Alalili systems are among the indigenous rangeland management strategies that face pressures from unsustainable land use practices and impacts of climate change. We aimed to establish the vascular fodder plants' composition and abundance, compared with historical vegetation data to understand their evolution and trends to inform sustainable management of rangelands in northern Tanzania. The vegetation composition of the northern Tanzania rangelands surveyed before the 1980s was compared to empirical data from a vegetation survey of Alalili in 2022. A cross-sectional design using purposive and stratified random sampling techniques was applied during the field survey. The quadrat count method was used to estimate the composition and diversity of fodder taxa in Alalili systems. Secondary data from the northern Tanzania rangelands before the 1980s were collected through a systematic literature review. Key informant interviews, focused group discussions, and household surveys were used to gather information about the community's knowledge of historical quality changes in the rangelands. Our results indicate that, before the 1980s, the rangelands of northern Tanzania had relatively higher fodder species composition (127 woody and 119 herbaceous species) than the Alalili systems in 2022 (119 woody and 82 herbaceous species). Fodder species composition and diversity were relatively higher in communal than in private Alalili (t = 4.18, P < 0.001). At the same time, the species density was lower in communal than in private Alalili (t = -2.7272, P = 0.008). This work suggests that Alalili systems still hold substantial diverse fodder plants that most northern Tanzanian rangelands used to harbor before the 1980s. Therefore, they can be considered reservoirs of vital fodder species that can be used to restore degraded rangeland areas in northern Tanzania and elsewhere.