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Tracing and quantifying water fluxes in the hydrological cycle is crucial for understanding the current state of ecohydrological systems and their vulnerability to environmental change. Especially the interface between ecosystems and the atmosphere that is strongly mediated by plants is important to meaningfully describe ecohydrological system functioning. Many of the dynamic interactions generated by water fluxes between soil, plant and the atmosphere are not well understood, which is partly due to a lack of interdisciplinary research. This opinion paper reflects the outcome of a discussion among hydrologists, plant ecophysiologists and soil scientists on open questions and new opportunities for collaborative research on the topic "water fluxes in the soil-plant-atmosphere continuum" especially focusing on environmental and artificial tracers. We emphasize the need for a multi-scale experimental approach, where a hypothesis is tested at multiple spatial scales and under diverse environmental conditions to better describe the small-scale processes (i.e., causes) that lead to large-scale patterns of ecosystem functioning (i.e., consequences). Novel in-situ, high-frequency measurement techniques offer the opportunity to sample data at a high spatial and temporal resolution needed to understand the underlying processes. We advocate for a combination of long-term natural abundance measurements and event-based approaches. Multiple environmental and artificial tracers, such as stable isotopes, and a suite of experimental and analytical approaches should be combined to complement information gained by different methods. Virtual experiments using process-based models should be used to inform sampling campaigns and field experiments, e.g., to improve experimental designs and to simulate experimental outcomes. On the other hand, experimental data are a pre-requisite to improve our currently incomplete models. Interdisciplinary collaboration will help to overcome research gaps that overlap across different earth system science fields and help to generate a more holistic view of water fluxes between soil, plant and atmosphere in diverse ecosystems.

Drought is expected to increase in frequency and severity in many regions in the future, so it is important to improve our understanding of how drought affects plant functional traits and ecological interactions. Imposing experimental water deficits is key to gaining this understanding, but has been hindered by logistic difficulties in maintaining consistently low water availability for plants. Here, we describe a simple method for applying soil water deficits to potted plants in glasshouse experiments. We modified an existing method (the "Snow and Tingey system") in order to apply a gradual, moderate water deficit to 50 plant species of different life forms (grasses, vines, shrubs, trees). The method requires less maintenance and manual handling compared to other water deficit methods, so it can be used for extended periods of time and is relatively inexpensive to implement. With only a few modifications, it is possible to easily establish and maintain soil water deficits of differing intensity and duration, as well as to incorporate interacting stress factors. We tested this method by measuring physiological responses to an applied water deficit in a subset of 11 tree/shrub species with a wide range of drought tolerances and water-use strategies. For this subgroup of species, stomatal conductance was 2-17 times lower in droughted plants than controls, although only half of the species (5 out of 11) experienced midday leaf water potentials that exceeded their turgor loss (i.e., wilting) point. Leaf temperatures were up to 8°C higher in droughted plants than controls, indicating that droughted plants are at greater risk of thermal damage, relative to unstressed plants. The largest leaf temperature differences (between droughted and well-watered plants) were in species with high rates of water loss. Rapid osmotic adjustment was observed in leaves of five species when drought stress was combined with an experimental heatwave. These results highlight the potential value of further ecological and physiological experiments utilizing this simple water deficit method to study plant responses to drought stress.

The data set contains images of leaf venation networks obtained from tree species in Malaysian Borneo. The data set contains 726 leaves from 295 species comprising 50 families, sampled from eight forest plots in Sabah. Image extents are approximately 1 × 1 cm, or 50 megapixels. All images contain a region of interest in which all veins have been hand traced. The complete data set includes over 30 billion pixels, of which more than 600 million have been validated by hand tracing. These images are suitable for morphological characterization of these species, as well as for training of machine-learning algorithms that segment biological networks from images. Data are made available under the Open Data Commons Attribution License. You are free to copy, distribute, and use the database; to produce works from the database; and to modify, transform, and build upon the database. You must attribute any public use of the database, or works produced from the database, in the manner specified in the license. For any use or redistribution of the database, or works produced from it, you must make clear to others the license of the database and keep intact any notices on the original database.

The Desert Lab in its early years was staffed largely by botanists from the New York Botanical Garden and supported the research of many botanists who were developing the new field of ecology. "Somewhat puffed up", he wrote, "we made a missionary trip around the country spreading the message to ecologists that "ecology is more powerful than ecologists" and that ecologists needed to emerge from their cocoon. The emerging environmental movement shook ecology and transformed it under the leadership of Odum, Bormann, Woodwell, and other ecologists. [Extracted from the article]

The aim of this study was to assess the phylogenetic relationships, ecology and ecophysiological characteristics of the dominant planktic algae in ice-covered lakes on James Ross Island (northeastern Antarctic Peninsula). Phylogenetic analyses of 18S rDNA together with analysis of ITS2 rDNA secondary structure and cell morphology revealed that the two strains belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in future. Immotile green algae are thus apparently capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strains grew in a wide temperature range, but the growth was inhibited at temperatures above 20 °C, indicating their adaptation to low temperature. Preferences for low irradiances reflected the light conditions in their original habitat. Together with relatively high growth rates (0.4-0.5 day) and unprecedently high content of polyunsaturated fatty acids (PUFA, more than 70% of total fatty acids), it makes these isolates interesting candidates for biotechnological applications. [ABSTRACT FROM AUTHOR]

Salinity and flooding are as two very important factors of soil degradation. They often occur together and cancause severe damage to plants. However, plant response to environmental stresses may vary with growth stage atwhich exposure occurs. A pot study was conducted in 2005-2006 in northern Aq Qala (northern Iran) to studycombine effects of waterlogging and soil salinity at different growth stages on grain yield and some yield componentsof two Iranian spring wheat genotypes, i.e. Kouhdasht and Tajan. Two salinity treatments were applied, viz. a nonsaline(ECe = 3 dS m-1) and saline soil (ECe= 10 dS m-1). The six waterlogging treatments within each set consistedof: control (no waterlogging), and waterlogging applied at tillering (T); stem elongation (SE); booting (B); grainfilling (GF); and two spells of waterlogging, i.e. at tillering and grain filling stages (T+GF). In this experiment,waterlogging was imposed by keeping pots in hypoxia conditions by adding water daily (during up to two weeks) to110% of available water holding capacity. Results reveal that highest reduction in grain yield; thousand grain weight(TGW) and harvest index (HI) were observed through waterlogging at T+GF for both wheat genotypes. Nonsignificantchanges in grain yield, TGW and HI were observed via waterlogging at B as compared to control.Kouhdasht showed better performance than Tajan under saline and saline × waterlogged conditions

Crops growing in salt-affected soils may suffer from physiological drought stress, ion toxicity, and mineral deficiency. A pot study was conducted in 2004-2005 in the Aghala area (northern Iran) to study the effect of different salinity levels, i.e. ECe= 3 (control), 8, 12 and 16 dS m-1 on wheat grain, yield components and leaf ion uptake of four Iranian wheat genotypes, i.e. Kouhdasht, Atrak, Rasoul and Tajan. Treatments were replicated three times in a completely randomized design in a factorial arrangement. Desired salinity levels were obtained by mixing adequate NaCl before filling the pots. Soil water was maintained at 70% of available water holding capacity. Results revealed that Kouhdasht and Tajan showed highest and lowest grain yield and its components as compared to other cultivars at different salinity levels. Leaf Na+ and Cl- concentrations of all genotypes increased significantly with increasing soil salinity, with the highest concentrations in Tajan, followed by Rasoul, Atrak and Kouhdasht cultivars, respectively. Highest leaf K+ concentration and K+: Na+ ratio were observed in Kouhdasht cultivar, followed by Atrak, Rasoul and Tajan, respectively. Therefore, Kouhdasht and Atrak were identified as the most salt-tolerant genotypes as compared to two other wheat genotypes.

This paper approaches by the soil-plant perspective the evaluation of plant ecophysiological parameters and biological indicators of soil (edaphic mesofauna) in different grassland ecosystems with different degrees of human intervention from the Northeastern Romania. We have studied natural reserves, pastures and hayfields, in two different geographical units - Central Moldavian Plateau and Moldavian Plain. Based on these results, it was considered the human impact through analysis of statistical indicators (arithmetic mean, standard deviation, coefficient of variation) in accordance with the characteristics of studied biotopes. Ecophysiological parameters were assessed by analysis of photosynthesizing pigments (chlorophylls and carotenoid pigments) and fractions of soluble carbohydrate. Variability of photosynthetic indicators was lower in the case of species from natural reserves and larger, but elevated in secondary meadows and pastures. Accumulation of the carbohydrates was discussed in relation with soil type and it was observed the smallest values occurred in anthropic ecosystems (pastures) and in the natural reserve of Central Moldavian Plateau. Bioedaphic indicators were represented by some main groups of soil mesofauna (mites, collembolans, and on the whole, other insects or groups of edaphic microarthropods), analyzed both in a quantitative and qualitative manner. The density of edaphic microarthropods from the grasslands of Moldavian Plain was higher than that of Central Moldavian Plateau. From the qualitative point of view generally, the mites are the dominant group and among them the oribatid mites prevails. The ratio between the main detritomicrophagous groups (oribatid mites/collembolans) is in the favour of the mites with few exceptions. Both quantitative and qualitative features of the edaphic mesofauna mostly depend on the biopedoclimatic stational conditions, especially to the degree of the environmental anthropization, humidity, type of soil etc. The most anthropized grasslands could be considered the hayfields from haplic chernozem in both studied geographic areas This study was financially supported by BIODIV Research Programme developed under coordination of National Institute of Research and Development for Biological Sciences Bucharest. [ABSTRACT FROM AUTHOR]

The expected and already observed increment in frequency of extreme climatic events may result in severe vegetation shifts. However, stabilizing mechanisms promoting community resilience can buffer the lasting impact of extreme events. The present work analyzes the resilience of a Mediterranean mountain ecosystem after an extreme drought in 2005, examining shoot-growth and needle-length resistance and resilience of dominant tree and shrub species (Pinus sylvestris vs Juniperus communis, and P. nigra vs J. oxycedrus) in two contrasting altitudinal ranges. Recorded high vegetative-resilience values indicate great tolerance to extreme droughts for the dominant species of pine-juniper woodlands. Observed tolerance could act as a stabilizing mechanism in rear range edges, such as the Mediterranean basin, where extreme events are predicted to be more detrimental and recurrent. However, resistance and resilience components vary across species, sites, and ontogenetic states: adult Pinus showed higher growth resistance than did adult Juniperus; saplings displayed higher recovery rates than did conspecific adults; and P. nigra saplings displayed higher resilience than did P. sylvestris saplings where the two species coexist. P. nigra and J. oxycedrus saplings at high and low elevations, respectively, were the most resilient at all the locations studied. Under recurrent extreme droughts, these species-specific differences in resistance and resilience could promote changes in vegetation structure and composition, even in areas with high tolerance to dry conditions. [ABSTRACT FROM AUTHOR]

Ferns usually have relatively lower photosynthetic potential than angiosperms. However, it is unclear whether low photosynthetic potential of ferns is linked to leaf water supply. We hypothesized that there is an evolutionary association of leaf water transport capacity with photosynthesis and stomatal density in ferns. In the present study, a series of functional traits relating to leaf anatomy, hydraulics and physiology were assessed in 19 terrestrial and 11 epiphytic ferns in a common garden, and analyzed by a comparative phylogenetics method. Compared with epiphytic ferns, terrestrial ferns had higher vein density (Dvein), stomatal density (SD), stomatal conductance (gs), and photosynthetic capacity (Amax), but lower values for lower epidermal thickness (LET) and leaf thickness (LT). Across species, all traits varied significantly, but only stomatal length (SL) showed strong phylogenetic conservatism. Amax was positively correlated with Dvein and gs with and without phylogenetic corrections. SD correlated positively with Amax, Dvein and gs, with the correlation between SD and Dvein being significant after phylogenetic correction. Leaf water content showed significant correlations with LET, LT, and mesophyll thickness. Our results provide evidence that Amax of the studied ferns is linked to leaf water transport capacity, and there was an evolutionary association between water supply and demand in ferns. These findings add new insights into the evolutionary correlations among traits involving carbon and water economy in ferns. [ABSTRACT FROM AUTHOR]

• Habitats that differ in soil resource availability are expected to differ for selection on resource-related plant traits. • Here, we examined spatial and temporal variation in phenotypic selection on leaf ecophysiological traits for 10 Helianthus populations, including two species of hybrid origin, Helianthus anomalus and Helianthus deserticola, and artificial hybrids of their ancestral parents. Leaf traits assessed were leaf size, succulence, nitrogen (N) concentration and water-use efficiency (WUE). • Biomass and leaf traits of artificial hybrids indicate that the actively moving dune habitat of H. anomalus was more growth limiting, with lower N availability but higher relative water availability than the stabilized dune habitat of H. deserticola. Habitats differed for direct selection on leaf N and WUE, but not size or succulence, for the artificial hybrids. However, within the H. anomalus habitat, direct selection on WUE also differed among populations. Across years, direct selection on leaf traits did not differ. • Leaf N was the only trait for which direct selection differed between habitats but not within the H. anomalus habitat, suggesting that nutrient limitation is an important selective force driving adaptation of H. anomalus to the active dune habitat. [ABSTRACT FROM AUTHOR]

Eucalypt trees are in decline throughout urban landscapes of south western Australia. This study investigated the cause of decline in Eucalyptus marginata and Corymbia calophylla trees in parkland and compared water and nutrient relations with healthy trees in adjacent bushland in Perth, Western Australia. It was hypothesized that: (i) trees were drought stressed through competition for soil water by the vigorous turf; (ii) excessive uptake of nitrogen, because of fertilizer application to turf, caused toxicity; and/or (iii) micronutrient (Cu, Fe, Mn and/or Zn) deficit was induced by high-pH irrigation water applied to turf around parkland trees. Leaf water potential showed aseasonal variation in the irrigated parkland trees and foliar δ13C indicated that parkland trees generally had low water-use efficiency and were not drought stressed relative to bushland trees. Foliar N levels were not significantly different between parkland and bushland trees indicating that excess N uptake was not a factor in the decline. Foliar total Fe, ‘metabolically active’ Fe, Cu and Zn concentrations were not significantly different between parkland and bushland trees. Foliar manganese concentrations were indicative of deficiency and significantly lower in parkland trees (5–14 µg g−1) relative to bushland trees (22–35 µg g−1). It is concluded that application of alkaline irrigation water to the parkland site reduced the plant-availability of Mn; however, our study of only one parkland site does not allow us to generalize the results across other parklands. [ABSTRACT FROM AUTHOR]

This paper outlines the trends in environmental design research providing an era by era analysis to illustrate the topics that researchers have addressed and why they have studied some more than others at particular times. This retrospective review shows which disciplines have been central to the development of the literature and those that have been peripheral. [ABSTRACT FROM AUTHOR]

Contemporary evolution may explain the success of some exotic plant invasions. However, the evolutionary response of recipient native plant populations to exotic invasion has received relatively little attention. Because plant populations are genetically variable, contemporary evolution may also occur in native populations following entry of invasive species. Previously, we documented molecular differences in native populations; here we extend these studies to evaluate growth of native species in a common garden experiment. We seek to determine if three populations of two native grass species ( Hesperostipa comata and Sporobolus airoides) demonstrate evidence of contemporary evolution in response to invasion by Acroptilon repens. We obtained 50 genets of the two native grass species from communities long-invaded (25–80 years) by A. repens and from adjacent, noninvaded areas, and planted five transplants of each genet into two A. repens infestations (Laramie and Fort Steele, Wyoming, USA) to document their growth and survival. Cumulative differences between collections from invaded and noninvaded communities were species-specific. S. airoides displayed a consistent positive response to long-term coexistence with A. repens, whereas the performance of H. comata originating from invaded communities was not different from H. comata collected from noninvaded communities. In general, genets from invaded communities had fewer tillers than genets from noninvaded communities, but their relative tiller production (percent increase) was greater for genets from invaded communities at both field transplant sites for both grass species. Basal area increase and overall performance of collections from invaded and noninvaded communities of origin depended on transplant site and grass species. The results suggest that native species have the potential for adaptation to coexist with exotic invasives, although that potential may differ among species. [ABSTRACT FROM AUTHOR]

Abstract: The combined effect of declining diversity and elevated temperature is a less-studied aspect of global change. We investigated the influence of those two factors and their possible interactions on leaf ecophysiological processes in artificial grassland communities. Changes at the leaf level are at the basis of changes at the community level (and vice versa) but have remained largely unexplored in biodiversity experiments. We focused on end-of-season responses to assess whether species richness and air temperature affect the duration of the growing season. Grassland model ecosystems were used in 12 sunlit, climate-controlled chambers. Half of these chambers were exposed to ambient air temperatures, while the other half were warmed 3°C. Each chamber contained 24 plant communities, created with nine grassland species: three grass species, three nitrogen (N) fixers and three non-N-fixing dicots. Each plant community consisted of either one, three or nine species in order to create different species richness levels. Various ecophysiological variables (processes and characteristics) and above ground biomass were influenced by temperature. In several variables, the effects of temperature and species richness varied with species. No single-factor species richness effect was found due to opposite responses of the species canceling out the effect. We expect that these interactions may increase with time. [Copyright &y& Elsevier]

The article discusses the study that examines how growth with invasive thistles impacts survival, growth, reproductive output and ecophysiology of native perennial bunchgrasses growing in two soil environments. The study authors measured plant performance in terms of survival, growth, reproduction and predawn water potential. The results revealed that soil depth, water availability and bunchgrass maturity acted in agreement to influence the impact of the invasive thistle on the native bunchgrass. Moreover, the combination of shallow soil and low water availability reduced the performance of invasive thistle and improved its negative effect on the growth and reproduction of native perennial bunchgrass.

Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi-natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition to biodiversity at the global scale. In particular, rates of N deposition within the newly defined 34 world biodiversity hotspots, to which 50% of the world's floristic diversity is restricted, has not been quantified previously. Using output from global chemistry transport models, here we provide the first estimates of recent (mid-1990s) and future (2050) rates and distributions of N deposition within biodiversity hotspots. Our analysis shows that the average deposition rate across these areas was 50% greater than the global terrestrial average in the mid-1990s and could more than double by 2050, with 33 of 34 hotspots receiving greater N deposition in 2050 compared with 1990. By this time, 17 hotspots could have between 10% and 100% of their area receiving greater than 15 kg N ha−1 yr−1, a rate exceeding critical loads set for many sensitive European ecosystems. Average deposition in four hotspots is predicted to be greater than 20 kg N ha−1 yr−1. This elevated N deposition within areas of high plant diversity and endemism may exacerbate significantly the global threat of N deposition to world floristic diversity. Overall, we highlight the need for a greater global approach to assessing the impacts of N deposition. [ABSTRACT FROM AUTHOR]

1. Many threatened bryophytes are restricted to patchy and temporary substrates such as dead wood and tree stems. Their persistence depends on successful colonizations of new patches. Spore germination may then be limited by substrate quality and wetness.2. In vitroexperiments were used to test the effects of pH and moisture on the establishment of spores of the moss speciesNeckera pennataHedw. andBuxbaumia viridis(DC) Moug.&Nestl.3. Low pH and water potential prolonged the lag phase preceding germination and reduced final germination. The interaction between pH and moisture suggests that high water availability facilitates germination at suboptimal pH, andvice versa.4. The results reflect the species’ habitats: the wood-inhabitingB. viridishad higher capacity to germinate at low pH, while spores of the epiphyteN. pennatashowed earlier germination at low water potential and survived longer in a dry state. This supports the notion that bryophytes are most strongly affected by substrate quality during establishment.5. We suggest that a trade-off exists among moss spores between the ability to colonize substrates with low moisture-holding capacity and low pH, and that the positive effect of high pH is largely that it speeds up germination thereby enabling the spores to exploit short, moist periods.Functional Ecology(2004)18, 907 –913 [ABSTRACT FROM AUTHOR]

We tested the hypothesis that the stable carbon isotope signature of ecosystem respiration (δ13CR) was regulated by canopy conductance (Gc) using weekly Keeling plots (n=51) from a semiarid old-growth ponderosa pine (Pinus ponderosa) forest in Oregon, USA. For a comparison of forests in two contrasting climates we also evaluated trends inδ13CR from a wet 20-year-old Douglas-fir (Pseudotsuga menziesii) plantation located near the Pacific Ocean. Intraannual variability inδ13CR was greater than 8.0‰ at both sites, was highest during autumn, winter, and spring when rainfall was abundant, and lowest during summer drought. Theδ13CR of the dry pine forest was consistently more positive than the wetter Douglas-fir forest (mean annualδ13CR:−25.41‰ vs.−26.23‰, respectively,P=0.07). At the Douglas-fir forest,δ13CR–climate relationships were consistent with predictions based on stomatal regulation of carbon isotope discrimination (Δ). Soil water content (SWC) and vapor pressure deficit (vpd) were the most important factors governingδ13CR in this forest throughout the year. In contrast,δ13CR at the pine forest was relatively insensitive toSWCorvpd, and exhibited a smaller drought-related enrichment (∼2‰) than the enrichment observed during drought at the Douglas-fir forest (∼5‰). Groundwater access at the pine forest may buffer canopy–gas exchange from drought. Despite this potential buffering,δ13CR at the pine forest was significantly but weakly related to canopy conductance (Gc), suggesting thatδ13CR remains coupled to canopy–gas exchange despite groundwater access. During drought,δ13CR was strongly correlated with soil temperature at both forests. The hypothesis that canopy-level physiology is a critical regulator ofδ13CR was supported; however, belowground respiration may become more important during rain-free periods. [ABSTRACT FROM AUTHOR]

Animal, plant, and microbial ecophysiologists have diverged greatly in the last few decades in the principal research questions they address (e.g., global change versus evolution), in the methods they use, and even in the professional societies to which they belong. Two symposia in 2001 brought these diverse groups together, with presentations by researchers who study two or three kingdoms in intimate interaction. The second symposium, the subject of this report, was sponsored by the Ecological Society of America's Physiological Ecology section. Several of the presentations showed, among other things, commonalities in chemical signaling among kingdoms, as well as exploitation of such signals and other metabolic pathways by parasites and their hosts. These and other important findings from such interkingdom and interdisciplinary research can help explain why current functional groups exist. Animal and plant ecophysiologists used to address highly analogous questions such as, How do organisms balance fluxes of water, solutes, heat, and radiation? A plant ecophysiologist is likely to measure whole-stand fluxes and aim to scale up to the globe; an animal ecophysiologist is more likely to take a highly molecular approach, as in the study of heat-shock proteins and their evolutionary history. Yet the two disciplines have much to offer each other, even in techniques alone. The dichotomy between the two fields is in active discussion among members of the Ecological Society of America's (ESA) Physiological Ecology section, which is largely made up of plant ecophysiologists, and the Society for Integrative and Comparative Biology (SICB).

Studies the relationship between plant growth and resource balance in an economic perspective. Outline of the economic theory; Major complication in extrapolating from economics to ecology; Characteristics of higher plants that facilitate the evaluation of economic parameters; Presentation of the four economic theorems on profit maximization and optimal resource allocation.

Investigates the influence of host species on mistletoe germination, early seedling development and establishment on two mistletoe varieties, amyema preissii and Lysiana exocarpi. Impact of potential hosts on seedling holdfast formation and leaf emergence; Height of seedling mortality during the first three months with considerable variation among different host species; Variations on the growth of seedlings on host and non-host species.

The New Phytologist Tansley Medal 2019 - Philippa Borrill and Kai Zhu She considers the opportunities for using cereal crops as experimental systems in her Tansley insight "Blurring the boundaries between cereal crops and model plants" (in this issue of I New Phytologist i , Borrill, pp. 1721-1727). Kai's Tansley insight is entitled 'Understanding forest dynamics by integrating age and environmental change' (Zhu, pp. 1728-1733) and it explores how global forest-age data and and hierarchical models can help us better understand forest dynamics. [Extracted from the article]

The recent passing of Larry Bliss on July 7 prompts reflections on the development of physiological ecology in the decades after the Second World War, as well as some important changes in ESA that occurred during Bliss's career, and that he helped to bring about. He cited Bliss and Tieszen's synthesis volumes from their respective biome studies as examples of this fruitful synergy between ecosystem ecology and physiological ecology. Bliss recounted his research in relation to petroleum exploration in Canada in his later address as past-president of ESA (Bliss [3]), where he recalled the slow and difficult process of building trust between the petroleum industry and scientific experts. [Extracted from the article]