Human disturbance impacts the integrity of sacred church forests, Ethiopia

Abstract

Land-use change can have profound effects on forest communities, compromising seedling recruitment and growth, and long-term persistence of forests on the landscape. Continued forest conversion to agriculture causes forest fragmentation which decreases forest size, increases edge effects and forest isolation, all of which negatively impact forest health. These fragmentation effects are magnified by human use of forests, which can compromise the continued persistence of species in these forests and the ability of the forests to support the communities that depend on them. We examined the extent and influence of human disturbance (e.g. weedy taxa, native and exotic tree plantations, clearings, buildings) on the ecological status of sacred church forests in the northern highlands of South Gondar, Ethiopia and hypothesized that disturbance would have a negative effect. We found that disturbance was high across all forests (56%) and was negatively associated with tree species richness, density, and biomass and seedling richness and density. Contrary to expectation, we found that forests < 15.5 ha show no difference in disturbance level with distance from population center. Based on our findings, we recommend that local conservation strategies not only protect large forests, but also the small and highly used forests in South Gondar which are critical to the needs of local people, including preserving large trees for seed sources, removing exotic and weedy species from forests, and reducing clearings and trails within forests.

Tree Community Composition and Dispersal Syndrome Vary with Human Disturbance in Sacred Church Forests in Ethiopia

“…We surveyed all woody trees and shrubs with a diameter at breast height (dbh) > 1 cm along three modified Gentry transects that were established from the wall around the center of the church towards the edge of each forest at three cardinal directions that were 120 • from each other (see Figure 3 in Cardelús et al 2019). Each transect was 2 m × length of the forest, which varied quite a bit among forests (18-350 m).…”

“…Habitat fragmentation, whereby previous contiguous forest is reduced to smaller patches of forests with increasing distances between patches, is considered one of the most significant drivers of species diversity decline [3][4][5][6]. Forest fragmentation has significant and negative impacts on species richness, abundance, and diversity worldwide (Turner 1996 and citations therein, Cardelús et al 2019). Patterns in species composition and turnover across forest fragments provide a mechanistic understanding of community structure drivers across a landscape [7], such as whether the distance between fragments or fragment size plays a larger role.…”

“…Overall there is a high degree of human disturbance in these forests (56%) as measured as the percent of the forest made up of non-native and weedy taxa, buildings, graves, trails, clearings (see Cardelús et al 2019 for details on how this was calculated). This influences the species richness of trees and seedlings, such that forests with a high degree of disturbance from trails, buildings, and plantings of exotic species, have lower tree species richness, density, and biomass, and lower seedling richness and density [28]. Efforts to demarcate the church boundary and in some cases reduce disturbance from people entering the forest to gather firewood or animals to graze include the erection of a small wall around the forest [22,29].…”

“…We examined the influence of elevation, forest size, degree of human disturbance, the presence of a wall, and the importance of local communities on forest management using Woredas, or districts, on species composition. We predicted that elevation would have a significant effect on species composition as it has affected various forest parameters such as woody species richness, tree density, and species composition [28,30]. We examined whether changes in species composition were more influenced by distance between forests (distance-decay relationships) or differences in forest sizes for all plant species and for plant species with varying dispersal syndromes.…”

Ecosystem Service Response to Human Disturbance in the Yangtze River Economic Belt: A Case of Western Hunan, China

“…Existing research efforts characterizing the impacts of human activities on the eco-environment have mainly focused on the following aspects: land surface [19,20], landscape structure [21][22][23][24][25][26], biodiversity [27][28][29][30], and ES [1,31,32]. Despite research efforts related to ES having increasingly shifted to the detection of the relationships between humans and ES in the context of sustainable development, there is scant research in spatial heterogeneity [31][32][33].…”