Litter and green biomass in a traditionally managed alkali landscape in Hungary (Hortobágy)

The study of biomass and its effect on species richness in grasslands and wetlands improves our understanding on vegetation dynamics. We provided detailed analysis of the aboveground biomass (total biomass, green biomass and litter) in an alkali landscape along a long productivity gradient. In the lowland area of Hungary (Hortobágy Puszta) we selected alkali (i-v) and loess grasslands (vi-viii) and wetlands (ix-xiii) for our study. The studied association types were the following: (i) Puccinellia open alkali grasslands, (ii) Artemisia and (iii) Achillea short alkali grasslands, (iv) Juncus short alkali grasslands, (v) Alopecurus alkali meadows, (vi) Festuca loess grasslands, (vii) Bromus loess grasslands, (vii) Stipa loess grasslands, (ix) Bolboschoenus alkali marshes, (x) Typha latifolia marshes, (xi) Carex vesicaria marshes, (xii) Typha angustifolia marshes and (xiii) Reeds (Phragmites australis). In grasslands, the lowest total biomass (sampled at the peak of biomass production) scores were found in open alkali grasslands (a mean of 113 g/m2), while the highest ones in Alopecurus alkali meadows (a mean of 2,316 g/m2). In wetlands higher scores were typical, ranging from a mean of 990 g/m2 (detected in Bolboschoenus alkali marshes) to 3,052 g/m2 (detected in Reeds). In grasslands, the highest amount of litter was detected in Alopecurus alkali meadows (as much as 1,856 g/m2) while in wetlands the highest amount of litter was found in Reeds (as much as 1,268 g/m2). Species richness was the highest at medium total biomass scores both in grasslands and wetlands. Our results suggest that litter is one of the major factors controlling species richness in highly productive grasslands and wetlands.