Abstract:
The Dipterocarpaceae family is a key component of tropical rainforests, including the
Sinharaja forest. The effects of light conditions (60%, 70%, and 80%) on seed
germination and early seedling development in 10 threatened Dipterocarpaceae
species were investigated. Seeds were collected from various locations within
Sinharaja Forest. A total of 135 mature seeds per species were germinated under the
60%, 70%, and 80% shade treatments in a randomized complete block design with
three replicates per treatment. Seedling traits: germination, number of leaves, basal
diameter, leaf area, and leaf thickness, were recorded fortnightly. Seed traits such as
length, width, dry mass, and seed coat ratio were also measured. Data were analyzed
using linear mixed-effects models with post-hoc comparison of means with Tukey’s
test. Linear regression analysis revealed that seed dry mass significantly influenced
height growth rate under 80% (p=0.0309) and 70% (p=0.025) shade conditions, while
the effect was marginally significant under 60% shade (p=0.058). Additionally, seed
dry mass was significantly related to the diameter growth rate under 80% shade
(p=0.027), but no significant effects were observed under 60% (p=0.149) and 70%
(p=0.131) shade conditions. The comparison of germination rates across the three
shade levels showed a significant effect of shade on germination rate (p=0.042),
indicating that different shade levels influence germination. However, no significant
differences were found among shade levels for diameter growth rate (p=0.851) and
height growth rate (p=0.329). These findings suggest shade significantly influences
seedling germination, particularly under higher shade levels, but do not uniformly
affect all growth parameters. Findings provide insights into the role of shade in
influencing early stages of Dipterocarpaceae species supporting conservation and
restoration strategies.
