Masting of trees affects the activity of large mammals that feed on their fruits, but, the effects of elevation have often been ignored; elevation may affect site productivity and thereby alter temporal patterns of masting in montane area, where forests and wildlife are often preserved. We investigated fruit production by 403 trees of six species that are preferred by Asian black bears over 10 years within a 30×30-km2 area ranging 700–1600 m elevations, as well as the horizontal and elevational structures of intraspecies and interspecies synchrony. Thereby, we discuss the relationships between the masting of multiple species and the movement patterns of Asia black bears in the study area.
We calculated three indices for evaluating the patterns of fruiting and masting for each tree: temporal mean fruiting density averaged across the study period, fruiting frequency during the study period, and coefficient of variation (the ratio of the temporal standard deviation of fruiting density to the mean). To evaluate the degree of fruiting synchrony between two trees, we used pairwise Spearman’s rank correlation. Using the between-tree annual correlation of fruiting density and distance, intraspecific spatial autocorrelations and interspecific correlations were analyzed using a spline correlogram.
Results/Conclusions
Higher elevation was related to greater temporal variation in fruiting for Quercus crispula. Among heterospecific relationships, two Quercus species and Swida controversa showed fruiting synchrony, whereas Prunus grayana produced more fruit when Quercus and Swida produced less. Fagus crenata and Castanea crenata did not exhibit masting synchrony, neither positive nor negative, with other species.
Spatially, most tested species showed positive autocorrelations with horizontal distance, particularly between close trees (4–10 km), whereas autocorrelations with elevational difference showed negligible spatial structure across elevational distance. Positive spatial correlations between different species were found only for the two Quercus species.
These findings align with annual variation in movement patterns among individual Asian black bears; in autumn of some years, some black bears stayed in small areas while others travelled long distances, and for other years, most black bears ranged widely over the landscape in search of food.