Abstract Rangelands provide ecosystem services that support approximately 30% of the human population. To maintain sustainable forage resources for animals in grasslands, it is essential to manage grazing pressures by adapting to changes in the quantity and nutritional quality of vegetation affected by climate change and subsequent shifts in plant interactions. To investigate how climate change and altered plant composition interact to impact forage quantity and quality, we conducted a field experiment involving warming and dominant plant removal treatments. We measured changes in the abundance and crude protein content of key forage species. Our results showed a 12% reduction in community‐level protein content due to warming. In contrast, plant species removal and the interaction between warming and removal treatments had only minor effects on community‐level crude protein content. Warming did not significantly affect the total abundance of palatable plant species, but it caused a decline in evenness in the forage plant community. Additionally, the relative cover of the high‐value forage species decreased slightly, while low‐quality forage species saw a modest increase under warming conditions. To prevent overgrazing and the long‐term degradation of rangelands in a warmer world, managers may need to reduce livestock stocking rates if forage nutritional quality declines, even without a reduction in forage quantity. This study highlights how even a single aspect of global change, such as warming, can lead to significant losses in forage quality—an effect that is expected to worsen as these ecosystems continue to dry.