throughout grassland ecosystems in mainland Africa and Madagascar. It is highly polymorphic, often classified as two taxa endemic to Madagascar:L. simplexsubsp.stipoidesandL. madagascariensis. A better understanding of the inter- and intra-specific variation between these taxa and its contributing environmental factors could improve our understanding of the history of Madagascar’s grasslands.2) Methods — The taxonomic status ofL. simplexsubsp.stipoidesandL. madagascariensiswas evaluated by morphometric analyses of 119 herbarium specimens. Species distribution modelling was used to determine the most important environmental factors underlyingthe L. simplexdistribution in Madagascar versus other African grasslands. We investigated ifL. simplexin Madagascar could be predicted by distributions across mainland Africa with niche overlap analyses.3) Key Result — African and Malagasy species exhibited variation potentially associated with environment. Specimens from northern and western Madagascar were taller with smaller spikelets than those from Southern Africa and central Madagascar.Loudetia simplextypically occurred in cooler temperatures with high precipitation and pronounced seasonality, but taller populations were found in warmer conditions. Projecting ecological niches of Southern Africa and East Tropical Africa onto Madagascar demonstrates much of the present distribution in the Central Highlands is expected from other natural African grasslands.4) Key Point — Malagasy and African individuals represent a single species, and the Malagasy species can be considered as a synonym of L. simplex. Distribution models are congruent with pre-human presence of grasslands in Madagascar.SOCIETAL IMPACT STATEMENTUnderstanding dominant species likeLoudetia simplexis necessary to understand the fire-driven grassy ecosystems they create. In Madagascar, grasslands are considered a low-value ecosystem despite their unique biodiversity and crucial importance as zebu rangeland. Only 1.8% of Madagascar’s grasslands are protected despite facing similar threats to forests and biodiversity loss. This study of common grasses will support the management of protected areas by providing information on resource management of vulnerable open ecosystems in Madagascar. Distribution models of common grass species and clear taxonomic classification can help land management stakeholders identify natural grasslands versus degraded forests.

Inguinal white adipose tissue (iWAT) is essential for the beneficial effects of exercise training on metabolic health. The underlying mechanisms for these effects are not fully understood, and here, we test the hypothesis that exercise training results in a more favorable iWAT structural phenotype. Using biochemical, imaging, and multi-omics analyses, we find that 11 days of wheel running in male mice causes profound iWAT remodeling including decreased extracellular matrix (ECM) deposition and increased vascularization and innervation. We identify adipose stem cells as one of the main contributors to training-induced ECM remodeling, show that the PRDM16 transcriptional complex is necessary for iWAT remodeling and beiging, and discover neuronal growth regulator 1 (NEGR1) as a link between PRDM16 and neuritogenesis. Moreover, we find that training causes a shift from hypertrophic to insulin-sensitive adipocyte subpopulations. Exercise training leads to remarkable adaptations to iWAT structure and cell-type composition that can confer beneficial changes in tissue metabolism.