Plant Clonal Integration Mediates the Horizontal Redistribution of Soil Resources, Benefiting Neighboring Plants

Abstract

Resources such as water taken up by plants can be released into soils through hydraulic redistribution and can also be translocated by clonal integration within a plant clonal network. We hypothesized that the resources from one (donor) microsite could be translocated within a clonal network, released into different (recipient) microsites and subsequently used by neighbor plants in the recipient microsite. To test these hypotheses, we conducted two experiments in which connected and disconnected ramet pairs of Potentilla anserina were grown under both homogeneous and heterogeneous water regimes, with seedlings of Artemisia ordosica as neighbors. The isotopes [(15)N] and deuterium were used to trace the translocation of nitrogen and water, respectively, within the clonal network. The water and nitrogen taken up by P. anserina ramets in the donor microsite were translocated into the connected ramets in the recipient microsites. Most notably, portions of the translocated water and nitrogen were released into the recipient microsite and were used by the neighboring A. ordosica, which increased growth of the neighboring A. ordosica significantly. Therefore, our hypotheses were supported, and plant clonal integration mediated the horizontal hydraulic redistribution of resources, thus benefiting neighboring plants. Such a plant clonal integration-mediated resource redistribution in horizontal space may have substantial effects on the interspecific relations and composition of the community and consequently on ecosystem processes.

Keywords: Potentilla anserina; [15N]; clonal integration; deuterium; environmental heterogeneity; hydraulic redistribution; stable isotope.

FIGURE 1

Experimental design. Three water treatments for connected ramet pairs or for disconnected, single ramets (A); and the sampling design with or without isotope labeling (B).

FIGURE 2

The ratio of δ¹⁵N (RN, above, in Experiment I) and the ratio of δD (RD, below, in Experiment II) in Potentilla anserina leaves (A,D), soils (B,E), and A. ordocia leaves (C,F) in the unlabeled, recipient containers with the high, medium and low water treatments that were connected to the P. anserina ramets with the high water supply. All means are significantly greater than 1 (one-sample t-tests). The F and P-values of the one-way ANOVA are also provided, and different letters indicate significant differences in means among treatments.

FIGURE 3

Biomass of P. anserina (A,C) and Artemisia ordosica (B,D) in the unlabeled containers with the high, medium, and low water treatments that were connected with or severed from the P. anserina ramets grown in the high water treatment in Experiment I (A,B) and Experiment II (C,D).