Pu‘u Maka‘ala Natural Area Reserve (PUUM) is a terrestrial NEON field site located in the South Hilo district on the Big Island of Hawai‘i. The 75.7 km2 (18,700 acre) reserve is managed by the Hawaii Department of Natural Resources. NEON samples 47.2 km2 (11,662.5 acres) at the reserve. Situated along an elevation gradient of 853 - 1899 m (2800 - 6230 ft.) on Mauna Loa, it features a range of habitat types, from shrubby grasslands to wet rainforest. The unique endemic diversity coupled with threats from invasive species makes Pu‘u Maka‘ala a compelling location to conduct long-term ecological research. The reserve is dedicated solely for the purpose of conservation, making the area extremely important for the protection of native species. PUUM is the only field site of the NEON Pacific Tropical Domain (D20), which includes all of the Hawaiian islands.