Distribution and Regeneration Potential of the Soil Seed Bank of Ericaceous Vegetation in the Bale Mountains

Abstract

ABSTRACT Questions The resilience of Afromontane ericaceous ecosystems depends heavily on their soil seed banks, yet the regeneration ecology of the dominant woody genus Erica is poorly known. We asked: (1) How do environmental variables and anthropogenic disturbance influence woody species distribution in standing vegetation and soil seed banks? (2) What is the relationship between soil seed bank density and greenhouse germination potential (emergence) of Erica species, and how does it vary among topographic positions? (3) What are the implications for field seedling establishment and conservation? Location Bale Mountains National Park, Southern Ethiopia. Methods Fifty microplots were established across three principal experimental sites (northeast slopes, southwest slopes, and the Sanetti Plateau). Standing vegetation composition, disturbance intensity (quantified on a five‐level scale), and environmental variables were recorded. The soil seed bank was assessed by physical extraction and a 180‐day greenhouse germination trial. Erica seed density and germination potential (seedlings emerged per m 2 ) were analyzed using generalized linear mixed models to test the effects of elevation, aspect, stoniness, and disturbance. Results We recorded 92 species in standing vegetation and 88 in the germinated seed bank; both were dominated by Asteraceae (22%) and Poaceae (8%). Erica seed density was highest on the Sanetti Plateau (9300 ± 3560 seeds m −2 ) but greenhouse germination potential there was extremely low (11 ± 20 seedlings m −2 ). Conversely, southwest‐facing slopes had lower seed density (2460 ± 938 seeds m −2 ) but significantly higher germination (160 ± 300 seedlings m −2 ). Elevation and surface stoniness were the primary abiotic constraints on Erica distribution ( p < 0.01). Disturbance significantly reduced Erica cover, field seedling establishment, moss, and litter ( p < 0.001). The relationship between seed density and germination was weak and non‐significant ( R 2 = 0.04, p = 0.061). Conclusions Erica regeneration is limited primarily by environmental filters and disturbance during the germination and establishment phase, rather than by seed availability, consistent with the regeneration niche concept. Conservation strategies must prioritize reducing livestock pressure and fire frequency, especially on the plateau, and protect southwest‐facing slopes as natural refugia for regeneration. Assisted restoration interventions are required in severely degraded areas to overcome the establishment bottleneck.