Effects of In Situ Burial and Sub-Optimal Storage on Seed Longevity and Reserve Resources in Sub-Tropical Mountain Cloud Forest Tree Species of Mexico

To design conservation and management strategies for sub-tropical moist forests, it is important to know how storage affects the longevity and germination of desiccation-sensitive seeds. These variables are controlled by a physiological process that is mainly associated with the seeds’ moisture content and reserve content, which can be significantly affected by environmental conditions. The objectives of this study were: (i) to evaluate the relationship between longevity and reserve content of sensitive and non-sensitive desiccation seeds (ii), and to describe how the in situ burial and sub-optimal storage (inside growth chambers) can affect seed longevity. In seeds of six mountain cloud forest tree species, germination and seed reserve content were quantified in seeds collected recently (control) and at five different times, along with storage for 31 or 35 days in situ and under suboptimal conditions. Freshly harvested seeds with higher soluble carbohydrate and lipid content and the presence of thermo-stable proteins had the longest-expected ecological longevity and mean germination time. In contrast to in situ burial, germination was negatively affected by storage time. Burial time significantly affected the rate and mean germination time in most of the species. For two species, a greater soluble carbohydrate or a lower starch and lipid content in seeds was found to be related to the high germination rate in storage. Our results show that the sub-optimal storage reduces the lifespan in most of the study species and increases seed damages through dehydration.