Effects Of Clonal Integration Research Articles

Effect of clonal integration on ramet population regeneration of two Fargesia (bamboo) species under simulated ingesting interference

Aims Herbaceous species can have compensatory growth after grazing.Clonal integration contributes greatly to the re-growth of clonal plants.To date,however,very few studies have addressed how clonal integration affects bamboos' regeneration at a ramet level.Our objectives were to test the following hypotheses:(1) clonal integration benefits bamboo's compensatory growth greatly after grazing and(2) differences in branching pattern of rhizomes lead to different contributions of clonal integration to the compensatory effects.Methods In Tangjiahe National Nature Reserve,we subjected Fargesia scabrida and F.denudata ramets within 1.2 m × 1.2 m plots to four clipping treatments,i.e.,no clipping and 25%,50% and 75% shoot removal,and kept rhizomes at the plot edges either connected or disconnected.Important findings In plots with no clipping,rhizome severing stimulated new shoot generation and population recruitment of F.scabrida,but reduced the height and biomass of new shoots.The shooting rate and recruitment of F.denudata were significantly decreased in plots where rhizomes remained connected.When rhizomes were kept connected,25% clipping reduced the biomass of F.scabrida,and 25% and 50% clipping reduced recruitment of F.denudata.However,rhizome severing increased the recruitment of F.denudata.Under 75% clipping,the recruitments of both bamboos did not decrease significantly,but the quality of new shoots declined.Such negative effects were negated or greatly ameliorated in F.scabrida when rhizomes were connected.In general,clonal integration contributes greatly to the growth of new ramets,but contributes little to compensatory growth of both bamboos after grazing.

Effects of Clonal Integration on Growth of Centella asiatica Suffering from Heterogeneous Saline Stress

Effects of Clonal Integration on Growth of Centella asiatica Suffering from Heterogeneous Saline Stress

酸雨和采食模拟胁迫下克隆整合对空心莲子草生长的影响

Effects of clonal integration on growth and reproduction of plants in heterogeneous environments have been extensively studied,but relatively little is known about the roles of clonal integration in homogeneous,stressful environments.We conducted a greenhouse experiment to investigate the effects of clonal integration on the stoloniferous invasive plant Alternanthera philoxeroides(alligator weed) under homogeneous,stressful environments,i.e.,under simulated acid rain and herbivory.There were three levels of acid rain treatments [pH = 6.5(control),4.5(mild acid rain) and 3.5(severe acid rain)],three levels of herbivory [0(control),50%(moderate herbivory) and 90% leaf removal(heavy herbivory)] and two levels of clonal integration(no integration-stolon connection was severed;with integration-stolon connection was intact).In the control(i.e.,no acid rain and no herbivory),severing stolon did not affect biomass or biomass allocation of alligator weed,but increased total stolon length,number of ramets and number of leaves.The simulated acid rain treatments did not affect biomass of alligator weed,no matter whether the stolons were intact or severed.When the stolons were left intact,the mild acid rain treatment(pH=4.5) markedly increased total stolons length and number of ramets,suggesting that mild acid rain may improve plant growth.Meanwhile,the acid rain treatments significantly affected biomass allocation to roots and stolons.Under mild acid rain treatment(pH=4.5) biomass allocation to stolons increased significantly,whereas that to roots decreased;however,severe acid rain(pH=3.5) did not affect biomass allocation of alligator weed.When the stolons were severed,the acid rain treatments did not affect growth or biomass allocation of alligator weed.The results suggest that alligator weed can well adapt to acid rain stress and clonal integration play a limited role under acid rain stress.When the stolons were left intact,the simulated herbivory treatments markedly affected biomass and number of leaves of alligator weed,but did not affect total stolon length or number of ramets.With increasing herbivory levels,biomass of alligator weed significantly decreased,but number of leaves increased.When the stolons were severed,effects of the herbivory treatments on biomass,total stolon length and number of leaves were the same as those in the intact clonal fragments.Therefore,despite the status of the stolons,the simulated herbivory treatments markedly decreased growth of alligator weed.The herbivory treatments also modified biomass allocation of alligator weed.With increasing herbivory levels,biomass allocation to leaves significantly increased and that to stolons and roots significantly decreased.The results suggest that alligator weed can also well adapt to herbivory stress and clonal integration also plays a limited role under herbivory stress.These features of alligator weed may be helpful for it to invade into new habitats,and clonal integration plays a limited role under homogeneous stressful,environments.

Effects of clonal integration on growth of stoloniferous herb <I>Centella asiatica</I> suffering from heterogeneous heavy metal Cd<SUP>2+</SUP> stress

Effects of clonal integration on growth of stoloniferous herb <I>Centella asiatica</I> suffering from heterogeneous heavy metal Cd<SUP>2+</SUP> stress

Effects of sediment burial on tropical ruderal seagrasses are moderated by clonal integration

Seagrasses are clonal plants that grow submerged in dynamic sedimentary environments where burial is a common occurrence. Clonal organisms may respond to burial in very different ways depending on how strongly integrated they are through horizontal rhizomes, but the effect of clonal integration under conditions of stress such as burial is poorly studied for seagrasses. We test the effect of burial on tropical seagrasses that occur in multispecific meadows by subjecting plants in mixed stands to burial of 0, 2, 4, 8 and 16 cm for 27 days. Treatments were divided into those where rhizomes were severed and those where rhizomes were left intact. We hypothesize that species withstand burial better if clonal integration is maintained (intact rhizomes). Results showed that all species tolerated burial of up to 4 cm without adverse effects but significant reductions in shoot density and biomass become evident at 8 cm of burial. Furthermore, Cymodocea serrulata and Syringodium isoetifolium were strong integrators, i.e. they provide support for buried shoots, whereas Halophila ovalis and Halodule uninervis were weak integrators that did not show evidence of subsidizing buried shoots. Vertical elongation was observed for C. serrulata and H. uninervis as a response to burial only when rhizomes were severed, leading us to speculate on whether species rely on vertical elongation as an escape strategy only in the absence of resource translocation. Our distinction between the responses of treatments with intact rhizomes from those with severed rhizomes may be extended to an interpretation of burial scale (intact rhizomes=broad spatial−scale burial; severed rhizomes=fine spatial−scale burial). We concluded that broad spatial−scale burial exceeding 4 cm leads to rapid loss or reduction of all species. However, fine spatial–scale burial exceeding 4 cm, such as those caused by shrimp mounds (bioturbation), is expected to favor C. serrulata and S. isoetifolium, while H. ovalis and H. uninervis are disadvantaged. Clonal integration is an important trait in moderating the response of seagrasses to sediment burial and in this way, helps them to cope in high-stress habitats.

Effects of clonal integration and light availability on the growth and physiology of two invasive herbs

Summary 1. Clonal plants benefit from the ability to translocate resources among interconnected ramets to colonize heterogeneous habitats. Clonal integration affects the resource level and morphological traits of ramets, and thus may influence their physiology and general performance. Although leaf gas exchange and its associated physiological adjustments are key traits to assess plant fitness, the effect of clonal integration on these functional traits is insufficiently understood. 2. In a glasshouse experiment, we addressed how clonal integration affects gas exchange properties, leaf characters and growth of ramets in two invasive plants, Alternanthera philoxeroides and Phyla canescens, under full sun and 85% shade. We also used stable‐isotope labelling to assess the maternal subsidy to daughter ramets. 3. Similar effects of connection were observed in both species for most gas exchange parameters and leaf characters. Clonal integration did not affect photosynthetic capacity and respiratory rates of ramets. When grown in shade, ramets connected with an unshaded mother plant displayed higher area‐based leaf nitrogen and chlorophyll content than severed ramets, but the additional nitrogen and chlorophyll was not translated to increased photosynthetic capability. Overall, severed ramets displayed significant light response for leaf nitrogen (area‐based), photosynthetic nitrogen use efficiency, chlorophyll to nitrogen ratio, and nitrogen stable‐isotope signature, but the light response was eliminated by clonal integration in connected ramets. 4. Both species displayed substantial maternal carbohydrate subsidy that benefited the growth of daughter ramets, but species‐specific patterns were observed in the growth of daughter ramets and the amount of subsidy. The amount of subsidy was independent of ramet growth light levels for P. canescens, but shaded, connected ramets of A. philoxeroides received more subsidy than unshaded controls, facilitating a larger growth improvement relative to severed counterparts than P. canescens. 5. Synthesis. We observed increased leaf nitrogen and chlorophyll in shaded, connected ramets of two clonal invasive plants. Clonal integration may facilitate nitrogen assimilation and allow pre‐acclimation to high‐light conditions for shaded, connected ramets, thus promoting the opportunistic expansion of these invaders on site scale. The species‐specific maternal subsidy pattern demonstrated that clonal plants possess different strategies to subsidize ramets under light‐limited conditions.

Clonal integration supports the expansion from terrestrial to aquatic environments of the amphibious stoloniferous herb Alternanthera philoxeroides

Effects of clonal integration on land plants have been extensively studied, but little is known about the role in amphibious plants that expand from terrestrial to aquatic conditions. We simulated expansion from terrestrial to aquatic habitats in the amphibious stoloniferous alien invasive alligator weed (Alternanthera philoxeroides) by growing basal ramets of clonal fragments in soils connected (allowing integration) or disconnected (preventing integration) to the apical ramets of the same fragments submerged in water to a depth of 0, 5, 10 or 15 cm. Clonal integration significantly increased growth and clonal reproduction of the apical ramets, but decreased both of these characteristics in basal ramets. Consequently, integration did not affect the performance of whole clonal fragments. We propose that alligator weed possesses a double-edged mechanism during population expansion: apical ramets in aquatic habitats can increase growth through connected basal parts in terrestrial habitats; however, once stolon connections with apical ramets are lost by external disturbance, the basal ramets in terrestrial habitats increase stolon and ramet production for rapid spreading. This may contribute greatly to the invasiveness of alligator weed and also make it very adaptable to habitats with heavy disturbance and/or highly heterogeneous resource supply.

Effects of clonal integration on photosynthesis of the invasive clonal plant Alternanthera philoxeroides

A greenhouse experiment examined whether clonal integration improves photosynthesis of ramets of alligator weed [Alternanthera philoxeroides (Mart.) Griseb.], a widespread invasive clonal plant in China, in heterogeneous (He) nutrient habitats. The connected pairs of ramets experienced different nutrient levels [high homogeneous (Ho) nutrient, low Ho nutrient, and two He nutrient treatments]. Clonal integration significantly improved the net photosynthetic rate, stomatal conductance, transpiration rate, and minimal and maximal chlorophyll fluorescence of ramets of alligator weed in low nutrient condition. These characteristics may contribute to the success of the ramets of alligator weed in invading contrasting habitats. The clonal integration of the invasive clonal plants may contribute significantly to their invasiveness.

The effects of clonal integration on morphological plasticity and placement of daughter ramets in black locust ( Robinia pseudoacacia)

We studied the field response of Robinia pseudoacacia L. to light, total soil nitrogen, available soil phosphorus and soil pH. Results indicated that there was very strong clonal integration between mother and daughter ramets. Mother ramets can provide nitrogen and phosphorus to daughter ramets sufficient for their continued growth through strong clonal integration, but cannot provide enough photosynthate. With clonal integration, soil nitrogen and phosphorus availability had no effect on biomass allocation to roots, number of ramets and length of connection roots. Biomass allocation to roots increased markedly and responded to nitrogen and phosphorus availability, when the connections were severed. Light had a significant effect on the percent of biomass allocation to leaves and number of ramets, but no effect on the length of connection roots. Daughter ramets allocated more resources to leaves, and clones placed more daughter ramets in high light patches than in low light patches. Soil pH had a significant effect on ramet number and connection root length. Clones concentrated in alkaline patches and escaped from acid patches through selective placement of daughter ramets and changing the length of connection roots. We suggest that the clonal integration may be very strong and provide sufficient soil resources to daughter ramets, then affect the daughter ramets’ morphology and placement, if the size of a specific ramet is significantly larger than the other ramets in an arbor clone.

Differential effects of clonal integration on performance in the stoloniferous herb Duchesnea indica, as growing at two sites with different altitude

Clonal integration may be adaptive and enhance the genet performance of clonal plants. Degree of clonal integration may differ between different environments . Here, a container experiment was used to determine how clonal integration affected the performance of the stoloniferous herb Duchesnea indica at two sites with different altitude along the transitional zone between the Qinghai-Tibet plateau and the Sichuan basin of Southwest China. In the experiment, the stolon between partially shaded two ramets experienced severing and intact treatments.We predicted that clonal integration would increase performance of whole clonal fragments and their shaded clonal parts at both sites. In both arctic and alpine environments, clonal plants may form highly integrated plant units (group of ramets).We predicted again that the reduction due to stolon severing in performance of whole clonal fragments and their shaded clonal parts would be greater at the site with high altitude than one with low altitude. The results indicated that the benefit for the shaded clonal parts and whole clonal fragments due to clonal integration was only observed at the site with high altitude. The results suggest that the performance of Duchesnea indica tends to be more responsive to the stolon severing at the site with high altitude than one with low altitude and support the second prediction. In addition, the effects of conditions of the sites and clonal integration on local morphological traits of ramets may be adaptive, five morphological traits of ramet-level (length of petiole, mean stolon internode length, specific petiole weight, specific stolon internode weight and specific leaf area) were investigated. Altogether, the results suggest that clonal integration might help D. indica plants to successfully inhabit the high-altitude habitat of the Qinghai-Tibet plateau of Southwest China, providing new evidences for the notion that clonal integration is an adaptive trait in stressful environments.

Clonal integration of the stoloniferous herb Fragaria vesca from different altitudes in Southwest China

In plants, species with clonal growth are able to directly transfer resources between potentially independent parts of the same genetic composition. As long as clonal parts remain connected, this heterogeneity among clonal parts may be alleviated by the exchange of resources. In Southwest China there is a transitional zone between Qinghai-Tibet plateau (relatively high altitudes) and Sichuan basin (relatively low altitudes), where the higher the altitude is, the more severe the habitat conditions are for growth of plants. The impact of clonal integration on plant performance may vary among species and habitats. So it was hypothesized that the impact of clonal integration on performance of clonal plants from high altitude could be greater than those from low altitude. The hypothesis was tested in a field container experiment in which clonal fragments of the stoloniferous herb Fragaria vesca from two populations located at different altitudes (1800 m a.s.l. and 3944 m a.s.l.) were grown in West China Sub-alpine Botanical Garden, the Chinese Academy of Sciences in Dujiangyan, Sichuan Province, China. The results indicate that under heterogeneous light environment, clonal integration between interconnected ramets occurred for F. vesca from the two populations located at different altitudes. The effects of clonal integration on biomass, total length of stolons and numer of ramets were not different between the two populations which originated from different altitudes. However, the effects of clonal integration on performance of whole clonal fragments, such as biomass and number of ramets, seemed to be greater for plants from 3944 m a.s.l. than from 1800 m a.s.l‥ So, clonal integration may not only be adaptive for F. vesca to successfully inhabit its habitats, but may also be more ecologically important for the clonal plants to grow in higher-altitude habitats. In addition, some morphological traits were studied in the experiment. The results have been discussed in the context of adaptation in clonal plants to environmental heterogeneity

The Effect of Clonal Integration on Plant Competition for Mosaic Habitat Space

The Effect of Clonal Integration on Plant Competition for Mosaic Habitat Space

Effects of clonal integration on response to sand burial and defoliation by the dune plant Ipomoea pes-caprae (Convolvulaceae)

This study examined the importance of clonal integration on the growth and mortality of a tropical dune plant, Ipomoea pes-caprae L. (Roth), in response to two stresses: sand burial and defoliation. Sand burial and artificial defoliation treatments were applied to one shoot on daughter ramets, some of which were connected to other ramets and some of which were not connected to other ramets. Sand burial significantly enhanced both stem growth and leaf production of the buried shoots, both for connected and unconnected ramets. Defoliation decreased stem growth of shoots other than the defoliated shoot, but only for unburied ramets. Defoliation also had a greater negative effect on growth of other shoots on connected ramets than on unconnected ramets. At the level of the entire ramet, burial stimulated both stem growth and leaf production for connected ramets, but not for unconnected ramets. These results support the hypothesis that physiological integration between ramets mediates the response to both sand burial and defoliation in Ipomoea pes-caprae.

Effects of clonal integration on plant plasticity in Fragaria chiloensis

The ability of clonal plants to transport substances between ramets located in different microsites also allows them to modify the plastic responses of individual ramets to local environmental conditions. By equalising concentrations of substances between ramets, physiological integration might decrease responses to local conditions. However, integration has also been observed to increase plasticity and induce novel plastic responses in ramets. To ask how integration modifies plant plasticity in the clonal herb, Fragaria chiloensis, ramets were given either low light and high nitrogen or high light and low nitrogen, simulating a pattern of resource patchiness in their native habitat. Ramets in contrasting light/nitrogen treatments were either connected or single. Effects of light/nitrogen and connection were measured at three levels of morphological organisation, the organ, the ramet, and the clonal fragment. Connection between ramets reduced or had no effect on plastic responses in leaf size at the level of the plant organ. This suggested that integration dampened certain plastic responses. Connection induced a new plastic response at the level of the clonal fragment, an increase in allocation to vegetative reproduction in patches of low light and high nitrogen. It is concluded that clonal integration can have different effects on plant plasticity at different levels of plant organisation. It appears that, at least in this species, integration can increase plasticity at the level of the clonal fragment and concentrate vegetative reproduction in particular microsite types.