We use remotely sensed data to estimate species diversity in Blouberg Nature Reserve (BNR) in the Limpopo province, South Africa to understand the state of biodiversity since communities’ involvement in conservation initiatives. To achieve this objective, Landsat series data collected before and after community involvement in biodiversity conservation were used in conjunction with selected diversity indices i.e., Shannon-Wiener Index (H’) and Simpson Index (D). Thirty 15 m × 15 m field plots were selected and all trees within each plot were identified, with the help of Botanists. Further, we applied regression analysis to determine the relationship between satellite derived tree species diversity and field observations. The results of the study demonstrated a significant (p < 0.5) variation in tree species diversity between 1990 and 2019. The highest relationship was obtained between H’ and the combined remotely sensed spectral data and as well as Indices (VIs) when compared to other derived satellite data. Further, the results showed positive significant relationship (p < 0.05) between the combined remotely sensed data and observed H’ index with r2 = 0.36 and r2 = 0.34 for the period before and after involving local communities in biodiversity conservation, respectively. Thus, the findings of the study indicate that the ecological condition of the reserve was slightly affected by the involvement of local communities in biodiversity conservation, for instance, volunteering in bush-encroachment eradication and decision-making. Overall, findings of the study underscore the relevance of remotely sensed data in assessing the ecological condition of protected areas and this information can help in decision-making.