JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Ecology. SUMMARY(1) Analysis of more than one-hundred plant species has shown certain consistently-recognizable biological age states in their ontogeny. These are called seed, seedling, juvenile, immature, virginile, reproductive (young, mature and old), subsenile and senile.(2) Each age state may be characterized by a particular combination of quantitative and qualitative features. Qualitative features used to define the various age states are: the manner of nutrition, the type of growth, the pattern of branching of the root and shoot systems, leaf form, the presence of a particular type of shoot, the ability to reproduce by seeds, the balance between living and dead structures, and the balance between actively-growing and fully-formed structures.(3) Quantitative characteristics change uninterruptedly during ontogeny, and as a rule follow a unimodal curve.(4) Age states of species representative of a variety of growth forms have been distinguished and described. These include trees, shrubs, semi-shrubs, low semishrubs, firmand loose-tussock plants, and the following categories of perennial herbs: long-and short-rhizomed, root-suckering, stoloniferous, bulbous, tuberbulbous, tuberous and tap-rooted.(5) On the basis of these age-state studies, three main types of ontogeny in polycarpic plants are defined, using as characterizing features architectural changes of the individual plant, the form and timing of break-up of the individual plant, and the extent of rejuvenation.

No abstract

Five types of life history are distinguished among herbaceous species growing in steppe grasslands in Kazakhstan: they include tussock plants, tap-rooted plants of various kinds and long-rhizome herbs. They vary in the structure and dynamics of their coenopopulations and in the extent to which they are maintained in coenoses by seed or by vegetative growth. An understanding of the morphology and ontogenetic development of plants in natural coenoses is an indispensible prerequisite for describing their coenopopulation characteristics. These in turn reveal how plant communities are organised as dynamic systems.

On a basis of analysis of original and published data collected from north-eastern regions of European Russia, two new associations of tall herb boreal forest communities have been characterized. The first one, named Aconito septentrionalis—Piceetum obovatae Zaugolnova et Morozova ex Zaugolnova et al. hoc loco, was proposed earlier (Zaugolnova, Morozova, 2004). Now it has been validly described. Association is distributed in northern and middle boreal subzones. The second one, named Pulmonaria obscurae—Piceetum abietis ass. nova hoc loco, is specified and validly described for the fist time. It is distributed in southern boreal subzone. These two associations can be considered as a quasi-climax succession stage of spruce forests on their eastern border in the Russian Plain. These communities have the highest species diversity among taiga forests Together with three others forest associations, earlier described from the Southern Urals (Martynenko et al., 2008), the mentioned two belong to a new sub-alliance Atrageno sibiricae—Piceenion obovatae suball. nov. hoc loco within alliance Piceion excelsae Pawłowsky in Pawłowski et al. 1928 (in boreal-forest class Vaccinio-Piceetea). Block of the sub-alliance diagnostic species includes a functional group of boreal tall herb species. Their ecological and geographic characteristics have been described.

No abstract