Clonal integration of Fragaria orientalis driven by contrasting water availability between adjacent patches

Experimental studies have shown that clonal plants can reciprocally translocate resources between interconnected ramets in heterogeneous environments. Resource contrast between patches in heterogeneous environments is the main external driver of integration effects. It was hypothesized that translocation of water between interconnected ramets was enhanced under higher levels of contrasts in water availability. A pot experiment with clonal fragments consisting of two interconnected ramets of F orientalis-a stoloniferous herb widely distributed in China-was conducted. In the experiment, each of the ramets of the clonal fragments was allocated to either a high or low water treatment. The rat-nets in the high water treatment were maintained at 90% field capacity while those in the low water treatment were maintained at 90, 60 and 30% field capacity, respectively. The ramet developmental stage (proximal or distal from mother rosette) was accounted for by allocating either proximal or distal ramets in the contrasting patches. In order to assess the role of physiological integration among ramets, the stolon was severed for half of the clonal fragments. Stolon severing and drought stress had significant effects on plant performance, which increased with the increase of contrast. However, the directionality of stressed ramets had no influence on most treatments. Based on performance measures, a cost-benefit analysis showed that the dry ramets benefited from clonal integration at the cost of the connected wet ramets. The results indicated that this clonal species is able to withstand soil-water heterogeneity through physiological integration, which is promoted under increasing levels of water contrast. Our results suggest that clonal plants might be suitable for vegetation restoration in dry areas due to superior survival strategies