Treesearch

Falcataria moluccana (albizia) is an exotic nitrogen (N)-fixing tree currently invading riparian forests in Hawai'i, U.S.A. This study examined how this invasion is impacting stream ecosystems by using naturally occurring stable isotopes of carbon (C) and N to compare food web structure between a noninvaded and an albizia-invaded stream reach on the island of Hawai'i. Isotopic signatures of particulate organic matter (POM), macroalgae, invertebrates, and fishes were collected and compared between the two stream reaches. Stable C isotopic signatures of organic matter sources (POM and...

Inter- and intra-site comparisons of the nitrogen (N) stable isotope composition of wetland plant species have been used to identify sources of N in coastal areas. In this study, we compared δ15N values from different herbaceous wetland plants across 34 different coastal wetlands from the five main Hawaiian Islands and investigated relationships of δ15N with land use, human population density, and surface water quality parameters (i.e., nitrate, ammonium, and total dissolved N). The highest δ15N values were observed in plants from wetlands on the islands of Oahu (8.7-14.6‰) and Maui...

Caterpillars living in aggregations may derive several benefits that outweigh the costs, including better survivorship and improved growth rates. I tested whether larval group size had an effect on these two vital rates in Euselasia chrysippe. These caterpillars feed gregariously during all instars and move in processionary form over the host plant and even pupate together. There was a positive relationship between group size and larval survivorship in the field, although genetic variability was not taken into account in this experiment. Under laboratory conditions, there was also a...

Freshwater forested wetlands are often found just upslope from mangrove forests in both high- and low-rainfall areas in the tropics. A case study on the island of Kosrae, Federated States of Micronesia, demonstrates how important both wetland types are to each other hydrologically and to local economies as well. Together, these wetlands form a landscape that provides goods worth the equivalent of nearly two-thirds the median household income in the region. Elsewhere around the world, similar contiguous pairs of wetlands are extensively used by local populations. However, while the importanc...

Mangroves on Pacific high islands offer a number of important ecosystem services to both natural ecological communities and human societies. High islands are subjected to constant erosion over geologic time, which establishes an important source of terrigeneous sediment for nearby marinecommunities. Many of these sediments are deposited in mangrove forests and offer mangroves a potentially important means for adjusting surface elevation with rising sea level. In this study, we investigated sedimentation and elevation dynamics of mangrove forests in three hydrogeomorphic settings on the...

The immature stages and life histories of Euselasia chrysippe (Bates, 1866) and E. bettina (Hewitson, 1869) are described, providing the first detailed morphological characters for the subfamily Euselasiinae. The larvae of Euselasia chrysippe and E. bettina specialize on several species of Miconia (Melastomataceae). The eggs are stalked (the first reported case of such in Lepidoptera) and laid in clusters on the underside of leaves. The larvae are gregarious and feed, rest, molt, and pupate ‘synchronously’. Both species have six larval instars which exhibit processionary behavior throughout...

Forest fragmentation is a common disturbance affecting biological diversity, yet the impacts of fragmentation on many forest processes remain poorly understood. Forest restoration is likely to be more successful when it proceeds with an understanding of how native and exotic vertebrates utilize forest patches of different size. We used a system of forest fragments isolated by volcanic activity 153 years ago in Hawaii to examine how long-term fragmentation, as well as fragment size and structural features affect the richness of native and exotic bird species. The total number of bird...

Extensive modifications of river systems have left floodplains some of the most endangered ecosystems in the world and made restoration of these systems a priority. Modified river ecosystems frequently support invasive species to the detriment of native species. Rana catesbeiana (American bullfrog) is an invasive amphibian that thrives in modified aquatic habitats. In 2004–2005 we studied the distribution of bullfrogs along a 98-km reach of the Trinity River below the Lewiston Dam to identify habitat characteristics associated with bullfrogs and to recommend actions to reduce their...

Parks and Protected Areas (PPA) have become increasingly important for societal well-being in Europe and the United States. Urbanization, detachment from nature, and demographic changes are fostering discussions about strengthening the social and cultural dimensions of management. The complexities and subtleties of incorporating PPAs into existing government and societal contexts are explored with a focus on institutional and governance principles and an emerging paradigm that might deal with some conflicts. We present two examples, in their respective institutional contexts, that illustrat...

Headwaters can represent 80% of stream kilometers in a watershed, and they also have unique physical and biological properties that have only recently been recognized for their importance in sustaining healthy functioning stream networks and their ecological services. We sampled 60 headwater tributaries in the South Fork Trinity River, a 2,430 km2, mostly forested, multiple–use watershed in northwestern California. Our objectives were: (1) to differentiate unique headwater types using 69 abiotic and vegetation variables measured at three spatial scales, and then to reduce these to informati...