Plant Ecology 138: 247-248, 1998. Plant Ecology An international journal Contoef Vnolutmes 1 38 Structure of herbaceous plant assemblages in a forested riparian landscape J. Lyon & C.L. Sagers Seed germination and seedling performance of two Mediterranean tree species, holm oak (Quercus ilex L.) and Aleppo pine (Pinus halepensis Mill.): a multifactor experimental approach M.J. Broncano, M. Riba & J. Retana Physiological and morphological acclimation of shade-grown tree seedlings to late-season canopy gap formation S.L. Naidu & E.H. DeLucia Differences in the vegetation of the North Iberian Peninsula during the last 16,000 years P. Ramil-Rego, C. Mufioz-Sobrino, M. Rodriguez-Guitian & L. Gémez-Orellana Nitrogen distribution and leaf area indices in relation to photosynthetic nitrogen use efficiency in savanna grasses N.P.R. Anten, M.J.A. Werger & E. Medina Analysis of vegetation structural diversity by Burnaby’s similarity index 71-87 L. Carranza, E. Feoli & P. Ganis The influence of soil depth on plant species response to grazing within a semi-arid savanna S.D. Fuhlendorf & FE. Smeins 89-96 Non-symmetric correspondence analysis: an alternative for species occurrences data C. Gimaret-Carpentier, D. Chessel, J.-P. Pascal 97-112 Riparian zones as havens for exotic plant species in the central grasslands T.J. Stohlgren, K.A. Bull, Y. Otsuki, C.A. Villa & M. Lee Defoliation and woody plant (Prosopis glandulosa) seedling regeneration: potential vs realized herb- ivory tolerance J.F. Weltzin, S.R. Archer & R.K. Heitschmidt 127-135 Development of black spruce growth forms at treeline D. Pereg & S. Payette 137-147 Nutrient concentration in Sphagna at increased N-deposition rates and raised atmospheric CO) con- centrations J. Jauhiainen, H. Vasander & J. Silvola 149-160 Longitudinal patterns of plant diversity in the North American boreal forest H. Qian, K. Klinka & G.J. Kayahara 161-178 Effects of nutrient and soil moisture on competition between Carex stricta, Phalaris arundinacea, and Typha latifolia P.R. Wetzel & A.G. van der Valk 179-190 Effects of grazing on plant species composition and spatial distribution in rangelands of the Sahel P. Hiernaux 191-202 248 The role of water depth and soil temperature in determining initial composition of prairie wetland coenoclines E.W. Seabloom, A.G. van der Valk & K.A. Moloney 203-216 Soil heterogeneity effects on canopy structure and composition during early succession B. Collins & G. Wein 217-230 Using image-analysis to quantify the horizontal vegetation pattern in two multi-species savanna grass- lands B. Fransen, M. de Boer, M. Terlou, H. During & W. Dijkman 231-237 Book reviews 239-242 Instructions to authors 243-246 247-248 Contents volume 138 / List of contributors List of Contributors Anten, N.P.R., 63 Molony, K.A., 203 Archer, S.R., 127 Munoz-Sobrino, C., 41 Broncano, M.J., 17 Naidu, S.L., 27 Bull, K.A., 113 Otsuki, Y., 113 Carranza, L., 77 Pascal, J.-P., 97 Chessel, D., 97 Payette, S., 137 Collins, B., 217 Pereg, D., 137 de Boer, M., 231 Qian, H., 161 DeLucia, E.H., 27 Ramil-Rego, P., 41 Dijkman, W., 231 Retana, J., 17 During, H., 231 Riba, M., 17 Feoli, E., 77 Rodriguez-Guitian, M., 41 Fransen, B., 231 Sagers, C.L., I Fuhlendorf, S.D., 89 Seabloom, E.W., 203 Ganis, P., 77 Silvola, J., 149 Gimaret-Carpentier, C., 97 Smeins, F.E., 89 Gomez-Orellana, L., 41 Stohlgren, T.J., 113 Heitschmidt, R.K., 127 Terlou, M., 231 Hiernaux, P., 19] van der Valk, A.G., 179, 203 Jauhiainen, J., 149 Vasander, H., 149 Kayahara, G.J., 161 Villa, C.A., 113 Klinka, K., 161 Weltzin, J.F., 127 Lee, M., 113 Wein, G., 217 Lyon, J., | Werger, M.J.A., 63 Medina, E., 63 Wetzel, P.R., 179