Vegetation of the Ultramafic Soils of Hinatuan Island, Tagana-An, Surigao Del Norte: an Assessmentas Basis forEcological Restoration RogerT. Sarmiento College of Forestry and Environmental Sciences, Caraga State University,Ampayon, ButuanCity, Philippines, 8600 Keywords: Biodiversity, Nickel mining, Stand composition and structure, Native flora. Study Area: Surigao del Norte, Philippines Coordinates: 9.753367° to 9.813161° N; 125.696155° to 125.741308° E Serpentine soils are generally poor in species diversity, show a high degree of endemism, and are always under threat due to anthropogenic and mining activities. In Hinatuan Island, Philippines, species diversity and density of trees were assessed in three selected sites comprising mostly of Leptospermum-Xanthostemon-Alstonia community. A total of 2,134 individualswith dbh >5 cm were recorded from 10 sampling stations and account to a density of 5,325 trees ha-1¬. About 135 vascular plant species belonging to 57 families and 109 genera were also encountered in the island, 42% of which were classif ied as trees. Despite the richness and density of species, the island ecosystem was classified to have very low Shannon-Weiner diversity index (H’ = 0.7738) overall. With the implementation of full-scale mining in the future, conservation and reforestation measures should be in place with native and indigenous tree species primarilyconsidered forecological restoration. Abstract Introduction: The Philippines contains a diverse range of forest formations that occur over different substrates and are often associated with distinct vegetation (Fernando et al., 2008; Ata et al., 2016). One forest formation is developed over ultramafic soils (frequently called ultrabasics or serpentines). In the past, very little was known about the geology and flora of ultramaf ic environments especially for the countries of Southeast Asia. But, several accounts are now available such as the ultramafic sites reported in the State of Odisha in India (Brooks, 1987), Mount Silam in Sabah, Malaysia (Proctor , 1988), Mount Piapi in the Talaud Islands, Indonesia (Proctor , 1994), Mount Giting-Giting onSibuyan Island, Philippines (Proctor , 1998), and Mount Kinabalu in Sabah (Aiba & Kitayama, 1999). Among them, in the Philippines, a number of ultramafic soil environments such as in Zambales in Central Luzon, Claver in Surigaodel Norte (Ata ., 2016), and Carrascal in Surigao del Sur (Sarmiento & Demetillo, 2017) were exploited for the "Nickel mining". As per the report of Department of Environment & Natural Resources -Mines and Geosciences Bureau, there are 48 registered metallic mines in the Philippines, 23 are located in Caraga Region where 20 of which are engaged in nickel mining. The vegetation of ultramafic rocks is often sparse, stunted and has rare and endemic in nature. Because of the et al. et al. et al. et al high concentrations of metallic elements such as Mg, Cr, and Ni, vegetationevolved into “hyperaccumulation” as the mechanism that is hypothesized to allow plants to survive on serpentine soils (Baker & Brooks, 1989). The ecology of serpentine systems is particularly interesting considering the high proportion of endemic plant species, their typical adaptive morphologies, and the distinctive structure of serpentinecommunities. Recently, the minerals industry is switching towards the environmentally responsible operations, through changes in its economic, environmental, and social practices. Conserving biodiversity is a key component for improving the environmental performance, primarily because most mining involves vegetation damage by clearance or by the surface disposal of wastes, often in pristine areas. Conservation and rehabilitation programs must always be embedded in management plans. In the preparation and revision of this, appropriate knowledge on the biological resource is vital. The present study aimed to determine the currentcomposition and diversity pattern of the existing terrestrial flora within Hinatuan Island and to provide information on theirconservation status and make recommendations for the ecological restoration of the island. The list of species provided herein is not a comprehensive documentation but merely reflect on the biodiversity richness of the island ecosystem. ISSN- 2348 5191 (Print) & 2348 8980 (Electronic) Author: AMBIENT APPRAISAL Vol. 5(2): 44-50 Year 2018 ambient SCIENCE Ambient Science, 2018: Vol. 05(2); 44-50 DOI:10.21276/ambi.2018.05.2.aa01
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Vegetation of the Ultramafic Soils of Hinatuan Island, Tagana-An,SurigaoDel Norte:anAssessmentasBasisforEcological Restoration
RogerT. Sarmiento
College of Forestry and Environmental Sciences, Caraga StateUniversity, Ampayon, Butuan City, Philippines, 8600
Keywords: Biodiversity, Nickel mining, Stand compositionand structure, Native flora.
Study Area: Surigao del Norte, PhilippinesCoordinates: 9.753367° to 9.813161° N;
125.696155° to 125.741308° E
Serpentine soils are generally poor in species diversity, showa high degree of endemism, and are always under threat duetoanthropogenicand mining activities. In Hinatuan Island,Philippines, species diversity and density of trees wereassessed in three selected sites comprising mostly ofLeptospermum-Xanthostemon-Alstonia community. Atotal of 2,134 individualswithdbh >5 cmwererecorded from10 sampling stations and account to a density of 5,325 treesha-1¬. About 135 vascular plant species belonging to 57families and 109 genera were also encountered in the island,42% of which were classif ied as trees. Despite the richnessand density of species, the island ecosystem was classif iedto have very low Shannon-Weiner diversity index (H’ =0.7738) overall. With the implementation of full-scalemining in the future, conservation and reforestationmeasuresshould be in placewith nativeand indigenous treespeciesprimarilyconsidered forecological restoration.
Abstract
Introduction:The Philippines contains a diverse range of forestformations that occur over different substrates and areoften associated with distinct vegetation (Fernando et al.,2008; Ata et al., 2016). One forest formation is developedover ultramaf ic soils (frequently called ultrabasics orserpentines). In the past, very little was known about thegeologyand floraof ultramaf icenvironments especially forthe countries of Southeast Asia. But, several accounts arenow available such as the ultramaf ic sites reported in theState of Odisha in India (Brooks, 1987), Mount Silam inSabah, Malaysia (Proctor , 1988), Mount Piapi in theTalaud Islands, Indonesia (Proctor , 1994), MountGiting-Giting onSibuyan Island, Philippines (Proctor ,1998), and Mount Kinabalu in Sabah (Aiba & Kitayama,1999). Among them, in the Philippines, a number ofultramaf ic soil environments such as in Zambales inCentral Luzon, Claver in Surigaodel Norte (Ata ., 2016),and Carrascal in Surigao del Sur (Sarmiento & Demetillo,2017) were exploited for the "Nickel mining". As per thereport of Department of Environment & Natural Resources-Mines and Geosciences Bureau, there are 48 registeredmetallic mines in the Philippines, 23 are located in CaragaRegionwhere 20 of whichareengaged in nickel mining.
The vegetation of ultramaf ic rocks is often sparse,stunted and has rare and endemic in nature. Because of the
et al.et al.
et al.
et al
high concentrations of metallic elements such as Mg, Cr,and Ni, vegetationevolved into “hyperaccumulation” as themechanism that is hypothesized to allow plants to surviveon serpentine soils (Baker & Brooks, 1989). The ecology ofserpentine systems is particularly interesting consideringthe high proportion of endemic plant species, their typicaladaptive morphologies, and the distinctive structure ofserpentinecommunities.
Recently, the minerals industry is switching towardsthe environmentally responsible operations, throughchanges in its economic, environmental, and socialpractices. Conserving biodiversity is a key component forimproving the environmental performance, primarilybecause most mining involves vegetation damage byclearance or by the surface disposal of wastes, often inpristine areas. Conservation and rehabilitation programsmust always be embedded in management plans. In thepreparation and revision of this, appropriate knowledge onthe biological resource is vital. The present study aimed todetermine the currentcomposition and diversity pattern ofthe existing terrestrial flora within Hinatuan Island and toprovide information on theirconservation status and makerecommendations for the ecological restoration of theisland. The list of species provided herein is not acomprehensive documentation but merely reflect on thebiodiversityrichnessof the island ecosystem.
the Tagana-an Nickel Mining Project of theHinatuan Mining Corporation is located in HinatuanIsland, Brgy. Talavera, Tagana-an, Surigao del Norte. Theisland is one of the 11 islands under the political jurisdictionof Tagana-anatabout 24 kilometers Eastof Surigao City.
Hinatuan Island has an approximate total land area of1,275.00 hectares, around 773.77 hectares is covered by anapproved Mineral Production Sharing Agreement (MPSA246-2007-XIII) executed by and between HMC and thePhilippine Government in the year 2007. Based on satelliteimages and reconnaissance survey, the land use of theisland can be classif ied into the following: a) built-upareas;b) mined out areas; c) reforestation areas; d) grasslands; e)coconut groves; f) secondary growth forest; g) natural barelands; h) swampyareas; i) mangroveareas.
sampling procedure was based on astandard line transect method. Total 3 to 4 quadrats havingthe dimension of 20 m x 20 m were laid out along eachtransect at an interval of 150 to 500 m apart depending onthe terrain and density of the prevailing vegetation. A GPSreceiver was used to determine coordinates with the upperright corner used as the reference. All plants inside quadratwith >5 cm dbh were recorded. Plants encountered in thetransect linewerealsotabulated to form thechecklist.
speciesidentif ication was done on the f ield itself. Field manualsand publications referring to the Philippine flora includedZamora & Co. (1986), Madulid (2002), Primavera (2009)were utilized to aid identif ication. Online website"PhytoImages" ( ) wasalso used to compare photographed species. Unfamiliarspecies were posted online thru a social media group Co’sDigital Flora of the Philippines (a public group of thebotanists, foresters, biologists and other plant enthusiasts)to conf irm species identif ication. The scientif icnomenclature and conservation status of species werecross-checked in the databases of The Plant List( ) and The IUCN Redlist ofThreatened Species ( ),respectively.
data was encoded on a spreadsheet andanalyzed using thevegetational analysis formula forspeciesimportance value (SIV). The SIV was computed as the sumof the relative frequency, relative density and relativedominance of a species in a community (SIV=RFreq+RDom+RDen). An SIV provides a better index thandensityaloneon the importanceor functionof aspecies inahabitat and also gives rank or order for a particular specieswithin thecommunity (Odum & Barret, 2005).
Shannon-Wiener (H’) diversity index, species richnessand evenness, on the other hand, the same were computedusing the PASTStatistical Software.
Resultsand Discussion:Field observations of sites: the Hinatuan Island ecosystemcould be described as a secondary forest on an ultramaf icsoil environment. It has as a unique assemblage of vascularand non-vascular flora from coastal areas to steep slopesand land surface in higher grounds. The vegetation typesare generally represented by- mangrove (Plate-1a),coastal/beach, secondary growth, agroforest, grasslands(Plate-1b), and farmlands. The mangrove areas are locatedon the southern portion of the island fronting seawatersand coastal areas along Lipata and Cortez. The ecosystemwas dominated by and otherassociated species like ,
, and .Grassland areas were observed on the different parts of
the island being dominated by withmarginal land shrubs such as and
. Towards higherelevation, speciescomposition gradually changed to and
communities. A small portion on the lowerelevation near the reforestation site was dominated byanother fern species called Bracken fern (
Pteridiumaquilinum C. bartramia,Macaranga bicolor Ficus septica
Ambient Science (2018) Vol.-05(2): p. 45
Plate-1: Panoramic views of the different land uses withinHinatuan Island. Mangrove areas, Grasslands, Coconutgroovesand, d) Secondary forest besideactive minesites.
composition of disturbed lands in the island was differentfrom other ultramaf ic sites in Northern Mindanao andwere mostly dominated by like theultramaf ic environs in Tubay and Carrascal (Sarmiento &Demetillo, 2017).
Coconut groves exist on the narrow isthmus and alongcoastlines (Plate-1c). Alongside slopes and steep ravineswere patches of secondary growth forest dominated byvarious species of vascular plants (Plate-1d). In a transect inLipata, Cortez area, plant community was composed of
species. The transectwest of mine base camp was dominated by
communities, while themangrove-beach forest was dominated by
community. A number ofspecies and ground orchid species were also encounteredalong bufferzonesof waterways. (Plate: 2).
a total of 135 vascular plant speciesbelonging to 57 families and 109 genera were encountered.The families with the most number of species wereFabaceae (15 species), followed by Moraceae (10),Myrtaceae (8) and Rubiaceae (6) while for the genera wereFicus (5 species), Pandanus (4) and Artocarpus & Lygodiumwith 3 specieseach. Based on habitatwhere thespecieswereencountered, 40% (54 of 135) of the identif ied species werefound on secondary growth forest, 22% (30 of 135) were incoastal/beach areas as well as in reforestation/ cultivatedareas, and only 16% (21 of 135) were found in marginal landsand grassland areas. (Table-1)
Transect 1 was generally composed of a community ofand species. The
transect has a species richness of 6 and a Shannon DiversityIndex (H’) of 0.7048 which was classif ied to be “very low”.The species
most important species in the area having the highest SIV.The plant community has a mean diameter of 7.67±1.51 cmcomprising young growth trees. The area has a meanpopulation density of 164 individuals per 400 m or about4,100 trees hectare (41 trees per 100m ). Basal area wascomputed to be 10,634.30 cm whereoccupying most of the area followed byand . (Table-2; Plate-3).
Transect 2 was located along Lipata-Cortez area fromlowerelevation towardssteepravinesand highergroundsofactive mining sites. Thevegetationof theareawasdescribedas an association of and
community. The was still themost abundant species having an average density of 52individuals per 400 m . Incomparison to theothertransects(Transect 1 and 3), Transect 2 had the highest Shannon’sDiversity Index (H’) with a value of 2.2733 but stillconsidered low based on a diversity scale. Larger diameterspecies such as and
exists in the area, but since has thehighest density, it occupies more space and thus has thehighest SIV in the plant community. The transect had ahigher richness comprising 16 species and a mean dbh of9.34±1.53 cm occupying a cumulative basal area of 13,461.70cm2 for all. Along the line yet outside sampling plots weretaller trees andother species in ravines and waterways, however were notincluded in the analysis yet formed part of the species list.(Table-3).
Transect 3 was established on a mangrove cove near thebase camp towardsa higherelevated beach forest. It had thehighest species richness with 18 species but has a uniqueassemblage of species composition as each quadrat in thesame transect was signif icantly different from each other.The f irst quadrat was established on the hilltop portion ofthe secondary forest where and
were the most dominant species. The thirdquadrat was situated on a mangrove cove close to the minebase camp and dominated byoccupying 80-95% of the 20 m x 20 m quadrat. The secondquadrat on the other hand was on stationed a steep slopebetween the and the
dominated community. It is composed of amixture of beach and secondary forest and the presence of
Leptospermum, OraniaGymnostoma L. amboinense
G. rumphianum, A. parviflora Oraniadecipiens L. amboinense
G. rumphianum, Buchanania arborescens
L. amboinense X.verdugonianus
Rhizophora apiculata
Leptospermum, XanthostemonRhozophora
2
several lianas and other climbing plants were prevalent.The terrain can be described as rocky and lose and thepresence of large boulders was a safety concern during thesurvey. (Table-4).
The species with the highest SIV was stillfollowed by as the species were the mostdominant in its respective quadrat. Some large treesreaching 30 cm dbh were present, however, the transecthad a mean dbh of 10.65±2.78 cm only. Considering speciesevenness for all transects, Transect 2 has the evenestdistribution of species with evenness index of 0.8199,followed by Transect 3 (0.5072) and Transect 1 (0.3933). Itsimply denotes that transects with high evenness valuehave a more uniform composition and distribution and nooronlya fewaredominantsoverthearea.
a total of 2,134 individuals withdbh >5 cm were recorded from the sampling stations. Thisnumberaccount toa species densityof 5,325 trees ha-1 oranaverage of 213 trees per 20 m x 20 m sampling quadrat. Thecomputed density was relatively higher compared to thedensity of the 2-hectare permanent biodiversity plots inMt. Makiling at 4,403 trees ha (Malabrigo, 2016) and the16-hectare permanent forest plot in Palanan, Isabela at4,999 trees ha (Co , 2006). This is understandablesince forests over ultramaf ic soils are described asvegetation where plants are usually stunted, small trunkdiameter and grow closer together (Madulid, 2002),forming a dense community. The average height of all treesinside the plots ranges from 2.97±0.75 m to 5.26±0.84 m.The beach/mangrove areas were comparatively taller thanthe secondary growth forest and trees on the marginal andgrassland areas. The vegetation on the beach/mangroveareas is a mixture of tall trees such as
and while vegetation onsecondary forest are dominated by and
which are naturally stunted being a slowgrowing species.
Total 42% of the identif ied species are classif ied astrees, 23% were accounted as shrubs, 19% as herbaceousspecies both annuals and perennials, 7% were vines bothwoody and non-woody, 5% were palms and palm likespecies, while theremaining 4% are fernsand fernallies.
outof the 135 species identif ied 127 are found to beindigenous in the Philippines of which 53 are endemic orare exclusively found only in the country. 6% of theenumerated species were classif ied as introduced in theisland either for rehabilitation or ornamental purposes.Among the exotics recorded include ,
and .The island ecosystem has a number of ecologically
sensitive species categorized as “Endangered” based onIUCN Redlist of Threatened Species. Among the listinclude
, and .Some noteworthy species observed in the island were
the following: (Plate- 2atod)
Resultsof the intensivestudyrevealed that thevegetationofthe forests over ultramaf ic soil environments of HinatuanMining Corporation in Hinatuan Island, Brgy. Talavera,Tagana-an, Surigao del Norte holds a remarkable diversityof trees and other vascular plants species. It also showedvery high species endemism and harbored a signif icantnumber of ecologically threatened trees. The informationdeveloped from this survey study can help to provide thesignif icant information on the dynamics of the plantspecies in an ultramaf ic environment wherein the islandecosystem was subjected to mining activities. This study aswell gives critical importance for the future researchactivities in the area. The established transect stationscould beaprincipal venue forcurrentand planned effortsofthe Hinatuan Mining Corporation towards attaining betterconservation and rehabilitation programs. Theinformation on the ecological status of the biodiversity inthe island should be disseminated to advocateconservation..
The author would like to thank the management and staff ofHinatuan Mining Corporation for the logistics and f inancialassistance during f ield survey and to Dr. Romell A. Seronay, Chief,Center for Research in Environmental Management and Eco-Governance of Caraga State University for the publicationsupport.
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