Increasing water availability stabilize species coexistence in Japanese old-growth forests

Abstract: The relative magnitudes of negative conspecific and heterospecific density dependence (NCDD and NHDD) have been widely used to explain tree species diversity. However, it remains unclear how the effects of NCDD and NHDD on tree growth change with temporal climate variability and the implications of any change for diversity maintenance. We used a repeated measured forest inventory dataset (19 one-hectare plots of old-growth natural forests with 11,560 trees spatially mapped from 2004 to 2018) in Japan to investigate how temporal climate variability affected NCDD and NHDD. Both climate water availability and temperatures increased during the study period. After accounting for the effects of spatial variation in annual temperature and water availability (precipitation minus potential evapotranspiration) and soil properties, NCDD increased while NHDD decreased with temporal increase in water availability. When assessed by tree status, we found that NCDD in saplings increased, while NHDD in adult trees decreased with temporally increasing water availability. Our findings suggest that increasing water availability strengthened NCDD in saplings and weakened NHDD in adults, potentially stabilizing species coexistence. This implies that higher water availability may play an important role in influencing species coexistence dynamics under climate warming.
File:
code_submit.R: R codes used for analysis.
meta_data.xlsx: Metadata describes briefly each variable.
data_submit.R: data used for analysis.