Table 1.

Studies finding woody encroachment in sub-Saharan Africa.

country	vegetation type	location	method	results	reference
a. Cameroon	enclosed savanna bordered by young semi-deciduous forests	4°20’ N, 13°43’ E	field inventory of woody species along transects and soil carbon isotope analysis	results suggest a fast, nonlinear advance of forest into savanna; forests <100 years old	[21]
b. Cameroon	forest–savanna mosaic	5°13’ N, 12°30’ E	transects and the analysis of aerial photographs/Landsat	gallery forest encroachment into surrounding savannas at 0.6–2 m yr−1 between 1950 and 1990	[22]
c. Cameroon	forest–savanna mosaic; forested in south, savanna with gallery forests to the north	6°0’ N, 12°48’ E	field data used to derive woody-cover to NDVI relationship. Landsat and ASTER for change detection	12.6% of the area showed significant positive change in canopy cover from 1986 to 2000, and 7.8% from 2000 to 2006	[23]
d. Cameroon	as above	6°0’ N, 12°48’ E	change in biomass detected by L-band radar: 1996–2007	significant woody encroachment in Mbam Djerem national park region; deforestation to east of park	[24]
e. Republic of Congo	forest–savanna mosaic	5°02’ S, 11°35’ E	leaf area index measurement, transects perpendicular to ecotone	forest progression into savanna at rate of 1–2 m yr−1	[25]
f. Republic of Congo	sharp forest–savanna boundary	4°00’ S, 12°30’ E	transects, soil sampling	carbon isotope analysis suggests forests expanding into savannas at 0.2–0.5 m yr−1	[26]
g. Ethiopia	dry savanna in southern Ethiopia	4°28’ N 38°11’ E	vegetation sampling inside and outside enclosures	enhanced grazing causes woody encroachment	[27]
h. Ethiopia	as above	4°50’ N, 39°00’ E	landscape classification	reduction in fire causing rapid woody encroachment and reduction in grass cover	[28]
i. Gabon	forest–savanna mosaic 55 km away from Libreville	0°20’ S, 9°20′ E	13C analysis of soil samples to build a chronosequence	forest expansion has occurred at ∼1 m yr−1 in coastal Gabon	[29]
j. Ivory Coast	forest islands in savanna woodland	7°25’ N, 5°17′ W	monitoring long-term vegetation plots	rapid reforestation	[30]
k. South Africa	woody savanna, heterogeneous in structure and water availability	Kruger: 24°0’ S, 31°29’ E Eastern Cape: 32°48’ S, 26°50’ E	filed studies combined with aerial photography analysis	kruger: threefold increase in woody cover in mesic savanna, no change in dry savannas. Eastern Cape: tree cover increased from 1% in 1973 to 50% in 2007	[31]
l. South Africa	sub-humid grasslands	28°9’ S′, 29°21′ E	aerial photographs, 1945–2006	tree density increased from 1976 onwards. Tree canopy area increased by 10-fold in 35 years	[32]
m. South Africa	rangelands and abandoned cultivated land	33°16’ S, 27°8’ E	analysis of multi-spectral SPOT images	11.5% increase in ‘slightly eroded (dense bush)’ category 1998–2008	[33]
n. South Africa	savanna woodland, different management types	28°02’ S, 32°12’ E	field transect evaluation and aerial photograph analysis	total tree cover increased from 14% in 1937 to 58% in 2004 in a conservation area, from 3% to 50% in a commercial ranching area, and 6% to 25% in a farmed area	[34]
o. Swaziland	low-veld savanna	26°15’ S, 31°50’ E,	analysis of aerial photographs and ground survey	shrub cover increased from 2% in 1947 to 31% in 1990	[35]
p. Uganda	transition from woody savanna to tall tropical forest	2°04’ N, 31°39’ E	combination of field studies and vegetation index-based satellite change detection	14% increase in woody vegetation over a 14-year period	[36]