**1. Introduction**

Tanzania's forests cover approximately 45.7 million ha, or about 55 % of the country's total land area, as of 2022 [1]. The forests provide essential goods and services [2]. In addition to providing economic benefits, Tanzanian forests and other woodlands serve as important habitats for a variety of animals and plant species. Over 10,000 plant species have been identified in these forests, with 305 being classified as threatened by the IUCN Red List and 276 being classified as endangered [3]. Despite the valuable goods and services that forests provide, high rates of deforestation and forest degradation persist [4, 5]. Forest degradation is a subset of the larger issue of land degradation. Deforestation and forest degradation continue at alarming rates, contributing significantly to the ongoing loss of biodiversity around the world. According to the last Global Forest Resources Assessment report (2020), deforestation has occurred at a rate of 469,000 ha per year. Forest degradation is defined as changes within the forest that have a negative impact on the structure or function of the stand and/or site, reducing the capacity to supply products and/or services [6]. Forest degradation alone contributed 25% of total emissions from deforestation and forest degradation even exceeding emissions from deforestation in some countries [7].

The major causes of forest degradation in the unreserved forest include heavy pressure from agricultural expansion, livestock grazing, development of human settlements, overgrazing, firewood and charcoal production, uncontrolled fires, timber extraction, development of infrastructure/industry, refugees, and most recently, the introduction of large-scale agriculture for bio-fuel production [5]. Several studies in Tanzania have investigated the various drivers, trends, and methods for assessing deforestation and forest degradation [4, 8, 9].

To sustainably provide goods and services from the forests, effective forest management initiatives are required. If these initiatives are implemented, Tanzania may ultimately be able to reduce emissions caused by deforestation and forest degradation. This would help it meet its emission reduction targets. This chapter discusses the findings of a systematic literature review of forest degradation in Tanzania, in terms of (1) trends in research on forest degradation, (2) research topics covered and gaps in research, (3) extent of forest degradation, (4) drivers of forest degradation, (5) methods of monitoring and assessment of forest degradation, (6) institutions involved in efforts to control forest degradation, and (7) spatial distribution of studies on forest degradation.
