Abstract:

Aims: This study examined the influence of environmental factors on the survival of introduced plants in a botanical garden, focusing on the effects of climate and soil differences between the botanical garden and the native ranges of the plants. 

Methods: We constructed mixed-effects Cox proportional hazards models to quantify the effects of climatic and edaphic differences on plant survival based on a database comprising 2,234 individuals from 1,232 introduced species at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences. 

Results: In climate-driven models, those based on the median values of climate variables across the species’ overall distribution ranges demonstrated the strongest empirical support (ΔAIC ≤ 3). In addition to species growth form, these models highlighted significant influence of mean annual temperature and minimum temperature of coldest month in the ranges of species studied, while precipitation of driest month, precipitation of wettest month, and annual precipitation in the ranges of species exhibited weaker yet statistically significant effects. Herbaceous plants showed a lower mortality risk than woody plants. In soil-driven models, those based on provenance soil conditions yielded the best performance. Topsoil organic carbon and gravel content emerged as the primary edaphic factors influencing survival. Herbaceous plants showed a higher mortality risk than woody plants. 

Conclusion: Climate and edaphic factors substantially impact the survival of ex situ tropical plants. Key drivers include the mean annual temperature, minimum temperature of coldest month, topsoil organic carbon, and topsoil gravel content in species’ native range, in addition to species growth form. Botanical gardens should prioritize aligning the overall climatic distribution of species and provenance edaphic conditions when planning introductions to enhance survival rates and the effectiveness of living collections.

Key words: ex-situ plant survival, mixed-effects Cox proportional hazards model, climatic factors, soil factors, tropics