2015). Moreover, people may have played a role in maintaining the newly formed
savannas in areas located in the periphery of the Congo forest.
Rainfall started increasing again after 1200 cal yr BP, leading to forest expansion,
a trend still observed today in some areas of Cameroon (Youta Happi 1998) and
CAR (Guillet et al. 2001). However, the more recent human activity is also important for explaining the current distribution and composition of forests and savannas
in central Africa (Willis et al. 2013; Morin-Rivat et al. 2017).
9.2.1.3 Recent History
Human occupation patterns were strongly modified following the colonization of the
central African region in the 1900s, which had impacts on current forest composition
(Van Gemerden et al. 2003; Engone Obiang et al. 2014; Morin-Rivat et al. 2017).
Indeed, even though local communities used to live deeper into the forest before the
colonial period, they were then forced to gather in the European trading centers and
villages along the main roads. This demographic change is now reflected in forest
composition, as the populations of tree species that dominate the canopy are now
aging (Engone Obiang et al. 2014; Morin-Rivat et al. 2017).
Following European colonization, deforestation and forest degradation also
started to increase. Indeed, the industrialization of the region (starting in ~1920)
was associated with the development of extensive oil palm, coffee, and rubber
plantations (Van Reybrouck 2012) (see Chap. 3, Vol. 1). This process is anecdotally
recorded in lake sediments, where forest degradation has been associated with the
increasing prevalence of fire within forest areas (Aleman et al. 2013). This supports
the notion that plantations and logging activities, coupled with the development of
roads, has been a major cause of forest degradation in the region.
However, despite these recent changes (and their impacts on the vegetation), the
tropical forests of central Africa have experienced relatively low deforestation rates
since the 1900s (Aleman et al. 2018), and even since the 1980s (Pan et al. 2011;
Achard et al. 2014), compared to the other tropical regions (Sodhi et al. 2010; ter
Steege et al. 2015). The socioeconomic and political instability that has plagued
most countries in the region since their independence from colonial powers have
prevented the large-scale expansion of agricultural activities and deforestation. More
recently, forest degradation, and specifically forest fragmentation (Malhi et al. 2014)
due to road development (Laurance et al. 2017) and logging (Laporte et al. 2007)
have been identified as a major threat for the biodiversity (Poulsen et al. 2011;
Abernethy et al. 2016; Ziegler et al. 2016, as also reported in the IPBES report for
Africa). If the broad region eventually stabilizes, a surge of land conversion may be
expected, particularly linked to the expanding oil palm sector (IPBES 2018).
The recent history of land use change also affected vegetation structure and
composition within savannas. First, fire was seen as a destructive force during the
colonial period that was responsible for the deforestation of extensive areas. Indeed,
most mesic savannas are located in areas where the rainfall range allows forests and
savannas to represent alternative stable states (i.e., 1000–2000 mm), and these
9 Long-Term Vegetation Change in Central Africa: The Need for an Integrated. . .
287
savannas in areas located in the periphery of the Congo forest.
Rainfall started increasing again after 1200 cal yr BP, leading to forest expansion,
a trend still observed today in some areas of Cameroon (Youta Happi 1998) and
CAR (Guillet et al. 2001). However, the more recent human activity is also important for explaining the current distribution and composition of forests and savannas
in central Africa (Willis et al. 2013; Morin-Rivat et al. 2017).
9.2.1.3 Recent History
Human occupation patterns were strongly modified following the colonization of the
central African region in the 1900s, which had impacts on current forest composition
(Van Gemerden et al. 2003; Engone Obiang et al. 2014; Morin-Rivat et al. 2017).
Indeed, even though local communities used to live deeper into the forest before the
colonial period, they were then forced to gather in the European trading centers and
villages along the main roads. This demographic change is now reflected in forest
composition, as the populations of tree species that dominate the canopy are now
aging (Engone Obiang et al. 2014; Morin-Rivat et al. 2017).
Following European colonization, deforestation and forest degradation also
started to increase. Indeed, the industrialization of the region (starting in ~1920)
was associated with the development of extensive oil palm, coffee, and rubber
plantations (Van Reybrouck 2012) (see Chap. 3, Vol. 1). This process is anecdotally
recorded in lake sediments, where forest degradation has been associated with the
increasing prevalence of fire within forest areas (Aleman et al. 2013). This supports
the notion that plantations and logging activities, coupled with the development of
roads, has been a major cause of forest degradation in the region.
However, despite these recent changes (and their impacts on the vegetation), the
tropical forests of central Africa have experienced relatively low deforestation rates
since the 1900s (Aleman et al. 2018), and even since the 1980s (Pan et al. 2011;
Achard et al. 2014), compared to the other tropical regions (Sodhi et al. 2010; ter
Steege et al. 2015). The socioeconomic and political instability that has plagued
most countries in the region since their independence from colonial powers have
prevented the large-scale expansion of agricultural activities and deforestation. More
recently, forest degradation, and specifically forest fragmentation (Malhi et al. 2014)
due to road development (Laurance et al. 2017) and logging (Laporte et al. 2007)
have been identified as a major threat for the biodiversity (Poulsen et al. 2011;
Abernethy et al. 2016; Ziegler et al. 2016, as also reported in the IPBES report for
Africa). If the broad region eventually stabilizes, a surge of land conversion may be
expected, particularly linked to the expanding oil palm sector (IPBES 2018).
The recent history of land use change also affected vegetation structure and
composition within savannas. First, fire was seen as a destructive force during the
colonial period that was responsible for the deforestation of extensive areas. Indeed,
most mesic savannas are located in areas where the rainfall range allows forests and
savannas to represent alternative stable states (i.e., 1000–2000 mm), and these
9 Long-Term Vegetation Change in Central Africa: The Need for an Integrated. . .
287