Wood anatomy and tree ring boundaries in woody species growing in Costa Rica

Abstract

Costa Rica has a tropical climate comprising diverse life zones with more than 2 000 tree species. This study aimed to determine the distinctiveness of annual rings (AR) and different types of AR according to variation of anatomical features, and assess the dendrochronological potential (DP) of 320 tree species of Costa Rica and their relationship to specific families and genera. The AR distinctiveness was categorised as (1) without a clear boundary, (2) well-defined and (3) more-or-less distinctive. The different types of AR were classified as: Type 1: density variation; Type 2: marginal parenchyma; Type 3: pattern of fibres/parenchyma; Type 4: vessel distribution; and Type 5: fibre band. The results revealed that 70 species (21.9%) had an indistinct AR boundary, 104 species (32.5%) had well-defined AR, and the remaining species (146 species, 45.6%) had more-or-less distinct AR. In relation to AR type, the 21.9% without a distinct AR boundary were categorised as lacking annual rings, 32 species were classified as Type 1, 20 species as Type 2, 30 species as Type 3, seven species as Type 4, 35 species as Type 5, and the remaining species had two or more AR types. Ten families had well-defined AR, 20 families lacked a distinct AR boundary and 16 families had more-or-less distinct AR. Forty-two genera did not have AR, 70 genera had well-defined AR, 79 genera were classified as more-or- less distinct AR, and 15 genera had AR of all three types. According to these results, 70 species did not show DP and 104 species with well-defined AR had high DP, which requires confirmation in subsequent studies.