Abstract. This paper describes patterns of below‐ground components in grassland ecosystems. It provides estimates of the contribution of below‐ground organs to the total phytomass of the community and of different species to the below‐ground phytomass; it describes the distribution of above‐ and below‐ ground organs of different species and the spatial and temporal correlation between above‐ground and below‐ground phyto‐mass – both total standing crop and net primary production. 10 Siberian grasslands (meadows and steppes) were investigated during 15 yr. Ca. 70 % of the living phytomass is located in the soil and no less than 70 % of the net primary production is allocated in below‐ground organs. Phytomass distribution in the soil layer is more homogeneous than above‐ground. For some species the spatial distribution within 1‐m2 plots of the green and below‐ground phytomass is similar, for others it is quantitatively or qualitatively different. According to the dominance‐diversity curve, the above‐ground size hierarchy is much stronger than the below‐ground one. The active growth of above‐ and below‐ground organs of a species may occur at different times of the season and it varies from year to year. Allocation of organic substances to rhizomes and roots occurs simultaneously and with proportional intensity.
We measured phytomass stock and production in Western Siberian mire ecosystems (palsa, ridge, oligotrophic and mesotrophic hollows, fen). To determine the contribution of different phytomass fractions into total production, we developed a method to estimate below-ground production (BNP). Standing crop of living above-ground phytomass on treeless plots varied from 300 to 660 g m -2 , reaching maximum on palsa, where 81% of phytomass consisted of Sphagnum mosses and lichens. In the hollows and the fen, Sphagnum percentage varied from 70 to 95%. Standing crop of living below-ground phytomass varied from 325 to 1,210 g m -2 . It consisted of woody stems, stem bases, rhizomes and roots, with the latter contributing from 30 to 60%. Total production of mire ecosystems in northern taiga of Western Siberia ranged from 350 to 960 g m -2 year -1 and depended on microtopography of the ecosystem (the presence of permafrost and water table depth). Production of treeless plant communities located on the elevated sites depended on the presence of permafrost: in comparison with the ridge, palsa production was lower. Production on the low sites increased with increase pH and reached maximum (960 g m -2 year -1 ) in poor fens. Bryophytes were the major producers above ground. Their production varied from 100 to 272 g m -2 year -1 and reached maximum on ridges. BNP contributed 37-66%, increasing due to increased contribution of sedges.
Abstract. This paper describes secondary revegetation and biological turnover development on coal‐mining spoils. Qualitative and quantitative changes in species composition, rate of succession, formation of plant bio‐mass structure and net primary production are described for revegetation stages with an undisturbed meadow system as a reference.
The development of biological turnover in grasslands has four stages. The first stage is characterized by the growth of weedy species, high above‐ground standing crop and production and low below‐ground production. The second stage includes the establishment of perennial grasses, a decrease in the above‐ground plant biomass and production, an increase of the below‐ground living and dead root mass, formation of the plant material structure (distribution of plant material among the compartments of the ecosystem) close to steady‐state pattern, the approach to the balance between net primary production and organic matter decomposition. During the third stage a mature species composition is formed and below‐ground production increases up to the steady‐state level. At the fourth stage the humus storage reaches its steady‐state value.
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