A simple model for the influence of habitat resource availability on lateral clonal spread

The shape of root systems in a mountain meadow: plastic responses or species-specific architectural blueprints?

The efficient uptake of nutrients depends on the ability of roots to respond to gradients of these resources. Although pot experiments have shown that species differ in their ability to proliferate their roots in nutrient-rich patches, the role of such differences in determining root shapes in the field is unclear. We used fine-scale quantitative (q)PCR-based species-specific mapping of roots in a grassland community to reconstruct species-specific root system shapes. We linked them with data from pot experiments on the ability of these species to proliferate in nutrient-rich patches and their rooting depth. We found remarkable diversity in root system shapes, from cylindrical to conical. Interspecific differences in rooting depths in pots were the main determinant of rooting depths in the field, whereas differences in foraging ability played only a minor role. Although some species with strong foraging ability did place their roots into nutrient-rich soil layers, it was not a universal pattern. The results imply that although the vertical differentiation of grassland species is pronounced, it is primarily not driven by the differential plastic response of species to soil nutrient gradients. This may constrain the coexistence of species with similar rooting depths and may instead favour coexistence of species differing in their architectural blueprints.

A starting guide to root ecology: strengthening ecological concepts and standardising root classification, sampling, processing and trait measurements

In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting-edge, meaningful and integrated knowledge. Consideration of the below-ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below-ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below-ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine-root vs coarse-root approach; (2) considering the specificity of root research to produce sound laboratory and field data; (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage); and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I-VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers' views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning.

A starting guide to root ecology: strengthening ecological concepts and standardising root classification, sampling, processing and trait measurements

In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting-edge, meaningful and integrated knowledge. Consideration of the below-ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below-ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below-ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine-root vs coarse-root approach; (2) considering the specificity of root research to produce sound laboratory and field data; (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage); and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I-VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers' views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning.

Evolution of clonal growth forms in angiosperms

Clonal growth of plants is attained by a number of morphologically different organs (e.g. stolons, rhizomes, and roots), which are not functionally equivalent. Consequently, these clonal growth organ (CGO) types can determine functional traits that are associated with clonality, although little is known about their evolutionary flexibility or the constraining role they play on clonal traits. We investigated the rates of evolutionary change by which individual CGOs are acquired and lost using a set of 2652 species of Central European flora. Furthermore, we asked how these individual CGOs constrain functionally relevant clonal traits, such as lateral spread, number of offspring, and persistence of connections. We show that plants can easily switch in evolution among individual types of CGO and between clonal and nonclonal habits. However, not all these transitions are equally probable. Namely, stem-based clonal growth and root-based clonal growth constitute evolutionarily separate forms of clonal growth. Clonal traits are strongly constrained by individual CGO types. Specifically, fast lateral spread is attained by stolons or hypogeogenous rhizomes, and persistent connections are attained by all rhizome types. However, the ease with which clonal organs appear and disappear in evolution implies that plants can overcome these constraints by adjusting their morphologies.

Survival and Growth of Epiphytic Ferns Depend on Resource Sharing

Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing) on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets) and another on groups (several ramets within a plot), with severed and intact rhizome treatments (without and with physiological integration) on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium) in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration) significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time.