Tree species in Tanzania 615
TABLE 2 Locations and status of subpopulations of C. porphyrantha and G. macrosiphon in Kenya and Tanzania. Site (Fig. 1) Number of mature trees
C. porphyrantha Kenya Longo Mwagandi, Shimba Hills National Park Pangani Rocks
Tanzania Bulwa forest fragment, East Usambara Mountains
G. macrosiphon Kenya Gongoni Forest Reserve Kaya Muhaka
Mrima Forest Reserve
Tanzania Amani Nature Reserve, East Usambara Mountains Bulwa forest fragment, East Usambara Mountains Kwezitu forest fragment, East Usambara Mountiains Udzungwa Mountains National Park Kihansi Gorge, Udzungwa Mountains
Rondo Nature Forest Reserve
1 2
6
3 4 5
6 6 6 7 8
9
Formerly 2, now extinct1 Not reported2
18
159 21 2
0 5 1 1 8
Not reported3
Source
Luke et al. (2018) Luke et al. (2018)
This study
Malombe et al. (2015) Malombe et al. (2015) Malombe et al. (2015)
This study This study This study
Luke & Verdcourt (2004)
H.J. Ndangalasi, unpubl. data, 2004–2015
Gwegime et al. (2014)
1The last two mature trees in Longo Mwagandi were killed by elephants (Luke et al., 2018). 2Luke et al. (2018) did not provide the number of mature trees but stated that the site is affected by limestone extraction. 3In six sites in Rondo Nature Reserve, two 1 km transects were surveyed per site and the species was recorded in three sites, but the number of mature trees was not reported.
was collected in 1910 ‘at Amani’.These twospecimens were subsequently destroyed in the Berlin herbarium during World War II (Hiepko, 1987). A third syntype, Grote 3763, was collected in 1912 from near Kihuhwi at 500 m; the speci- men at Berlin was destroyed but a duplicate was preserved in the East African Herbarium. Despite these early records, G. macrosiphon has not been reported since 1912 from the East Usambara Mountains during the many subsequent wide-scale studies of trees there (Hamilton & Bensted-Smith, 1989; Frontier Tanzania, 1996a,b, 2001a,b, 2002a,b)orintwo targeted searches for it in Amani Nature Reserve (Luke & Verdcourt, 2004) and Kihuhwi (A. Mndolwa, pers. comm., 2023). We also failed to relocate it in the Dodwe River area. Of the eight sites in which G. macrosiphon has been recorded in Kenya (Kaya Muhaka and Gongoni and Mrima Forest Reserves) and Tanzania (Amani Nature Reserve, Bulwa forest fragment, Udzungwa Mountains National Park, Kihansi Gorgeand RondoNatureForestReserve), thelargest popula- tion is in Gongoni Forest Reserve,with 159 mature trees (Fig. 1, Table 2; Malombe et al., 2015). Thesizeclass distribution of G. macrosiphon in Gongoni Forest Reserve (Malombe et al., 2015) and the EastUsambaraMountains (Fig. 2)iscom- parable, indicating similar recruitment and the ability tomain- tain a small subpopulation. Cola porphyrantha was previously known at two sites in
Kenya (LongoMwagandi in Shimba Hills National Park and Pangani Rocks; Fig. 1, Table 2; Cheek, 2007). When first discovered in 2000 at 950 m altitude in the East Usambara Mountains, this was the only known record in Tanzania,
and was 500 m higher than the records in Kenya (Cheek, 2007). Only five mature individuals were reported then, and the small forest fragment was described as heavily affected by human activities (Table 2; Cheek, 2007). The 18 mature trees and high recruitment at different onto- genetic stages (Fig. 2) are suggestive of a subpopulation that is currently stable but small. The eight saplings found at c. 120 mfrom themain stand of mature trees are probably a result of seed dispersal by blue monkeys, although for the downslope plot, runoff from heavy rains could also have carried seeds from higher up. Cola porphyrantha and G. macrosiphon are narrowly dis-
tributed in the East Usambara Mountains and are currently known to co-occur only in an unprotected forest fragment surrounded by tea plantations and subject to heavy anthro- pogenic disturbance because of proximity to a large village. Although the part of the fragment where these two species occur was little disturbed, probably because of the steep and rocky terrain, widespread cutting of saplings, poles and trees threatens this forest fragment. These species require protection at this site, by either the government or the village authorities, as does the unprotected forest nearKwezitu wherewe located a single G. macrosiphon. An additional concern, at least for G. macrosiphon,is thatfungalattack,seedpredation and seedling herbivory appear to impact early recruitment (Malombe et al., 2015;H.J.Ndangalasi&N.J. Cordeiro, pers. obs., 2022–2024). As we have a basic understanding of the flowering and fruiting periods of these two species (Table 1), andalsoofseedgermination andseedlinggrowth rates
Oryx, 2024, 58(5), 611–617 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000462
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