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Although numerous studies have independently tested the roles of physiological integration and parental effects on the performance of clonal plant species, few have assessed them simultaneously. Moreover, the capacity for physiological integration differs greatly within species of clonal plants. We conducted a greenhouse experiment with eight genotypes of the clonal herb Hydrocotyle verticillata. In the first phase, we either severed or maintained the connections between the original proximal nodes (the basal portion) and the new distal nodes (the apical portion) of each genotype. In the second phase, the ramets in the apical portion produced in the first phase were selected and cultivated, and their connections were subjected to the same severance treatments. In the first phase, the negative effects of severance on the apical portion balanced the positive effects of severance on the basal portion, resulting in no net effect of severance on total mass, leaf mass, stem mass, and ramet number for the whole clone. In the second phase, the effects of parental severance on stem mass of the apical portion of H. verticillata varied among the eight genotypes. Additionally, the positive effect of physiological integration on offspring generations was greater in the apical portion and the whole clone of one genotype when the parental connections were intact than when they were severed, whereas it was greater in the apical portion of another genotype when the parental connections were severed than when they were intact. Our results suggest that clonal parental effects can influence the capacity for physiological integration of offspring generations and that these effects may differ among genotypes within a species. [ABSTRACT FROM AUTHOR]

Many invasive plants can reproduce through both seeds and clonal growth. In habitats, interacting seedlings may originate from the same mother, and interacting ramets originating from the same plant may not be adjacent to each other in the stolon, particularly for vines that can show curved growth. However, in a homogeneous environment, how kinship and integration between adjacent/non-adjacent ramets affect plant growth and feedback with soil biota has been less studied. We address these questions using an invasive stoloniferous vine Mikania micrantha. We found that sibling groups and stranger groups did not differ in biomass production, root allocation and feedback with soil biota, indicating that kin recognition is unlikely in M. micrantha. For two-ramet stolon fragments in which interacting ramets were adjacent to each other, older ramets allocated more biomass to roots than younger ramets when integrated, particularly in comparison with disconnected ramets from different genotypes, indicating that a division of labor was induced. For four-ramet stolon fragments in which there were two unrooted ramets between the two rooted, interacting ramets, integration increased biomass allocation to roots, possibly because only two of the four ramets could absorb belowground resources and a lower shoot allocation decreased aboveground light competition. When inoculated with soil biota conditioned by the four-ramet integrated fragments, plants of M. micrantha also increased biomass allocation to roots. These results indicate that the distance between interacting ramets in the stolon may affect the integration effect and feedback with soil biota in clonal plants. [ABSTRACT FROM AUTHOR]

Aims: N rhizodeposition plays a vital role in regulating rhizosphere soil N dynamics. However, its effects on the rhizosphere soil N cycle in clonal plants and the underlying mechanism remain unclear. Methods: 15N solutions with different concentrations were injected into young or connected mature ramets of Moso bamboo (Phyllostachys edulis), respectively, in the field, to explore the response of rhizosphere N transformation to N rhizodeposition. Results: 15N injection increased the 15N abundance in the rhizosphere soil of both young and mature ramets, with higher 15N abundance in 20–40-cm layer than that in 0–20-cm layer. Functional genes involved in nitrification and denitrification in the rhizosphere were upregulated when young ramets received low- and medium-N solutions. However, the genes showed diverse responses to high-N treatment in young ramets, with increased abundances of ammonia-oxidizing bacteria and decreased levels of ammonia-oxidizing archaea, comammox, and denitrifiers. In contrast, the functional genes involved in denitrification in the 20–40-cm layer of rhizosphere soil were upregulated by high-N treatment in mature ramets. Additionally, partial-least-squares path modeling revealed 15N abundance in the soil indirectly affected N mineralization, N mineralization directly affected nitrification, and nitrification directly affected denitrification in a positive manner. Conclusion: The variations of N rhizodeposition and transformation process in both connected ramets is highly consistent in responding to different N treatments, but the nitrifiers and denitrifiers in the deeper rhizosphere soil were more sensitive to N rhizodeposits than those in the upper rhizosphere soil. [ABSTRACT FROM AUTHOR]

Clonal integration is an important ecological advantage of clonal plants. To ask whether clonal integration can help invasive plants escape space limitations, we tested the hypothesis that it can promote the growth of apical ramets when their connected basal ramets grow in limited space. We conducted a greenhouse experiment on the common perennial herb Hydrocotyle vulgaris. Clonal fragments consisting of pairs of connected ramets grew with basal ramets in three different sizes of pots (small, medium, and large) and apical ramets in large pots, and the connection between ramets was either severed or left intact. Pot size significantly affected the growth of basal ramets such that the biomass, number of leaves and flowers, and stolon length were in general greater in medium pots than in large and small pots when stolons were intact and were greater in medium and large pots than in small pots when stolons were severed. Furthermore, pot size interacted with severance to affect the performance of H. vulgaris. When the basal ramets grew in small pots, the intact stolon resulted in a significant promotion of apical ramet growth, but such positive effect was not found when the basal ramets grew in medium and large pots. Our results suggest that H. vulgaris is able to promote the growth of apical ramets to occupy the surrounding areas through clonal integration when the space where basal ramets grow is limited. [ABSTRACT FROM AUTHOR]

Although numerous studies have independently tested the roles of physiological integration and parental effects on the performance of clonal plant species, few have assessed them simultaneously. Moreover, the capacity for physiological integration differs greatly within species of clonal plants. We conducted a greenhouse experiment with eight genotypes of the clonal herb Hydrocotyle verticillata. In the first phase, we either severed or maintained the connections between the original proximal nodes (the basal portion) and the new distal nodes (the apical portion) of each genotype. In the second phase, the ramets in the apical portion produced in the first phase were selected and cultivated, and their connections were subjected to the same severance treatments. In the first phase, the negative effects of severance on the apical portion balanced the positive effects of severance on the basal portion, resulting in no net effect of severance on total mass, leaf mass, stem mass, and ramet number for the whole clone. In the second phase, the effects of parental severance on stem mass of the apical portion of H. verticillata varied among the eight genotypes. Additionally, the positive effect of physiological integration on offspring generations was greater in the apical portion and the whole clone of one genotype when the parental connections were intact than when they were severed, whereas it was greater in the apical portion of another genotype when the parental connections were severed than when they were intact. Our results suggest that clonal parental effects can influence the capacity for physiological integration of offspring generations and that these effects may differ among genotypes within a species.

It is naturally common that different proportions of ramets in a clone lose rooting conditions due to habitat stress or obstacles, which potentially affects the overall growth of the clonal plant to different extents. However, so far, little attention has been paid to such phenomena and much less to the underlying ecological mechanisms. Taking Zoysia japonica as material, through an experiment with two nutrition levels in the habitats and five rooting ramet proportions in the clones, the impacts of proportions of rooting ramets in the clone on the overall growth were tested and the ecological mechanisms were analyzed. The results showed that there was no significant difference in the total clonal biomasses among the clones with five rooting ramet proportions under high and low nutrition levels, except for that with 0% rooting ramet proportion. Under both high and low nutrition levels, the lower rooting ramet proportions (0% and 25%) in the clones significantly decreased the number of the so‐called A‐ and B‐ramets, root biomass, stolon length per unit biomass, and root–shoot ratio, but significantly increased the stolon biomass of the clones. Stolon elongation was promoted under high nutrient level, and biomass allocations to stolons and roots increased under low nutrition levels. A‐ramet biomasses accounted for about 50% and 30% of the total biomasses of the whole clone under high and low nutrition levels, respectively. These results might be reasonably explained in terms of clonal integration, compensatory growth, division of labor, and bet‐hedging strategy. [ABSTRACT FROM AUTHOR]

Resistance traits of plants can be activated both at the damaged site and undamaged parts. Systemic resistance induced by local exogenous abscisic acid (ABA) application alleviated negative effect of low water availability on growth performance of clonal plant. However, timing of systemic resistance was poorly understood. Timing of systemic resistance refers to its activation and decay time within clonal network. Clonal fragment of Centella asiatica with four successive ramets (including first-oldest, second-older, third-old and fourthyoung ramets) subjected to low water availability (20% soil moisture content) was used to explore effects of local exogenous ABA application on the timing of resistance activation and decay. Systemic resistance activated by local exogenous ABA application after 4 days remained at least 28 days. Compared with control, biomass accumulation of whole clonal fragment, root biomass and ratio of belowground to aboveground biomass significantly increased by local exogenous ABA application after 28 days. It is suggested that rapid activation and delay of resistance response induced by local exogenous ABA application within clonal network may improve fitness of clonal plant subjected to abiotic stress. [ABSTRACT FROM AUTHOR]

Different sizes of clonal fragments contain various number of ramets with different spacer lengths, which strongly affects the redistribution of photosynthetic assimilates. Although clonal integration significantly affects rhizosphere processes via microbial enzymes under heterogeneous conditions, the effects of clonal fragment size (ramet number and spacer length) on rhizosphere N turnover processes remain poorly understood. Here, we sampled clonal fragments of Phyllostachys bissetii with different ramet numbers and spacer lengths to determine the relative effects of clonal integration and fragment size on rhizosphere processes and resource availability. We found that clonal integration had positive effects on the C and N availability of shaded ramets in clonal fragments with different ramet numbers, owing to the large resource storage in the fragment. However, it only promoted the dissolved organic carbon of the shaded ramets in clonal fragments with different spacer lengths. Results of regression analyses indicated that the response ratios of the soil variables of the shaded ramets first increased when the spacer length was about less than 30 cm and then decreased when the spacer became longer (about >30 cm), suggesting a cost–benefit tradeoff in the fragment. The contribution of the size of clonal fragment to the soil N turnover process was higher than that of clonal integration, whereas its contribution to soil C availability had the opposite effect. These results further revealed the mechanism of the size of clonal fragment in affecting the rhizosphere processes of stressed ramets, which is critical for the adaptation of P. bissetii to stressed habitats and further bamboo ecosystem N turnover under climate change. [ABSTRACT FROM AUTHOR]

Contexts: The expansion of fast-growing Moso bamboo (Phyllostachys edulis) into forests is likely further favored by climate change, creating more transitional regions within forests. Such forest-bamboo transitional zones provide windows to look at ecological processes driving bamboo's interaction with competing species across space. Objectives: We tested the hypothesis that spatial patterns at different scales of the ecotone can inform bamboo's invasive spread and its competitive engulfing strategy, with the allocation of biomass and resources within a bamboo colony being a key life-history strategy to facilitate its spatial spread. Methods: We used remote sensing imagery and field survey data to analyze the dynamics of bamboo-tree transitional boundaries in Tianmu Mountain Nature Reserve (TMNR) in southeastern China. We evaluated bamboo's spatial spread and its allocation of resources along the transitional gradient. Results: Both remote sensing and field data showed bamboo recovery and advancement into tree territories after the extensive logging of bamboo but with a slower spread compared to historical records. The spatial distributions of bamboo and tree stems were not random at their transitional interfaces and were affected by competition. Successful bamboo expansion into trees required close coordination between stems and rhizomes within a colony, as they served different functions in clonal integration. Conclusions: Our study initiates a scale-dependent analysis of shifts in bamboo-tree boundaries, which provides insights on how to accurately predict future bamboo distributions under climate change accounting for interspecific competition and bamboo's clonal integration of resources. [ABSTRACT FROM AUTHOR]

Background and aims: Clonal integration between ramets under heterogeneous environment has crucial implications for the clonal plants, is widely distribute in the arid ecosystems because it helps to transfer water and nutrients from the habitats with high moisture or fertility to lower ones. How the clonal integration affects the plant productivity and nutrient uptake under heterogeneous environment still remains unclear. Methods: Leymus chinensis and the neighbouring Stipa grandis grew at two soil moisture environments (homogeneous water content: 8% in both the donor and recipient compartments; or heterogeneous water content: 16% in the donor and 8% in the recipient compartments) and two root connections (connected or severed L. chinensis). After 4 weeks of growth, the plants of donor L. chinensis were labelled with either 15NH4+ or 15NO3−. Results: The biomass of recipient L. chinensis and S. grandis and N uptake rate by S. grandis were larger under heterogeneous water water content with connected roots than that with severed roots. The NO3− uptake rate was 40 times faster than that of NH4+ by all the plants irrespective of soil moisture condition and root connection. Consequently, clonal integration increased N translocation from donor to recipient ramets and subsequent N utilization by neighbouring S. grandis. Unexpectedly, NH4+ uptake by recipient L. chinensis with severed roots was 1.5 times faster than that with connected roots under homogeneous environment, this largely ascribed to that the translocation of NH4+ from donor to recipient L. chinensis through common mycorrhizal networks (CMNs). Conclusions: Clonal integration increases plant biomass and N uptake in heterogeneous environment and weakens them in homogeneous environment. Plants prefer direct NO3− uptake, whereas arbuscular mycorrhizal fungi preferentially translocate NH4+ to recipient clonal ramets. These findings indicate that clonal plants rely on the clonal integration of clonal roots and CMNs to acquire N from soil. [ABSTRACT FROM AUTHOR]

Introduction: Clonal integration of connected ramets within clones is an important ecological advantage. In this study, we tested the hypothesis that the effects of clonal integration on performance of donor and recipient ramets when one resource is heterogeneous can be influenced by the availability of another resource of donor ramets. Methods: We conducted a greenhouse experiment on the widespread, perennial herb Glechoma longituba. Clonal fragments consisting of pairs of connected ramets were grown for seven weeks. The younger, apical ramets were exposed under 30% or 100% light condition and the older, basal ramets were treated with three levels of nutrients. The connections between ramets were either severed or left intact. 30% light condition negatively affected the growth of apical ramets, basal ramets and the whole fragments. Results: Clonal integration significantly increased the growth of apical ramets, but decreased the growth of the basal ramets. Medium and high level nutrient availability of basal ramets significantly increased the growth of apical ramets, basal ramets and the whole fragments. At the high nutrient level, the reduction in growth of basal ramets from clonal integration was decreased, but the growth responses of apical ramets and the whole fragments to clonal integration were not influenced by nutrient availability. Conclusion: The results suggested that clonal integration was benefit to the growth of apical ramets of Glechoma longituba but at the cost of reducing the growth of basal ramets. Although the high nutrient level could reduce the cost that clonal integration brought to the unshaded basal ramets, but could not increase the benefit that clonal integration brought to the shaded apical ramets and whole fragment. [ABSTRACT FROM AUTHOR]

Aims: Small islands of safety, accompanied by clonal integration, could have important impacts on plant performance in stressful environments. Although the effects of environmental heterogeneity and clonal integration on clonal plant growth have been well studied, little attention has been paid to the impacts of islands of safety and the interaction with clonal integration on plant performance in the context of soil contamination. Methods: We conducted an experiment consisting of two soil treatments (with/without an island of safety, i.e., a patch with uncontaminated soil, located in the middle of cadmium-contaminated soil) and two stolon connection statuses (stolon between the mother ramets and their daughter ramets was either severed or kept connected) using the stoloniferous clonal plant Glechoma longituba. Results: Overall, the presence of the safe island significantly increased the number of ramets, total mass, leaf mass, and stolon mass of the daughter ramets and the whole clone. Clonal integration significantly decreased the number of ramets, total mass, leaf mass, and stolon mass of mother ramets. The presence of the island of safety enhanced total mass, leaf mass, and stolon mass of the mother ramet in the group with severed stolons and root mass and root to shoot ratio in the group with connected stolons. Conclusions: Building islands of safety can contribute to daughter ramet growth in a contaminated ecosystem, which suggests assembling smaller safe islands coupled with clonal plants with strong clonal integration may be a promising measure to vegetation restoration in heavy metal contaminated ecosystem. [ABSTRACT FROM AUTHOR]

Invasion success of clonal plants is closely related to their unique clonal life history, and clonal division of labor is a crucial clonal trait. However, so far, it is unclear whether invasive alien clonal species generally possess a greater capacity for division of labor than native species and whether this pattern is affected by environmental conditions. To test whether patch contrast affects the differences in the capacity for division of labor between invasive alien and native clonal plants, we selected five pairs of exotic invasive and native clonal plant species that are congeneric and co-occurring in China as experimental materials. We grew the clonal fragment pairs of these invasive and native plants under high, low, or no contrast of reciprocal patchiness of light and nutrient, respectively, with ramet connections either severed (division of labor prevented) or kept intact (division of labor allowed). The results showed that connection significantly decreased the proportion of biomass allocated to roots in distal (younger) ramets, whereas it increased in proximal (older) ramets of all studied plants under high -contrast treatments. This clear pattern strongly indicated the occurrence of division of labor. Furthermore, the connection had a more pronounced effect on the pattern of biomass allocation of invasive alien plants, resulting in a greater increase in biomass for invasive alien plants compared to native plants. These findings suggest that the invasive alien plants possess a greater capacity for division of labor, which may confer a competitive advantage to them over natives, thus facilitating their invasion success in some heterogeneous habitats such as forest edges where light and soil nutrients show a high negative correlation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Estuarine wetlands are highly heterogeneous due to strong interactions between freshwater input and seawater intrusion. However, little is known about how clonal plant populations adapt to heterogeneous salinity in soil environments. In the present study, the effects of clonal integration on Phragmites australis populations under salinity heterogeneity were studied using field experiments with 10 treatments in the Yellow River Delta. Clonal integration significantly increased plant height, aboveground biomass, underground biomass, root-shoot ratio, intercellular CO2 concentration, net photosynthetic rate, stomatal conductance, transpiration rate, and stem Na+ content under homogeneous treatment. Under the heterogeneous salt treatment, clonal integration significantly affected total aboveground and underground biomass, photosynthetic traits, and stem Na+ content under different salt gradients. The increase in salt concentration inhibited the physiological activity and growth of P. australis to varying degrees. Compared with the heterogeneous saline environment, clonal integration was more beneficial to P. australis populations in the homogeneous saline habitat. The results of the present study suggest that P. australis prefers homogeneous saline habitats; however, plants can adapt to heterogeneous salinity conditions via clonal integration. [ABSTRACT FROM AUTHOR]

Rhizomatous growth and associated physiological integration can allow a clonal dune species to potentially compensate for the selective removal of leaves associated with herbivory. Hydrocotyle bonariensis is a rhizomatous clonal plant species that is abundant in the coastal dune environments of the southeastern United States that are inhabited by large feral horse populations. H. bonariensis has been shown to integrate resources among ramets within extensive clones as an adaptation to resource heterogeneity in sandy soils. In this study, we hypothesized that clonal integration is a mechanism that promotes H. bonariensis persistence in these communities, despite high levels of herbivory by feral horses. In a field experiment, we used exclosures to test for herbivory in H. bonariensis over a four-month period. We found that feral horses utilized H. bonariensis as a food species, and that while grazing will suppress clonal biomass, H. bonariensis is able to maintain populations in a high grazing regime with and without competition present. We then conducted an experiment in which portions of H. bonariensis clones were clipped to simulate different levels of grazing. Half of the clones were severed to eliminate the possibility of integration. We found that after 12 weeks, the mean number of leaves and ramets increased as the grazing level increased, for integrated clones. Integrated clones had significantly increased biomass production compared to the severed equivalents. Our research suggests that rhizomatous growth and physiological integration are traits that allow clonal plant species to maintain populations and to tolerate grazing in coastal dune environments. [ABSTRACT FROM AUTHOR]

Background: Resource translocation among interconnected ramets can improve the growth performance of the recipient ramets and influence soil properties and microbial communities in the rooting zone. However, scanty attention has been paid to the effect of this clonal integration on soil biotic and abiotic characteristics of neighboring species around the recipient ramets. Methods: We conducted a soil heterogeneous experiment in which the mother ramet of the ramet pair for Vallisneria natans was planted in a high-nutrient patch, and the daughter ramet was planted in a low-nutrient patch with conspecific neighbors V. natans or heterospecific neighbors Myriophyllum spicatum. The stolons between ramet pairs were severed or left intact. Results: Our results showed that effects of clonal integration on growth of the daughter ramet depend on the identity of neighboring species. Overall growth of neighbors V. natans was not affected by clonal integration, while growth of neighbors M. spicatum was greatly reduced. Soil properties and microbial community composition (especially bacteria) in the rhizosphere of neighboring plants were significantly influenced by clonal integration, and these effects were more obvious in the rhizosphere of neighbor V. natans than those in the rhizosphere of neighbors M. spicatum. Conclusion: Our study suggests that clonal integration may play a vital role in facilitating nutrient cycling, modifying habitat heterogeneity and affecting interspecific interactions and even the community structure. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Clonal integration benefits clonal plants by buffering environmental stress and increasing resource extraction efficiency. However, the number of connected ramet generations that benefit from clonal integration in a clonal system has received relatively little attention. A pot experiment was conducted to evaluate the extent of physiological integration within the clonal system of Vallisneria natans consisting of a mother ramet and three sequentially connected offspring ramets. Mother ramets were grown in full sunlight, and offspring ramets were heavily shaded with limited light availability. Stolons between mother ramets and offspring ramets were severed or connected, but connection among the three offspring ramets remained. The photosynthetic ability of unshaded mother ramets of V. natans was significantly enhanced, but their biomass accumulation was greatly reduced when connected to shaded offspring ramets. Clonal integration significantly increased biomass accumulation, C and N availabilities, extracellular enzyme activities and microbial biomass of the first ramet generation (adjacent ramet), but not later ramet generations. Our results indicate that support from the mother ramet of V. natans may be limited to the adjacent offspring ramet in a clonal system under severe light stress, implying an effect of ramet generation. Our results contribute to a better understanding of the hierarchy and segmentation of clonal plants. These findings suggest that the extent of clonal integration plays a vital role in ecological interactions of the ramet population. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant invasion is one of the most serious threats to ecosystems worldwide. When invasive plants with the ability of clonal growth invading or colonizing in new habitat, their interconnected ramets may suffer from heterogeneous light. Effects of clonal integration on allelopathy of invasive plants are poorly understood under heterogeneous light conditions. To investigate the effects of clonal integration on allelopathy of invasive plant Wedelia trilobata under heterogeneous light conditions, a pot experiment was conducted by using its clonal fragments with two successive ramets. The older ramets were exposed to full light, whereas the younger ones were subjected to 20% full light. The younger ramets of each clonal fragment were adjacently grown with a target plant (one tomato seedling) in a pot. Stolon between two successive ramets was either severed or retained intact. In addition, two tomato seedlings (one as target plant) were adjacently grown in a pot as contrast. Compared with severing stolon, biomass accumulation, foliar chlorophyll and nitrogen contents, chlorophyll fluorescence parameters and net photosynthetic rates of the target plants as well as their root length and activity, were significantly decreased when stolon between interconnected ramets of W. trilobata retained intact. Under heterogeneous light conditions, transportation or sharing of carbohydrate between two successive ramets enhanced allelopathy of the young ramets subjected to 20% full light treatment. It is suggested that clonal integration may be important for invasion or colonization of invasive plants with ability of clonal growth under heterogeneous light conditions. [ABSTRACT FROM AUTHOR]

Aim: Soil abiotic and biotic conditions are often spatially variable, challenging plants with a heterogeneous environment consisting of favorable and unfavorable patches of soil. Many stoloniferous clonal plants can escape from unfavorable patches by elongating stolon internodes, but aggregate in favorable ones through shortening stolon internodes. However, whether the connected mother and daughter ramets of these plants can use their stolons to respond to plant-soil feedbacks (PSFs) is largely unknown. Methods: In the conditioning phase, we grew either Hydrocotyle vulgaris or Glechoma longituba clonal plants separately in mesocosms to condition bulk soil. In the feedback phase, we grew connected mother and daughter ramets of each species in soil inoculated with the unsterilized or sterilized soil conditioned by conspecifics. We grew the plants for 12 weeks and measured the growth of the mother and daughter ramets separately. Results: The daughter ramets of H. vulgaris produced more biomass, greater number of ramets and longer stolon internodes when grown in soil with sterilized inocula than with unsterilized inocula. However, no difference was found for the daughter ramets of G. longituba. In general, for both species, soil inoculum treatment on the mother ramet did not influence the performance of daughter or mother ramets. Conclusions: We conclude that biotic PSFs differed not only among different species, but also in physically-connected ramets of the same clone. Moreover, physiological integration or plasticity in stolon internode lengths cannot help H. vulgaris alleviate the negative effects of PSFs. [ABSTRACT FROM AUTHOR]

Rhizomatous growth and associated physiological integration can allow a clonal dune species to potentially compensate for the selective removal of leaves associated with herbivory. Hydrocotyle bonariensis is a rhizomatous clonal plant species that is abundant in the coastal dune environments of the southeastern United States that are inhabited by large feral horse populations. H. bonariensis has been shown to integrate resources among ramets within extensive clones as an adaptation to resource heterogeneity in sandy soils. In this study, we hypothesized that clonal integration is a mechanism that promotes H. bonariensis persistence in these communities, despite high levels of herbivory by feral horses. In a field experiment, we used exclosures to test for herbivory in H. bonariensis over a four-month period. We found that feral horses utilized H. bonariensis as a food species, and that while grazing will suppress clonal biomass, H. bonariensis is able to maintain populations in a high grazing regime with and without competition present. We then conducted an experiment in which portions of H. bonariensis clones were clipped to simulate different levels of grazing. Half of the clones were severed to eliminate the possibility of integration. We found that after 12 weeks, the mean number of leaves and ramets increased as the grazing level increased, for integrated clones. Integrated clones had significantly increased biomass production compared to the severed equivalents. Our research suggests that rhizomatous growth and physiological integration are traits that allow clonal plant species to maintain populations and to tolerate grazing in coastal dune environments.

Bamboos are fast-growing, aggressively-spreading, and invasive woody clonal species that often encroach upon adjacent tree plantations, forming bamboo–tree mixed plantations. However, the effects of bamboo invasion on leaf carbon (C) assimilation, and nitrogen (N) and phosphorus (P) utilization characteristics remains unclear. We selected four different stands of Pleioblastus amarus invading Chinese fir (Cunninghamia lanceolata) plantations to investigate the concentrations, stoichiometry, and allometric growth relationships of mature and withered leaves of young and old bamboos, analyzing N and P utilization and resorption patterns. The stand type, bamboo age, and their interaction affected the concentrations, stoichiometry and allometric growth patterns of leaf C, N, and P in both old and young bamboos, as well as the N and P resorption efficiency. Bamboo invasion into Chinese fir plantations decreased leaf C, N, and P concentrations, C:N and C:P ratios, N and P resorption efficiency, and allometric growth exponents among leaf C, N, and P, while it only slightly altered N:P ratios. PLS-PM analysis revealed that bamboo invasion negatively impacted leaf C, N, and P concentrations, as well as N and P utilization and resorption. The results indicate that high N and P utilization and resorption efficiency, along with the mutual sharing of C, N, and P among bamboos in interface zones, promote continuous bamboo expansion and invasion. Collectively, these findings highlight the significance of N and P utilization and resorption in bamboo expansion and invasion and provide valuable guidance for the establishment of mixed stands and the ecological management of bamboo forests. Bamboo (Pleioblastus amarus) invasion into Chinese fir (Cunninghamia lanceolata) plantations negatively impacts N and P utilization and resorption efficiency, and high nutrient utilization, resorption and clonal integration promote bamboo expansion and invasion. [Display omitted] • Bamboo invasion alters leaf C, N, and P concentrations, stoichiometry, N and P resorption, and allometric patterns. • High N and P utilization and resorption efficiency drive bamboo expansion and invasion. • Mutual nutrient sharing among bamboo ramets in interface zones promotes continuous bamboo expansion and invasion. • Understanding of bamboo invasion informs the establishment of mixed plantations and ecological management of bamboo stands. [ABSTRACT FROM AUTHOR]

The majority of problematic invasive plants exhibit clonal growth, and the clonal traits are widely recognized as critical determinants contributing to their invasiveness. Division of labor represents a crucial advantage associated with clonal growth; therefore, it is reasonable to anticipate that this particular trait may confer a growth advantage upon invasive clonal species in comparison to native ones. To test this hypothesis, we conducted a comparative experiment in the greenhouse involving the highly invasive plant Alternanthera philoxeroides , its native congener A. sessilis , and its native co-occurring Jussiaea repens. We grew clonal fragments of these three stoloniferous plants under negative spatial covariance of light and soil nutrients while either preventing or allowing division of labor through severing or keeping intact their stolon connections. The results showed that stolon connection significantly increased the root mass to shoot mass ratio of basal ramets under low light and high soil nutrient conditions, but greatly decreased it in the apical ramets under high light and low soil nutrient conditions, suggesting induced division of labor in all studied plants. Moreover, the invasive plant A. philoxeroides demonstrated a greater capacity for division of labor than its co-genus and co-occurring native partners, which conferred it with greater growth performance at the whole clonal fragment level. Given that the commonly observed competitive superiority of invasive clonal plants over co-occurring native species due to their high intrinsic growth rates, these findings suggest that the division of labor may confer a competitive advantage upon some invasive clonal plants, thereby facilitating their successful invasion in heterogeneous habitats characterized by a strong negative correlation between light availability and soil nutrient levels. • Division of labor is a critical clonal trait that affects the success of plant invasion. • Invasive plants may benefit from division of labor more than natives. • The division of labor was induced in all studied plants in heterogeneous habitats. • Greater specialization led to more biomass increase in an invasive plant compared to natives. • Division of labor may give invasive plants a competitive edge, aiding their invasion. [ABSTRACT FROM AUTHOR]

Tidal wetlands worldwide are undergoing rapid invasions by tall‐growing clonal grasses. Prominent examples are invasions by species of the genera Spartina, Phragmites and Elymus. The responsible physiological and ecological drivers of these invasions are poorly understood. Physiological integration (PI) is a key trait of clonal plants, which enables the exchange of resources among ramets. We investigated PI in Elymus athericus, which has been rapidly spreading from high‐marsh into low‐marsh environments of European salt marshes during the last decades. We applied a nitrogen stable‐isotope approach to trace nutrient translocation between ramets in a factorial mesocosm experiment. The experiment was set up to mimic an invasion pattern commonly found in tidal wetlands, i.e. from high‐elevated and rarely flooded into low‐elevated and frequently flooded microenvironments. We tested for intraspecific variability in PI by including two genotypes of Elymus that naturally occur at different elevations within the tidal frame, a high‐marsh (HM) and a low‐marsh (LM) genotype. PI strongly increased offspring ramet aboveground and belowground biomass by 62 and 81%, respectively. Offspring ramets under drained conditions had 95% greater belowground biomass than those under flooded conditions. LM genotype offspring ramets produced 27% more aboveground biomass than HM genotypes. Offspring ramets were clearly more enriched in 15N under flooded versus drained conditions; however, this positive effect of flooding on δ15N was only significant in the LM genotype. Our findings demonstrate the importance of PI for the growth of Elymus offspring ramets and thereby for the species' capacity for fast vegetative spread. We show that offspring ramets under stressful flooded conditions are more dependent on nutrient supply from parent ramets than those under drained conditions. Our data furthermore suggest a higher degree of adaptation to flooding via PI in the LM versus HM genotype. In conclusion, we highlight the importance of assessing PI and intraspecific trait variability to understand invasion processes within ecosystems. [ABSTRACT FROM AUTHOR]

Many aquatic plants are characterized by clonal growth through which the mother ramet can support offspring ramets by providing resources. The capacities of exploring space, sampling environment and overcoming establishment risks for offspring ramets could be enhanced with the resource support of the mother plant, which may change over time. This study aimed to investigate whether there is a change of clonal integration between mother ramets and offspring ramets in the submerged macrophyte Vallisneria natans with growth time. The stolons between mother ramets and daughter ramets were severed or intact at different growth times (7th day, 17th day, or 27th day after planting). The anatomical structure of the stolons and the morphological, biomass and nitrogen traits of the plants were measured. The results showed that the anatomical structure of the stolon changed significantly over time. The growth and clonal reproduction of daughter ramets were markedly improved by clonal integration on the 14th day but not on the 24th day or 34th day. In addition, there was no significant cost to support daughter ramets in terms of the total biomass of mother ramets. Our results highlight that the growth and clonal reproduction of daughter ramets of V. natans relies on mother ramets in the early stage and support from mother ramets declines with increasing independence of daughter ramets. [ABSTRACT FROM AUTHOR]

Summary: Clonal integration often increases fitness of clonal plants, but it may decrease it when some but not all connected plants (ramets) within a clone are parasitized.This hypothesis was synthesized in a conceptual model and tested by growing pairs of connected ramets of two congeneric clonal plants, Sphagneticola trilobata and Sphagneticola calendulacea, with and without parasitizing one ramet with Cuscuta australis and with and without severing the connection (allowing or preventing integration).Consistent with the model, integration in S. calendulacea did not affect biomass of the parasitized ramet, decreased biomass of its connected, unparasitized ramet by 60% and of the clone by 40%, and increased biomass of the parasite by 50%. By contrast, integration in S. trilobata did not affect biomass of the clone or the parasite. The parasite increased export of nitrogen‐15 from the connected, unparasitized ramet seven‐fold in S. calendulacea but did not affect export in S. trilobata.Parasitism can cause clonal integration to negatively affect fitness in clonal plants because parasites can import resources from connected, unparasitized ramets, possibly partly through signaling. This is the first experimental demonstration that clonal integration can decrease fitness in plants induced by parasitism and may help explain community‐level effects of parasites. [ABSTRACT FROM AUTHOR]

Under unfavourable conditions, clonal plants benefit from physiological integration among ramets, sharing resources and information. Clonal integration can buffer against environmental changes and lets the plant clone work as a 'macro' organism. Molecular signals that regulate this phenomenon are completely unknown in marine plants.Here we present a first comprehensive study providing insights into the metabolic role of different types of ramets (i.e. apical vs. vertical) in the foundation species Posidonia oceanica. Plants were exposed to 80% diminishing irradiance level (LL) in a controlled mesocosm system. Subsequent multiscale variations in whole transcriptome expression, global DNA methylation level, photo‐physiology, morphology and fitness‐related traits, were explored at different exposure times. We tested the hypothesis that vertical shoots (the 'vassals') can provide vital resources to apical shoots (the 'kings') under energy shortage, thus safeguarding the whole clone survival.Whole transcriptome analysis of leaves and shoot‐apical meristems (SAMs) emphasized signatures of molecular integration among ramets, which strongly correlated with higher organization‐level responses. In both shoots types, the exposure to LL resulted in a growth slowdown throughout the experiment, which started from immediate signals in SAMs. In apical shoots, this was linked to an acclimative response, where they were suffering a mild stress condition, while in vertical ones it fell in a more severe stress response. Yet, they suffered from sugar starvation and showed a clear cellular stress response in terms of protein refolding and DNA repair mechanisms. Several epigenetic mechanisms modulated the observed gene‐expression patterns and the cross‐talk between DNA methylation and the cellular energetic status appeared to regulate shoot metabolism under LL.Synthesis. Our results demonstrate a high level of specialization of integrated ramets within seagrass clones and a 'division of labour' under adverse conditions. Vertical shoots appear to do 'most of the job' especially in terms of resource providing, whereas activated functions in apical shoots were restricted to few important processes, according to an 'energy‐saving' strategy. The response of vertical shoots could be seen as a 'sacrificing response' allowing the survival of 'the king' that is key for ensuring propagation and population maintenance, and for the colonization of new environments. [ABSTRACT FROM AUTHOR]

While many clonal plants are highly successful invaders, the contribution of clonal integration (i.e. the translocation of resources among ramets) to invasion is often unknown. We used model simulations to ask if clonal integration would facilitate photosynthate translocation, if the performance of daughter ramets might be enhanced by clonal integration, and if shaded ramets benefited relatively more from transferred photosynthate. Then, to test if photosynthate translocation augmented performance of emerging daughter ramets for a globally invasive grass (Imperata cylindrica), we combined a 13CO2 pulse‐chase experiment with a greenhouse experiment manipulating light levels and rhizome attachment. We found that acropetal photosynthate transfer occurred between all sampled parent–daughter ramet pairs and that this resource sharing led to higher biomass and tiller production when rhizomes between parent and daughter ramets were intact. We also found that the benefits of integration to recipient clones outweighed the costs to donors, since there was no reduction in parent plant performance due to sharing. Additionally, our data analyses show that photosynthate transfer was likely of greater benefit in overcoming growth constraints in shade than in full sun (posterior probability ~96.5%), a result that is further supported by our numerical simulations from a basic growth model. Thus, resource sharing among clonal plants may be a critical but underappreciated trait of invasive species. More generally, photosynthate transfer is a probable mechanism that explains why clonal integration can be particularly beneficial in heterogeneous resource environments. [ABSTRACT FROM AUTHOR]

Clonal integration can benefit the performance and fitness of clonal plants in heterogeneous environments. Although trade-offs of sexual and asexual reproduction are key life-history strategies to assess the plant fitness and adaptive abilities, the effects of clonal integration on these is less studied. In this study, a pot experiment was conducted to test how reproductive strategies were affected by clonal integration of clonal plant species Leymus chinensis growing in heterogeneous saline-alkali soils. The results showed that clonal integration had no significant effect on total biomass of whole clone of L. chinensis. The total biomass of younger ramets was higher (+32.8%, P < 0.001) under integration condition, while at the cost of the older ramets (-21.7%, P < 0.001). Moreover, the ratio of ear biomass to clonal growth organs (CGO) biomass was slightly reduced by 31.7% (P = 0.09). For younger ramets, clonal integration enhances biomass allocation towards CGO, while reducing allocation towards ear growth, and the ratio of ear/CGO biomass was significantly reduced by 39.1% (P < 0.01). Results indicated that clonal integration reduced the ratio of ear to clonal growth organ biomass of whole clone, and more biomass was allocated to younger ramets for spatial expansion. Clonal integration influenced reproductive strategies of L. chinensis , while its impact is not depended on nutrient levels or defoliation interference. The study emphasized the significance of clonal integration in promoting the growth of offspring ramets and, consequently, enhancing their abilities to expand rapidly. It could enhance the spatial expansion of L. chinensis on a site scale and provide high potential for restoration of patchy degraded grassland where it is dominant. • Clonal integration improved younger ramets growth at the cost of older ramets. • Clonal integration reduced the ratio of ear to clonal growth organ biomass of whole clone. • Clonal integration affected reproductive allocation regardless of stress/disturbance intensities. • Younger ramets allocated more biomass for expansion under clonal integration conditions. [ABSTRACT FROM AUTHOR]

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Highlights from the article: Lated herbivory), two treatments of real herbivory (herbivory Herbivory of the apical ramets significantly affected leaf, Figure 2: biomass (a, c-e), number of ramets (b) and root to shoot ratio (f) of the basal ramets of Alternanthera philoxeroides. Figure 3: biomass (a, c-e), number of ramets (b) and root to shoot ratio (f) of the apical ramets of Alternanthera philoxeroides. Un-attacked basal ramets to apical ramets suffering from her-.

Previous studies have elucidated the mechanisms, ecological implications and constraints on transportation or sharing of defence signals among interconnected ramets of clonal plants suffering from localised herbivore damage. To our knowledge, few studies have been conducted to provide insights into the ecological implications on transportation or sharing of stress signals for clonal plants subjected to water stress. As a chemical elicitor, ABA can induce resistance response in plants suffering from water stress. A pot experiment was conducted to explore transportation or sharing of stress signals among interconnected ramets by using clonal fragments of Centella asiaticas (L.) Urban with four successive ramets (oldest, old, mature and young) subjected to low water availability (20% soil moisture contents). Compared with control, foliar oxidative stress of the old, mature and young ramets significantly decreased, and antioxidant capacity was increased when exogenous ABA was applied to the oldest ramets. Meanwhile, foliar PSII activity and chlorophyll content of the old, mature and young ramets significantly increased. Compared with control, biomass accumulation and ratio of below-ground/aboveground biomass of whole clonal fragments were significantly increased by ABA application to the oldest ramets. However, similar patterns were not observed when exogenous ABA was applied to the young ramets. Our results show that transportation or sharing of stress signals among interconnected ramets improves systemic resistance of clonal networks to water stress, which is dependent on directionality of vascular flows. Compared with the old or mature ramets, the young ramets displayed stronger resistance response (such as higher antioxidant enzymes activities and proline content, lower O2•− production rate and malondialdehyde content) to water stress as well as higher PSII activity and chlorophyll content when exogenous ABA was applied to the oldest ramets. Thus, transportation or sharing of stress signals may favour young ramets that are most valuable for growth and fitness of clonal plant subjected to environmental stress. It is suggested that transportation or sharing of stress signals among interconnected ramets may confer clonal plants with considerable benefits in adapting to spatio-temporal heterogeneous habitats. Stress signals induced by ABA can improve a plants' resistance to water stress. We investigated the effects of transportation of stress signals among interconnected ramets on resistance response of clonal plant Centella asiatica subjected to water stress. Our results demonstrate that transportation of stress signals among interconnected ramets improved systemic resistance and growth performance of whole clonal fragments. [ABSTRACT FROM AUTHOR]

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Many amphibious clonal plants in aquatic-terrestrial ecotones commonly expand from terrestrial to aquatic habitats. Nutrient availability and light intensity are both key factors affecting plant growth in aquatic habitats, but little is known about the role of nutrient availability and light intensity in aquatic habitats during the expansion of amphibious clonal plants from terrestrial to aquatic habitats, when clonal integration is maintained. We conducted a greenhouse experiment to simulate expansion from terrestrial to aquatic habitats of the amphibious clonal plant Hydrocotyle vulgaris. We grew basal portions of clonal fragments in soil and connected the apical portions of the same fragments to water which subjected to three levels of nutrient availability under a low or a high light condition. High nutrient level and light condition increased the growth of the apical portions of H. vulgaris and thus increased the performance of the whole clones. Meanwhile, root-shoot mass ratio of the apical portions and the basal portions were higher at the high light condition and the low nutrient level. Results suggest that the relatively high levels of nutrients and light condition in aquatic habitats can improve the expansion of apical portions from terrestrial to aquatic habitats. Our results also suggest that maintaining clonal integration may benefit the expansion of H. vulgaris via the trade-off of biomass allocation which can optimize the utilization of resources. These results may provide theoretical basis for community dynamics prediction and vegetation restoration in the ecotones such as wetlands. • We tested the effects of nutrient and light on the growth of H. vulgaris when expanded from terrestrial to aquatic habitat. • High levels of nutrients and light promote the growth of apical ramets and whole plants of H. vulgaris. • Root-shoot mass ratio responds differently to the variation of nutrient availability and light intensity. • High levels of nutrients and light may contribute to the expansion of H. vulgaris from terrestrial to aquatic habitats. [ABSTRACT FROM AUTHOR]

Sand burial and wind erosion caused by sand movement are common phenomena in desert environments, but the effects on clonal shrub have rarely been investigated. Here, we assessed how sand movements affect the population regeneration capacity of juvenile clonal fragments of the shrub Calligonum mongolicum growing in mobile desert sand dunes. We investigated the population status and natural regeneration capacity in three types of mobile dunes (heavy wind erosion, heavy sand burial and moderate sand burial). Clonal propagation of C. mongolicum was markedly different across sites. Moderate sand burial sites had the largest ramet density and bud number per unit length of rhizome, and the overwinter survival rate was significantly higher at sand burial sites than at wind erosion sites, suggesting that C. mongolicum may have well adapted to the moderate sand burial environment. We further examined the effects of clonal integration on clonal regeneration of this species. Physiological, biochemical and morphological characteristics of parent and daughter ramets growing in heterogeneous sandy habitats (sand burial or wind erosion) were measured. The results showed that being connected or severed from the maternal plant critically determined survival of daughter ramets on wind eroded rhizomes. When eroded rhizomes remained connected, the mother ramets had the highest chlorophyll a, b and a + b contents. However, both the mother plant and the daughter ramets undergoing erosion had higher proline and soluble protein levels than sand buried ramets. Meanwhile, the daughter ramets undergoing sand burial had higher photosynthetic rates (Pn), chlorophyll fluorescence parameters (Fm and Fo), and phenotypic traits of assimilating shoots, i.e., node number, length and volume than wind-eroded ramets. However, significant differences with mother plants, whether connected or severed, were very limited. It was concluded that moderate sand burial environments promoted clonal reproduction and growth of C. mongolicum. Additionally, physiological integration with mother raments in favorable conditions can alleviate stress on daughter ramets exposed to wind erosion. This physiological effect may do not occur for sand buried daughter ramets. These survival strategies and phenotypic responses should be carefully considered in shrub and sand dune management in sand fixation plantations of C. mongolicum.

The clonal invasion of Wedelia trilobata (L.) Hitch has spread to edges of mangrove areas, which leads to the formation of flooding-stressed areas such as waterlogged and submergence. This study purpose to investigate the clonal integration mechanism of W. trilobata in stress of flooding type combination. This study was conducted in greenhouse with four combinations of flooding treatment on mother ramet (MR) and daughter ramet (DR) for 25 days. Several parameters were measured are shoot growth, relative growth rate (RGR), biomass, biomass allocation, adventitious root growth, and lenticel hypertrophy. The highest clonal performance was observed for the combination of field capacity (MR)- waterlogged (DR). The lowest performance was observed for the combination of waterlogged (MR)-submergence (DR). There were decreases in the shoot growth, RGR, and biomass allocation in mother ramet. However, adventitious root growth and lenticel hypertrophic increased in daughter ramet. The increase of flooding pressure suppresses the performance of clonal plants. Clonal integration buffered clonal plants by improving the performance of daughter ramet in the combination of flooding type. The clonal integration has facilitated W. trilobata invasion in inundated areas.

ABSTRACT In a pot experiment, clonal ramets of Cynodon dactylon, a stolon herbaceous plant, were treated with heterogeneous lighting. Proximal ramets (elder ramets) were subjected to shade stress at three different degrees, and stolons between proximal and distal ramets of each pair were treated in a connected or severed manner. Results showed that in moderate shade stress, the number of ramets and leaves, biomass, net photosynthetic rate (Pn), maximum quantum yield (Fv/Fm), effective quantum yield of PSII (ФPSII), and soil and plant analysis development values (SPAD) of proximal ramets were significantly reduced, regardless of whether stolons were kept intact or severed. However, the growth of distal ramets was not significantly influenced, and keeping the stolons intact also did not bring apparent benefits for the whole clonal fragments. These results show that clonal integration does not help alleviate the shade stress suffered by proximal ramets and the costs of distal ramets and does not significantly influence the whole clonal fragments. The possible reasons are that distal ramets may be at the cost of metabolism for resource transportation when the proximal ramets suffer from shade stress; thus, clonal integration is not favorable.

Most aquatic plants applied to ecological restoration have demonstrated a clonal growth pattern. The risk-spreading strategy plays a crucial role in facilitating clonal plant growth under external environmental stresses via clonal integration. However, the effects of different concentrations of nanoplastics (NPs) on the growth traits of clonal aquatic plants are not well understood. Therefore, this study aimed to investigate the impact of NPs exposure on seedlings of parent plants and connected offspring ramets. A dose response experiment (0.1, 1, and 10 mg L -1 ) showed that the growth of Eichhornia crassipes (water hyacinth) was affected by 100 nm polystyrene nanoplastics after 28 days of exposure. Tracer analysis revealed that NPs are accumulated by parent plants and transferred to offspring ramets through stolon. Quantification analysis showed that when the parent plant was exposed to 10 mg L -1 NPs alone for 28 days, the offspring ramets contained approximately 13 ± 2 μg/g NPs. In the case of connected offspring ramets, leaf and root biomass decreased by 24%-51% and 32%-51%, respectively, when exposed to NP concentrations ranging from 0.1 to 10 mg L -1 . Excessive enrichment of NPs had a detrimental effect on the photosynthetic system, decreasing the chlorophyll content and nonphotochemical quenching. An imbalance in the antioxidant defense systems, which were unable to cope with the oxidative stress caused by NP concentrations, further damaged various organs. The root system can take up NPs and then transfer them to the offspring through the stolon. Interference effects of NPs were observed in terms of root activity, metabolism, biofilm composition, and the plant's ability to purify water. However, the risk-spreading strategy employed by parent plants (interconnected offspring ramets) offered some relief from NP-induced stress, as it increased their relative growth rate by 1 to 1.38 times compared to individual plants. These findings provide substantial evidence of the high NP enrichment capacity of E. crassipes for ecological remediation. Nevertheless, we must also remain aware of the environmental risk associated with the spread of NPs within the clonal system of E. crassipes , and contaminated cloned individuals need to be precisely removed in a timely manner to maintain normal functions.

Aims Clonal integration can increase performance of clonal plants suffering from environmental stress, and clonal plants in many wetlands commonly face stress of flooding accompanied by salinity. However, few studies have tested roles of clonal integration in amphibious plants expanding from terrestrial to aquatic saline habitats. Methods Basal (older) ramets of clonal fragments of Paspalum paspaloides were grown in soil to simulate terrestrial habitats, whereas their apical (younger) ramets were placed at the surface of saline water containing 0, 50, 150 and 250 mmol l−1 NaCl to mimic different salinity levels in aquatic habitats. Stolons connecting the apical and basal ramets were either intact (connected) to allow clonal integration or severed (disconnected) to prevent integration. Important Findings Increasing salinity level significantly decreased the growth of the apical ramets of P. paspaloides, and such effects on the leaf growth were much higher without than with stolon connection after 60-day treatment. Meanwhile, leaf and total mass ratios of the connected to the disconnected apical ramets were higher at high than at low saline treatments. Correspondingly, Fv/Fm and F/Fm′ of the apical ramets were higher with than without stolon connection in highly saline treatments. The results suggest that clonal integration can benefit the spread of apical ramets from terrestrial soil into saline water, and that the positive effects increase with increasing salinity. However, clonal integration did not significantly affect the growth of the whole fragments. Due to clonal integration, Na+ could be translocated from the apical to the basal ramets to alleviate ion toxicity in apical ramets. Our results suggest that clonal integration benefits the expansion of P. paspaloides from terrestrial to aquatic saline habitats via maintained photosynthetic capacities and changed biomass allocation pattern. [ABSTRACT FROM AUTHOR]

The clonal invasion of Wedelia trilobata (L.) Hitch has spread to riverside and edges of mangrove areas, which leads to the formation of flooding-stressed areas such as waterlogged and submergence. This study purpose to investigate the clonal integration mechanism of W. trilobata in stress of flooding type combination. This study was conducted in greenhouse with four combinations of flooding treatment on mother ramet (MR) and daughter ramet (DR) for 25 days. Several parameters were measured are shoot growth, relative growth rate (RGR), biomass, biomass allocation, adventitious root growth, and lenticel hypertrophy. The highest clonal performance was observed for the combination of field capacity (MR)- waterlogged (DR). The lowest performance was observed for the combination of waterlogged (MR)-submergence (DR). There were decreases in the shoot growth, RGR, and biomass allocation in mother ramet. However, adventitious root growth and lenticel hypertrophy increased in daughter ramet. The increase of flooding pressure suppresses the performance of clonal plants. Clonal integration buffered clonal plants by improving the performance of daughter ramet in the combination of flooding type. The clonal integration has facilitated W. trilobata invasion in inundated areas. [ABSTRACT FROM AUTHOR]

Sand burial and wind erosion caused by sand movement are common phenomena in desert environments, but the effects on clonal shrub have rarely been investigated. Here, we assessed how sand movements affect the population regeneration capacity of juvenile clonal fragments of the shrub Calligonum mongolicum growing in mobile desert sand dunes. We investigated the population status and natural regeneration capacity in three types of mobile dunes (heavy wind erosion, heavy sand burial and moderate sand burial). Clonal propagation of C. mongolicum was markedly different across sites. Moderate sand burial sites had the largest ramet density and bud number per unit length of rhizome, and the overwinter survival rate was significantly higher at sand burial sites than at wind erosion sites, suggesting that C. mongolicum may have well adapted to the moderate sand burial environment. We further examined the effects of clonal integration on clonal regeneration of this species. Physiological, biochemical and morphological characteristics of parent and daughter ramets growing in heterogeneous sandy habitats (sand burial or wind erosion) were measured. The results showed that being connected or severed from the maternal plant critically determined survival of daughter ramets on wind eroded rhizomes. When eroded rhizomes remained connected, the mother ramets had the highest chlorophyll a, b and a + b contents. However, both the mother plant and the daughter ramets undergoing erosion had higher proline and soluble protein levels than sand buried ramets. Meanwhile, the daughter ramets undergoing sand burial had higher photosynthetic rates (P n), chlorophyll fluorescence parameters (F m and F o), and phenotypic traits of assimilating shoots, i.e., node number, length and volume than wind-eroded ramets. However, significant differences with mother plants, whether connected or severed, were very limited. It was concluded that moderate sand burial environments promoted clonal reproduction and growth of C. mongolicum. Additionally, physiological integration with mother raments in favorable conditions can alleviate stress on daughter ramets exposed to wind erosion. This physiological effect may do not occur for sand buried daughter ramets. These survival strategies and phenotypic responses should be carefully considered in shrub and sand dune management in sand fixation plantations of C. mongolicum. [ABSTRACT FROM AUTHOR]

In this study, a pot experiment was conducted and clonal fragment of Phyllostachys bissetii with two successive ramets was used as experimental materials to examine the effects of clonal integration on the patterns of nitrogen, allocated to photosystem in P. bissetii under heterogeneity light environment. The main results were as follows:(1)When grown in shade, ramets connected with an unshaded mother plant displayed higher potential maximum net photosynthetic rate(Pmax), leaf nitrogen content(NM and NA), chlorophyll content and total partition coefficients of leaf nitrogen in photosynthetic apparatus(PT)than severed ramets.(2)The connected apical ramets had higher partition coefficients of leaf nitrogen in carboxylation components and bioenergetics components than that of in light-harvesting components.(3)There were no significant differences in unit-area leaf mass and nitrogen content between the two treatments of connected and severed proximal ramets in natural lighting conditions, while connected ramets displayed higher Pmax, PT and chlorophyll concentration. The results suggested that clonal integration affects the patterns of nitrogen allocated to photosystem in shaded apical ramets, and ensure young ramets maintain higher photosynthetic capacity, which impel the whole clone fragment had higher survival advantages. [ABSTRACT FROM AUTHOR]

Exploring the mechanism of plant species persistence in fragmented landscapes has already become a major issue in spatial ecology. Most of previous models predicted that habitat loss and fragmentation negatively impact plant species persistence, while empirical studies found diverse responses of plant species to habitat fragmentation, suggesting that some critical process may be overlooked in these models. Clonal species has the ability to well explore the resources under habitat fragmentation via clonal integration. However, responses of such species to habitat fragmentation have rarely been considered, especially in the aforementioned models. Here we developed a pair approximation model by considering clonal integration to explore the underlying mechanism of species’ diverse responses to habitat fragmentation. The persistence of global dispersers (i.e. species with seed reproduction) depends on habitat loss not habitat fragmentation, whereas the persistence of local dispersers (i.e. species with clonal reproduction) or mixed dispersers (i.e. species with both seed and clonal reproduction) is influenced by both habitat loss and habitat fragmentation. Furthermore, habitat fragmentation shows diverse effects (i.e., positive, neutral or negative effects) on the persistence of local dispersers or mixed dispersers via clonal integration. Our results provide theoretical guidance for species conservation, which highlights the crucial role of species’ ecological traits in response to habitat loss and fragmentation. [ABSTRACT FROM AUTHOR]

Clonal integration plays an important role in clonal plant adapting to heterogeneous habitats. It was postulated that clonal integration could exhibit positive effects on nitrogen cycling in the rhizosphere of clonal plant subjected to heterogeneous light conditions. An in-situ experiment was conducted using clonal fragments of Phyllostachys bissetii with two successive ramets. Shading treatments were applied to offspring or mother ramets, respectively, whereas counterparts were treated to full sunlight. Rhizomes between two successive ramets were either severed or connected. Extracellular enzyme activities and nitrogen turnover were measured, as well as soil properties. Abundance of functional genes (archaeal or bacterial amoA , nifH ) in the rhizosphere of shaded, offspring or mother ramets were determined using quantitative polymerase chain reaction. Carbon or nitrogen availabilities were significantly influenced by clonal integration in the rhizosphere of shaded ramets. Clonal integration significantly increased extracellular enzyme activities and abundance of functional genes in the rhizosphere of shaded ramets. When rhizomes were connected, higher nitrogen turnover (nitrogen mineralization or nitrification rates) was exhibited in the rhizosphere of shaded offspring ramets. However, nitrogen turnover was significantly decreased by clonal integration in the rhizosphere of shaded mother ramets. Path analysis indicated that nitrogen turnover in the rhizosphere of shaded, offspring or mother ramets were primarily driven by the response of soil microorganisms to dissolved organic carbon or nitrogen. This unique in-situ experiment provided insights into the mechanism of nutrient recycling mediated by clonal integration. It was suggested that effects of clonal integration on the rhizosphere microbial processes were dependent on direction of photosynthates transport in clonal plant subjected to heterogeneous light conditions. [ABSTRACT FROM AUTHOR]