Many tree recruitment studies in African savannas target individual factors that limit recruitment, yet recruitment of some species could be limited by an interplay of environmental filters. This study investigated the effects of land use and microsite availability on early seedling recruitment of Acacia tortilis in riverine woodlands in north-western Zimbabwe. The riverine woodlands were divided according to the level of human disturbance into protected and unprotected sites. Each site was further divided into riverine and off riverine microsites. In each microsite, we laid five main plots (100 × 50 m) and nine seedling subplots (5 × 5 m) nested in each main plot, making a total of 60 main plots and 180 subplots. We found higher seedling recruitment in unprotected than protected sites. Although seeder density was twice greater in protected than unprotected sites, seed bank density was lower in the former by a factor of 1.5. Tree cover and herbaceous biomass was 1.4 and 1.8 times greater in protected than unprotected sites, respectively but were negatively correlated with seedling density. Across all microsites, herbivory-related mortality was less than 40% while drought-related mortality was more than 60%. Put together, the results suggest that higher recruitment in unprotected sites was most likely facilitated by domestic ungulates through seed dispersal and grass suppression which enhanced the quality of regeneration sites. We conclude that encroachment of A. tortilis in communal grazing sites is not only important for its conservation but for a variety of goods and services derived from it.

非洲大草原的许多树木招募研究都针对限制招募的个别因素，但是某些物种的招募可能会受到环境过滤器相互作用的限制。这项研究调查了土地利用和微地点可利用性对相思树苗早期募集的影响在津巴布韦西北部的河流林地中。根据人为干扰的程度将河岸林地分为保护区和非保护区。每个站点进一步分为河流微站点和河流微站点。在每个微型站点中，我们在每个主图中都放置了五个主要地块（100×50 m）和九个幼苗子图（5×5 m），总共形成了60个主要地块和180个子图。我们发现未受保护的地点比受保护的地点有更高的幼苗募集量。尽管保护区的播种机密度是未保护区的两倍，但前者的种子库密度却低了1.5倍。受保护的树木盖度和草本生物量分别比未保护的区域高1.4倍和1.8倍，但与幼苗密度呈负相关。在所有微型网站上，与草食相关的死亡率低于40％，而与干旱相关的死亡率则超过60％。综上所述，结果表明，有蹄类动物通过种子散布和抑制杂草提高了再生部位的质量，这很可能促进了有蹄类动物对未保护部位的更高募集。我们得出结论认为，社区放牧地中的玉米曲霉不仅对其保护具有重要意义，而且对由此产生的各种商品和服务也很重要。