Inventory and conservation of endangered , endemic and economically important flora of hamiguitan range , southern Philippines

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IntroductIon
Mount Hamiguitan Range Wildlife Sanctuary in Davao Oriental is a protected area covering 6 834 ha located between 6°46'6°40'01" to 6°46'60" N and 126°09'02" to 126°13'01" E. The mountain is known for its unique characteristics and the largest pygmy 'bonsai forest' in the country.This forest type has a substrate predominated by ultrabasic rocks.The rock weathers leaving the soil with an unusually high concentration of iron and magnesium causing it to be unproductive for agricultural activities.Only a specialized group of plants grow on this type of forest which is often low, heath-like shrubs.Nepenthes alata Blanco, a facultative ultrabasic, as well as obligate ultrabasic species of Nepenthes (Nepenthaceae) were found to be numerous in the area.Other ultrabasic indicator species such as Scaevola micrantha (Krause) C.Presl (Goodeniaceae), Scaevola sp., Suregada glomerulata (Blume) Baill.(Euphorbiaceae) and Ochrosia glomerata (Blume) F.Muell.(Apocynaceae) were also found thriving in the vegetation.
The unique biodiversity resources in Mt Hamiguitan Range have not been spared from destruction such as timber poaching, illegal logging and overharvesting of forest products and resources.This will be aggravated because of the forthcoming mining activities.As a result, elements of the important flora and fauna may be lost before they are recorded, studied and conserved.
This research aimed to inventory and assess the flora in Mt Hamiguitan Range Wildlife Sanctuary and its surroundings.Specifically, it aimed to identify and describe the vegetation types; determine the diversity and species importance values (SIV); assess the conservation status of the species whether endemic, endangered, rare and economically important; and, determine the threatened and endemic species distributions and habitats for conservation.

Vegetation types
Field reconnaissance and transect walks were conducted to identify and describe the vegetation types occurring in Mt Hamiguitan Range.On basis of species composition, altitude and other ecological indicators, we identified four vegetation types as a basis for further analysis.In addition, the term agroecosystem is used to refer to the cultivated areas around the villages.

Diversity indices
To determine species richness, transect walks were undertaken and sampling plots were established with the assistance of Bantay Gubat.Per vegetation type a 2-ha transect walk was conducted with a local expert and transect belts were established.
A total of thirty-two 20 × 20 m sampling plots were established in all vegetation types, each type with 6 sampling plots except for the dipterocarp forest with 14 plots.Within these plots, a 5 × 5 m subplot was laid out to determine the species richness for shrubs, vines and herbs.We assessed species diversity by using the Shannon index of general diversity (H): H = -Σ ndbh/Ndbh log ndbh/Ndbh where ndbh = total diam at breast height of individual tree species Ndbh = total diam at breast height of all tree species The Species Importance Value (SIV) was computed using the formula of Brower & Zar (1977):

Identification of threatened and endemic species and habitats for conservation
The type of vegetation, altitude, and location of endemic, endangered, rare and economically important species and their habitats were recorded whenever they were encountered.Transect diagrams were prepared to identify the location and distribution of the threatened and endemic species.The result of this method will be the basis for in situ conservation of the threatened habitats and species.

Vegetation types
We identified four vegetation types: dipterocarp forest, montane forest, typical mossy forest and mossy-pygmy forest.

Species richness
Transect walk and sampling plots revealed a total of 878 species, 342 genera and 136 families.Of these, 698 were angiosperms, 25 gymnosperms, 141 ferns and 14 fern allies (Table 1, 2).This number of species in Mt Hamiguitan is 68 % lower than those observed in Mt Malindang which has 1 200 species (Arances et al. 2004), but more species of gymnosperms were observed in Mt Hamiguitan than in Mt Malindang Range.
Among the vegetation types, the montane forest exhibits the highest species richness with 462 species.This is 113 % higher than those observed by Arances et al. (2004) in the montane forest of Mt Malindang Range.The higher species richness in this vegetation type might be due to the intact forest and to the more diverse habitats.
The typical mossy forest with 246 species contains more endemic and rare species.The lower species richness in the dipterocarp forest compared to the montane forest despite the numerous sampling plots (14 plots) may be attributed to the small plot size which is less than the standard set for this type of forest (Fig. 1).It could also be attributed to the exploitation of forest resources as source of livelihood.The presence of tall trees with bigger diam at breast height may also limit the growth of smaller plants.

Species diversity index
The highest diversity value for trees could be observed in the montane forest with H = 1.70, followed by the dipterocarp forest (H = 1.63).The mossy-pygmy forest is less diverse, with H = 1.32 and the lowest diversity value was observed in the mossy forest with H = 1.27.endemism is given in Table 5, a breakdown of the status of these species in taxonomic groups is presented in Table 6, and into vegetation types in Table 7.Of the species found in Mt Hamiguitan Range, 163 (37 %) are endemic to the Philippines which is equivalent to 5 % of the total number of endemic plants in the Philippines (Table 5).Thirty-five species (7 %) are threatened, 33 species (7 %) rare and 204 species (43 %) were assessed as economically important (Table 6).Of the 530 threatened species in the Philippines, 35 (7 %) were found in Mt Hamiguitan ( The montane forest had the highest average number of species per plot ( 27) and the highest number of individuals (84).This might be due to the relative absence of human activities and the environmental itself that favours growth of trees.Calophyllum blancoi (Clusiaceae) was observed in all vegetation types.Merrill (1926)  Assessment of the endemicity of trees per vegetation type, based on the sampling plots, revealed that the mossy-pygmy forest possesses the highest number of endemic species having a value of 32 % (Table 7).This confirms the results of Arances et al. ( 2004) in Mt Malindang that as elevation increases there is also an increasing number of endemic plants.
The largest numbers of rare species were observed in the montane to the mossy-pygmy forest with 22-23 species in each type, which is equivalent to 67-70 % of the total rare species in Mt Hamiguitan Range.The smallest number of rare species was observed in the agro-ecosystem (Table 7).Economically important species occur in all vegetation types and are not particularly common in the agro-ecosystem.Gnetum latifolium Blume (Gnetaceae), Schizaea inopinata Selling (Schizaeaceae), S. malaccana Hook., Platycerium coronarium (Konig ex Muell.)Desv.(Polypodiaceae), Psilotum nudum (L.) P.Beauv.(Psilotaceae) and P. complanatum Sw. are noteworthy (Fig. 2).However, there is a need to protect and conserve the habitat of Nepenthes copelandii in the montane, mossy and mossy-pygmy forests in San Isidro since this plant species is critically endangered, endemic and rare (Fig. 3).Mt Hamiguitan mountain range is the habitat of six species of pitcher plants which is 50 % of the total number of Nepenthes in the Philippines.It could also be noted that five species of Shorea were observed in the dipterocarp forest.While Shoreaspecies are common in other Asian countries (Ashton 1992), these dipterocarps are critically endangered, endemic and vulnerable in the Philippines.
Of the four species of Schizaea occurring in the Philippines, three have been found in Mt Hamiguitan Range, viz.Schizaea dichotoma (L.) J.Sm., S. inopinata and S. malaccana.The last two species are of equal botanical importance as these are new records in Mindanao and collected only once or twice in the Philippines (Table 9).Schizaea inopinnata was collected only once in Bohol in 1923 while S. malaccana was recently collected only in Mindoro andSibuyan in 1993 (Barcelona et al. 1996).
Another important finding is the number of new records for the Philippines and for Mindanao ( Density of threatened species is highest in the dipterocarp forest and decreases at higher elevation.Species richness was highest in the montane forest and lowest in typical mossy forest.Endemism increases from the dipterocarp to the montane forest but is lower in the mossy forest. (Dipterocarpaceae) and vines (Smilax spp., Smilacaceae) dominate the forest.The height of trees ranges from 5 -30 m.The montane forest is situated around 6°44'08" N and 126°20'08" E, with altitude ranging from 920 -1160 m.Agathis philippinensis Warb.(Araucariaceae), various species of Nepenthes sp.(Nepenthaceae) and epiphytes characterize this type.The height of trees ranges from 5 -25 m, decreasing as the altitude increases.The typical mossy forest is situated around 6°42'16" N and 126°11'52" E, in altitude ranging from 1160 -1350 m.Mosses form thick mats covering roots and tree trunks.Calophyllum blancoi Planch.& Triana (Clusiaceae), Dacrydium elatum (Roxb.)Wall.(Podocarpaceae), Calamus spp.(Arecaceae) and Pinanga spp.(Arecaceae) species are dominant in the area.Freycinetia sp.(Pandanaceae) are the dominant epiphytic plants, often festooned over large trees.The height of trees ranged from 6 -15 m.The mossy-pygmy forest is situated around 6°43'24" N and 126°11'11" E, ranging in altitude from 1160 -1600 m.However, pygmy forest (but not mossy) was also observed as low as 75-275 m in Mati around 6°43'44" N and 126°13'27" E. The mossy-pygmy forest occupies c. 225 ha.The height of trees ranges from 0.5-2.5 m and the average diam is 8 cm.The forest is dominated by Leptospermum sp.(Myrtaceae), Weinmannia sp.(Cunoniaceae), Elaeocarpus sp.(Elaeocarpaceae) and Dacrydium sp.(Podocarpaceae).Abundant mosses are present on the forest floor.

Fig. 1
Fig. 1 Species accumulation curve in four vegetation types.

Fig. 2
Fig. 2 Transect diagram of Mt Hamiguitan showing the altitudinal distribution of vegetation types, threatened, rare, endemic and economically important species from Hamiguitan Peak to Sitio Magum, Mati.

Fig. 3
Fig. 3 Transect diagram of Mt.Hamiguitan showing the altitudinal distribution of vegetation types, threatened, rare, endemic and economically important species from Sitio Tumalite to Hamiguitan Peak.

table 1
Total number of families, genera and species of flora in Mt Hamiguitan Range.

table 2
Species richness in the different vegetation types in Mt Hamiguitan Range based on sampling plot and transect walk.

Table 8 )
(Heaney & Regalado 1998)r plants in Mt Hamiguitan Range is higher compared to the Malindang Range whereArances et  al. (2004)found only 23 % endemic species.Inventory of trees within the thirty-two 20 × 20 m sampling plots revealed a total of 184 species of trees and 1 762 individuals with an average of 20 species and 67 individuals.Average numbers per plot are given in Table3, and the most important species are listed in Table4.In the dipterocarp forest, an average of 64 individuals of trees was observed in all sampling plots.Lithocarpus llanosii Rehder has the highest species importance value, followed by Shorea astylosa Foxw.andZanthoxylum diabolicum Elmer (Rutaceae).These tree species with the highest species importance values differ from those recorded in Mt Malindang where Cyathea brevipes Copel.(Cyatheaceae)rankedfirst with 79 %, followed by Lithocarpus philippinense (A.DC.)Rehder(Arancesetal. 2004).Lithocarpus and Shorea are also dominant in the dipterocarp forest of Mt Apo(Heaney & Regalado 1998).Species composition of trees in the different vegetation types of Mt Hamiguitan Wildlife Sanctuary.* trees with less than 10 cm dbh were also counted.

table 4
Summary of top five species of trees in the different vegetation types with their species importance value (SIV) and ranks.

table 5
reported that C. blancoi could be observed in the primary forest at low and medium altitude and is often abundant there.Two species were observed in both dipterocarp and montane forest, namely Schefflera sp.(Araliaceae) and Endemism in the Philippines compared to Mt Hamiguitan Range.Based on specimens identified to species only.
(Madulid 1991)the StAtuS oF the FlorA oF Mt hAMIguItAn rAngeThe Philippines is the home of 3 557 endemic species with 26 endemic genera of vascular plants.Of these, 3 200 species are angiosperms, 6 gymnosperms and 351 pteridophytes (ferns and fern allies)(Madulid 1991).In Mt Hamiguitan Range, we were able to identify 477 species to species level.A comparison of

table 8
Assessment of the status of species of Phanerogams per vegetation type.Status of threatened species: CES = Critically endangered species; ES = Endangered species; V = Vulnerable; OTS = Other threatened species.Endangered, endemic and rare species of plants that must be given high priority for protection and conservation.
Some of the rare and endemic plants observed are Calamus merrillii Becc., C. ornatus var.philippinensis Becc., Nepenthes alata, N. argentii Jebb & Cheek, N. mira Jebb & Cheek and N. copelandii Merr.The presence of the rare species such as table 7 Table 10).Eight new records of plant species in Mindanao include Elaeocarpus argenteus Merr., E. verticillatus Elmer, Patersonia lowii Stapf (Iridaceae), Astronia lagunensis Merr.(Melastomataceae), Nepenthes argentii, N. mira, Schizaea inopinata and S. malaccana.Nepenthes maxima is a new record for the Philippines, until now being reported from Sulawesi, New Guinea and the Moluccas.Noteworthy is also the discovery of the endemic genus Greeniopsis (Rubiaceae).Of the six Philippine species of Greeniopsis, two species, Greeniopsis euphlebia Merr.and G. megalantha Merr.were found to be common in the area, from agro-ecosystem to mossy forest.
concluSIonSMt Hamiguitan Range is the habitat of one new record in the Philippines and 8 new records for Mindanao and harbours some endemic, threatened, rare and economically important species of plants needing high priority for protection and conservation.

table 9
Total number and percentage of endemic species of trees, averages of 6 sampling plots per vegetation type.