Ecosystems & Development Journal 5(1): 11‐22 October 2014 ISSN 2012‐3612 ABSTRACT This paper provides an inventory of the riparian flora of the Riparian Flora Kaliwa River Watershed (KRW) in Sierra Madre Mountain Range, Philippines including stand structure, plant diversity, of Kaliwa River Watershed endemism and ecological status. A total of 386 morpho-species belonging to 278 genera and 95 families were recorded from the in the Sierra Madre Mountain study area. There are at least 60 Philippine endemics reported, six of which are Luzon endemics. Twenty-two species were listed Range, Philippines under either the Philippine Red List or on the IUCN Red List of Threatened Species. Results of the plant diversity assessment Pastor L. Malabrigo Jr.a, revealed that biodiversity in riparian forests in KRW is still high Arthur Glenn A. Umalia, and despite the obvious massive disturbance in the area. b Jovito P. Elec Keywords: Island endemics, Kaliwa River Watershed, Philippine endemics, plant diversity, riparian flora, threatened species INTRODUCTION the Philippine government with regard to the proposed Kaliwa The tropical forests of the Philippines are now classified as the Low Dam project. It provides an inventory of the riparian flora fourth most vulnerable forest eco-region in the world with only of the KRW including stand structure, plant diversity, endemism 7% remaining original forest cover (Conservation International and ecological status. These information are critically important 2011). Considering the fact that tropical forests shelter more for better protection and conservation of the watershed. than 60% of the world’s biodiversity and consistent with claims that the Philippines is one of the most diverse countries in the world on an acre per acre basis, it is safe to assume that a MATERIALS AND METHODS significant number of local species were gone along with the forests. The Kaliwa River Watershed (KRW), part of the Sierra The plant diversity assessment was conducted on February 26 to Madre Mountain Range that stretches from Northeastern to March 30, 2013. Assessment was focused on the remaining patches of forests which are mostly located along the main Southeastern Luzon, has not been spared from the massive deforestation in the country. Recent biodiversity assessment Kaliwa River and its tributaries. Nested quadrat sampling revealed that majority of the watershed’s original forest cover technique (Figure 1) was used to assess and characterize the structure and species composition of the different plant has been severely depleted as a result of shifting cultivation, animal grazing and upland agriculture. communities. This method is the most applicable in areas where almost all of the major plant groups are present. For large woody plants with diameters equal or greater than 10 cm, measurements Kaliwa River Watershed has a total area of 27,608 ha wherein the southeastern side covers the municipality of Tanay, Rizal of diameter at breast-height (DBH), merchantable height (MH), while the northeastern part straddles the municipality of General and total height (TH) were done inside the 20m × 20m quadrat. Frequency of shrubs, poles and saplings inside the 5m × 5m Nakar, Quezon. Based on the watershed’s development and management plan (FMB-DENR 1999), more than half (53.35%) quadrat was counted, while percentage cover of grasses and other of its total area was still covered by forests. However, a ground cover inside the 1m × 1m quadrat was determined. A total of nineteen quadrats were surveyed with elevation ranging from significant reduction in its forest cover was observed in the last few years (Villegas & Pollisco 2008; Bucayu 2003; Laluan 113 to 212 m above sea level (Figure 2). 2003; Vidal 2002). The residual forests, comprising the largest Additional survey to account for other species occurring outside area of the watershed were the preferred sites for illegal timber poaching. The native Dumagats engaged in fuel wood gathering the quadrats was made using transect method. Floristic survey and charcoal making activities which possibly contributed to (only involved listing of species encountered without any forest degradation and the loss of biodiversity. measurements) was conducted from the 19 10m × 100m transects along the different tributaries. The geographical locations of the 19 transects surveyed are shown in Figure 3. This paper is a result of a comprehensive biodiversity study as part of the environmental impact assessment commissioned by Diversity indices (i.e. Shannon (H’), Simpson’s (D), and Evenness (J)) and similarity matrix for each sampling transects a Assistant Professor, Department of Forest Biological Sciences, College of Forestry and Natural Resources, University of the Philippines Los Baños were generated using MultiVariate Statistical Package (MVSP a Research Assistant, Department of Forest Biological Sciences, College of Forestry 3.1) software. Shannon Index gives an estimate of species and Natural Resources, University of the Philippines Los Baños richness and distribution. Evenness Index indicates how evenly b GIS Specialist, Watershed Management Division, Burgos Wind Power Corporation, Energy Development Corporation Corresponding author: [email protected] 11 species and/or individuals are distributed inside a plot or quadrat. Simpson’s Index gives the probability of getting different species when two individuals were drawn (without replacement) inside a plot. In addition, endemism and ecological status of the different species were assessed to determine the ecological importance of the vegetation in the area. Species names followed the latest Angiosperm Phylogeny Group classification (Stevens 2001 onwards) while the common names adapted that of Rojo (1999). plot. In addition, endemism and ecological status of the different species were assessed to determine the ecological importance of the vegetation in the area. Figure 3. Location map of the different transects surveyed. RESULTS AND DISCUSSION General Description of the Project Area The study area is situated between 14° 35' 42.014” to 14° 37' 21.084” north latitude and 121° 26' 27.715” to 121° 28' 29.95" east longitude, and covers Sitio Cablao and Sitio Tinipak of Brgy. Pagsangahan, Municipality of General Nakar, Province of Que- zon. Based on the actual survey mapping conducted, there are 12 river tributaries draining to the main Kaliwa River namely: Ma- yayimit, Makidata, Mainit, Cablao, Lagundi, Dayinitan, Tiniri- kan, Bangian, Salok, Kiatap, Limuranin, and Maytungtong (Figure 4). It is important to mention that only six of these creeks are reflected in the available maps of NAMRIA and even on the online Google map. This alone is already an important contribu- tion to better understand the project site, and as a future reference Figure 1. Nested quadrat sampling design used in the survey. about the area. Figure 4. Location map of the study area showing Kaliwa River Figure 2. Location map of the different sampling quadrats. and its 12 tributaries. 12 Ecosystems & Development Journal The project site is generally a production area planted with agri- The relative density, relative dominance and relative frequency cultural crops with remnant of natural forests along the steep values for each tree species in all the quadrats were determined to slopes of the rivers. Common agricultural crops planted in the obtain their Importance Value (IV), a standard measure in ecol- area include Coconut (Cocos nucifera L.), Kalamansi (Citrus ogy that determines the rank relationships of species. High Im- madurensis Lour.), Kape (Coffea arabica L.), Mangga portance values of species indicate a composite score for high (Mangifera indica L.) and Lanzones (Lansium domesticum relative species dominance, density and frequency. Based on the Correa). Natural forests have very limited extent and concen- computed IV (Table 1), the five most important species (with the trated along the sharp gradients of the riverbanks. The remaining highest IV) are Hagimit (F. minahassae) (32.94), Tibig (F. nota) vegetation is spared from agricultural conversion mainly because (26.23), Binunga (Macaranga tanarius (L.) Muell.-Arg.) (19.32), of the inappropriateness (steep slope, therefore prone to erosion) Tangisang bayawak (F. variegata) (19.30) and Hauili (F. septica) of the area for planting. The remaining natural forests are domi- (12.79). Except for Binunga, all belong to the genus Ficus whose nated by common riparian species such as Mangagos (Homonoia members are known to be water-loving species hence, commonly riparia Lour.), Mimisan (Syzygium mimicum (Merr.) Merr.), found in rivers and creeks. Binunga, on the other hand, is a highly Aunasin (Ardisia pyramidalis (Cav.) Pers.) and several species of versatile pioneer species. It grows in a wide range of elevation figs (Ficus spp.). and temperature. Plant Diversity and Ecological Assessment Table 1. Top ten trees with the highest Importance Value (IV) Tree Flora Species Count RDen RF RDom IV Ficus minahas‐ A total of 84 tree species were recorded to have a diameter of 21 6.774 2.941 23.221 32.936 sae more than 10 cm. Majority of the quadrats surveyed have less than 20 individuals per quadrat. Only five quadrats have recorded Ficus nota 29 9.355 4.118 12.760 26.232 20 individuals or more. The average number of trees per plot is Macaranga only 16 individuals or an average density of only about 0.04 tree/ 20 6.452 4.118 8.753 19.322 m2 (4 trees for every 100 m2). The low tree density of the quadrats tanarius can be attributed to the relatively young forest along the river- Ficus variegata 16 5.161 4.118 10.026 19.305 banks. In addition, most of the riparian tree species (e.g. Ficus spp.) are naturally small diameter trees. The tree with the largest Ficus septica 14 4.516 4.118 4.155 12.789 diameter is Saplungan (Hopea plagata (Blanco) Vidal), which recorded a DBH of 105 cm (Figure 5), followed by Balobo Neonauclea 13 4.194 3.529 4.782 12.505 (Diplodiscus paniculatus Turcz.), Tangisang bayawak (Ficus media variegata Blume), Hagimit (Ficus minahassae (Teijsm.