-- consider a locally managed tablespace with uniform extent sizes of 1M

SQL> select * from dba_tablespaces where tablespace_name='LOCAL_UNIFORM';

TABLESPACE_NAME                BLOCK_SIZE INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS
------------------------------ ---------- -------------- ----------- -----------
MAX_EXTENTS PCT_INCREASE MIN_EXTLEN STATUS    CONTENTS  LOGGING   FOR EXTENT_MAN
----------- ------------ ---------- --------- --------- --------- --- ----------
ALLOCATIO PLU SEGMEN
--------- --- ------
LOCAL_UNIFORM                        8192        [b]1048576[/b]     1048576           1
 2147483645            0    [b]1048576[/b] ONLINE    PERMANENT LOGGING   NO  LOCAL
UNIFORM   NO  MANUAL

-- as you see, the minimum extent length is also set at 1M. You cant alter it for locally managed tablespace

SQL> alter tablespace LOCAL_UNIFORM minimum extent 64k;
alter tablespace LOCAL_UNIFORM minimum extent 64k
*
ERROR at line 1:
ORA-25143: default storage clause is not compatible with allocation policy

--Lets create a table with 512K initial and next

SQL> create table t(x int) storage(initial 512k next 512k) tablespace local_uniform;

Table created.

SQL> analyze table t compute statistics;

Table analyzed.

-- but its allocated 1M which is the uniform extent size

SQL> select EXTENT_ID,BYTES from user_extents where segment_name='T';

 EXTENT_ID      BYTES
---------- ----------
         0    1048576

SQL> select table_name,initial_extent,next_extent,blocks from user_tables where table_name='T';

TABLE_NAME                     INITIAL_EXTENT NEXT_EXTENT     BLOCKS
------------------------------ -------------- ----------- ----------
T                                      524288     1048576          0

-- although the initial_extent shows as 512K

-- lets try altering the storage parameters

SQL> alter table t move tablespace local_uniform storage(initial 64k next 64k);

Table altered.

SQL> analyze table t compute statistics;

Table analyzed.

SQL> select table_name,initial_extent,next_extent,blocks from user_tables where table_name='T';

TABLE_NAME                     INITIAL_EXTENT NEXT_EXTENT     BLOCKS
------------------------------ -------------- ----------- ----------
T                                       65536     1048576          0

SQL> select EXTENT_ID,BYTES from user_extents where segment_name='T';

 EXTENT_ID      BYTES
---------- ----------
         0    1048576

-- no effect

Using [url=http://www.orafaq.com/forum/t/21684/0/]Deallocate space[/url] , you can decrease the initial_extent and release space, but not below the uniform extent size of the locally managed tablespace. 

For such small objects, you will need to create another locally managed tablespace with the appropriate uniform extent size( say 1m ) ,so as not to waste space and then move those small tables.

Hope this helps
Thiru