Variety Of Growth Forms Research Articles

An assessment of small islands coral cover and coral-reef fish diversity at Oba Sub-district, Halmahera Island

Study on the percentage of coral cover four small islands of Oba Sub-district, Halmahera Island of North Maluku Utara Province was carried out in April 2021.The four small islands of Oba Sub-district studied are Woda Island, Raja Island, Tamin Island, and Guratu Island. The study applied systematic sampling method that included collecting coral reef data using UPT (Underwater Photo Transect) method and coral fish data collection using visual census method. Study results showed that live coral coverage of reefs on the four small islands of Oba Sub-district had the highest value of 5.415% and the lowest value of 4.29%. There was positive relationship between coral growth form diversity and fish diversity. High diversity of coral growth forms was significantly related to high diversity of target reef fish.

Microclimatic Warming Leads to a Decrease in Species and Growth Form Diversity: Insights From a Tropical Alpine Grassland

Due to warming, changes in microclimatic temperatures have shifted plant community structure and dynamics in tundra and alpine regions. The directionality and magnitude of these changes are less known for tropical alpine ecosystems. To understand the likely trajectory of these shifts in the Andes, we conducted a warming experiment in the northern Andes—using open-top chambers (OTC). In this study, we ask (1) how do OTCs affect air and soil temperatures in microclimates of tropical alpine regions, year-round and during the dry season? (2) What are the effects of 7 years of warming on (a) the aboveground biomass (AGB) and (b) the plant taxonomic and growth form diversity? We installed five monitoring blocks in 2012 at ca. 4,200 m asl with 20 OTCs and 50 control plots randomly distributed within each block. We measured AGB, plant community diversity, and growth form diversity between 2014 and 2019. After 7 years of warming, we found significant increases in mean monthly (+0.24°C), daily (+0.16°C), and night air temperatures (+0.33°C) inside the OTCs, and the OTCs intensified microclimatic conditions during the dry season. Additionally, OTCs attenuated extreme temperatures—particularly in the soil—and the number of freezing events. AGB significantly increased in OTCs, and by 2019, it was 27% higher in OTCs than in control. These changes were driven mainly by a progressive increment of tussock grasses such as Calamagrostis intermedia, typical of lower elevations. The increase of tussocks led to a significant decrease in species diversity and evenness inside OTCs, but not in species richness after accounting by sampling time. Furthermore, cushions and herbs decreased inside OTCs. Our results show that experimental warming using OTCs in equatorial regions leads to decreased daily thermal amplitude and night temperatures rather than the level of increase in mean temperatures observed in temperate regions. The increase of tussocks and decrease in diversity of species and growth forms due to prolonged modifications in microclimatic temperature might be a step toward shrub-dominated ecosystems. Further research on this topic would help understand shifts in growth form dominance and the direction and rate of change of the system.

Knowledge Gaps in Taxonomy, Ecology, Population Distribution Drivers and Genetic Diversity of African Sandalwood (Osyris lanceolata Hochst. & Steud.): A Scoping Review for Conservation.

The increasing demand for ornamental, cosmetic and pharmaceutical products is driving exploitation of plant species globally. Sub-Saharan Africa harbours unique and valuable plant resources and is now a target of plant resource depletion. African Sandalwood (Osyris lanceolata), a multi-purpose and drought-tolerant species, has seen increased exploitation for the last thirty years and is now declared endangered. Initiatives to conserve O. lanceolata are not yet successful in Africa due to poor understanding of the species. This review surveys relevant research on the ecology, taxonomy, population dynamics, genetic diversity and ethnobotany of O. lanceolata, and highlights gaps in the literature for further research. A scoping review of grey literature, scholarly papers and reports was applied with pre-determined criteria to screen relevant information. Review findings indicate O. lanceolata is a globally distributed species with no identified center of origin. In Africa, it ranges from Algeria to Ethiopia and south to South Africa; in Europe it occurs in the Iberian Peninsula and Balearic Islands; in Asia from India to China, and also on Socotra. The species has a confusing taxonomy, with unresolved issues in nomenclature, country range distribution, extensive synonymisation and variation in growth form (shrub or tree). The species population is reported to be declining in Africa, but information on population dynamics across its entire range of distribution is anecdotal. Additionally, ecological factors influencing spatial distribution and survival of the species remain unknown. A variety of uses are reported for O. lanceolata globally, including: cultural; medicinal and food; dye; perfumery; timber; ethnoveterinary and phytoremediation. Key research areas and implications for conservation of O. lanceolata in Sub-Saharan Africa are proposed.

The birth of modern rainforests

Paleoecology The origin of modern rainforests can be traced to the aftermath of the bolide impact at the end of the Cretaceous. Carvalho et al. used fossilized pollen and leaves to characterize the changes that took place in northern South American forests at this time (see the Perspective by Jacobs and Currano). They not only found changes in species composition but were also able to infer changes in forest structure. Extinctions were widespread, especially among gymnosperms. Angiosperm taxa came to dominate the forests over the 6 million years of recovery, when the flora began to resemble that of modern lowland neotropical forest. The leaf data also imply that the forest canopy evolved from relatively open to closed and layered, leading to increased vertical stratification and a greater diversity of plant growth forms. Science , this issue p. [63][1]; see also p. [28][2] [1]: /lookup/doi/10.1126/science.abf1969 [2]: /lookup/doi/10.1126/science.abh2086

Integrating Arctic Plant Functional Types in a Land Surface Model Using Above‐ and Belowground Field Observations

AbstractAccurate simulations of high‐latitude ecosystems are critical for confident Earth system model (ESM) projections of carbon cycle feedbacks to global climate change. Land surface model components of ESMs, including the E3SM Land Model (ELM), simulate vegetation growth and ecosystem responses to changing climate and atmospheric CO2 concentrations by grouping heterogeneous vegetation into like sets of plant functional types (PFTs). Many such models represent high‐latitude vegetation using only two PFTs (shrub and grass), thereby missing the diversity of vegetation growth forms and functional traits in the Arctic. Here, we use field observations of biomass and leaf traits across a gradient of plant communities on the Seward Peninsula in northwest Alaska to replace the original ELM configuration for the first time with nine Arctic‐specific PFTs. The newly developed PFTs include: (1) nonvascular mosses and lichens, (2) deciduous and evergreen shrubs of various height classes, including an alder PFT, (3) graminoids, and (4) forbs. Improvements relative to the original model configuration included greater belowground biomass allocation, persistent fine roots and rhizomes of nonwoody plants, and better representation of variability in total plant biomass across sites with varying plant communities and depth to bedrock. Simulations through 2100 using the RCP8.5 climate scenario and constant PFT fractional areas showed alder‐dominated plant communities gaining more biomass and lichen‐dominated communities gaining less biomass compared to default PFTs. Our results highlight how representing the diversity of arctic vegetation and confronting models with measurements from varied plant communities improves the representation of arctic vegetation in terrestrial ecosystem models.

Making the most of your pollinators: An epiphytic fig tree encourages its pollinators to roam between figs.

Ficus species are characterized by their unusual enclosed inflorescences (figs) and their relationship with obligate pollinator fig wasps (Agaonidae). Fig trees have a variety of growth forms, but true epiphytes are rare, and one example is Ficus deltoidea of Southeast Asia. Presumably as an adaptation to epiphytism, inflorescence design in this species is exceptional, with very few flowers in female (seed‐producing) figs and unusually large seeds. Figs on male (pollinator offspring‐generating) trees have many more flowers. Many fig wasps pollinate one fig each, but because of the low number of flowers per fig, efficient utilization by F. deltoidea's pollinators depends on pollinators entering several female figs. We hypothesized that it is in the interest of the plants to allow pollinators to re‐emerge from figs on both male and female trees and that selection favors pollinator roaming because it increases their own reproductive success. Our manipulations of Blastophaga sp. pollinators in a Malaysian oil palm plantation confirmed that individual pollinators do routinely enter several figs of both sexes. Entering additional figs generated more seeds per pollinator on female trees and more pollinator offspring on male trees. Offspring sex ratios in subsequently entered figs were often less female‐biased than in the first figs they entered, which reduced their immediate value to male trees because only female offspring carry their pollen. Small numbers of large seeds in female figs of epiphytic F. deltoidea may reflect constraints on overall female fig size, because pollinator exploitation depends on mutual mimicry between male and female figs.

The PhenObs initiative: A standardised protocol for monitoring phenological responses to climate change using herbaceous plant species in botanical gardens

Abstract Changes in phenology induced by climate change occur across the globe with important implications for ecosystem functioning and services, species performance and trophic interactions. Much of the work on phenology, especially leaf out and flowering, has been conducted on woody plant species. Less is known about the responses in phenology of herbaceous species induced by global change even though they represent a large and important part of biodiversity worldwide. A globally coordinated research effort is needed to understand the drivers and implications of such changes and to predict effects of global change on plant species phenology and related ecosystem processes. Here, we present the rationale of the PhenObs initiative—botanical gardens as a global phenological observation network. The initiative aims to collect data on plant phenology in botanical gardens which will be used alongside information on plant traits and site conditions to answer questions related to the consequences of global change: What is the variation in plant phenology in herbaceous species across the growing season and in response to changes in climate? How can plant phenology be predicted from species’ trait composition, provenance, position and extent of the distribution range and species’ phylogeny? What are the implications of this variation with respect to species performance and assembly, biotic interactions (e.g. plant–pollinator interactions) as well as ecosystem processes and services under changing land use and climate? Here, we lay out the development of a straightforward protocol that is appropriate for monitoring phenology across a vast diversity of growth forms of herbaceous species from various habitats and geographical regions. To focus on a key number of stages necessary to capture all aspects of plant species phenology, we analysed associations between 14 phenological stages. These data were derived from a 2‐year study on 199 species in four German botanical gardens. Based on the relationships of the phenological stages, we propose to monitor three vegetative stages (‘initial growth’, ‘leaves unfolding’ and ‘senescence’) and two reproductive stages (‘flowers open’ and ‘ripe fruits’) to fully capture herbaceous species phenology. A free Plain Language Summary can be found within the Supporting Information of this article.

<strong>DIVERSITY AND DISTRIBUTION OF NIGERIAN LEGUMES (FABACEAE)</strong>

This study provides the first comprehensive checklist and analysis of the species of Fabaceae from Nigeria, based on over 5000 herbarium collections and the completed "Flora of West Tropical Africa (FWTA)". We report 552 taxa, belonging to 540 species in 155 genera from six subfamilies, with an outstanding number of taxa (36) representing new records for the country. We mapped the distribution of the species using their occurrence records obtained from GBIF and our own field and herbarium collections. The majority of taxa (43%) was distributed in the savanna vegetation of northern Nigeria, followed by the adjacent tropical forest formations of southern Nigeria (34%), and they were found in highest percentages in Papilionoideae (67%) and Caesalpinioideae (19%), followed by Deterioideae (11%), Cercidoideae and Dialioideae (6% each) and Duparquetioideae (<1%) subfamilies. Endemic and native taxa were 5 and 73% respectively. The most prevalent subfamilies in terms of endemicity were Papilionoideae (14 species), and Deterioideae (11 species), while the most prevalent genera were Indigofera (three species), Dalbergia (three species), Brachystegia (two species) and Cryptosepalum (two species). We found that the majority (37%) of the species were phanerophytes and the fewest were cryptophytes (0.7%). These results suggest that Nigeria has a considerable diversity of legumes, with a predominant distribution in the savanna, probably due to the demanding environmental conditions limiting the dispersion of generalists or invasive species. The diversity of growth forms and distribution patterns of Nigerian legumes could be useful in screening these plants for other potential uses, such as conservation planning or specific agricultural purposes. We recommend a similar study on other families as this will help locals, natural scientists, governments and conservation bodies to recognise and appreciate the flora of the country.

The response of lichen growth forms to fire frequency: a case study in oak forests of the southern Russian Far East

Epiphytic lichens are used as sensitive indicators of environmental changes. Lichen growth forms are related to biotic and abiotic factors. In the present study, we investigate the response of lichen growth form diversity to fire frequency. In the oak forests of the southern Primorsky Krai, we established 43 sampling plots of 25 m x 25 m each. All plots were assigned to four fire history regimes defined by the combination of fire marks. A total of 168 epiphytic lichen species were recorded. They were classified into 12 groups of growth forms. The linear regression model demonstrated that the taxonomic diversity of epiphytic lichens and the growth form diversity were highly and positively correlated. Increasing fire frequency resulted in limited damage to growth form diversity of the epiphytic lichen communities, whereas species diversity drastically decreased with increasing fire frequency. The diversity of most growth form groups were connected with the gradient of fire frequency. Diversity of growth forms tolerant to a wide environmental variety, such as foliose species with narrow lobes, crustose granular verrucose, and compact crustose, drastically decreased under regular fire events. In contrast, growth forms adapted to sheltered and humid environments, such as foliose gelatinous, foliose inflated, and foliose with broad lobes, were absent on the plots with regular and frequent fire events. Thus, due to the close relationship between morphological traits and specific environmental conditions, certain groups of growth forms can be used as indicators of fire regimes of forests.

NATIVE VASCULAR FLORA OF BEHALI RESERVE FOREST (ASSAM, INDIA) WITH GLOBAL IUCN RED LIST ASSESSMENT OF TWO ENDEMIC SPECIES

The investigations of flora and fauna in Protected Areas provide important contributions to the knowledge on the status of unmanaged natural ecosystems. In 2017–2019, we studied the vascular plant flora of Behali Reserve Forest (Assam, India). The reserve forest covers 140.16 km2 area of semi-evergreen forest. We investigated the taxonomic composition of the flora and diversity of growth forms of species and habitats. In addition, we conducted global IUCN Red List assessment of two endemic species, Aristolochia assamica and Chlorophytum assamicum. We found that the vascular plant flora of Behali Reserve Forest consists of 281 taxa, including 272 species, one subspecies and eight varieties. They belong to 206 genera and 79 families. Among them, Pandanus unguifer was recorded for the first time for the flora of Assam. In growth form spectrum of vascular plants, trees, vines and shrubs predominated, followed by epiphytes, forbs or herbs, geophytes, annuals and parasites. The largest number of vascular plants was found in dense forests, while open habitats were characterized by the smallest species richness. Chlorophytum assamicum is assessed as CR B1ab(iii)+2ab(iii); D, and Aristolochia assamica as EN B2ab(iii). At the same time, there is a threat of reduction or disappearance of their populations. This is especially crucial for C. assamicum, represented by a single world population. Undoubtedly, further investigations of flora could result in an increase in number of the vascular plant flora of Behali Reserve Forest, as well as providing essential insights into population trends of several other species as per IUCN Red List categories and criteria.

Post‐fire changes in plant growth form composition and diversity in Andean páramo grassland

AbstractQuestionsFire suppression policies have been widely adopted in the páramo grasslands of the northern Andes to protect their biodiversity and ecosystem services. Páramos have been regularly burned for many years, and it is not clear how páramo vegetation will respond to significant changes in their fire regimes. This study investigates differences in plant growth form composition, light levels and soil temperatures in páramo plots representing a range of recovery times since the last fire.LocationReserva Ecológica El Ángel and La Bretaña Nature Reserve, Carchi, Northern Ecuador.MethodsWe assessed the frequency of ten páramo growth forms, vegetation height, soil temperature, and light intensity in fifteen fire sites with historical records of fire (<1–15 years since fire), and one recently unburned site (at least 40 years since fire). A chronosequence of sites was used to assess potential changes in plant community composition in post‐fire succession of páramo.ResultsThe recovery of páramo vegetation after fire comprised three phases: initial recruitment with high growth form diversity, followed by reduced diversity, light and soil temperatures in dense tussock vegetation, and ultimately canopy height stratification with a return of diversity. All but one of the plant growth forms were represented in each of the three phases, and the changes reflected differences in relative abundance.ConclusionsPost‐fire páramo succession is characterised by clear shifts in the relative abundance of plant growth forms, ending with (co‐)dominance of upright shrubs. The long‐term consequences of such shifts for biodiversity and ecosystem function, given the widespread adoption of fire suppression policies in the páramo, need careful, evidence‐based consideration.

Low soil disturbance during boreal forest well site development enhances vegetation recovery after 10 years

Boreal forests are increasingly exposed to industrial well site development. Little information exists on the optimal construction and reclamation strategies needed for vegetation recovery, including methods of well site preparation, soil storage, woody debris management, and revegetation. In this study we examined intermediate-term (10 yr) recovery of vegetation on 33 well sites distributed across NE Alberta, Canada, constructed and reclaimed using different site preparation methods, including high (HD), intermediate (ID), and low intensity (LD) disturbance of surface soils. Comparisons also included soil piling methods on HD sites, debris management on ID and LD sites, and tree planting on all sites. Comparisons were made to adjacent uncut forest to assess similarity, and at a subset of locations to harvested clear cuts. Ten years into recovery, vegetation was most similar between uncut forest and well sites developed using LD construction methods in species richness, diversity, and cover of vegetation growth forms and ground cover components (bare soil, litter, moss and lichen). Well sites using HD and ID had vegetation more dissimilar to uncut forest. Clear cuts harvested at the same time as the well sites also differed in composition from the forested controls, but remained more similar to the LD well sites than the HD and ID well sites. Effects of reforestation (tree planting), the technique of soil piling, and different forms of woody debris management (spreading vs windrowing) had little impact on vegetation recovery. Overall results highlight the importance of using LD well site preparation techniques where possible to keep mineral soil and embedded plant propagules intact to maximize boreal forest recovery following disturbance.

Patterns of plant species richness and growth form diversity in critical habitats of the Nama-Karoo Biome, South Africa

The distribution patterns and determinants of biodiversity in the Nama-Karoo Biome are poorly known. This poses a problem for conservation given the impact that future developments (e.g. uranium mining, fracking) and global climate change are likely to have on the region's biodiversity. This study investigated the potential role that several environmental and climatic variables play in determining species richness, relative cover, and growth form diversity in two habitat types: plains and rocky dolerite hillslopes. The study area extended over a 600 km longitudinal environmental gradient in the Upper Karoo in which mean annual precipitation varied from 100 to 600 mm from west to east. A pairwise floristic survey approach was implemented, using modified Whittaker plots in each habitat type at 30 sites within the shale gas exploration area in the Upper Karoo bioregion. The results showed that total species richness was significantly higher (p < 0.01) in slope habitats than in plains habitats across the environmental gradient. The greatest diversity in both habitat types in terms of species richness and relative cover was in the low woody shrubs growth form. Similar plant associations on slopes aggregated spatially and conformed closely to their respective vegetation types, while those in plains habitats were interspersed with no clear clustering. A combination of soil, environmental and climatic parameters emerged as significant explanatory variables for modelling total species richness and relative cover of the five dominant growth forms. Habitat type was a significant explanatory variable for total species richness and relative cover. In the current vegetation map of South Africa, the vegetation types for the Upper Karoo bioregion are coarse, giving the impression of homogeneity in what is a highly heterogeneous landscape. Further mapping of fine-scale biodiversity patterns is needed in order to better inform conservation and management practices in the Nama-Karoo Biome.

Identification of Conserved Gene-Regulatory Networks that Integrate Environmental Sensing and Growth in the Root Cambium

Cambium drives the lateral growth of stems and roots, contributing to diverse plant growth forms. The root crop is one of the outstanding examples of the cambium-driven growth. To understand its molecular basis, we used radish to generate a compendium of root-tissue- and stage-specific transcriptomes from two contrasting inbred lines during root growth. Expression patterns of key cambium regulators and hormone signaling components were validated. Clustering and gene ontology (GO) enrichment analyses of radish datasets followed by a comparative analysis against the newly established Arabidopsis early cambium data revealed evolutionary conserved stress-response transcription factors that may intimately control the cambium. Indeed, an invivo network consisting of selected stress-response and cambium regulators indicated ERF-1 as a potential key checkpoint of cambial activities, explaining how cambium-driven growth is altered in response to environmental changes. The findings here provide valuable information about dynamic gene expression changes during cambium-driven root growth and have implications with regard to future engineering schemes, leading to better crop yields.

Species richness and phylogenetic diversity of different growth forms of angiosperms across a biodiversity hotspot in the horn of Africa

AbstractWoody and herbaceous plants are differentially influenced by the environment, with non‐random association with the evolutionary history of these taxa and their traits. In general, woody plants may have climate‐dominated niches, whereas herbaceous plants may have edaphic and microhabitat‐dominated niches. Here, we explored and mapped how the patterns of species richness, phylogenetic diversity, and structures of total, woody, and herbaceous plants vary across the geographical regions and with respect to 12 environmental variables across Ethiopia and Eritrea, in the horn of Africa. Our result showed that both richness and phylogenetic diversity had almost the same tendency in total woody and herbaceous plants, in which they showed positive relationships with annual precipitation, precipitation annual range of climate, all the three variables of topography, and total nitrogen and total extractable phosphorus of soil, and negative relations with mean annual temperature. Compared with the total and herbaceous plants, the environmental variables explained greater variance both in the standardized effect size phylogenetic diversity and net relatedness index for woody plants. Our results highlight that, on the large spatial scales, the environmental filtering process has played a greater role in structuring species into local communities for woody plants than for herbaceous plants.

Seeing beyond the trees: a comparison of tropical and temperate plant growth forms and their vertical distribution.

Forests are the most diverse and productive terrestrial ecosystems on Earth, so sustainably managing them for the future is a major global challenge. Yet, our understanding of forest diversity relies almost exclusively on the study of trees. Here, we demonstrate unequivocally that other growth forms (shrubs, lianas, herbs, epiphytes) make up the majority of vascular plant species in both tropical and temperate forests. By comparing the relative distribution of species richness among plant growth forms for over 3,400 species in 18 forests in the Americas, we construct the first high-resolution quantification of plant growth form diversity across two ecologically important regions at a near-continental scale. We also quantify the physical distribution of plant species among forest layers, that is, where among the vertical strata plants ultimately live their adult lives, and show that plants are strongly downshifted in temperate forests vs. tropical forests. Our data illustrate a previously unquantified fundamental difference between tropical and temperate forests: what plant growth forms are most speciose, and where they ultimately live in the forest. Recognizing these differences requires that we re-focus ecological research and forest management plans to encompass a broader suite of plant growth forms. This more holistic perspective is essential to conserve global biodiversity.

Changes in niche differentiation and environmental filtering over a hydric stress gradient

AbstractAimsDiversity in communities is determined by species’ ability to coexist with each other and to overcome environmental stress that may act as an environmental filter. Niche differentiation (ND) results in stronger intra- than interspecific competition and promotes coexistence. Because stress affects interactions, the strength of ND may change along stress gradients. A greater diversity of plant growth forms has been observed in stressful habitats, such as deserts and alpine regions, suggesting greater ND when stress is strong. We tested the hypothesis that niche differences and environmental filters become stronger with stress.MethodsIn a semiarid grassland in southern Mexico, we sowed six annual species in the field along a hydric stress gradient. Plants were grown alone (without interactions), with conspecific neighbors (intraspecific interactions) or with heterospecific neighbors (interspecific interactions). We analyzed how the ratio of intra- to interspecific competition changed along the gradient to assess how water availability determines the strength of ND. We also determined if hydric stress represented an environmental filter.Important FindingsWe observed stronger intra- than interspecific competition, especially where hydric stress was greater. Thus, we found ND in at least some portion of the gradient for all but one species. Some species were hindered by stress, but others were favored by it perhaps because it eliminates soil pathogens. Although strong ND was slightly more frequent with stress, our species sample was small and there were exceptions to the general pattern, so further research is needed to establish if this is a widespread phenomenon in nature.

Genome-wide identification, phylogeny, and expression analysis of the SBP-box gene family in Euphorbiaceae

BackgroundEuphorbiaceae is one of the largest families of flowering plants. Due to its exceptional growth form diversity and near-cosmopolitan distribution, it has attracted much interest since ancient times. SBP-box (SBP) genes encode plant-specific transcription factors that play critical roles in numerous biological processes, especially flower development. We performed genome-wide identification and characterization of SBP genes from four economically important Euphorbiaceae species.ResultsIn total, 77 SBP genes were identified in four Euphorbiaceae genomes. The SBP proteins were divided into three length ranges and 10 groups. Group-6 was absent in Arabidopsis thaliana but conserved in Euphorbiaceae. Segmental duplication played the most important role in the expansion processes of Euphorbiaceae SBP genes, and all the duplicated genes were subjected to purify selection. In addition, about two-thirds of the Euphorbiaceae SBP genes are potential targets of miR156, and some miR-regulated SBP genes exhibited high intensity expression and differential expression in different tissues. The expression profiles related to different stress treatments demonstrated broad involvement of Euphorbiaceae SBP genes in response to various abiotic factors and hormonal treatments.ConclusionsIn this study, 77 SBP genes were identified in four Euphorbiaceae species, and their phylogenetic relationships, protein physicochemical characteristics, duplication, tissue and stress response expression, and potential roles in Euphorbiaceae development were studied. This study lays a foundation for further studies of Euphorbiaceae SBP genes, providing valuable information for future functional exploration of Euphorbiaceae SBP genes.

Species-Specific Responses of Submerged Macrophytes to Simulated Extreme Precipitation: A Mesocosm Study

More frequent extreme climate events (e.g., extreme precipitation) are to be expected in the future, and such events may potentially have significant effects on freshwater ecosystems. In the present mesocosm study, the effects of simulated extreme precipitation on submerged macrophytes were evaluated for three different macrophyte community (MC) treatments (MC1, MC2 and MC3). MC1 consisted of only Vallisneria denseserrulata, while MC2 and MC3 included three and six species of various growth forms. Two treatments of extreme precipitation (EP) were simulated—an extreme treatment (E) simulating a sudden increase of water level from 75 cm to 150 cm within one day and a gradual treatment (G) simulating an increase to the same water level within 3 months, combined with two control treatments. Total macrophyte community biomass was resilient to the EP and MC treatments, while species-specific variations in responses, in terms of biomass, maximum height, and sexual reproduction, were found. For instance, E led to earlier flowering of Potamogeton lucens and production of more flowers, while it had adverse effects on the flowering of Ottelia alismoides. We conclude that freshwater ecosystems with high coverage of submerged macrophytes may be overall resilient to extreme precipitation under nutrient-limited conditions, especially communities with diverse growth forms.

A new approach for modelling water transport in fossil plants

ABSTRACTThe origin of xylem in the Silurian was a major step in plant evolution, leading to diverse growth forms with various mechanical and hydraulic properties. In the fossil record, these properties can only be investigated using models based on extant plant physiology. Regarding hydraulics, previous studies have considered either the properties of a single tracheid or of a set of independent tubes. Here, we use the analogy between the flow of water under tension in a plant and an electrical circuit to develop an extension of Wilson’s single tracheid model to the tissue scale. Upscaling to the tissue-level allows considering wood as a heterogeneous tissue by taking into account differences in tracheid density and the presence of rays. The new model provides a more biologically accurate representation of fossil wood hydraulic properties. The single tracheid and new tissue models are applied to two conspecific specimens of Callixylon (Progymnospermopsida, Archeopteridales) from the Late Devonian of Morocco. Differences are shown at the tissue level that cannot be suspected at the single tracheid level. Callixylon represents the first trees with a conifer-like wood and is a major component of Late Devonian floras world-wide. Our results show that the anatomical disparity of its wood might have led to hydraulic plasticity, allowing growth in various environmental conditions. More generally, the new tissue-model suggests that the various combinations of tracheid and ray sizes present in Palaeozoic plants might have led to a higher variety of ecophysiologies than suspected based solely on the properties of individual tracheids.