temperatures and the highest rainfall in the country. The country's rainy season generally runs from late October to March, and the hot climate is moderated by increasing altitude. Zimbabwe is faced with recurring droughts. In 2019, at least 55 elephants died because of drought. Severe storms are rare. Biodiversity Zimbabwe contains seven terrestrial ecoregions: Kalahari acacia–baikiaea woodlands, Southern Africa bushveld, Southern miombo woodlands, Zambezian Baikiaea woodlands, Zambezian and mopane woodlands, Zambezian halophytics, and Eastern Zimbabwe montane forest-grassland mosaic in the Eastern Highlands. The country is mostly savanna, although the moist and mountainous Eastern Highlands support areas of tropical evergreen and hardwood forests. Trees found in the Eastern Highlands include teak, mahogany, enormous specimens of strangler fig, forest Newtonia, big leaf, white stinkwood, chirinda stinkwood, knobthorn and many others. In the low-lying parts of the country fever trees, mopane, combretum and baobabs abound. Much of the country is covered by miombo woodland, dominated by brachystegia species and others. Among the numerous flowers and shrubs are hibiscus, flame lily, snake lily, spider lily, leonotis, cassia, tree wisteria and dombeya. There are around 350 species of mammals that can be found in Zimbabwe. There are also many snakes and lizards, over 500 bird species, and 131 fish species. Environmental issues Large parts of Zimbabwe were once covered by forests with abundant wildlife. Deforestation and poaching has reduced the amount of wildlife. Woodland degradation and deforestation caused by population growth, urban expansion and use for fuel are major concerns and have led to erosion which diminishes the amount of fertile soil. Local farmers have been criticised by environmentalists for burning off vegetation to heat their tobacco barns. The country had a 2019 Forest Landscape Integrity Index mean score of 6.31/10, ranking it 81st globally out of 172 countries. Government Zimbabwe is a republic with a presidential system of government. The semi-presidential system was abolished with the adoption of a new constitution after a referendum in 2013. Under the constitutional changes in 2005, an upper chamber, the Senate, was reinstated. The House of Assembly is the lower chamber of Parliament. In 1987 Mugabe revised the constitution, abolishing the ceremonial presidency and the prime ministerial posts to form an executive president—a presidential system. His ZANU-PF party has won every election since independence—in the 1990 election the second-placed party, Edgar Tekere's Zimbabwe Unity Movement (ZUM), obtained 20% of the vote. Politics During the 1995 parliamentary elections most