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Fig. 1. Evolution of shrew community structure in the last decadestoothed shrew was represented only by few individualsrecorded in “Codri” forest reserve. Its abundance didn’toverpass 2% from the shrew population. The pigmyand lesser white-toothed shrews had approximately thesame frequency and constituted about 20% from thewhole shrew population.In the 1980’s the abundance of common shrew wasmaintaining at high level and the species constitutedmore than half of shrew population (fig. 1). It was theonly species among shrews that was recorded in forestshelter belts (Munteanu, Savin, 1990). In opposite,the Mediterranean water shrew dominance decreasedbelow 20 %, this species being common only in naturalreserves in biotopes near water sources, while in theother ecosystems it became very rare. The abundanceof Pigmy shrew increased by about 10 %, especially in„Codri” forest reserve in wet biotopes (Averin et al., 1984),but it still was rather rare on the republic territory. Theabundance of Crocidura genus species was very low,below 10 % each species.In 1990’s the changes of economic conditions leadto the changes of ecosystems’ structure and to themodification of the Republic of Moldova landscape. Vastsingle-crop agricultural fields from the agrarian complexof 70-80’s that occupied large territories were dividedin parcels cultivated with various annual, biannual andperennial cultures. Many lands were abandoned anduncultivated. The process of natural habitat destructionwas rather intense. In such stressful conditions the shrewspecies density decreased drastically by comparingwith other mammal groups. In this period the commonshrew proved to be the most well adapted species withthe largest limits of ecological valence. Thus, it hadthe highest abundance among soricid mammals andconstituted almost 80 % from the shrew population. Thedensity of other shrew species was very low: the pigmyshrew constituted 10 %, the Mediterranean water shrew– about 8 %, the lesser white-toothed shrew – about 5%, while the white toothed shrew – only 1-2 % (fig. 1).The last species was very rare in the past century, soit was included in the Red Book of Moldova as criticallyendangered.After 2000 many abandoned lands and reverted totheir more or less natural state as natural biotopes, suchas pastures, meadows, grazing lands etc. At the sametime, the processes of anthropization, urbanization anddegradation of the natural ecosystems occur all over theterritory of the republic. In this context the modification ofthe shrew community’s structure continued.The common shrew remain the dominant species inthe population, but its abundance decreased significantly(to 43 %) by comparing with the end of XXth century.It is more tolerant to the environment conditions andto anthropogenic activity by comparing to other shrewspecies. It was recorded in the majority of studied naturaland anthropogenic biotopes (F=94 %). The pigmy shrewfrequency was also rather high – 88 %, but it is morerare, with the abundance of 35 % (fig. 1). The density ofbicolor white-toothed shrew increased up to 8,8 % and itsfrequency was rather high with the value of 9,7 % while inits preferred habitats the frequency of the species reach42 % (Nistreanu et al., 2008). The lesser white-toothedshrew has the same biotopic preferences as the previousspecies and it was more frequent (17,8 %) and abundant(12,5 %). The Mediterranean water shrew was the rarestshrew among other species after 2000. Its frequencywas very low (below 5 %), it being registered only nearaquatic basins of natural reserves, and the abundancewas of 2,4 %.In 2008 the structure of shrew communities onthe territory of Moldova is totally different (fig. 2). Thedominant species was the lesser white-toothed shrewwith 51.32 %, which constituted more than half of shrewpopulation. Its frequency constituted 40 % in naturalecosystems and more than 85% in urban environment.The species N. anomalus wasn’t registered in any of thestudied ecosystems. The other species had approximatelythe same abundance (fig.2). The trappability index variedfrom 2 % to 16 % from all the micromammal species.In 2009 the proportion of shrew species within thecommunity chanced again. The dominant species was thecommon shrew with over 44%, followed by bicolor whitetoothedshrew, with about 30 % (fig. 2). In opposite to theprevious year C. suaveolens had the lowest abundance.— 149 —