Flora 201 (2006) 547–554 The effects of clonal integration on morphological plasticity and placement of daughter ramets in black locust (Robinia pseudoacacia) Xian-Qiang Zhang a , Jian Liu a,b , Clive V.J. Welham c , Cheng-Cheng Liu a , Da-Ning Li a , Li Chen a , Ren-Qing Wang a,b,Ã a The Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Jinan 250100, PR China b The Institute of Environment Science, Shandong University, Jinan 250100, PR China c Forest Ecosystem Management Simulation Group, Department of Forest Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 Received 26 September 2005; accepted 12 December 2005 Abstract 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. r 2006 Published by Elsevier GmbH. Keywords: Clonal integration; Morphological plasticity; Robinia pseudoacacia; Soil resources; Selective placement Introduction Physiological integration in clonal plants as a response to heterogeneity in abiotic and biotic factors is well documented (Alpert, 1991; Alpert and Stuefer, 1997; De Kroon and Schieving, 1990; Stuefer et al., 1996; Yu et al., 2002; Zhang et al., 2002). Integration involves the sharing of resources among connected parts (ramets). In general, resources are transported from ramets located in resource-rich patches to ramets located in resource-poor patches (Alpert and Stuefer, 1997; Birch and Hutchings, 1994; Hutchings et al., 2000; Stuefer et al., 1996; Welham et al., 2002; Wijesinghe and ARTICLE IN PRESS www.elsevier.de/flora 0367-2530/$ - see front matter r 2006 Published by Elsevier GmbH. doi:10.1016/j.flora.2005.12.002 Ã Corresponding author. The Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Jinan 250100, PR China. E-mail address: rqwang@sdu.edu.cn (R.-Q. Wang).