Physiological integration ameliorates effects of serpentine soils in the clonal herb Fragaria vesca

Abstract

Small‐scale heterogeneity in soil characteristics and the facility of clonal systems to spread may lead to situations where parent ramets in favourable microhabitats are connected to offspring in stressful conditions. Clonal plants are physiologically integrated if connections among ramets allow transport of resources. Thus, ramets in favourable habitats may provide support to developing or stressed ramets. We examined effects of integration in Fragaria vesca growing in patches of contrasting quality (potting compost vs serpentine soil). Serpentine soil was used to create unfavourable growing conditions. We assessed whether survival, biomass and photosynthetic efficiency (estimated by fluorescence and reflectance) of parents and offspring were affected by integration and soil quality. Integration increased photochemical efficiencies of parents but more consistently in parents with offspring growing in serpentine soils. We suggest that the assimilate demand from offspring enhanced the photosynthetic efficiency of parents by a mechanism of feedback regulation. This result extends the concept of physiological integration in clonal plants to include photochemical responses. Connected parents also showed significantly higher biomass than disconnected parents. In our system, integration did not entail costs for the whole clone in terms of biomass. Integration also improves the survival, growth and photochemical efficiency of developing ramets, suggesting that integration represents a mechanism for increasing survival in stressful habitats, as the serpentine soils.

Competition among plant species that interact with their environment at different spatial scales

“…Our integrators thus suffer a cost for allocation to poorer patches, which plasticity in allocation or limited integration could potentially ameliorate. Empirical studies have suggested that such a cost can be either present (Salzman & Parker 1985;de Kroon et al 1998) or insignificant, perhaps due to plant plasticity (Roiloa & Retuerto 2006) or partial integration (Slade & Hutchings 1987c). Plants also can avoid costs of supplementing ramets in poorer patches by avoiding growth there (Hartnett & Bazzaz 1983;Slade & Hutchings 1987a-c;Evans 1988;Sutherland & Stillman 1988;Evans & Cain 1995).…”

Effects of Physiological Integration and Fertilization on Heavy Metal Remediation in Soil by a Clonal Grass

“…When subjected to heavy metal stress, it is likely that heavy metals reduced the ability of the plants to assimilate resources, e.g., carbon, water, or nutrients [13,20]. More biomass allocation to roots may be related to the reduction in resource uptake and photosynthesis [20]. A possibly strengthened resource supply could alleviate the heavy metal stress to a greater extent.…”

“…If necessary, data were Ln-transformed before analysis pollution marginally increased biomass allocation to roots (Table 1, P = 0.088). When subjected to heavy metal stress, it is likely that heavy metals reduced the ability of the plants to assimilate resources, e.g., carbon, water, or nutrients [13,20]. More biomass allocation to roots may be related to the reduction in resource uptake and photosynthesis [20].…”

“…Feedback regulation between source and sink may lead to compensatory growth of photosynthesis efficiency in connected ramets without pollution [20,23]. Support offered by ramets living in environments out of stress supplies excessive resources to these ramets in stressful environments and increases the fitness of the whole clone system [29].…”

“…This case-named physiological integration has been proven to enhance the tolerance of ramets to different environmental stress, including trampling [14], resource shortages [17], shading [18], sand burial, and related wind erosion [16]. Some clonalplants have been confirmed to have excellent adaptability to heavy metal pollution by special clonal characteristics [19][20][21][22]. Translocation of contaminants from ramets in the patchily polluted habitat might spread toxins throughout the whole clones [19], which could be important for successful survival of clonal plants under contamination stress.…”