Disturbances such as grazing, cultivation, and fire burning can cause changes in the ecosystem (Stephenson & Calcarone, 1999). The nature of the transformation of an ecosystem depends on the extent and the agent of disturbance (Svenssson, 2010). To some extent, disturbances in an ecosystem augment species richness by lowering one or more species (Overbeck et al., 2005). When arable land refrains from any sort of disturbance, species of everlasting shrubs and trees may emerge and dominate the area (Prévosto et al., 2011; Ferreira et al., 2020). Although the expansion of these shrubs creates refuges sites for some of the plant species (Schweiger et al.,2015; Atala, 2020), it is also the cause of the decline in species richness, diversity, and abundances (Guido et al., 2017; Listopad et al., 2018; Zhou et al., 2019; Schreiner-McGraw et al., 2020).Tanzania's southern highlands form one of the most attractive tourist destinations in the country. This includes the Uporoto, Kipengere, and Livingstone mountain ranges, as well as the Eastern Arc Mountains (Lovett &Prins, 1994; Davenport & Ndangalasi, 2003). The area has a high degree of species diversity, more importantly, there are some species endemic to the place while others with restricted range of distribution (Nyomora, 2009). The mountain grasslands are ecosystems renowned for their high diversity and species richness (Payne et al., 2017). But, today the integrity of many grassland ecosystems is in jeopardy due to shrubs’ ingression (Knapp et al., 2008; Matson & Bart, 2013; Barbosa da Silva et al., 2016; Jane Turpie, et al., 2019). Kitulo National Park, which is part of these mountain ranges, is characterized by forest and grassland ecosystems within which epiphytic and terrestrial orchids are found. The orchids belong to the family Orchidaceae that comprise species known worldwide for their spectacular flowers of various shapes and colors hence highly valued aesthetically (Zhang et al., 2018). However, they are the most threatened species and their diversity is globally trending down (Swarts& Dixon, 2009; Wraith & Pickering, 2017). One of the drivers of their decline is the alteration of habitat which could be attributed to ecological succession (Slaviero et al., 2016; Vogt-Schilb et al., 2016). The expansion of Helichrysum species (shrubs) in some parts of the grassland in Kitulo National Park is also attributed to ecological succession. But, there is a knowledge gap about the response of terrestrial orchid species to shrub expansion. Thus, this study aims to generate such information which is crucial for the establishment of a sustainable management approach to the park ecosystem and hence ensure the conservation of orchids. The study intends to: assess the extent of distribution of shrubs and their association with environmental variables in the park; evaluate the effect of Helichrysum species (shrubs) on the orchid species in the park, and assess orchid species diversity and Helichrysum abundance along a continuum of grazing and fire regimes around and within Kitulo National Park. Data collection involves the application of a Geographic Information System (GIS) for mapping and random selection of the sampling points. Laboratory analysis of soil chemical properties complemented by the simple and rapid ribbon methods for evaluation of the textural properties of soil in the study sites. Laboratory analysis of the chlorophyll and flavonoid contents in orchids’ leaves for assessment of plant stress due to competition. Other information was collected through observation and measurement in the field. The data are analyzed by the generalized linear model to evaluate the association of shrubs distribution to the environmental variables. The variation in the abundance of Helichrysum species with respect to different historical land uses was analyzed by using the Kruskal-Wallis H test.