TY - GEN N1 - Pages 132-178 ; 24 cm N1 - Bibliographical references (pages 169-176) N1 - Abstract in English N1 - 24 cm N2 - Data are given on the number of predators in different types of grassland ecosystems. In unutilized ecosystems predators form 5—46% of the fauna biomass in the above ground layer, i.e. 0,6—80 mg dry weight/m2. The percent of predators are smaller in the ground layer and soil, being only 0,4—12%, although the biomass of these animals is far greater, Teaching a value of 8—3000 mg of dry weight/m2 (Tables I, II).The amount of plant production determines the biomass of fauna, this including the biomass of predators. A relation was found between the amount of plant production (living or dead) and the biomass of predators. There is also a relation between the biomass of potential food of predators (herbivores and saprovores) and the biomass of predators (Figs. 1, 2). The regression function of the relations described above was found to be statistically significant.The biomass of predators aboveground is relatively small and is concentrated chiefly in the ground layer and the upper layer of soil. 38% of the total biomass of predators is present in the thin layer scarcely 1 cm thick, soil-litter interface (Table III). < {The material contained in a large number of studies has shown that human activities in meadows usually bring about reduction of predator biomass and reduction in the proportion of predators in the community (Tables IV—XI). Even treatments stimulating the abundant development of fauna, such as organic fertilization, usually lead to reduction in the biomass of predators. The effect on predators of such treatments as grazing, hay harvest, fertilization and also transformation of steppe into cultivated land is examined. The reverse process — increase in biomass of predators — takes place when cultivation cease.The suggestion has been made that it is chiefly predatory polyphages which disappear from cultivated meadows, whereas predators with specialized food preferences may become more important. This exchage may cause intensification of fluctuations in numbers of animals, since polyphagous predators may bring about effective reduction in the moderate increasing prey population size. The specialized predators act intensively, but with a considerable delay in time in relation to the increase in the numbers of their prey.Studies on the reduction and on control of numbers are most often concerned with pests. Data given in the text on the effect of predatory polyphages on the numbers of their prey have therefore been obtained from this literature. N2 - Data have also been given on the exploitation rate of the herbivore and saprophage trophic level by predators in grassland ecosystems (Table XIX). The data are scarce however and should be regarded with caution. The consumption efficiency of invertebrate predators (ratio of predators consumption to production of the previous trophic level, as can be concluded from this comparison, varies within wide limits from several to about 100%. After excluding the highest values, which are undoubtedly over-estimated, average predator consumption efficiency is 38%. Consumption efficiency of predators is higher than that found in these ecosystems for plant feeding invertebrates.Comparison of exploitation rate by predators in different ecosystems gives grounds for assuming that there is more intensive exploitation of prey by predators in poor than in fertile ecosystems and that it is greater in the below than above ground layer (Table XIV).It has been shown that habitats with slow litter decomposition rate lasting several years are characterized by a relatively high percentage of predators (Table XV). The proportion of predator to saprophage respiration gradually decreases as transition to ecosystems with rapid turnover of matter proceeds- (Fig. 4). Results are given of experiments showing that predators of the soil- litter interface may exert an inhibiting effect on mineralization processes (Table XVI and Fig. 5). This is of course an indirect, the result of the exploitation of saprophages.Data on the bioenergetics of common predatory species are given in the final section. The efficiency of certain energetic transformations in predator populations is discussed in relation to transformations in populations of animals living on food of plant origin. The data given in Tables XVII—XX may prove useful in calculating energy flow through the trophic level of predators. L1 - http://rcin.org.pl/Content/153870/PDF/WA058_109528_P3259-23_Eko-Pol-B.pdf M3 - Text J2 - Invertebrate predators in grasslands PY - 1977 IS - 2 EP - 178 KW - grasses KW - meadows KW - grasslands KW - grassland invertebrates KW - predatory animals A1 - Kajak, Anna A2 - Polska Akademia Nauk. Komitet Ekologii PB - Państwowe Wydawnictwo Naukowe VL - 23 CY - Warszawa SP - 132 T1 - Drapieżce bezkręgowe w ekosystemach trawiastych UR - http://rcin.org.pl/dlibra/publication/edition/153870 ER -