Evolution of clonal growth forms in angiosperms

Tuber, or not tuber: Molecular and morphological basis of underground storage organ development

Underground storage organs occur in phylogenetically diverse plant taxa and arise from multiple tissue types including roots and stems. Thickening growth allows underground storage organs to accommodate carbohydrates and other nutrients and requires proliferation at various lateral meristems followed by cell expansion. The WOX-CLE module regulates thickening growth via the vascular cambium in several eudicot systems, but the molecular mechanisms of proliferation at other lateral meristems are not well understood. In potato, onion, and other systems, members of the phosphatidylethanolamine-binding protein (PEBP) gene family induce underground storage organ development in response to photoperiod cues. While molecular mechanisms of tuber development in potato are well understood, we lack detailed mechanistic knowledge for the extensive morphological and taxonomic diversity of underground storage organs in plants.

Belowground morphology as a clue for plant response to disturbance and productivity in a temperate flora

Plants possess a large variety of nonacquisitive belowground organs, such as rhizomes, tubers, bulbs, and coarse roots. These organs determine a whole set of functions that are decisive in coping with climate, productivity, disturbance, and biotic interactions, and have been hypothesized to affect plant distribution along environmental gradients. We assembled data on belowground organ morphology for 1712 species from Central Europe and tested these hypotheses by quantifying relationships between belowground morphologies and species optima along ecological gradients related to productivity and disturbance. Furthermore, we linked these data with species co-occurrence in 30 115 vegetation plots from the Czech Republic to determine relationships between belowground organ diversity and these gradients. The strongest gradients determining belowground organ distribution were disturbance severity and frequency, light, and moisture. Nonclonal perennials and annuals occupy much smaller parts of the total environmental space than major types of clonal plants. Forest habitats had the highest diversity of co-occurring belowground morphologies; in other habitats, the diversity of belowground morphologies was generally lower than the random expectation. Our work shows that nonacquisitive belowground organs may be partly responsible for plant environmental niches. This adds a new dimension to the plant trait spectrum, currently based on acquisitive traits (leaves and fine roots) only.

Comparison of Growth and Physiological Effects of Soil Moisture Regime on Plantago maritima Plants from Geographically Isolated Sites on the Eastern Coast of the Baltic Sea

The aim of the present study was to evaluate the morphological and physiological responses of P. maritima plants from five geographically isolated sites growing in habitats with different conditions to different substrate moisture levels in controlled conditions. Plants were produced from seed and cultivated in a greenhouse at four relatively constant soil moisture regimes: at 25, 50, and 75% soil water content and in soil flooded 3 cm above the surface (80% F). The two morphological traits that varied most strikingly among P. maritima accessions were the number of flower stalks and the number of leaves. Only plants from two accessions uniformly produced generative structures, and allocation to flowering was suppressed by both low moisture and flooding. Optimum shoot biomass accumulation for all accessions was at 50 and 75% soil moisture. The Performance Index Total was the most sensitive among the measured photosynthesis-related parameters, and it tended to decrease with an increase in soil water content for all P. maritima accessions. The initial hypothesis-that plants from relatively dry habitats will have a higher tolerance against low soil water levels, but plants from relatively wet habitats will have a higher tolerance against waterlogged or flooded soil-was not proven. The existence of three ecotypes of P. maritima within the five accessions from geographically isolated subpopulations on the eastern coast of the Baltic Sea at the level of morphological responses to soil water content can be proposed. P. maritima plants can be characterized as extremely tolerant to soil waterlogging and highly tolerant to soil flooding and low soil water content.

Functional and ecological diversification of underground organs in Solanum

The evolution of geophytes in response to different environmental stressors is poorly understood largely due to the great morphological variation in underground plant organs, which includes species with rhizomatous structures or underground storage organs (USOs). Here we compare the evolution and ecological niche patterns of different geophytic organs in Solanum L., classified based on a functional definition and using a clade-based approach with an expert-verified specimen occurrence dataset. Results from PERMANOVA and Phylogenetic ANOVAs indicate that geophytic species occupy drier areas, with rhizomatous species found in the hottest areas whereas species with USOs are restricted to cooler areas in the montane tropics. In addition, rhizomatous species appear to be adapted to fire-driven disturbance, in contrast to species with USOs that appear to be adapted to prolonged climatic disturbance such as unfavorable growing conditions due to drought and cold. We also show that the evolution of rhizome-like structures leads to changes in the relationship between range size and niche breadth. Ancestral state reconstruction shows that in Solanum rhizomatous species are evolutionarily more labile compared to species with USOs. Our results suggest that underground organs enable plants to shift their niches towards distinct extreme environmental conditions and have different evolutionary constraints.

The central role of stem cells in determining plant longevity variation

Vascular plants display a huge variety of longevity patterns, from a few weeks for several annual species up to thousands of years for some perennial species. Understanding how longevity variation is structured has long been considered a fundamental aspect of the life sciences in view of evolution, species distribution, and adaptation to diverse environments. Unlike animals, whose organs are typically formed during embryogenesis, vascular plants manage to extend their life by continuously producing new tissues and organs in apical and lateral directions via proliferation of stem cells located within specialized tissues called meristems. Stem cells are the main source of plant longevity. Variation in plant longevity is highly dependent on the activity and fate identity of stem cells. Multiple developmental factors determine how stem cells contribute to variation in plant longevity. In this review, we provide an overview of the genetic mechanisms, hormonal signaling, and environmental factors involved in controlling plant longevity through long-term maintenance of stem cell fate identity.

Wood anatomy and dendrochronological potentiality of some woody shrubs from the southern Mediterranean coast in Egypt

In tropical and subtropical regions, much research is still required to explore the dendrochronological potential of their trees. This study aims to evaluate the anatomical structure and dendrochronological potential of three Mediterranean desert shrubs in Egypt (Lycium schweinfurthii var. schweinfurthii, L. europaeum, and Calligonum polygonoides subsp. comosum) supported by X-ray density. The results showed that the target species had distinct growth rings at macroscopic and microscopic levels. The vessel traits reflected the adaptability of each species with the prevailing arid climate conditions. After the exclusion of the non-correlated series, we obtained three site chronologies that cover the years 2013-2022 for L. schweinfurthii, 2012-2022 for L. europaeum, and 2011-2022 for C. comosum. The mean series intercorrelation was 0.746, 0.564, and 0.683 for L. schweinfurthii, L. europaeum, and C. comosum, respectively. The EPS (expressed population signal) values ranged from 0.72 to 0.80, while the SNR (species-to-noise ratio) ranged from 9.1 to 21.5. Compiling all series of L. schweinfurthii raised the EPS value to 0.86. The chronologies developed for the studied species were relatively short since we dealt with multi-stemmed shrubs. The average percentage difference between latewood density (LWD) and earlywood density (EWD) in C. comosum, L. europaeum, and L. schweinfurthii were 11.8% ± 5.5, 5.2%± 1.87, and 3.6% ± 1.86, respectively. X-ray densitometry helped in the precise determination of the ring borders of the studied species. The relationships between the radial growth of the studied species and the climate variables were weak to moderate but mostly not significant (i.e., r < 0.7). Generally, the radial growth of the target species had a weak to moderate positive correlation with temperature and precipitation during the wet season (winter), while negatively correlated with temperature for the rest of the year, particularly in summer. Our data agrees with earlier findings that ring formation starts at the beginning of the long vegetative stage, then the rest of the assimilated carbohydrates are directed to the flowering and fruiting at the end of the vegetative stages. For more efficient dendrochronological studies on subtropical and Mediterranean trees, we recommend carrying out xylogenesis studies, collection of phenological data, sampling 45-80 trees per species, using new techniques, and choosing homogeneous and close sites for wood sampling.

Halophytic Clonal Plant Species: Important Functional Aspects for Existence in Heterogeneous Saline Habitats

Plant modularity-related traits are important ecological determinants of vegetation composition, dynamics, and resilience. While simple changes in plant biomass resulting from salt treatments are usually considered a sufficient indicator for resistance vs. susceptibility to salinity, plants with a clonal growth pattern show complex responses to changes in environmental conditions. Due to physiological integration, clonal plants often have adaptive advantages in highly heterogeneous or disturbed habitats. Although halophytes native to various heterogeneous habitats have been extensively studied, no special attention has been paid to the peculiarities of salt tolerance mechanisms of clonal halophytes. Therefore, the aim of the present review is to identify probable and possible halophytic plant species belonging to different types of clonal growth and to analyze available scientific information on responses to salinity in these species. Examples, including halophytes with different types of clonal growth, will be analyzed, such as based on differences in the degree of physiological integration, ramet persistence, rate of clonal expansion, salinity-induced clonality, etc.

A bump in the node: The hydraulic implications of rhizomatous growth

PREMISE

Rhizomatous growth characterizes numerous taxa among vascular plants. While abundant information exists on nutrient sharing and demography, the question of how these metameric organisms move water through their bodies remains largely unstudied. Moreover, we lack an understanding of the evolutionary implications of rhizomatous growth across vascular plants. Here, we examined these questions by investigating how rhizomatous growth and vascular construction affect whole-plant hydraulic function.

METHODS

In five terrestrial fern species with diverse vascular construction, we used microcomputed tomography and bright-field microscopy to examine vascular construction across nodes along the rhizome. These data were integrated with measurements of leaf stomatal conductance under rooted and uprooted conditions to relate vascular patterning and hydraulic architecture to leaf water status.

RESULTS

Similar to phytomers of woody seed plants, nodal regions in rhizomatous ferns are areas of hydraulic resistance. While water is shared along the rhizomes of these investigated species, hydraulic conductivity drops at nodes and stomatal conductance declines when nodes were locally uprooted. Together, our data suggest that nodes are chokepoints in axial water movement along the rhizome.

CONCLUSIONS

Nodal chokepoints decrease hydraulic integration between phytomers. At the same time, chokepoints may act as "safety valves", hydraulically localizing each phytomer-potentially decreasing embolism and pathogen spread. This suggests a potential trade-off in the principal construction of the fern rhizome. Moreover, we propose that shoot-borne roots (homorhizy) and the prostrate habit of rhizomatous ferns decrease the hydraulic and structural burdens that upright plants typically incur. The absence of these hydraulic and structural demands may be one reason ferns (and many rhizomatous plants) lack, or have minimally developed, secondary xylem.

What determines root-sprouting ability: Injury or phytohormones?

PREMISE

Root-sprouting (RS) is an evolutionarily independent alternative to axillary stem branching for a plant to attain its architecture. Root-sprouting plants are better adapted to disturbance than non-RS plants, and their vigor is frequently boosted by biomass removal. Nevertheless, RS plants are rarer than plants that are not root-sprouters, possibly because they must overcome developmental barriers such as intrinsic phytohormonal balance or because RS ability is conditioned by injury to the plant body. The objective of this study was to identify whether phytohormones or injury enable RS.

METHODS

In a greenhouse experiment, growth variables, root respiration, and phytohormones were analyzed in two closely related clonal herbs that differ in RS ability (spontaneously RS Inula britannica and rhizomatous non-RS I. salicina) with and without severe biomass removal.

RESULTS

As previously reported, I. britannica is a root-sprouter, but injury did not boost its RS ability. Root respiration did not differ between the two species and decreased continuously with time irrespectively of injury, but their phytohormone profiles differed significantly. In RS species, the auxins-to-cytokinins ratio was low, and injury further decreased it.

CONCLUSIONS

This first attempt to test drivers behind different plant growth forms suggests that intrinsic phytohormone regulation, especially the auxins-to-cytokinins ratio, might be behind RS ability. Injury, causing a phytohormonal imbalance, seems to be less important in spontaneously RS species than expected for RS species in general.

Effect of Rhizome Severing on Survival and Growth of Rhizomatous Herb Phragmites communis Is Regulated by Sand Burial Depth

Rhizome fragmentation and sand burial are common phenomena in rhizomatous clonal plants. These traits serve as an adaptive strategy for survival in stressful environments. Thus far, some studies have been carried out on the effects of rhizome fragmentation and sand burial, but how the interaction between rhizome fragmentation and sand burial affects the growth and reproduction of rhizomatous clonal plants is unclear. We investigated the effect of the burial depth and rhizome fragment size on the survival and growth of the rhizomatous herb Phragmites communis using 288 clonal fragments (6 burial depths × 8 clonal fragment sizes × 6 replicates) in a field rhizome severing experiment. The ramet survival of the rhizomatous species significantly increased with the sand burial depth and clonal fragment size (p < 0.01), and the effects of the clonal fragment size on ramet survival depended on the sand burial depth. Sand burial enhanced both the vertical and horizontal biomass (p < 0.05), while the clonal fragment size affected the vertical biomass rather than the horizontal biomass. Sand burial facilitated the vertical growth of ramets (p < 0.05) while the number of newly produced ramets firstly increased and then decreased with the increasing clonal fragment size, and the maximal value appeared in four clonal fragments under a heavy sand burial depth. There is an interaction between the burial depth and rhizome fragment size in the growth of rhizome herbaceous plants. The population growth increases in the increase of sand burial depth, and reaches the maximum under severe sand burial and moderate rhizome fragmentation.

Autopolyploid establishment depends on life-history strategy and the mating outcomes of clonal architecture

Polyploidy is a significant component in the evolution of many taxa, particularly plant groups. However, new polyploids face substantial fitness disadvantages due to a lack of same-cytotype mates, and the factors promoting or preventing polyploid establishment in natural populations are often unclear. We develop spatially explicit agent-based simulation models to test the hypothesis that a perennial life history and clonal propagation facilitate the early stages of polyploid establishment and persistence. Our models show that polyploids are more likely to establish when they have longer life spans than diploids, especially when self-fertilization rates are high. Polyploids that combine sexual and clonal reproduction can establish across a wide range of life histories, but their success is moderated by clonal strategy. By tracking individuals and mating events, we reveal that clonal architecture has a substantial impact on the spatial structure of the mixed diploid-polyploid population during polyploid establishment: altering patterns of mating within or between cytotypes via geitonogamous self-fertilization, the mechanisms through which polyploid establishment proceeds, and the final composition of the polyploid population. Overall, our findings provide novel insight into the role of clonal structure in modulating the complex relationship between polyploidy, perenniality, and clonality and offer testable predictions for future empirical work.

Fire exclusion changes belowground bud bank and bud-bearing organ composition jeopardizing open savanna resilience

Belowground bud bank regeneration is a successful strategy for plants in fire-prone communities. It depends on the number and location of dormant and viable buds stored on belowground organs. A highly diverse belowground bud-bearing organ system maintained by a frequent interval of fire events guarantees the supply of a bud bank that enables plants to persist and resprout after disturbance. We investigated how different fire exclusion and fire frequencies, affected the herbaceous layer in tropical savannas, by assessing belowground persistence and regeneration traits. Contrary to our hypothesis, we found that under a shorter fire exclusion period, the total bud bank increased at a lower fire frequency. But sites at longer fire exclusion and infrequent fire, the bud bank was smaller the longer the period since the last fire. However, the major shift was concerning organ diversity since fire exclusion was more related to loss of belowground diversity rather than decreasing of the belowground bud bank size. Furthermore, fire-associated bud-bearing structures like xylopodia disappeared in the fire suppressed areas, whereas clonal organs, such as rhizomes, developed in the bud bank. By quantifying belowground bud bank traits under different fire histories, we highlight the importance of the local fire regime on the composition of the belowground plant components, which can affect the tropical savanna aboveground plant community. Given that, loss of the belowground bud-bearing component of the plant community will have a direct effect on vegetation regeneration in post-fire environments, and consequently, on plant community resilience.

Comparative root anatomy and root bud development after injury in two perennial herbs

A bud bank is a pool of dormant meristems that enable plants to resprout after injury. While the bud bank on stem organs is established prior to injury as the stem grows, the bud bank on roots is considered at least partly formed as a response to disturbance events. To date, only woody species have been examined, and the establishment of reparative buds after injury without connection to the root vascular system has been confirmed; for herbs, no data are available. We tested whether root buds are formed spontaneously or induced after plant damage by studying root anatomy following plant injury in two congeneric perennial herbs. In a pot experiment with young plants of Inula britannica (root sprouter) and I. salicina (non-root sprouter), whole aboveground biomass was removed. Roots were sampled five times at 1-week intervals after disturbance events to evaluate bud occurrence and size, root and vessel diameters, sclerenchyma areas and carbohydrate storage. Compared to non-root-sprouting I. salicina, root-sprouting I. britannica presented more secondary thickening that was connected to adventitious bud formation and improved the root storage and transport capacity necessary for resprouting. Plant injury, in contrast to expectations, did not cause increased bud formation in I. britannica, and all buds were connected to the root vascular system. No root buds were observed in I. salicina. Our study implies that plants using bud banks on roots might depend on preformed buds. Comparative studies examining more species are needed to assess the generality of our findings.

The complete chloroplast genome sequence of Bolboschoenus planiculmis (Cyperaceae)

Bolboschoenus planiculmis is a typical wetland sedge with both ecological and agricultural value. We report the first complete chloroplast genome sequence of this species. The total genome size is 186,539 bp, containing a large single-copy region (LSC) of 104,654 bp, a small single copy region (SSC) of 9,659 bp and two inverted repeats (IRs) of 36,113 bp by each. The GC content is 33.59%. The genome encodes 105 unique genes, including 71 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Phylogenetic analysis shows this species has a strong sister relationship with Cyperus. Our work could be helpful in understanding the evolution of Cyperaceae.

Incorporating clonality into the plant ecology research agenda

A longstanding research divide exists in plant ecology: either focusing on plant clonality, with no ambition to address nonclonal plants, or focusing on all plants, ignoring that many ecological processes can be affected by the fact that some plants are clonal while others are not. This gap cascades into a lack of distinction and knowledge about the similarities and differences between clonal and nonclonal plants. Here we aim to bridge this gap by identifying areas that would benefit from the incorporation of clonal growth into one integrated research platform: namely, response to productivity and disturbance, biotic interactions, and population dynamics. We are convinced that this will provide a roadmap to gain valuable insights into the ecoevolutionary dynamics relevant to all plants.

Artificial selection optimizes clonality in chaya (Cnidoscolus aconitifolius)

The clonal propagation of crops offers several advantages to growers, such as skipping the juvenile phase, faster growth, and reduced mortality. However, it is not known if the wild ancestors of most clonal crops have a similar ability to reproduce clonally. Therefore, it is unclear whether clonality was an ancestral condition, or if it evolved during domestication in the majority of these crops. Here, I assessed some traits that are relevant to clonal propagation using stem cuttings from chaya (Cnidoscolus aconitifolius) and compared these traits to those of its wild ancestor. Chaya is highly relevant crop to food security in its domestication center (Yucatan Peninsula) and is now cultivated in several countries. Chaya is also an excellent model for assessing the effect of domestication on clonality because wild relatives and selection targets are known. Specifically, I compared resistance to desiccation, water and resource storage, as well as the production of new organs (shoots and leaves) by the stems of wild and domesticated plants. I also compared their performance in root development and clone survival. I found that, relative to their wild ancestors, the stem cuttings of domesticated chaya had 1.1 times greater storage capacity for water and starch. Additionally, the stems of domesticated plants produced 1.25 times more roots, 2.69 times more shoots and 1.94 more leaves, and their clones lived 1.87 times longer than their wild relatives. In conclusion, the results suggest that artificial selection has optimized water and starch storage by stems in chaya. Because these traits also confer greater fitness (i.e. increased fecundity and survival of clones), they can be considered adaptations to clonal propagation in the agroecosystems where this crop is cultivated.

Comparative analysis of root sprouting and its vigour in temperate herbs: anatomical correlates and environmental predictors

BACKGROUND AND AIMS

Root sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves as both a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, namely the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (1) whether the presence or absence of specific tissues in roots can promote or limit RS; and (2) whether there is some relationship between RS ability, RS vigour and species niche.

METHODS

We studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits and the relationship between RS and parameters of species niches.

KEY RESULTS

A quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern, but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats.

CONCLUSIONS

Our study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS - ability and vigour - should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats.

Epigenetics and the success of invasive plants

Biological invasions impose ecological and economic problems on a global scale, but also provide extraordinary opportunities for studying contemporary evolution. It is critical to understand the evolutionary processes that underly invasion success in order to successfully manage existing invaders, and to prevent future invasions. As successful invasive species sometimes are suspected to rapidly adjust to their new environments in spite of very low genetic diversity, we are obliged to re-evaluate genomic-level processes that translate into phenotypic diversity. In this paper, we review work that supports the idea that trait variation, within and among invasive populations, can be created through epigenetic or other non-genetic processes, particularly in clonal invaders where somatic changes can persist indefinitely. We consider several processes that have been implicated as adaptive in invasion success, focusing on various forms of 'genomic shock' resulting from exposure to environmental stress, hybridization and whole-genome duplication (polyploidy), and leading to various patterns of gene expression re-programming and epigenetic changes that contribute to phenotypic variation or even novelty. These mechanisms can contribute to transgressive phenotypes, including hybrid vigour and novel traits, and may thus help to understand the huge successes of some plant invaders, especially those that are genetically impoverished. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

Get the shovel: morphological and evolutionary complexities of belowground organs in geophytes

Herbaceous plants collectively known as geophytes, which regrow from belowground buds, are distributed around the globe and throughout the land plant tree of life. The geophytic habit is an evolutionarily and ecologically important growth form in plants, permitting novel life history strategies, enabling the occupation of more seasonal climates, mediating interactions between plants and their water and nutrient resources, and influencing macroevolutionary patterns by enabling differential diversification and adaptation. These taxa are excellent study systems for understanding how convergence on a similar growth habit (i.e., geophytism) can occur via different morphological and developmental mechanisms. Despite the importance of belowground organs for characterizing whole-plant morphological diversity, the morphology and evolution of these organs have been vastly understudied with most research focusing on only a few crop systems. Here, we clarify the terminology commonly used (and sometimes misused) to describe geophytes and their underground organs and highlight key evolutionary patterns of the belowground morphology of geophytic plants. Additionally, we advocate for increasing resources for geophyte research and implementing standardized ontological definitions of geophytic organs to improve our understanding of the factors controlling, promoting, and maintaining geophyte diversity.

Aging, stress, and senescence in plants: what can biological diversity teach us?

Aging, stress, and senescence in plants are interconnected processes that determine longevity. We focus here on compiling and discussing our current knowledge on the mechanisms of development that long-lived perennial plants have evolved to prevent and delay senescence. Clonal and nonclonal perennial herbs of various life forms and longevities will be particularly considered to illustrate what biological diversity can teach us about aging as a universal phenomenon. Source-sink relations and redox signaling will also be discussed as examples of regulatory mechanisms of senescence at the organ level. Whether or not effective mechanisms that biological diversity has evolved to completely prevent the wear and tear of aging will be applicable to human aging in the near future ultimately depends on ethical aspects.

Responses of Plant Bud Bank Characteristics to the Enclosure in Different Desertified Grasslands on the Tibetan Plateau

Asexual reproduction is the main mode of alpine plant reproduction, and buds play an important role in plant community succession. The purpose of this study is to explore whether the desertified grassland can recover itself through the existing bud bank. The bud bank composition, distribution and size of different desertified grasslands were studied using unit volume excavation on the Tibetan Plateau. The bud bank consisted of tiller, long and short rhizome buds, and more than 40% of buds were distributed in the 0-10 cm soil layer. Enclosure changed the bud density, distribution and composition. The bud densities were 4327 and 2681 No./m2 in light and middle desertified grasslands before enclosure, while that decreased to 3833 and 2567 No./m2 after enclosure. Tiller bud density and proportion of middle desertified grassland were the highest, increased from 2765 (31.26%, before enclosure) to 5556 No./m3 (62.67%, after enclosure). There were new grasses growing out in the extreme desertified grassland after enclosure. The meristem limitation index of moderate desertified grassland was the lowest (0.37), indicating that plant renewal was limited by bud bank. Plants constantly adjust the bud bank composition, distribution, and asexual reproduction strategy, and desertified grasslands can recover naturally, relying on their bud banks through an enclosure.

Young clonal and non-clonal herbs differ in growth strategy but not in aboveground biomass compensation after disturbance

Clonal plants have more traits enabling individual persistence (larger belowground storage of buds and assimilates), whereas non-clonal plants have more traits enabling population persistence (a higher reliance on regeneration from seeds). This difference presumably makes those groups respond differently to disturbance. We asked whether this difference is already expressed in the first year of the plant's life. In a pot experiment with 17 congeneric pairs of clonal and non-clonal herbs, we investigated response to a disturbance at the individual level. We were interested whether the leaf C/N ratio (a proxy reflecting active growth and photosynthetic efficiency), the R/S ratio (a proxy for belowground storage) and the amount of compensated biomass differ between clonal and non-clonal herbs. Moreover, we asked whether compensation for the loss of aboveground biomass after disturbance can be predicted by the R/S ratio or explained by the leaf C/N ratio. We found that clonal herbs have higher leaf C/N and R/S ratios than non-clonal herbs. Under disturbance, the leaf C/N and R/S ratios decreased in the clonal herbs and increased in the non-clonal herbs. However, the clonal and non-clonal plants did not differ in biomass compensation ability. Neither the R/S ratio nor the leaf C/N ratio explained the compensation abilities of the herbs. These results show that even though the growth strategies of clonal and non-clonal plants and their reactions to disturbance are different, the groups are similarly capable of compensating for the loss of aboveground biomass. Clonal plants do not have an advantage over non-clonal plants under disturbance during their first year of life.