Kim Hy Proposed Nature Reserve - Frontier-publications.co.uk

Pithecellobium sp.). The extant upper canopy is composed mainly of Excentiodendron cf.
tonkinensis (26 individuals accounting for over 15% of the basal area of wood), joined by
a handful of specimens of Pometia cf. pinnata (Sapindaceae). Dipterocarps
(Dipterocarpus and Hopea) are also present in small numbers. The strong dominance of
Streblus/Excentiodendron makes this type of forest somewhat less diverse than the mixed
type in terms of families and genera of trees. Ground flora is sparse due to the shade
provided by the extensive middle canopy, a large proportion being saplings of canopy
trees such as Excentiodendron (20% of the ground flora stems), Streblus, Dalbergia
(Fabaceae), Wendlandia (Rubiaceae) and Garcinia. Other woody species more sparsely
distributed in the forest are also represented here, such as Ficus (Moraceae) and Acer
(Aceraceae), alongside smaller populations of various herbaceous plants, particularly
Impatiens(Balsaminaceae), and members of Araceae and Orchidaceae.
FPC is an example of this type of forest at a lower altitude (530m), situated close to the
Imperata cylindrica/shrub-covered basin floor which increases the amount of the ambient
light in the lower reaches of the plot. As a result, ground flora is rather more extensive,
with a comprehensive carpeting of species of Polypodiaceae. However, elsewhere in the
plot, the pattern is similar, with dominant Excentiodendron forming the upper canopy
(c.12-20m) this time alongside Garcinia and Spondias sp. The latter is softwood with
little economic value, which often forms an extensive emergent canopy sparsely
distributed above forest on limestone. Together these three genera account for over 70%
of the basal area of wood in the plot due to the large tree sizes. Meanwhile, once more,
Streblus dominates the lower middle canopy, Antidesma (Euphorbiaceae) and Litchi
(Sapindaceae) forming the upper middle canopy, and Excentiodendron, Streblus and
other woody saplings such as Xylopia sp. (Annonaceae) strongly characterising the
ground flora. Despite having been recorded as one of the main vegetation types within
the reserve, areas containing Streblus sp. were found to be relatively patchy and
restricted: Sreblus was actually absent or represented by one or two individuals in most
plots.
The second, more widespread forest type exhibits more mixed and varied patterns of
dominance. Previous studies by Birdlife International identified species such as
Terminalia myriocarpa (Combretaceae), Pometia pinnata (Sapindaceae), and Bischofia
javanica (Euphorbiaceae) in this forest type, although few of these were recorded in the
Frontier plots and none were found to be dominant, suggesting some degree of
heterogeneity in this more mixed type. The majority of the forest in Frontier’s survey
across the altitudinal range was found to be more diverse with regard to both tree and
ground flora, or at least to exhibit dominance of various different genera replacing
Streblus in the middle storeys. These are principally from Euphorbiaceae (Mallotus,
Antidesma and Glochidion) and Fagaceae (mainly Lithocarpus, also Castanopsis).
Similar to FPB and FPC, the upper and emergent canopies are heavily dominated by
species of Tiliaceae (principally Excentiodendron cf. tonkinensis but also Colona sp.)
which account for a mean of 48.54% of basal area of wood from only 15% of the
individuals across the remaining plots. Other large specimens of Michelia
(Magnoliaceae), Markhamia (Bignoniaceae), Acer, Garcinia, Pometia, Lithci, Sweitenia
(Meliaceae) and Elaeocarpus (Elaeocarpaceae) sp., as well as larger specimens of the
middle canopy trees, also complement the upper storeys. Forest stratification is
Frontier Vietnam Forest Research Programme Technical Report No.24. 33