Human-Altered Tree-Based Habitats and Their Value in Conserving Bird and Bat Diversity in Northeast Luzon, The Philippines - Smallholder Tree Growing for Rural Development and Environmental Services - page 337

Table 16.1 Survey localities, number of households in the nearest settlement, distances to con-
tiguous forest and caves and the habitat types surveyed per locality (Field observations, NSO 2000
and Van der Lans 2005)
Locality
(municipality) a

Households Distance to

forest (km) b

Distance to
cave (km) b

Habitat types surveyed

Dunoy (SM) 6 0.1 5.7 Shrub-land
Divisoria (SM) 10 0.4 7.7 Gmelina forest
Homegarden shrub-land
Vibanara (IL) 187 0.9 7.5 Gmelina forest shrub-land
Villa Miranda (SM) 100 1.3 8.8 Gmelina forest
Homegarden shrub-land
Puerta (C) 100 1.6 1.3 Gmelina forest shrub-land
Dy Abra (T) 115 1.8 2.2 Gmelina forest
Homegarden shrub-land
Masipi East (C) 260 2.5 1.6 Gmelina forest
Homegarden
Malibabag (P) 282 3.7 4.0 Homegarden shrub-land
Baculod (SP) 115 12.7 10.3 Gmelina forest
Homegarden shrub-land
Moldero (T) 274 13.9 12.8 Gmelina forest
Homegarden shrub-land
Naquilian (N) 50 18.1 18.0 Gmelina forest
a Municipality codes: SM = San Mariano, IL = Ilagan, C = Cabagan, T = Tumauini,
P = Penablanca, SP = San Pablo, N = Naquilian. All survey sites in Isabela Province, except for
Malibabag in Cagayan Province
b Euclidian distances calculated in ArcView using GPS positions of survey localities (centre) to conti-
guous forest and nearest caves using the most recent available forest cover map (NAMRIA 1995)

same elevational floristic ecotone (Ashton 2003). Not all 11 localities included all
three human-altered habitat types investigated in this study: homegardens were
surveyed in seven localities, Gmelina arborea plantations (henceforth named
Gmelina forest; Photo 16.1) in eight localities and shrub-land in nine localities
(Table 16.1).
The three human-altered habitat types differed in various aspects. Homegardens,
with an average area of 1,031 m 2 per household (see Snelder, Chapter 2, this vol-
ume), were privately owned, situated next to houses and consisted of a variety of
vegetables, tuber crops and fruit and timber trees. The surveyed Gmelina forests
ranged in size from 0.16 to 25 ha and consisted of mature trees which were not (yet)
being harvested. Gmelina forests were owned by private individuals, community
organizations or government with use rights granted to local communities. Like the
homegardens, we regard the studied Gmelina forests therefore as smallholder
tree-based systems. The shrub-land concerned a broad mixed habitat category
including deforested land with small trees or solitary large trees, fallow land cov-
ered with grass, herbs and shrubs, mainly used for livestock grazing and firewood
collection, and some cropped fields. The uncultivated areas could regenerate into
secondary forest but frequent fires and grazing pressure generally prevent this
(Masipiqueña et al. 2000; Lasco et al. 2001). The shrub-land was assumed less
suitable for forest species than homegardens and Gmelina forests. Only shrub-land