Other mountains within this area are Mount Lanang (2,313 m), Mount Ayek-ayek (2,819 m), Mount Pangonan Cilik (2,833 m), Mount Keduwung (2,334 m), Mount Jambangan (3,020 m), Mount Gentong (1,951 m), Mount Kepolo (3,035 m), and Mount Malang (2,401 m). The Semeru forest area has many rivers that are former lava lines from Mount Semeru. The Semeru group is considered to be very productive, producing volcanic matters such as lava, volcanic ash, and hot cloud and spreading it to the surrounding area. The lower area is surrounded with fertile rice fields. Climate The climate in Bromo Tengger Semeru is cold, especially in winter from May until September. There is heavy rainfall in summer, while there is little to no precipitation in winter. Nighttime temperatures in winter commonly fall below zero degrees Celsius, with potential for frost and light snow. It is classified as a subtropical highland. Ecosystem According to height and temperature differences, the forests within the area can be classified into three zones: Sub-montane zone (750 – 1,500 m) This zone is classified as a tropical rainforest. It can be found in the southern area of Semeru, East Semeru (Burno), and West Semeru (Patok Picis). This zone is dominated with plants of the families Fagaceae, Moraceae, Anacardiaceae, Sterculiaceae, and Rubiaceae. There are also liana trees, such as a variety from the genus Calamus, Piper, Asplenium, and Begonia, and other plants from the family Araceae, Poaceae, and Zingiberaceae. There are also 225 species of orchid in this area. Montane zone (1,500 – 2,440 m) Plant life is greatly reduced in this area. Most of the species that grow in this area are pioneer species. There are also some wooden plants such as cemara (Casuarina junghuhniana), (Vaccinium varingifolium), kemlandingan gunung (Albizia lophantha), acacia bark (Acacia decurrens) and bottom plants such as Javanese edelweiss or senduro (Anaphalis longifongila and Anaphalis javanica), Imperata cylindrica, Pteris sp., Themeda sp. and Centella asiatica. The Tengger Sand Sea in Tengger Caldera is a special ecosystem. The area is covered in volcanic sedimentation of sand from Mount Bromo activities. The resulting area is believed to be the only known desert-like area in Indonesia. The Tengger Sand Sea has been protected since 1919. Subalpine zone (above 2,400 m) The flora that cover this area are (Vaccinium varingifolium) and cemara (Casuarina junghuhniana). Kemlandingan gunung (Albizia lophantha) and Javanese edelweiss can also be found growing in this zone. On Mount