Motoko S. Fujita

BIRDS TRANSPORT NUTRIENTS TO FRAGMENTED FORESTS IN AN URBAN LANDSCAPE

The influence of urbanization on nutrient cycling is vaguely known. Here we document that birds, especially those increasing in urban areas (such as crows, Corvus macrorhynchos and C. corone), affect nutrient cycles. Using fecal traps, we measured phosphorus (P) and nitrogen (N) input from the excrement of birds in fragmented forests in an urban landscape. Sources of avian feces were examined on the basis of carbon (C), N, and P percentages and stable isotopes of delta15N and delta13C. Nitrogen and P input was aggregated in the urban landscape, being especially high at the forest where crows roosted during winter. The annual P input due to bird droppings (range 0.068-0.460 kg x ha(-1) x yr(-1); mean 0.167 kg x ha(-1) x yr(-1)) was 12.4% of the total of other pathways in typical forests and 52.9% in the evergreen forest where crows roosted. The annual N input due to bird droppings (range 0.44-3.49 kg x ha(-1) x yr(-1); mean 1.15 kg x ha(-1) x yr(-1)) was 5.2% of the total of other pathways in typical forests and 27.0% in the evergreen forest used by roosting crows. Expected sources of nutrients in feces included insects in the breeding season, fruits in autumn, and mammals and birds in winter. Stable isotopes suggested that the source of nutrients in forests used by roosting crows was from outside the forest. Therefore, birds played a significant role as transporters of nutrients from garbage (including fish, livestock, and/or C4 plants such as corn, with high delta15N and delta13C) in residential and business areas to fragmented evergreen forests, especially near their winter roosts.

Roles of fragmented and logged forests for bird communities in industrial Acacia mangium plantations in Indonesia

Industrial timber plantations severely impact biodiversity in Southeast Asia. Forest fragments survive within plantations, but their conservation value in highly deforested landscapes in Southeast Asia is poorly understood. In this study, we compared bird assemblages in acacia plantations and fragmented forests in South Sumatra to evaluate each habitat’s potential conservation value. To clarify the impact of habitat change, we also analyzed the response of feeding guild composition. Five habitat types were studied: large logged forest (LLF), burnt logged forest (BLF), remnant logged forest (RLF), 4-year-old acacia plantation (AP4), and 1-year-old acacia plantation (AP1). Estimated species richness (Chao 2) was highest in LLF then AP4 and BLF, while AP1 and RLF had lower estimated species richness. Community composition was roughly divided into two groups by non-metric multidimensional scaling ordination: acacia plantation and logged forest. Sallying substrate-gleaning insectivores, such as drongos, broadbills, and some flycatchers, were restricted to LLF, whereas acacia plantation hosted many terrestrial frugivores, such as doves. Although fragmented forests in our study site lacked several common tropical forest species, these fragments provide an important habitat for some sallying and terrestrial insectivores. A network of small riparian remnant forests could be a complementary habitat for some species, while the conservation value of burnt forest might be low. In conclusion, the highly fragmented forests in plantations are suboptimal habitats for birds but are still very important, because large primary forest blocks have been nearly lost in the surrounding landscape.

Yearly Variation of Acacia Plantation Forests Obtained by Polarimetric Analysis of ALOS PALSAR Data

Applications of remote sensing by microwaves have become widely adopted in forest management, but microwave backscattering mechanisms in plantations remain poorly understood. This study attempts to understand backscattering characteristics under different forest structural conditions in plantation forests of fast-growing acacia trees in Sumatra, Indonesia. A general four-component scattering power decomposition method was applied to ALOS PALSAR data collected from 2007 to 2010 to see the variations of acacia plantation. The yearly variation in decomposition powers was compared to forest inventory data with visual assessments of stand conditions. The results were highly consistent with the field-measured data. Based on the variation patterns of decomposition powers, we can identify the presence of understory and distinguish between damaged and well-grown stands. The PALSAR data analysis can also reveal partial damages within a forest compartment, even minor damage in younger forests. This in-depth study indicates that changes in forest stand composition and the growth and degradation of plantation forests can be monitored by transitions in the polarimetric parameters.

Low conservation value of converted habitat for avifauna in tropical peatland on Sumatra, Indonesia

Peat swamp forest is an important refuge for biodiversity in Southeast Asia and is now becoming a target of exploitation. The scarcity of information on avifauna and ecology of birds in peat swamp forests prevents understanding of the effects of land use change on avifauna. In this study, we describe the bird assemblages in habitats with different land uses by comparing species richness, community composition, and feeding guild patterns in Bukit Batu, Indonesia. Bird assemblages in natural peat swamp forests (NPF), high-maintenance industrial acacia plantations (planted acacia forest, PAF), low-maintenance rubber plantations (jungle rubber forest, JRF), and village areas (VIL) were studied using a fixed-radius point-count method. Of the 95 species observed, 45, 20, 35, and 48 species were observed in NPF, PAF, JRF, and VIL, respectively. Estimated species richness was the highest in NPF, followed by VIL, JRF, and PAF. NPF had the highest species diversity and β-diversity, more endangered species, and a distinctive species composition characterized by fly-catching insectivores. The relative conservation value of PAF was notably low, particularly compared with JRF. The avifauna in VIL was characterized by more generalists that favor open spaces and therefore is not considered an important habitat for forest-dependent birds that are of conservation concern. Our results indicate that NPF has irreplaceable value for bird diversity conservation, but low-maintenance rubber plantations were home to several forest-dependent species and partially supported bird diversity, particularly compared with high-maintenance acacia plantations.