Rome — The recent upheavals in the Italian Communist Party have left its leaders as politically resolute as ever but have emphasized the party's uncertain future. With the loss of Enrico Berlinguer as leader and the unanimous election of Alessandro Natta to succeed him, the leaders of Italy's Communists have shown their decision to continue Berlinguer's line of independence from the Soviet bloc.
Mr. Natta was a close collaborator and friend of Mr. Berlinguer. In his acceptance speech Natta declared his intention of ''going forward with the policies of Berlinguer.''
Natta's election came only 10 days after Italian Communists won 27 seats in the European Parliament and 33.3 percent of the Italian vote, putting them ahead of their opposition rivals, the Christian Democrats, for the first time - by 0.3 percent.
What the opposition and critics of the Communist Party called ''a sympathy vote'' and what the Communists themselves called a victory turned out to be partially true on both counts. Last weekend a regional election in Sardinia (Berlinguer's home region) and in 88 municipalities up and down the country gave the Communists only 28.6 percent of the vote and the Christian Democrats 32.2 percent.
Nevertheless, these results represented an increase for the Communists on the regional elections in 1979 and a decrease for their rivals. Although the electoral ranks of the Communist Party remain still solid, their potential growth is not so great as party leaders had hoped.
Natta and his colleagues face somewhat diminished prospects for the party's future. The heady days of Berlinguer's Eurocommunism and possible compromise and power-sharing with the Christian Democrats are gone.
The Communist-and-Socialist coalition city councils that governed nearly all of Italy's main cities (Milan, Rome, Bologna, Venice, Turin, Genoa, Naples, and Florence) after the landslide Communist victory of 1976 elections are reduced to running Milan, Rome, Turin, Genoa, Venice, and Bologna, with Communist mayors in charge of Rome, Turin, and Bologna.
The Communist Party remains a huge political force in Italian society, with some 1.7 million card-carrying voters and about one-third of the electorate. But it has never been in a position to offer its faithful voters a government post, or even a satisfactory alliance with either of Italy's two other major political parties - the Christian Democrats or the Socialists, the party of the current prime minister, Bettino Craxi.
Natta called on his party to show one of its most characteristic strengths - unity - or what Berlinguer once called the ''unity of several voices.'' He took care to outline the main points on which his party line would follow that of Berlinguer.
What he did not dwell on was any reference to Soviet policy, which Berlinguer had sharply criticized in the past, particularly in regard to Afghanistan and Poland. Some observers have taken this to be a conciliatory gesture to the minority pro-Soviet faction of the party.