Forest gaps regulate seed germination rate and radicle growth of an endangered plant species in a subtropical natural forest

Jing Zhu; Lan Jiang; De-Huang Zhu; Cong Xing; Meng-Ran Jin; Jin-Fu Liu; Zhong-Sheng He

doi:10.1016/j.pld.2021.10.003

Forest gaps regulate seed germination rate and radicle growth of an endangered plant species in a subtropical natural forest

Plant Divers. 2021 Nov 1;44(5):445-454. doi: 10.1016/j.pld.2021.10.003. eCollection 2022 Sep.

Authors

Jing Zhu¹, Lan Jiang¹, De-Huang Zhu², Cong Xing¹, Meng-Ran Jin¹, Jin-Fu Liu¹, Zhong-Sheng He¹

Affiliations

¹ Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
² College of Ecology and Resources Engineering, Wuyi University, Wuyishan, Fujian, 354300, China.

Abstract

The survival rate of Castanopsis kawakamii from seed to seedling is relatively low, leading to difficulties in the regeneration of its natural forests. Forest gaps play a vital role in plant regeneration and biodiversity maintenance in forest ecosystems. Unfortunately, our understanding of the effects of gap size and within-gap position on the seed germination and radicle growth of C. kawakamii is still limited. In particular, our knowledge on the relationship between gap size and environmental factors and their influence on seed germination and radicle growth is incomplete. In the present study, we studied the influences of forest gaps and within-gap position on seed regeneration on the germination and radicle growth of an endangered species C. kawakamii in a subtropical natural forest in China. We selected three large gaps (LG, gap size above 200 m²), three medium gaps (MG, gap size 50-100 m²), three small gaps (SG, gap size 30-50 m²), and non-gap (NG), and planted the seeds of C. kawakamii in five positions within each gap. The results showed that (1) the influence of forest gaps on seed germination rate was, from highest to lowest, medium gaps (51%), non-gap (47%), small gaps (40%) and large gaps (17%), and the seed germination rate was the highest in all positions in medium gaps, with the exception of the east position. (2) Radicle length in forest gaps was, from highest to lowest, medium gaps, small gaps, large gaps and non-gap, and it was the highest in the east, south, west and north positions of medium gaps. (3) Canopy openness (gap size) and air temperature were the main factors influencing seed germination and radicle growth of C. kawakamii. We concluded that medium-sized gaps were the most suitable for seed germination and radicle growth of C. kawakamii, and they promote the regeneration of this endangered species in the investigated natural forest.

Keywords: Castanopsis kawakamii; Forest gap; Radicle growth; Seed germination; Within-gap position.