Factors driving the expansion of Helichrysum splendidum in Menz-Guassa community conservation area of the Afroalpine ecosystem of Ethiopia
Background: The rapid expansion of Helichrysum splendidum shrub into Menz-Guassa community conservation area has resulted in the scarcity of Guassa grasses and this has threatened the livelihoods of the local community.
Objective: A field survey was undertaken to examine the effect of human disturbance and soil burrows on the expansion of H. splendidum.
Materials and Methods: Two transects were laid out along altitudinal gradient with a 200 m interval and 15 quadrats (5 m 5 m each) were arranged on each quadrat at every 100 m for data collection on the level of human disturbance, number of soil burrows, and the abundance of H. splendidum. In total, 90 composite soil samples were collected from three soil layers (litter, 0–3 cm and 3–6 cm) from the five subplots (size: 1 m x 1 m each) which were established in the four corners and one in the center of each quadrat. The soil seed bank study was undertaken in the greenhouse and the seedlings grown were identified to the species level the density of which was recorded. The General Linear Model (GLM) was employed to test the effects of human disturbance and soil burrows on the abundance and density of seedlings of H. splendidum.
Results: The results showed that abundance of H. splendidum significantly increased with increasing level of human disturbance, but decreased with the increasing number of soil burrows (P < 0.001). Higher germination density was recorded from soil seed bank with moderate and high levels of human disturbance compared to soil banks with very high levels human disturbance. However, the density of seedlings showed an increasing trend with increasing the number of soil burrows.
Conclusion: Our overall results suggest that human disturbances (i.e., grass cutting and wood collections) and soil burrowing by mole rats are the major drivers of the expansion of H. splendidum and hence mechanisms that halt such process need be sought to restore the cover of Guassa grass on which the livelihoods of the local community largely depend.