Gusev A.P. Change of Ecologic Conditions in the Course of Progressive Successional Replacement of Communities in a Broad-Leaved Landscape (Polesia Province, Belarus) / A.P. Gusev// Contemporary Problems of Ecology, 2009. – vol. 2.– №5. – PP. 405-410.
Abstract—Aprogressive succession in a broad-leaved landscape (Polesia province, Belarus) has been studied.The study has revealed phytocenotic changes in species composition, biological and phytosociological spectra,and ecotope features along succession gradient. It was demonstrated that the greatest changes occur at the stageof forest ecosystem formation.
DOI: 10.1134/S1995425509050026
Key words: progressive succession, ecotope, broad-leaved landscape, microclimate, Belarus
It is important to study vegetative successions thatoccur after the natural vegetation and the humic horizonhave been mechanically destroyed by construction, cabling,and long agricultural use. The study yields dataon ecosystem resistance to anthropogenic impact andallows us to assess and predict the self-regenerating capacityof the man-transformed ecosystems and to suggestappropriate measures on recultivation andrehabilitation of the disturbed ecosystems. As a matterof fact, we have little data on spontaneous progressivesuccessions in East-European broad-leaved landscapesthat have been in long use.
In 1998 through 2007 successions were studied inthe Polesia province (southern Belarus), which is characterizedby alluvial terraced, fen and secondary water-ice landscapes. Field geobotanic studies were conducted using standardmethods of sample plots and ecologic profiling.Successional series were inferred from 414 releves ofthe early stage, 290 releves of the tall grass stage, 81releves of the meadow stage, and 97 releves of the foreststage. The sample plots varied from 25 (initialstages) to 400 (forest stages) m2 in area. A fewnonforest stages were studied on 100 m2 sample plots,tall grass and meadow stages on 100 m2 sample plots.The data obtained were processed using theBraun-Blanquetecologo-floristic method.
Early progressive successions were studied repeatedlyon permanent sample plots; meadow and foreststages were studied using the method ofecologic-genetic series.
The analysis differentiated the following mainsuccessional series in the study area: (1) successionseries of flat and flat-undulating above-floodplain terraceswith subsurface alluvial sand and interrupted water-ice sandy loam cover; (2) successional series ofrunoff gullies pits, and other depressions. Theseecotopes are overmoistened and waterlogged; (3)successional series of dunes, ridges, and technogenicsand landscapes.
All the releves are ordered along the succession gradientdivided into the five stages: early, tall grass,meadow, small-leaved (birch-aspen) forest, andbroad-leaved forest. Successive changes in the vegetativecover were characterized in terms of species composition,biological and phytosociological spectra ofthe vegetation.
The following are the main ecological changes thatoccur along the succession gradient: (1) decreased temperatureindicated by lower values of the thermoclimaticindicators; (2) decreased temperaturefluctuations shown by lower values of the continentalityindicators (maximum values occur in the earlysuccession and minimum values occur in thebroad-leaved forest); (3) decreased illumination, withminimum in the broad-leaved forest stage and highershading, respectively; (4) increased water content insoils, with the greatest difference between the meadowand the small-leaved forest stages; (5) lower variabilityof moisture (moderately variable in the initial stage toslightly variable in the forest stages); (6) lower salt contentin soils with the maximum in the initial stages andminimum in the forest stages; (7) lower nitrogen contentin soils with the maximum in the initial stage; (8)higher humic content with the maximum in thebroad-leaved forest stage; (9) no considerable changesin soil pH, i.e., subacid in all stages.Thus, the greatest ecological transformations occurbetween the meadow stage and the small-leaved foreststage when trees affect their habitat most significantly.
In the early succession, changes of most parameters arewith a statistical error.
Trees have the strongest effect on the habitat, that iswhy the time they appear and natural regeneration inthe initial stage, as well as in the following stages, affectthe rate and degree of ecotope transformation. Substratetransformation is in close connection with phytomassamount: the greater the community phytomass, thestronger is its effect upon the habitat (phytomassamount determines the volume of biological cycle, i.e.the amount of chemical elements involved in the cycle).The efficiency of recultivation and rehabilitation of disturbedlandscapes, as well as of spontaneous progressivesuccession, is determined by the rate of formationof a community with the maximum possiblephytomass, i.e. forest ecosystem.
