Article

Under natural conditions, plant growth and spec ies composition of the vegetation are often limited by the availability of soiI nutrients rather than by li ght or water. This paper tries to answer the questione Are Ihere differences in the interactive effects of plant indi viduals, physico-chemical factors and the community of soil mi croorganisms that indi cate the development of different plant strategies for survival in nutrient-poor habitats? After a de finition of the effect plant roots may have on the surrounding soil (the rhizosphere effect), the paper reviews the ev idence for its mie on soil organi c matter mineralisation and therefore, of nutri ent ava ilability on different speeies and on soils of different fertility. C011lparison be tween annual and perennial species of Bromus, indicates a better efficiency of the former to thrive in nutrient-poor habitats, both in relati ve quanti ti es and in temlS of the cost of mining soil nutrients.