Ecological constraints on population dynamics
Results indicated that seed germination rate of Arenaria polytrichoides was lower at both low (0/5 ℃) and high (20/25 ℃) temperatures than at intermediate (10/15 ℃) temperatures, while high light availability (more than 50% of full light, with full light defined as 7000 lx) promoted it (Figure S3 and S4B, C). Thus, the intermediate temperature was the most ‘conducive’ for seed germination. However, seedlings persisted longer at lower temperatures, and the higher water and light availability treatments also promoted their survival (Figure S4).
Simulated short-term extreme climate events significantly reduced the survival rate of seedlings younger than 60 days old, but had weaker effects on seedlings grown for 90 days under ‘conducive’ conditions (Figure 4A; Table S3). The latter also had high tolerance of a long-term extreme climate treatment simulated as long winter (Figure 4B). In contrast, seedlings that had been exposed to the short-term extreme climate treatment were highly vulnerable to the long-term treatment, although their degree of vulnerability depended on their age when exposed to the short-term treatment (Figure 4B). Generally, older seedlings had higher tolerance of the long-term extreme climate treatment, and thus higher overwintering capacity.