VEGETATION ANALYSIS OF THE LAWAAN CBRM SITE

- An Assessment of its Floristic (Seed Plants –Trees) Biodiversity

Nestor T. Baguinon, Ph.D.

INTRODUCTION

Lawaan, Eastern Samar was surveyed in November 2002. The author prepared for this survey by first compiling a database for the seed plant flora of Samar Island. References used were three volumes of the Enumeration of Philippine Flowering Plants by Merrill (1923-1926), twelve volumes of the revisions of Malesian plants in the Flora Malesiana, and the Revised Lexicon of Philippine Trees by Rojo (1999). The 992 species of seed plants compiled in this database is presented in a table below.

Table 1. Summary of 992 Species of Samar Seed Plants
Elevation Preference	Habitat	All habits	Tree only	Endemic Trees
Seashore or Coastal Ecosystems	Open and Thickets	135	53	14
	Secondary Forests	5	2	1
	Primary Forests	18	13	3
From seashore not exceed 500	Open and Thickets	40	20	6
	Secondary Forests	42	28	13
	Primary Forests	201	148	109
From seashore to <1000	Open and Thickets	67	18	6
	Secondary Forests	87	42	11
	Primary Forests	187	120	68
Medium elevation not over 1000	Primary Forests	18	11	9
Medium elevation to over 1000	Open and Thickets	41	20	6
	Secondary Forests	35	23	4
	Primary Forests	116	91	51
	TOTAL	992	589	301
Total for Open Ecosystems		283	111	32
Total for Secondary Forests		169	95	29
Total for Primary Forest		540	383	240
		All habits	Tree only	End. Trees
Total for Species Prefer Coastal		158	68	18
Toral for Species Prefer <500 m		283	196	128
Total for Species Prefer <1000		341	180	85
Total for Species in Medium Elev		18	11	9
Total for Species Tolerate >1000		192	134	61
Source of information: Merrill (1923-1926), Flora Malesiana and Rojo (1999)

The output of this compilation shows that there are about 992 indigenous species of seed plants recorded for the island of Samar. Since, the Philippines is credited to about 8,000 species of seed plants, this Samar floristic record represents 12.04% of the total seed plant flora of the Philippines. Compared to the other islands, Samar has less number of plant species partly because its mountain landscape is lower in elevation compared to the other islands of Luzon (Dickerson, 1928).

The topography of Lawaan, Eastern Samar (Fig. 1) reflects the provincial Samar topography, mountains are not greater than 800 m asl in height. In the study area the highest point is between 500 and 600 m asl. Samar lacks montane and mossy forests that could have added species normal on these forest types. Plant species like those in the family of oaks (Fagaceae), laurels (Lauraceae), and tea (Theaceae) that can go beyond 1000 meters in Samar are are found mixed with lowland species in evergreen dipterocarp rainforest. In other islands with high mountains, middle and high elevation species are the least prone to extinction because such species can seek refuge to elevations higher than 800 m asl. Thus, even if the first 500 meters are totally converted to agroecosystems with disastrous impact on lowland species, middle to high elevation species continue to live, unless such areas are also converted.

In Samar Island, complete agroecosystem conversion of forests from sea level to 500 m asl elevation would definitely extirpate primary forest seed plant species. Including coastal species, this would mean an extirpation of 540 primary forest dwelling species out of 992 total indigenous Samar seed plant species. Out of 540 primary forest seed plant species, 383 species are tree taxa. Of this number, 240 species are endemic Philippine tree species including 50 unique only to Samar Island, e.g. Quisumbing gisok Hopea quisumbingiana and Samar gisok H. samarensis.

The pioneer plant species of the secondary forest (169 species of which 111 are tree taxa) and thickets (283 species, 95 tree taxa) have greater chances of resisting extirpation at the wake of deforestation in the first 500 m asl zones. This is on condition that fallowing is practiced. Under a belt of intensive agriculture, agroforestry, timber plantations and analogue forests, or a combination of these, most of the primary forest species stand no chance. However, the secondary forest species may be tolerated if they are not thinned as weed species, while species of the thickets may continue to fill spaces unsuitable to any agroecosystem.

However, if multi-stakeholders, once and for all, define on the ground and on the map land for natural biodiversity on the one hand and land for agroecosystem on the other hand, then ecological governance would be meaningful. The conservation of indigenous species, habitats and gene pools on all elevations, from the coasts to the summits of mountains, will have a material, social and political basis. This also means that biodiversity conservation is alive even outside designated protected areas.

In Lawaan, the process of conversion was rapid. There was logging followed by kaingin and finally by land speculation. With the present Community-based Forest Resources Management (CBFRM) project under the municipality of Lawaan, this threat may yet be thwarted. In this respect, a sound land use planning involving multi-stakeholders and guided by vegetation and other scientific data would be imperative. This is necessary to save natural biodiversity while at the same time open avenues to optimize land use that permits sustainable agriculture alongside with land earmarked for ecological succession towards full natural forest ecosystem recovery and restoration at all elevations.

OBJECTIVES

The aim of this study therefore is to provide a listing of the seed plant species of Lawaan, describe the plant communities upon which these are found at different elevations and classify these communities according to their species attributes and importance values. With these, the CBFRM will be better equipped in delineating land for Nature and land for Man.

REVIEW OF LITERATURE

The SIBP Project has yet to write its technical reports. Certainly, their output will be valuable in contextualizing the present work in terms of the whole Samar Island biodiversity.

Biodiversity is simply the attribute of any land in terms of its species richness, the kinds of habitats and mosaic of successions that support diverse populations that permit more or less broad population gene pools (Boyle and Bontawee, 1994).

In pristine landscapes viewed in varying time and space dimensions, one would see the vegetation as a mosaic of successional patterns (Baguinon, in press). A glance at this landscape at any given point in time reveals a seemingly static array of gaps, building-up phase forests and mature forests. Through time however, the situation is very dynamic. Gaps advance to building-up forests and in turn building-up forests metamorphose into mature forests. Then at many places across the landscape are sporadic events that sees gaps being formed by natural causes such as the fall of dead trees, forest fire created by lightning, windthrow due to typhoons, landslips due to earthquakes, etc. Cat and mouse style, gaps will close and closed canopies open in endless cycles thus permitting an unendless niche for the whole spectrum of plant (and animal) species, from pioneer ones to climax ones. Seen at short interval of times, the landscape species richness would be more or less the same.

This maximum landscape level number of indigenous species is symbolically denoted as S (Baguinon in press) and those counted by people in inventories may be denoted as S’ (read S prime). S’ estimates S. The value of S’ varies from S depending upon the skill of the enumerator in identification, the representativeness of the observation samples and the completeness of the habitats (or strata) sampled. Assuming samples are statistically representative, the S may be overestimated if the enumerator is a splitter (S’ > S) or underestimated (S” < S) if the enumerator is a lumper. The enumerator is a splitter if he regards varieties, formas, subspecies as different species even if they are only one species and a lumper if the enumerator regards sibling species as one species when in fact they are two or more look-alike species.

Why is the S important? The health of the landscape is measured by the change in S through time. A healthy landscape must have an S unchanging through time, meaning there is no extinction or extirpation of indigenous and endemic species as long as the stress factor is limited to a threshold level (for example, the stress factor could be logging or agroecosystem conversion of forest). In other words, the P/Q ratio is fixed and the distribution of the subsets of P’s are distributed in all habitats and elevation zones. Note that the concept of S strictly excludes exotic species because they are aliens with respect to the pristine ecosystems.

Thus, S is not the same as species richness sensu Gruezo (2000) who summed exotic, domesticated and weed species together with indigenous ones. In the presentation of his results, he concluded that the agroforestry zone has higher diversity based on Shannon-Wiener Diversity Index log base 2 (e.g. H’=4.28) than the natural dipterocarp midmontane forest zone (e.g. H’=3.89) although their number of species are almost the same, i.e. 368 and 374, respectively. For the purpose of this report we denote Gruezo’s species richness as ΣS and ΣS > S for any given landscape that has included man and his crops and weeds. A decreasing S and an increasing ΣS is an unhealthy symptom. It may indicate extinction or extirpation of some elements in S as exotic elements in ΣS increase in the landscape or some of them escapes into natural forests and become bioinvasive and eventually excludes vulnerable indigenous species that may have similar niche as the invading alien.

Man came to occupy pristine areas through his farms, his built-up areas, his logging of timber, his mining activities and his settlements. Settlements, roads, sedentary farms, agroforestry farms, industrial tree plantations, coconut plantations are permanent gaps unless abandoned (Quimio, 1996). Logging (Severo, 1949) and small subsistence swiddens (Olofson, 1981) are temporary gaps. If their intensity and magnitude of occurrence is small (e.g. adding a little bit more to the gaps already being created naturally) or within carrying capacity, the overall gaps will still be overwhelmed by the rate of natural regeneration and biodiversity status should remain at equilibrium. However, the real situation was that natural forest regeneration has always been overwhelmed by the rate of timber harvesting and by the increasing rate of farm expansion (e.g. coconut plantations and swiddens). Simply stated, anarchy instead of ecological governance has been prevailing.

Under this anarchic circumstance, the natural forest continues to shrink while the agroecosystems expand. In other words, if the former is P and the latter is Q, the landscape P/Q ratio continues to decrease across the landscapes, since P and Q are mutually exclusive, i.e. P = 1 – Q (Baguinon, in press). Abandoned logging concessions (with their residual forests still in tact) have the largest P/Q ratio. The coastal plains and beaches have the least. But by zooming the present through the future at the present rates of landscape change compounded by rapid population growth, the scenario is bleak for natural biodiversity (p) which resides in P. Agroecosystem biodiversity (q) which resides in Q expands at the expense of p and P.

Virtucio et al (1977) studied newly logged dipterocarp forests all over the archipelago. Among the many sites (231 out of 12 provinces) was West Samar. The aim of this study was to find out how much more wood can be harvested in selectively logged dipterocarp forests taking into consideration not only the few 22 commercial dipterocarp species and 23 commercial non-dipterocarp species but also 35 potentially commercial species and 261 lesser known species. In 1992, the USAID-DENR-NRMP also conducted a total forest inventory of logged and unlogged forests in three sites in the archipelago, one of which was conducted at Casandig, Paranas, West Samar. Most of the species enumerated in these two studies were also encountered in Lawaan, East Samar.

Reported commercial dipterocarp species for West Samar in 1977 (Virtucio et al, 1977) were the following: Apitong Dipterocarpus grandiflorus, Hagakhak D. validus, Dalingdingan Hopea foxworthyi, Saplungan H.plagata, Bagtikan Parashorea malaanonan, Almon Shorea almon, Yakal-yamban S. falciferoides falciferoides, Mayapis S. palosapis, Red Lauan S. negrosensis, Tanguile S. polysperma, White Lauan S. contorta, Yakal S. astylosa and Narig Vatica mangachapoi. Additional dipterocarp species is added to this list as per 1992 inventory at Paranas, namely, Palosapis Anisoptera thurifera thurifera, Panau Dipterocarpus gracilis, Hasselt’s Panau D. hasseltii, Manggachapui Hopea acuminata, Gisok-gisok Hopea philippinensis, Quisumbing’s gisok Hopea quisumbingiana, Samar gisok H. samarensis, Manggasinoro Shorea assamica philippinensis, and Guijo S. guiso. Eleven (11) of the dipterocarp species (underlined) were reported in the present study.

Listed non-dipterocarp commercial species in 1977 for west Samar were the following: Bolong-eta Diospyros pilosanthera, Dangula/Kuliipapa Teijsmanniodendron ahernianum, Katmon Dillenia philippinensis, Lanete Wrightia pubescens laniti, Makaasim Syzygium nitidum, Malabayabas Tristaniopsis decorticata, Malugai Pometia pinnata, Molave Vitex parviflora, Nato Palaquium luzoniense. Five (5) among the non-dipterocarp species (underlined) occurs in Lawaan.

Potentially commercial non-dipterocarp species are the following: Bitaog Calophyllum inophyllum, Duklitan Planchonella nitida, Kamatog Sympetalandra densiflora, Karaksan Linociera ramiflora, Lanipau Terminalia copelandii and Ulayan Lithocarpus llanosii. The underlined species (3 species) occurs in the Lawaan study site.

Lesser-known species are, Agusus Paratrophiis philippinensis, Alagasi Leucosyke capitellata, Ata-ata Diospyros mindanaensis, Alupag Litchi chinensis philippinensis, Bagalunga Melia dubia, Bagarbas Hydnocarpus sumatrana, Bagoadlau Xanthostemon philippinensis, Bagobahi Memecylon cordifolium, Bagonangka, Bagotambis Syzygium leytense, Bahai Ormosia calavensis, Balobo Diplodiscus paniculatus, Balukanag Chisocheton cumingianus , Batino Alstonia macrophylla , Bato-bato Drypetes littoralis, Bayag-usa Voacanga globosa, Binukaw Garcinia binucao, Narig Vatica mangachapoi, Bulong cadios, Cabrin, Callicarpa sp,, Canarium sp, Gatasan Garcinia venulosa, Gubaan, Himbabau Broussoneita luzonica, Honggo, Iloilo Aglaia argentea, Isis Ficus ulmifolius, Kangko Aphanamixis polystachya , Katilma Diosphyro nitida, Katong matsing Chisocheton pentandrus, Kulipapa Teijsmanniodendron ahernianum, Malakalumpang Sterculia ceramica, Malalomboi Eugenia mimica, Malanangka Parartocarpus venenosus , Malaruhat Cleistocalyx operculatus, Malasaging Aglaia diffusa, Marabutom Ficus subcordata, Nangka *Artocarpus heterophyllus, Niog-niogan Ficus pseudopalma, Pagsahingin Canarium asperum, Paitan Syzygium costulatum, Pandakaking gubat, Pangi Pangium edule, Piling-liitan Canarium luzonicum, Pototan Bruguiera sexangula, Lithocarpus sp, Salak Elaeocarpus octopetalus, Saliksikon, Syzygium sp,Tabhisan Talauma reticulata, Tagotoi Palaquium foxworthyi, Tagkan Palaquium pinnatinervium, Takulao Miliusa vidalii, Tanghas Myristica elliptica, Tigau Callicarpa sp, Tikoko Teijsmanniodendron pteropodum, Tula-tula Mallotus floribundus, Wakatan, and Yabnob Horsfieldia megacarpa . Underlined species (14 species) occur in Lawaan study site.

A checklist of tree species from Lawaan, Paranas and all Samar Island (e.g. trees in secondary and primary forests) is shown in Appendix XXXV. In Paranas, 36% of tree species are in the checklist of tree taxa prepared for Samar Island, e.g. current Samar S’. This means that 64% of Paranas tree taxa are either new records for Samar or unidentified by the enumerator and therefore cannot be matched with existing records in Samar S’. Sometimes the herbarium samples brought by the enumerator may match with voucher specimens but the voucher specimen can be only identified at the genus level and identification would just be the genus plus the herbarium accession number, for example Garcinia sp PNH 3314. It is also possible that the herbarium sample matches with a voucher specimen bearing its old scientific name and not with the accepted valid taxonomic names. Both valid and invalid names may appear in the checklist although they are synonymous and overestimates the real number of species. Unless the enumerator makes a thorough taxonomic literature review, this error is difficult to correct.

The problem with the Philippine National Herbarium (PNH) is that most of its collections have been lost during the bombings by US liberation forces during World War II. This explains situations when herbarium specimen does not match with any voucher specimen in the herbarium and remains unidentified even at the family level. The key voucher specimens are not in PNH but are in foreign herbaria as duplicates of those destroyed in World War II. An inevitable error comes from lofty trees that are unknown but herbarium sample cannot be collected. Sometimes, local guides give vernacular names but sometimes they do not. For those with vernacular names, the name may be matched with Madulid’s Compilation of Vernacular Names of Philippine Plants but this could lead or mislead. If climbers are part of the party and can bring down specimens with flowers and/or fruit, then herbarium specimens may be mailed to the appropriate taxonomic authorities for identification. They will inform if the specimen belongs to a new species, new subspecies or a new record.

CBRM must maintain its own herbarium or even arboretum and label its identified and unidentified specimens coupled with maintaining a database for them. Through this it is possible to accurately estimate the local landscape S. Through time with more collections and more herbarium work, the value of S’ will close with S. At this point, S’ becomes a very powerful barometer for gauging the health of a landscape using natural biodiversity as parameter. It would be ideal if a land use plan reconciles the contradiction between P and Q such that once and for all S no longer decreases in value through time. In a situation where the apparent S’ value is short of the S value because there had been local species extirpation, a reintroduction and habitat restoration program for these lost species would again bring back the local landscape S.

The application of geological information systems (GIS) is very important in mapping natural resources (Bantayan, 2000). It can be used as a tool to reflect ground survey and aerial photographs into maps. The P’s and the Q’s can be indicated and color-coded to show their spatial relations. However, the eye of the beholder is also important in the usefulness of the GIS. There will be contrasting difference between the GIS output of one that separates Ps and Qs from one that lumps artificial and natural forests together. For example, land use maps of the Makiling Forest Reserve include Mahogany Plantations as part of the entity forest, although they separate forests from botanic gardens and parks.

In this report, man-made plantations even if dominated by trees are agroecosystems and therefore subsets of the Q instead of the P. Unpublished undergraduate theses of Alvarez (2001); Castillo (2002) and Thinley (2002) warn that reproductives of the exotic Large leaf mahogany (Swietenia macrophylla) borne from such plantations are invading natural forests. Alvarez and Castillo found that the value of the quadrats’ Shannon-Wiener Diversity Index decreases when corresponding cover of Mahogany increases. This shows that Mahogany gains at the expense of indigenous species. Two years after the warnings of these students no action has been taken yet to check bioinvasion in Mt. Makiling.

Few people would know how a virgin or old growth forest would be different from residual or secondary growth dipterocarp forest. Whitford (1911) documented that the Lauan Type Dipterocarp Forest of Northern Negros may yield in one hectare 428.99 cubic meters of commercial dipterocarp mercantable timber based on the volume of trees 40 cm and over in diameter. But, Serevo (1949) claims that for Northern Negros also, 142 trees having 15 cm and over in diameter can yield 499.8 cubic meters timber per hectare. Eighty seven (87) trees are below 50 cm dbh with corresponding volume of 44.58 cubic meters (9%) while fifty-five trees (55) equal or above 50 cm dbh may yield 455.22 cubic meters (91%).

These two authors do not have information for Samar dipterocarp old growth forest. Geographically, Surgao old growth dipterocarp forest is the closest to Eastern Samar that Serevo (1949) described as follows.

“…the understory is very complex. Toog, tinaan-pantai, makaasim, and nato are co-dominant with dipterocarps. Massive trees 100 cm and over are distributed far apart, short boled with large spreading crown. Dipterocarpaceae although retaining superiority both in number and volume for trees 50 cm and above, 82% and 90%, respectively, outnumbered both individually and by volume, for trees 10-40 cm in diameter, being only 17% and 27%, respectively. At that level, dipterocarps claim 32% of trees but 81% of volume were dipterocarps. “

Serevo (1949) documented for Agusan lauan type forest to be composed of 330 trees equal or greater to 10 cm dbh. Out of this 123 were dipterocarp trees (37%) and 207 trees from other famillies (63%). Of this number, 87 trees equal or greater to 20 cm dbh had 391.76 cubic meters timber volume for dipterocarp trees (97%). There were 46 trees equal or greater to 20 cm dbh for other species with timber yield of only 9.86 cubic meters (3%). For dipterocarps alone, 31% of trees and 2% of volume belong to trees 20 to 40 cm dbh, but 69% of the number and 98% of the volume belong to trees equal or greater to 50 cm dbh.

The same Agusan stand was measured after tractor logging and it was composed of 97 trees equal or greater to 10 cm dbh. Of this number 52 trees were dipterocarps (53%) and 45 were other species (47%). The volume of 48 trees equal or greater to 20 cm dbh was 42.90 cubic meters of which 39.15 cubic meters were dipterocarps (91%) and only 3.75 cubic meters belonged to other species. Of the dipterocarps alone, trees 20-40 cm dbh comprise 79% of the number and 26% of the volume, while trees greater than 50 cm dbh and over had 21% of the number and 74% of the volume. The forest was removed of 233 trees (70%) and 358.13 cubic meters of timber (89%). Serevo claims 60% of the forest was laid bare due to logging roads, skid ways, tractor paths and a number of log landings with average radius of 25 meters. Only 40% were true residual forests.

Virtucio et al (1977) observed from four Visayan provinces (Leyte, Negros Occidental, Negros Oriental and West Samar) that a newly logged dipterocarp forest may have as many as 758 trees per hectare with diameters 5 to 100 cm dbh and an average volume of 180 cubic meters. Of the 758 trees, 27% belonged to Dipterocarpaceae, 8% to commercial non-dipterocarp trees, 3% potential commercial species and 62% lesser known species. Commercial dipterocarp species had an average of 205 trees per hectare with 128 cubic meters; commercial non-dipterocarp trees had an average of 61 trees/ha and 13 cubic meters, potentially commercial non-dipterocarp trees had 23 trees/ha and about 4 cubic meters and finally 470 trees/ha and corresponding 36 cubic meters/ha. Finally, the number of unidentified trees were 25 trees per hectare.

Tandug (1986) observed from a newly logged dipterocarp forest in Ayungon, Negros an average of 166 trees per hectare and a corresponding average volume of 255 cubic meters per hectare for commercial dipterocarp species, 33 trees and 10.73 cubic meters for current commercial non-dipterocarps, 17 trees and 4.90 cubic meters for potenttially commercial non-dipterocarps, and 88 trees and 25.94 cubic meters of lesser-known species. The following individual tree volume formula for eastern and western Visayas were used for dipterocarps and non-dipterocarps as per regional volume tables generated by the Bureau of Forestry, UPCF and USAID in 1963.

For dipterocarps : Vol = 0.00005231 (D²H)

For non-dipterocarps : Vol = 0.00004874 (D²H)

Where

D = diameter at breast height in centimeters

H = merchantable height in meters

Vol = gross volume inside bark in cubic meter

Mauricio (1982) observed natural reproduction in different logged-over stands of different ages, 2, 3, 4, 8, 12, and 16 years after logging. Out of an initial 8,356 trees not greater than 5 cm and 57 trees with not more than 10 cm dbh at the end of second year after logging, succeeding ages showed an increased representation of higher diameter classes. For example, during the 8^th year after logging, the frequency distribution of the different age classes were as follows, 5472, 353, 105, 22, 10 and 4 for diameter classes (cm) 5, 10, 15, 20, 25 and 30. Thus, during the 8^th year the remaining reproductives surviving was about 71%. However, during the 16^th year, the frequency distribution of the trees were 4060, 398, 213, 102, 46, 10, 2 and 6 for the diameter classes 5, 10, 15, 20, 25, 30, 35 and 40 cm dbh, respectively. The remaining surviving reproductives at the end of the 16^th year was 57%. Recruits in understory will further be reduced as they grow to compete with one another. Individual trees that are free from competitors will have the edge over trees that grew with a nearby competitor tree. Recruits compete for space, nutrients, sunlight and water.

METHODOLOGY

Vegetation Analysis of the Tree Layer

Thirty-one quadrats each measuring 20 m by 20 m were spread in the area as shown in Fig. 1. Trees greater than 10 cm dbh were enumerated. Their diameters at breast height (DBH) were measured using a diameter tape. Heights were measured with Haga altimeter. The first major branch serves as the highest point for merchantable height (MHT) and the tip of tree as highest point for total height (THT). The diameter and merchantable height data are used to compute the cover (or dominance) in terms of merchantable volume in cubic meters using Equation 1. The DBH in centimeters is converted first into meter units before multiplying its square with the constant .7854 and with the MHT in meters.

Cover = .7854 x DBH² x (MHT) - - - - - - - - Equation 1

Three parameters are used to compute the Importance Value (I.V.) namely, Relative Cover, Relative Density and Relative Frequency as follows:

Relative Cover of a particular species is computed by Equation 2.

Cover_sp

Relative Cover_sp = ---------------------- x 100 - - - - - - - - - - - - - Equation 2

Total Cover_{all spp}

Relative Density of a particular species is computed by Equation 3.

Number of trees_sp

Relative Density_sp = ----------------------------------- x 100 - - - - - Equation 3

Total Number of treee_{all spp}

In order to determine the Frequency of any given species, the quadrat is divided into four equal parts, i.e. grids 1, 2, 3 and 4. Thus, if a particular species is represented in all four grids, its frequency is 4/4 = 1 by the formula below. A species with .5 frequency means it occurs in 2 out of 4 grids.

Occurrence of the species in four grids

Frequency_sp = ------------------------------------------------------------ - - Equation 4

Total number of grids

The Relative Frequency is computed by using Equation 5.

Frequency_sp

Relative Frequency_sp = ------------------------------- x 100 - - - - Equation 5

Total Frequency_{all spp}

I.V._sp = Rel. Cover + Rel. Density + Rel. Frequency

Vegetation Analysis of the Undergrowth

Circumscribed in the quadrat are four 1 meter by 5 meter rectangular quadrats. All woody seed plants less than 10 cm were listed and the number of individuals counted. Only two parameters are used to determine the IV of the undergrowth species, the Relative Density and Relative Frequency. To determine the Relative Density of the undergrowth, Equation 3 is used and to determine the Relative Frequency Equations 4 and 5 are also used. Thus, the I.V. for any given undergrowth species is given by

I.V. _sp = Relative Density _sp + Relative Frequency _sp - - - - - - - Equation 6

Finally, two 1 m by 1 m quadrats were used to observe some aspects of the undergrowth herbs. The observations for the herbs will be qualitative.

Computation of the Shannon-Wiener Diversity Index

The I.V. values of all species in any given Plot or Quadrat are used to compute the Shannon-Wiener Diversity Index. The sum of the I.V.’s represents N, while the individual I.V. of each species represents n in Equation 7 for the Shannon-Wiener Diversity Index H’. Hence,

H’ = - [Σ (n _i / N) x log _e (n _i / N)] - - - - - - - - - - - - - - - Equation 7

Table 2 illustrates the meaning of the Shannon-Wiener Diversity Index. Given 10 species in a quadrat each species with 10 individuals apiece, the value of H’ using log base e is 2.3026. When the number of species increases say 20 species each with 10 individuals, the H’ increases to 2.9957. In a situation where the number of species is the same, say 10 species but one species has 91 individuals while the rest has 1 apiece, H’ value will decrease from 2.3026 to only .5003. Shannon-Wiener Diversity Index increases with increasing number of species and increasing evenness of the allocation of individuals among the species. Table 2 also compares the H’ value if instead of log base e one uses log base 2 and/or log base 10.

Table 2. Comparison of Shannon-Wiener Diversity Indices.

No.Species	Data	Number of individuals	log base e	Log base 2	log base10
10	10 each species	100	2.3026	3.3219	1.0000
10	91, others 1 each	100	0.5003	0.7218	0.2173
20	10 each species	200	2.9957	4.3219	1.3010
20	181, others 1 each	200	0.5937	0.8565	0.2578

One should compare H’ values of two or more plots if and only if they were computed using the same log function.

Ordination Analysis through Principal Component Analysis (PCA)

Pair-wise comparison of 31 plots using Sorensen’s Similarity Index Formula takes the following n x (n-1)/2 calculations or 31x30=930 calculations. Thus, comparison of any pair of plots a versus b (or a x b) by Sorensen’s Formula is given by Equation 8.

2 x W

S _{a x b} = -------- x 100 - - - - - - - - - - - - - - - - - - - Equation 8

A + B

where,

W = the number representing the lesser of two importance values of a species shared by Plot a and Plot b.

A = the sum of I.V.’s of all species present in Plot a.

B = the sum of I.V.’s of all species present in Plot b.

The 930 S _{a x b} values are entered in a 31 by 31 square matrix composed of 31 diagonals with values of 1. The diagonal only means that its cells satisfy the situation a=b (e.g. a x b = Plot 1 x Plot 1) and therefore the similarity is 1 or 100%. In a similarity matrix table, the upper right portion is the mirror image of the lower left portion since similarity matrices are all symmetric matrices. Unlike in a dissimilarity-similarity matrix table wherein the upper right triangular matrix contains the dissimilarity indices while the lower left contains its complement of similarity indices. The dissimilarity index formula is given by Equation 9, thus

D _{a xb} = 1 - S _{a x b} - - - - - - - - - - - - - - - - - - - - - - - - - - - Equation 9

The similarity matrix table is input for ordination analysis through Principal Component Analysis (PCA). PCA is done with the help of the computer under the menu Data Reduction under Factor Analysis in the computer software Statistical Program for the Social Sciences (SPSS). The dissimilarity-similarity matrix table, on the other hand, is input for the Polar Ordination Analysis (Mueller-Dombois and Ellenberg, 1974).

The computer program generates for each Plot two numbers, PCA score 1 and PCA score 2. In the present study, the computer generated 31 paired PCA1 and PCA2 numbers. Plotting the 31 pairs of numbers in a two-dimensional graph results into a scattergram that shows the geometric distances among 31 pairwise comparisons. The axes of the scattergram are PCA 1 scores for the abscissa and PCA 2 scores for the ordinate. The observed values of PCA 1 and PCA 2 scores may be used as Y1 and Y2 variables respectively and other associated environmental parameters measured for each plot as independent variables X1, X2, . . ., X_k, i.e. Associated environmental variable measured for each Plot could have been slope, elevation, coordinates, soil factors, microclimatic factors, etc.

RESULTS AND DISCUSSION

The Lawaan Number of Tree Species, S’

The total number of tree species enumerated in the 31 plots was S’ = 203 (Please see Appendix I) including both identified and unidentified tree species. Certainly, this number is an underestimate considering that the sampling area is not representative of the total sampling space. This is the reason why many taxa were observed in the vicinities of the plots but were outside the plots and so are not included in the checklist. Note that Tandug (1986) enumerated 221 species out of standing trees in Negros Oriental.

Of this number, 115 species were among the 478 tree species recorded for Samar Island from lowland primary and secondary forests. Hence, by subtracting 201 – 115, the remainder 86 represent taxa that cannot be identified with known Samar records. Some of the 86 taxa could be new species, or new records, or synonyms of taxa already listed for Samar but bear different names. There are 44 out of the 115 species that are endemic for the Philippines. A few of the endemics are probably Samar-centered, like the following species. Bagaoring Beilschmiedia nervosa and Tiga Tristaniopsis micrantha are unique to Samar and Leyte Islands. Samar lanutan Mitrephora samarensis is confined to Samar-Biliran. Bagoadlau Xanthostemon philippinensis has been recorded so far from Samar to Camarines. Malaalahan Guioa discolor is distributed from Quezon to Samar. Bolster Katmon Dillenia bolsterii is in Samar and Surigao. Unique to Samar are Samar Yabnob Horsfieldia samarensis, Quisumbing gisok Hopea quisumbingiana and Samar gisok H. samarensis.

The total forest inventory in nearby Casandig, Paranas, West Samar in 1992 had accounted 174 identified tree species as compared to 169 tree species for Lawaan (201 tree species if including unidentified taxa). From these two collections, 87 species are common to both sites and the Lawaan-Paranas collections are about 50% similar using Sorensen’s Similarity formula. Out of 169 Lawaan tree species, 94 are in the Samar Island records of 478 tree species, the remainder of 75 are Lawaan tree species that are not in the said records. For the Paranas collection of 174 tree species, 90 match with the records, but 84 do not. The percentages of the tree species that are not in the Samar-wide records are therefore very comparable, 44% and 48%, respectively.

It is possible that these taxa not in the Samar-wide records could have been new records for Samar Island while it may be probable that some of the unidentified collections may add up new species. This high number of unidentified taxa is also reflective of the incompleteness of Philippine herbaria as the original collections were burned in World War II. Sending well-prepared herbarium specimens with flowers and/or fruits to foreign herbaria for identification would be one solution. Unfortunately, the survey was not timed when most of the forest trees were not in bloom and if in bloom cannot be collected as they are very lofty trees.

The total list of undergrowth species that includes shrub, liana and trees less than 10 cm dbh were enumerated through four 1m x 5m rectangular quadrats. A checklist of woody species in the undergrowth is shown in Appendix Table II. There are 260 woody species listed in Appendix Table II. Of this total number, 217 were wildlings/poles of tree species that have been enumerated. This means that 43 species were shrub and liana species. Of the number of trees, there were 123 species of trees that have not been encountered in the thirty one (31) 200 sq m plots and 94 species that were already accounted in the said plots.

Thus, with this additional tree species from the undergrowth, the Lawaan S’ = 203 + 123 = 326 tree species. This number 326 is still an underestimate of Lawaan S. If this number will be updated by new finds in the field, the Lawaan S’ increasingly will become a better estimate of Lawaan S.

Note that for the whole Samar Island S’ for lowland primary and secondary forest is 478. Of course, it has to be understood that the ultimate value of Lawaan S is expected to be always less than the Samar S value. At this point, it is not possible to get the percentage of Lawaan S’ with respect to the Samar S’. This would probably become a possibility after the SIBP has presented its results. New species and new records will update the existing Samar S’ based on SIBP output. The new Samar S’ will also be closer to the Samar S.

Vegetation Analysis for the Tree Layer

The result of vegetation analysis of the raw data for the tree layer in Appendix Table I is presented in Appendix Table III to XXXIII and summarized in Table 3. Most of the area corresponds to the so-called Lowland Dipterocarp Forest (Whitford, 1911) and among the five subtypes of dipterocarp forest, the Lawaan dipterocarp forest in general may be classified as Lauan Dipterocarp Forest Subtype. This is due to the conspicuous importance of Red Lauan Shorea negrosensis and Mayapis S. palosapis which is strongly noted in Plots 1-15 and 18-26.

Plots 16 and 17 are also dipterocarp forests but they present Bagtikan Parashorea malaanonan instead, although Mayapis occurs in Plot 17. Plots 27 to 31, definitely represent a different vegetation type resembling the Molave Forest Type common in limestone derived soils and features normally deciduous tree species such as Molave Vitex parviflora, Narra Pterocarpus indicus, and Kalantas Toona calantas.

Mayapis and Red Lauan are the most important species in the 25 plots classified as belonging to the Lauan Dipterocarp Forest Subtype. Red Lauan occurred in Plots 1 to 11, Plot 15, Plots 18-19, and Plots 23 to 26 while Mayapis occurred in Plots 5-6, Plot 8, Plots 10-14, and Plots 17-26. Both species appeared 18 times out of 25 plots (72% frequency), excluding Plot 16 that harbored neither species.

Table 3. Summary of the vegetation analysis of the tree layer for 31 plots in Lawaan Study Site.

PLOT	Coordinates		Eleva-tion (m a.s.l.)	No. of Trees	No. of Species	^aVolume (cu.m.)/400 m^2	Shannon-Wiener Index (H’)
	North	East
1	11^o 10’ 02.40’’	125^o15’ 36.6’’	290	40	24	9.7434	2.9776
2	11^o 10’ 07.16’’	125^o15’ 36.6’’	283	36	20	12.3860	2.7065
3	11^o 10’ 01.30’’	125^o15’ 41.4’’	260	44	28	11.6548	3.0686
4	11^o 10’ 43.60’’	125^o15’ 19.3’’	340	31	19	16.9190	2.6582
5	11^o 10’ 44.70’’	125^o15’ 20.3’’	310	21	14	8.9130	2.3298
6	11^o 10’ 41.50’’	125^o15’ 19.3’’	340	27	21	25.1791	2.9261
7	11^o 10’ 48.50’’	125^o15’ 01.0’’	400	23	13	10.1826	2.3758
8	11^o 10’ 46.30’’	125^o15’ 04.9’’	395	21	15	24.5591	2.4625
9	11^o 10’ 45.50’’	125^o15’ 06.5’’	447	27	19	34.8900	2.6452
10	11^o 11’ 01.10’’	125^o15’ 00.7’’	447	31	15	15.5338	2.3409
11	11^o 11’ 01.20’’	125^o14’ 38.0’’	448	22	10	7.7432	2.0518
12	11^o 11’ 03.40’’	125^o14’ 59.4’’	450	24	11	7.6638	2.0552
13	11^o 11’ 01.10’’	125^o15’ 00.7’’		36	13	22.2038	2.3950
14	11^o 11’ 00.70’’	125^o14’ 43.6’’	490	24	10	23.7494	1.7083
15	11^o 11’ 01.70’’	125^o14’ 45.7’’	506	42	17	11.6966	2.3796
16	11^o 11’ 02.24’’	125^o15’ 01.1’’	420	21	12	10.5187	2.3670
17	11^o 11’ 01.80’’	125^o14’ 57.9’’	435	23	15	25.9899	2.4639
18	11^o 11’ 43.30’’	125^o15’ 38.1’’	465	38	18	89.5320	2.7049
19	11^o 11’ 44.20’’	125^o15’ 37.3’’	490	22	14	41.3750	2.4081
20	11^o 11’ 14.14’’	125^o15’ 38.5’’	435	23	14	37.6866	2.2711
21	11^o 11’ 14.14’’	125^o15’ 38.5’’	435	29	19	63.2800	2.4752
22	11^o 12’ 09.50’’	125^o16’ 06.6’’	380	30	23	35.4486	2.9713
23	11^o 12’ 09.50’’	125^o16’ 06.6’’	380	30	20	21.2865	2.8565
24	11^o 12’ 00.30’’	125^o17’ 00.3’’	320	34	20	52.9896	2.6919
25	11^o 10’ 19.50’’	125^o16’ 40.6’’	121	31	20	24.7879	2.7086
26	11^o 10’ 08.80’’	125^o16’ 40.5’’	69	23	15	26.4264	2.5371
27	11^o 11’ 43.00’’	125^o20’ 13.2’’	90	25	19	43.4058	2.7224
28	11^o 11’ 40.40’’	125^o20’ 12.0’’	130	28	11	42.1898	2.1584
29	11^o 11’ 20.10’’	125^o20’ 09.5’’	130	20	12	5.9090	2.2054
30	11^o 11’ 30.01’’	125^o30’ 00.0’’	200	21	11	10.5156	1.0228
31	11^o 11’ 30.01’’	125^o20’ 11.6’’	200	21	10	5.7332	1.9394

^a Volume based on V = .7854 x Merchantable height as basis of Cover/Dominance; this is not to be confused with timber volume formula used by Tandug (1986).

In Table 3, the plots with highest Shannon-Wiener Diversity Indices (H’) arranged in a descending order were Plot 3 (H’ = 3.0686), Plot 1 (H’ = 2.9776), Plot 22 (H’ = 2.9713), and Plot 6 (H’ = 2.9261) all belong to the Lauan Dipterocarp Forest Subtype. The H’ is high for plots with the highest number of species, for example, 28, 24, 23, and 21 species, respectively, for Plots 3, 1, 22 and 6. Note that among the Lauan Dipterocarp Forest Type plots, Plot 14 had the lowest H’ = 1.7083 with only 10 species, followed by Plot 11 with 10 species and H’ = 2.0158. The Shannon-Wiener Diversity Index arose from the assumption that high number of species in an area suggests a healthy area. This value increases further if the resources are equitably shared among the species. At the community level, gaps understandably have low H’ values. The secondary forest is expected to be high because pioneer species and climax species are found together. In the mature phase, only the climax species reign and thus its H’ is expected to be lower than those of the secondary or building-up phase forest. Plots 3, 1, 22 and 6 show that they are building-up phase forests. If the dominant dipterocarp species are allowed to grow and cast shade below, the understory trees will be suppressed and the undergrowth will become very sparse. The change of H’ value of a building-up forest shifting to mature forest would be a decreasing value. At the landscape level, more time is needed before the Lawaan site will recover lost mature phase forests and recover a balanced or equilibrium gap: building-up: mature ratios.

Mayapis and Red lauan were together in 11 plots, namely, Plots 5, 6, 8, 10, 11, 18, 19, 23, 24, 25 and 26. Red lauan was most important in 8 plots, namely, Plots 1, 2, 9, 11, 15, 18, 19, and 25 while Mayapis was most important in 11 plots, namely, Plots 5, 6, 7, 8, 13, 14, 20, 21, 22, 24, and 26. Thus, Mayapis slightly edged Red lauan by 3 plots.

The densities and volumes per hectare basis of dipterocarp species and groupings of non-dipterocarp species were computed in Appendix Table XXXIV. The results are entered in Table 4. It shows Mayapis and Red lauan share 81% of the timber volume contributed by dipterocarps and 43% of the total timber volume. In terms of the number of trees, the 72 trees for Mayapis and 58 trees for Red lauan, together make up 64% of dipterocarp trees and 18% of total trees.

Table 4 shows that the Lauan Dipterocarp Subtype in Lawaan has a tree density of 734 trees/hectare and a total timber volume of 433 cubic meters. Out of this, the dipterocarps had 200 trees/hectare (27%) and 228 cubic meters (53%) of timber compared to non-dipterocarps with 534 trees/hectare (73%) and corresponding timber volume of 205 cubic meters (47%). The Lawaan tree density of 734 trees/hectare is comparable with the Visayan average of 758 trees/hectare (Virtucio et al 1977), by coincidence 27% were also dipterocarps. However, the average timber volume was 180 cubic meters/hectare as compared to 433 cubic meters/hectare for Lawaan. Surprisingly, there were only 303 trees/hectare in Negros Oriental (Tandug, 1986) but the timber volume was considerable at 296.5 cubic meters.

For trees less than 15 cm dbh, dipterocarps had 22 trees and .67 cubic meters timber and non-dipterocarps dominate with 167 trees/hectare and 5.29 cubic meters timber for a total of 195 trees and 5.96 cubic meters timber. Note that at small diameter trees the ratio of dipterocarp to non-dipterocarp is very low for both tree density and timber volume. At larger diameter classes the ratio increases for both number of trees and timber volume. Thus, at 15-34 cm dbh class, the dipterocarps had 109 trees and 36.76 cubic meters as against non-dipterocarps with 286 trees and 65.34 cubic meters. At dbh class above 35 cm dbh, the dipterocarps had 69 trees and 190.841 cubic meters as against non-dipterocarps 81 trees and 134.31 cubic meters. In the big diameter classes, the dipterocarps owned 53% of the timber volume, conversely in the less than 15 cm dbh class the dipterocarps’ share was only 11%.

Table 4. Summary of the number of trees and timber volumes per diameter size classes.

A. LAUAN DIPTEROCARP SUBTYPE (PLOTS 1 to 26 except Plot 16)

DIPEROCARPS
TAXA/GROUP	<15 cm DBH		15-34		>34		Total Taxa/Group
	No. Trees	Volume	No. Trees	Volume	No. Trees	Volume	No. Trees	Volume
Almon	1	0.0452	12	5.7701	5	8.5129	18	14.3282
Mayapis	6	0.1774	31	11.6089	35	86.8185	72	98.6048
Palosapis	2	0.0491	3	1.3636	3	6.0768	8	7.4895
Q. gisok	2	0.0684	6	1.5748	2	3.012	10	4.6552
Red lauan	7	0.1787	32	9.3235	16	73.7956	55	83.2978
Yakal	1	0.019					1	0.019
Yakal gis	1	0.0527	4	0.9416	3	1.931	8	2.9253
Yakal yam	2	0.0779	4	0.4994			6	0.5773
Dalingding			1	0.4287			1	0.4287
Manggas			1	0.1385			1	0.1385
Tangile			12	4.2561	4	7.7475	16	12.0036
White lauan			3	0.8594			3	0.8594
Bagtikan					1	2.9488	1	2.9488
Total Dipt.	22	0.6684	109	36.7646	69	190.8431	200	228.2761
NON-DIPTEROCARPS
CND	6	0.1646	4	1.7908	2	2.8008	12	4.7562
LKS	138	4.0358	215	44.0559	79	131.5137	432	179.6054
PCND	23	1.0947	67	12.4045			90	13.4992
Total Non-Dipt.	167	5.2951	286	58.2512	81	134.3145	534	197.8608
G.TOTAL	189	5.9635	395	95.0158	150	325.1576	734	426.1369

In the four Visayan logged-over forests average timber volume of 180 cubic meters, 27% were dipterocarps, 8% commercial non-dipterocarps (CND), 3% potentially commercial non-dipterocarps (PCND), and 62% lesser-known species (LKS). In Lawaan, out of a total volume of 426 cubic meters, 53.57% were dipterocarps, 1% commercial non-dipterocarps, 3% potentially commercial, and 43% LKS. The Lawaan percentage for dipterocarps is higher than the Visayan average value.

The raw data of tree species in plots identified with the Molave Forest Type (Plots 16, 27, 28, 29, 30 and 31) were computed for the number of trees per hectare and timber volume in cubic meters per hectare in Appendix Table XXXIVb. By blowing up the data based on 6 plots (2,400 sq m) to hectare basis, the density of trees was found to be 500 per hectare with timber volume of 291 cubic meters per hectare.

Table 4. Summary of the number of trees and timber volumes per diameter size classes (continuation).

B. MOLAVE AND SECONDARY FOREST (Plots 6, 27, 28, 29, 30, and 31)

PER 6 PLOTS or 2400 sq. m.
GROUP	<15 cm		15-34 cm		>35		Total
	No	Volume	No	Volume	No	Volume	No	Volume
DIPTEROCARP
Bagtikan					1	1.6974	1	1.6974
White lauan					1	9.3216	1	9.3216
Total Dipterocarp					2	11.0190	2	11.0190
NON-DIPTEROCARP
CND	2	0.0689	11	2.0380	4	14.1225	17	16.2294
LKS			73	13.6583	16	24.7338	89	38.3921
PCND	18	0.5229	9	2.2745	3	1.9106	30	4.7080
Total Non-Dipterocarp	20	0.5918	93	17.9708	23	40.7669	136	59.3295
TOTAL	20	0.5918	93	17.9708	25	51.7859	138	70.3485
Percent of Total	14.49%	0.84%	67.39%	25.55%	18.12%	73.61%	100.00%	100.00%
PER HECTARE BASIS
GROUP	<15 cm		15-34 cm		>35		Total
	No	Volume	No	Volume	No	Volume	No	Volume
DIPTEROCARP
Bagtikan					4	7.0726	4	7.0726
White lauan					4	38.8403	4	38.8403
Total Dipterocarp					8	45.9129	8	45.9129
NON-DIPTEROCARP
CND	8	0.2871	46	8.4917	17	58.8442	71	67.6230
LKS	0	0.0000	304	56.9100	67	103.0583	371	159.9684
PCND			38	9.4772	13	7.9609	50	17.4381
Total Non-Dipterocarp	8	0.2871	388	74.8789	96	169.8634	492	245.0295
TOTAL	8	0.2871	388	74.8789	104	215.7763	500	290.9423

Compared with the Lauan Forest, the Molave Forest is less dense in number of trees by 32% and less in timber volume also by 32%. Only two species of dipterocarps were enumerated, Bagtikan and White lauan. These two species are known dipterocarps in semi-evergreen dipterocarp monsoon forests such as in the western seaboard of Luzon and in young volcanoes such as Mt. Makiling and Mt. Banahaw. Most of the dominant tree and co-dominant species are light-demanding tree species such Molave, Dao, Kalumpit, Adgau, Alagao, Anonang, Narra, Malapapaya, Labayo, etc. and secondary trees such as Anislag, Bugnang-pula, Bonot-bonot, Lagapak, Alim, Tangisang bayawak, Amamali, Banai-banai, etc.

Ordination Analysis - the Tree Layer

An ordination analysis of the tree layer in the 31 plots through Principal Component Analysis (PCA) is shown in Fig. 2. This was computed by using the pair-wise comparisons of the 31 plots as shown by the similarity matrix data in Table 5.

The cluster composed of Plots 1, 2, 3, 4, 7, 15 and 19 feature the dominance of Red lauan and the absence of Mayapis. The presence of Lunai Dacryodes rostrata joins together Plots 4, 7 and 15. Plots 1, 2, 3 and 9 share Malaalahan Guioa discolor, Bakan ihalas Litsea sp and Malaruhat puti Syzygium sp.

The second cluster consists of Plots 5, 6, 8, 10, 11, 12, 18 and 25. This cluster features the presence of Mayapis and Red lauan together. In addition, the cluster also features the frequent occurrence of Malaruhat pula Syzygium sp, Ata-ata Diospyros mindanaensis and Duguan Myristica philippinensis.

The third cluster is composed of Plots 13, 14, 20, 21, 22, 23, 24 and 26. It features the dominance of Mayapis and the absence of Red lauan. The frequency of Baritadiang Parinari costata, Uakatan Planchonella velutina, Tikoko Teijsmanniodendron pteropodum and Ulayan Lithocarpus sp is noted.

Plots 16 and 17 had little similarity with the above clusters although spatially the two plots are located adjacent to them and both had Bagtikan Parashorea malaanonan. Plot 17 is still considered a dipterocarp forest but belongs to another subtype. Plot 17 also features Mayapis Shorea palosapis, Almon Shorea almon aside from Bagtikan. Plot 16 shares with Plot 17 the following species, namely Lipakon Lithocarpus celebicus, Hagimit Ficus minahassae, and Toog Petersianthus quadrialatus.

Plot 16 is related with Plots 27, 28, 29, 30 and 31 because of the common presence of Hagimit Ficus minahassae. Other species were Tangisang bayawak F. variegata variegata, Kalumpit Terminalia microcarpa and Toog Petersianthus quadrialatus occur scattered or sporadic on these plots.

The cluster that groups together Plot 28, 29, 30 and 31 bounded by the common presence of Ilang-ilang Cananga odorata and Molave Vitex parviflora. Sporadically scattered among them were Toog, Banai-banai Radermachera pinnata and Malapapaya Polyscias nodosa. Kalantas Toona calantas, Upling-gubat Ficus ampelas and Lisak Neonauclea bartlingii binds together Plots 29, 30 and 31. Of the four plots, only Plot 28 harbors a dipterocarp species, White lauan Shorea contorta. This species is capable of tolerating open forests even in many Philippine dry monsoon areas. The presence of Kalantas Toona calantas, Dao Dracontomelum dao and Narra Pterocarpus indicus make the deciduous character of the Plot. These two together with Magabuyo Celtis luzonica, Malaikmo Celtis philippensis, Pakak Artocarpus treculiana, Malapinggan Trichadenia philippinensis, and accentuate the old second growth character.

Species with extreme pioneering habits in this cluster are plenty, enumerated as follows, Alagao Premna odorata, Adgau P. subglabra, Alim Melanolepis multiglandulosa, Amamali Leea aculeata, Anislag Securinega flexuosa, Binungang mabolo Macaranga hispida, Gubas Endospermum peltatum, Hagupit Ficus sp., Hambabalud Neonauclea formicaria, Lisak Neonauclea bartlingii, Salingkugi Albizia saponaria, Tabgun Ficus ruficaulis, and Upling buntotan Ficus guyeri.

One would imagine that Plots 16 and 17 contain light demanding tree species that are shared with plots identified with Molave Forest plots such Alangas Ficus heteropoda, Hagimit Ficus minahassae, Tangisang bayawak Ficus variegata, Malapapaya Polyscias nodosa and Bangkal inalon Nauclea orientalis. These light demanding species have pioneering habits and are the ones that take part in the immediate colonization of gaps created at the expense of old growth Dipterocarp Forests. It is to be noted that pioneer species common in the Western Visayas were not observed like Binunga Macaranga tanarius. Binunga Melia dubia, Inyam Antidesma ghaesembilla and Dita Alstonia scholaris.

Vegetation Analysis for the Undergrowth

Vegetation analysis for the undergrowth was accomplished through computations reflected in Appendix Tables XXXV to LXV. Table 6 shows side by side the values of the Shannon Wiener Diversity Indices (H'), number of individuals and number of species of the tree and undergrowth layers. By inspection, there is none or only little linear relationship between the tree layer H' compared with undergrowth layer H' neither does H' versus volume.

Table 6. Summary of the vegetation analysis of the undergrowth, data compared with those of the tree layer.

	Shannon Wiener Diversity Indices (H')		No. of Individuals		No. of Species		Volume of Tree Layer or Cover
Plot	Tree	Undergrowth	Tree	Undergrowth	Tree	Undergrowth
1	2.9776	3.6842	40	69	24	44	9.7434
2	2.7065	3.2853	36	44	20	30	12.3860
3	3.0686	3.2297	44	197	28	38	11.6548
4	2.6582	2.9189	31	120	19	30	16.9190
5	2.3298	2.9750	21	27	14	20	8.9130
6	2.9261	2.9062	27	53	21	22	25.1791
7	2.3758	3.3229	23	83	13	31	10.1826
8	2.4625	2.4988	21	28	15	14	24.5591
9	2.6452	2.7170	27	50	19	17	34.8900
10	2.3409	2.7019	31	30	15	16	15.5338
11	2.0518	2.5566	22	38	10	15	7.7432
12	2.0552	2.7811	24	60	11	21	7.6638
13	2.3950	2.4173	36	80	13	15	22.2038
14	1.7083	3.0416	24	73	10	25	23.7494
15	2.3796	2.9469	42	51	17	22	11.6966
16	2.3670	2.2762	21	38	12	13	10.5187
17	2.4639	2.5090	23	66	15	14	25.9899
18	2.7049	2.1683	38	342	18	13	89.5320
19	2.4081	2.2482	22	232	14	16	41.3750
20	2.2711	2.7297	23	61	14	19	37.6866
21	2.4752	2.8431	29	97	19	22	63.2800
22	2.9713	2.7870	30	125	23	20	35.4486
23	2.8565	2.6481	30	348	20	21	21.2865
24	2.6919	3.0303	34	168	20	26	52.9896
25	2.7086	3.3159	31	137	20	34	24.7879
26	2.5371	2.3462	23	77	15	12	26.4264
27	2.7224	2.2534	25	30	19	10	43.4058
28	2.1584	2.4698	28	96	11	14	42.1898
29	2.2054	2.3338	20	83	12	13	5.9090
30	1.0228	2.1958	21	59	11	11	10.5156
31	1.9394	1.8350	21	55	10	8	5.7332

Ordination Analysis - Undergrowth Layer

Using the importance values of the undergrowth species in the 31 plots, a pair-wise similarity comparison was computed and entered in the 31 x 31 similarity matrix in Table 7. Out of this data matrix, ordination by Principal Component Analysis (PCA) was computed and plotted into the graph in Fig. 3.

The graph in Fig 3 is similar with the graph in Fig 2, although this time the plots of the Lauan Forest Subtype show overlaps between the Red lauan, Mayapis-Red lauan and Mayapis stands. This similarity between the ordination of the tree layer and undergrowth layer only confirms each other. The result shows that based on the undergrowth the dipterocarp stands intergrade between one another. The locations of young dipterocarp forest Plots 16, 17 and 27 are consistent, but Plot 15 has moved departing from its group to a location close to Plot 17. Plots 9 and 11 joined the Red lauan undergrowth plots. Mayapis stands' Plot 20, 23 and 24 joined the main cluster of the Mayapis-Red lauan stands. In exchange, Plot 25 moved closer to the Mayapis stand cluster.

Cluster 1 is composed of Plots 1, 2, 3, 4, 7 and 9 of the Red lauan plots (color coded navy blue) and Plots 10 and 11 are of the Mayapis-Red lauan plots (color coded pink).

Plot 1 - Blumeodendron, Pavetta, Kwakya, Ata-ata, Lunai, Malaalahan and Bago.

Plot 2 - Malapaho, Lunai, Antidesma cordato-stipulacea, Drypetes, Knema, Canthium, Lasianthus

Plot 3- Tiagkot, Manggasinoro, Malaalahan, Malapaho, Balakbakan, Taingang baboy, Liusin, Katurog, Malaruhat bundok

Plot 4- Malaalahan, Lasianthus, Kamagsang itim, Malaruhat bundok, Barit, Taingang baboy, Bariw, Aglaia sp, Pamintaogon, Nangkaon

Plot 7- Pamintaogon, Lasianthus, Malaruhat bundok, Kulipapa, Bagoadlau, Bitanghol, Smilax, Lunai, Fagraea, Pavetta

Plot 9- Malapaho, Pamintaogon, Sarcandra, Taingang baboy, Lasianthus, Bolster katmon

Plot 10 - Balihud, Lunai, Lasianthus, Almon, Bakan, Baritadiang, Kamagong bundok, Kamala, Palosapis, Sandalino

Plot 11 - Lasianthus, Lanos haba, Lunai, Antidesma cordato-stipulacea, Malasalab, Smilax, Bitanghol, Alahan puti, Baritadiang, Tiagkot, Ulayan

Cluster 2 is composed of Plots 5, 6, 8, 12, 18 (pink), 20, 23, 24 (yellow) and 19 (navy blue). Pink plots are identified with Mayapis-Red lauan cluster.

Plot 5- Lithocarpus "kinaimito", Baccaurea tetrandra, Balatbuwaya, Lipakon, Saurauia, Tirukan itim.

Plot 6- Lasianthus, Maratungao, Nangkaon, Balihud, Ulayan, Balukbok, Almon, Suyak daga

Plot 8- Karimbaboi, Kulis daga, Dalingdingan, Smilax, Salasik, Malabuho, Kamagsa, Tabgun, Taingang baboy, Pavetta, Magalumod, Allophyllus

Plot 12- Ulayan, Tangile, Lasianthus, Dimorphocalyx, Bolster katmon, Baritadiang, Tiagkot

Plot 18- Pamintaogon, Red lauan, Quisumbing gisok, Bolster katmon, Ulayan, Baritadiang, Palosapis, Tabsik

Plot 20- Baritadiang, Lanutan sapa, Anang, Ervatamia, Bangkal inalon, Duguan mabolo, Dungau, Sakat

Plot 23- Taba, Tagkan, Quisumbing gisok, Pamintaogon, Gigabi, Ulayan, Bago, Tikoko, Bagoadlau

Plot 24- Red lauan, Ulayan, Mayapis, Baliktan, Karimbaboi, Taingang baboi, Nangkaon bundok, Kwakya, Batikuling

Plot 19- Pamintaogon, Bolster katmon, Tikoko, Red lauan, Tangile, Malaruhat bundok

Cluster 3 is composed of Plots 13, 14, 21, 22, 26 (yellow) and Plot 25 (pink). The yellow plots are identified with Mayapis stands.

Plot 13- Tangile, Mayapis, Malapaho, Taguhangin, Tikoko, Bolster katmon, Pamintaogon, Lithocarpus, Magulumod, Saritan, Nangkaon

Plot 14- Mayapis, Tangile, Lanos haba, Pavetta, Baritadiang, Suyak daga, Bignay baging

Plot 21- Mayapis, Lanutan sapa, Baritadiang, Taguhangin, Uakatan, Kangko, Nangkaon, Taingang baboy, Ata-ata, Anuping

Plot 22- Mayapis, Tagkan, Tabon, Malasangki, Ulayan, Ayum, Kangko, Ata-ata, Garcinia oligophlebia

Plot 26- Mayapis, Almon, Kaminggi, Tikoko, Dimorphocalyx, Kulipapa, Balatbuwaya, Katong balog

Plot 25- Tikoko, Mayapis, Bolster katmon, Horsfieldia ardisiifolia, Uakatan, Tamayuan, Parungan, Ata-ata, Balatbuwaya

Cluster 4 is composed of Plots 16, 17, 27 (aqua green) and Plot 15 (navy blue).

Plot 16- Toog, Basikong kalawang, Balihud, Anahaw, Bolster katmon, Palayan

Plot 17- Almon, Bagtikan, Alagasi, Bangkal inalon, Sukalpi, Tiagkot, Karimbaboi, Bolster katmon, Anubing, Ficus, Horsfieldia, Mali-mali, Lunai, Yabnob

Plot 27- P. langguna, Tikoko, Basikong kalawang, Kalantas, Kanis, Malapapaya, P. arborescens, Apanang

Plot 15- Taingang baboi, Suyak daga, Nangkaon bundok, Lunai, Liusin, Bakan, Binukaw, Ervatamia, Malaalahan, Pagingang haba, Sukalpi

Cluster 5 is composed of Plots 28, 29, 30 and 31 (brown).

Plot 28- Salingkugi, Molave, Banai-banai, Toog, Malapapaya, Amamali, Hamindang pailig, Lagapak, Karimbaboi, Lanete

Plot 29- Banai-banai, Lanutan sapa, Hagimit, Amamali, Alim, Alagasi, Malaikmo, Basikong, Malapinggan, Pospos, Upling buntotan

Plot 30- Lisak, Banai-banai, Alagasi, Pusopuso, Balatbuwaya, Anislag, Malaikmo, Toog

Plot 31- Lisak, Alagasi, Hagimit, Upling gubat, Basikong kalawang, Laneteng pula

The undergrowth stands of plots in the Molave Forest are obviously distinct from the rest. The pattern exhibited by the ordination of the undergrowth only reflects those of the tree layer pattern.

Herbaceous Layer

The herbaceous layer is probably underestimated because of the small size of quadrat used and the inability to pin down collections to species identification due to the lack of flowering/fruiting herbarium material. The persistent presence of wild ginger Bariw Pandanus copelandii, Alpinia glauca and Sarrat Scleria sp is noticeable. Peripheral and occasional species were Tagbak Alpinia (Kolowratia) elegans, Hagithit Phrynium philippinensis, Banagan Smilax sp, Hedyotis, Bamban Donax cannaeformis, Stachytharpeta jamaicensis, Freycinetia sp, ferns like Tectaria, Kilob Dicranopteris linearis, Drynaria quercifolia, Nephrolepis biserrata, fern allies such as Selaginella sp, wildlings of erect palms like Anahaw Livistona rotundifolia, Stilted pinanga Pinanga samarensis, Sarawag Pinanga insignis, Marighoi Heterospathe intermedia, Banga Orania palindan, Anibong Oncosperma tigilaria and rattans such as Calamus spp, Daemonorops spp, and Plectocomia elongata. In plots under open forests such as in Plots 27 to 31, open herbaceous elements were also recorded such as Cogon Imperata cylindrica and Talahib Saccharum spontaneum.

CONCLUSION

The Lawaan forests examined are characteristically divided into the following forest types, namely, the Lauan Dipterocarp Forest Subtype dominated by Mayapis Shorea palosapis and Red lauan S. negrosensis and the Molave Forest with a lot of Ilang-ilang (Cananga odorata),Toog (Petersianthus quadrialatus) and Banai-banai (Radermachera pinnata). The Dipterocarp Forest is mostly above 100 m asl to 500 m asl. The latter forest is found at low elevations between 100 to 200.

The Lawaan Dipterocarp Forest varies in species composition, variants such as Bagtikan (Parashorea malaanonan)-White Lauan (Shorea contorta) Dipterocarp Forest (Plot 16, 17), Mayapis Dipterocarp Forest and Red Lauan Dipterocarp Forest. The latter two are the more common variations of the Lawaan Dipterocarp Forest comprising twenty-four out of twenty-six plots.

In terms of the number of trees, the Lawaan Dipterocarp Forest is comparable with the Visayan average. However, the Lawaan Dipterocarp Forest timber volume is almost thrice bigger than the Visayan average. It is not sure if such disparity has ecological meaning since variation in the intensity of previous logging operations and time lapse after logging varies. The Lawaan has higher percentage of Dipterocarp timber volume (53%) compared to the Visayan average of only less than 30%. Other than the two dominants were the following Palosapis Anisoptera thurifera thurifera, Tangile S. polysperma, Almon S. almon, Yakal yamban S. falciferoides, Manggasinoro S. assamica philippinensis, Yakal S. astylosa, Quisumbing gisok Hopea quisumbingiana, Yakal gisok H. samarensis, and Dalingdingan H. foxworthyi. Unlike other Samar forests, the absence of the Apitong group of species Dipterocarpus spp. is noticeable.

The lowland non-dipterocarp forest is here considered a member of the Molave Forest due to the presence of Molave Vitex parviflora and co-dominant deciduous species such as Ilang-ilang Cananga odorata, Dao Dracontomelum dao, Narra Pterocarpus indicus, Alagao Premna odorata, Adgau P. subglabrata, many Ficus spp such as Hagimit Ficus minahassae, Tabgun F. ruficaulis, Basikong F. botryocarp etc. Banai-banai Radermachera pinnata is characteristic.

The undergrowth pattern of diversity reflects similar pattern with their respective tree layers as indicated by their respective ordination analyses. The undergrowth plots within the Dipterocarp Forest categories intergrade with one another.

The herbaceous layer are characterized by a rich array of life forms dominated by wild gingers Alpinia, sarrat Scleria, members of Pandanaceae Freycinetia and Pandanus, members of the Palmae such as Pinanga, Heterospathe, Orania, and spiny Oncosperma, including climbing ones such as Calamus, Plectocomia and Daemonorops.

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