Research

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Current Projects

Climate Change Impacts on Hawaiian Biodiversity and Fresh Water Resources: Building Capacity for Research, Education, and Community-based Mitigation.  United States Forest Service Research Joint Venture.

Pacific Island streams provide numerous ecologic (i.e., habitat for endemic flora and fauna), economic (i.e., drinking water, food), and cultural values (i.e., medicinal plants, source of local legends). Reduced water quantity and quality from climate change, the invasion of watersheds by exotic trees and feral pigs/goats, and the interaction of these two stressors threatens stream function as well as the services that they provide. The objectives of this project are to utilize both modeling and field studies in order to: (1) Model how climate change, the spread of invasive species, and the interaction of these two stressors will alter water quantity and quality in Hawaiian streams; (2) use model forecasting to examine how declines in precipitation affect biotic communities in riparian areas; (3) use long-term monitoring across precipitation gradients to examine how changes in stream flow will alter C and nutrient dynamics, growth and reproduction of endemic stream fauna, and food web structure.

See 2011 Project Summary (4-page color pdf) for more information on this project.

See 2010 Project Summary (4-page color pdf) for more information on this project.

Caption: Photos and further information coming soon.

 

Using Diffuse Reflectance Spectroscopy to Quantify and Predict Soil Carbon Content in Agricultural Soils of Hawaii. USDA CSREES TSTAR Project.

As soil carbon is associated with both soil quality and fertility, it is a critical component of agroecosystems. In Hawai‘i there is currently an increasing need for techniques that can quantify the variability of soil total carbon (Ct) across agricultural landscapes in both space and time.  However, traditional laboratory analysis of the large number of samples needed for accurate assessment of spatial and temporal variability of soil Ct is so time-consuming and expensive that it limits the degree to which this variability can be characterized. This has created a “data crisis,” in which a lack of information is the major bottleneck for monitoring soil Ct at the field and landscape levels. Thus, there is a tremendous need for new techniques to measure Ct that are faster, cheaper, and more reliable than traditional methods. Visible/near-infrared (VNIR)- and mid-infrared (MIR)-diffuse reflectance spectroscopy (DRS) are exciting new technologies that have the potential to revolutionize soil monitoring by allowing for samples to be scanned rapidly, inexpensively, and non-destructively. Spectra produced from these scans can be related to laboratory-based measurements of Ct with chemometric modeling. This allows for collection and processing of greater numbers of soil samples in order to better characterize how changes in management practices affect fertility and soil carbon sequestration at increasingly finer spatial and temporal scales. The objectives of this TSTAR Project are as follows: (1) employ VNIR- and MIR-DRS to scan a large number (>500) of archived soil samples from the NRCS National Soil Characterization Database in Lincoln, NE for which laboratory measurements of soil Ct data are already available; (2) model the relationship between diffuse reflectance spectra and laboratory-measured Ct with chemometrics; (3) use chemometric models developed in Objective 1 to predict Ct in freshly-collected samples from agricultural fields in Hawai‘i under different management; and (4) validate predictive models of soil Ct for use by the Agricultural Diagnostic Service Center (ADSC).

Lincoln Archive

Caption: A photo of the NRCS soil archive in Lincoln, Nebraska. Members of the Bruland Lab recently spend a week at the archive scanning soil samples from Hawaii, Guam, and other Pacific Islands with our VNIR diffuse reflectance spectrometer for a TSTAR-funded research project.

Click here to download a JPEG of a poster on this project that was presented at the 2010 AGU Meeting in San Francisco, CA.

 

Effects of Feral Pigs on Erosion, Runoff, and Water Quality in the Manoa Watershed. McIntire-Stennis Forestry Research Project.

Export of sediments and nutrients from forested watersheds are often assumed to be quite low due to low erosion and tight nutrient cycling.  However, this assumption requires further investigation in Hawai’i due to impacts of feral pigs (Sus scrofa).  These exotic ungulates have been shown to disrupt the forest subcanopy and litter layers, increase soil erosion, alter nutrient cycling through fecal inputs, and impact native stream biota.  Feral pigs not only cause significant onsite damages, they also cause serious offsite problems.  For example, pig-derived sediments, nutrients, and pathogens travel downslope and downstream during precipitation events and eventually into coastal areas and onto coral reefs.  One study estimated that as much as three-fourths of the sediments in the Ala Wai Canal in Waikiki come from erosion in the forested areas in the upper sections (Mānoa Valley) of the watershed (Dashiell 1998).  Feral pig populations in Mānoa Valley have increased rapidly and been the subject of numerous community meetings during the last year.  While, major feral pig eradication and fencing programs have been carried out for decades in areas such as Haleakala National Park and Hawai’i Volcanoes Nation Park, little research has been conducted in other Hawaiian watersheds to document their effects on water quality.  Thus, the overall objective of this project is to determine the role of feral pigs in contributing to sediment, nutrient, and pathogen export from the Mānoa Watershed of O'ahu.  Specifically, the project will involve three components: (1) establishing fenced pig exclosures in the forested headwaters of the watersheds to examine the recovery of understory vegetation and changes in erosion that occur when pigs are excluded from small plots established across various slopes, (2) measuring soil physical and chemical properties in the areas within and adjacent to the exclosure plots in the Mānoa Watershed, (3) measuring sediment and nutrient levels in Mānoa Stream during baseflow and storm events.  We will also be monitoring feral piug activity at our unfenced sites with motion activated game cameras. The focus of the project and the majority of the fieldwork will occur in Mānoa Valley, just north of the University of Hawai’i campus.

To check on recent rainfall amounts in Mānoa Valley click here.

To check stream gauge data from Waiakeakua Stream (a tributary of
Mānoa Stream) click here.

A evening photo of two feral pigs in one of our runoff plots in December 2010.

Another evening photo of a feral pig in another plot during November 2010.

 

Anammox Activity and Nitrogen Dynamics in Flooded Taro Soils of Hawaii. USDA/CSREES/NRI Progam.

Iin February 2006, sediment samples were collected from 5different taro patches, including the patch where the experiment was conducted, the Hanalei River (Kauai), and a duck pond adjacent to the River and tested for the presence of anammox species by our Michigan State University partners.  All samples showed a positive identification of the 16S rRNA gene sequence closely related to the marine species of anammox which have also been specifically identified in a freshwater river.  A positive identification of the bacteria responsible for anammox in these taro soils is not only a novel finding (they has never been detected in agricultural soils), but suggested that more research was needed to examine the impact of this process on N dynamics in intensively-managed food production systems.  The determination of anammox activities in flooded agricultural soils is of special interest due to its potential impact on N dynamics and crop productivity and the need for consistent models predicting N losses in relation to fertilizer inputs.  As a previously unknown mechanism of N loss, anammox may be an important determining factor in pursuing specific agricultural management decisions.  Hence, the overall goal of this project is to acquire a better understanding of the fundamental mechanisms driving N dynamics in flooded taro systems in order to improve N fertilizer management. The project has two objectives: 1) determine the distribution of anammox in flooded taro soils of Hawaii and evaluate its contribution to N2 production, and 2) determine the effects of different N fertilizer practices on anammox activity, N dynamics, and crop yield under flooded conditions. The project will also test the following hypotheses: 1) anammox is ubiquitous in Hawaii taro soils and its activity contributes significantly to N2 production in the anoxic layer of taro soils, and 2) N fertilizer practices can be optimized to ameliorate anammox-N loss while maintaining taro yields under flooded conditions.

BrulandDeenikTaro

Caption: Drs. Bruland and Deenik collecting soil samples from a taro loi on Kauai.

 

Rapid Assessment and Trajectory Modeling of Changes in Soil Carbon Across a Southeastern Landscape.  USDA/CSREES/NRI Progam.

The goal of this research, which began in Sept. 2007, is to assess the effects of land cover/land use (LC/LU) change on carbon stocks giving special attention to translating site-specific carbon pools (labile, recalcitrant and total carbon) to landscape scales. The objectives of the project are to: (i) determine soil carbon pools in various ecosystem types across a large landscape cutting across LC/LU and climatic/hydrologic gradients; (ii) investigate the strength and magnitude of relationships between environmental landscape properties and corresponding carbon pools within a GIS; (iii) derive functional models relating measured soil carbon fractions to soil spectra in the visible/near-infrared (VNIR) range to develop rapid and cost-effective soil carbon prediction models; (iv) model change trajectories, i.e. assess historic and actual soil carbon stocks and turnover rates in various ecotypes; and (v) Upscale site-specific VNIR-derived and laboratory-measured soil carbon pools to the landscape scale by modeling spatial autocorrelations and covariations with environmental landscape properties.  This methodology is based on comprehensive historic (~1,300 soil samples) and reconnaissance (~1,000) soil samples representing various ecotypes.  Relationships between soil carbon pools and environmental landscape properties will be investigated using analysis of variance, multivariate regression methods and canonical correlation analysis.  Chemometric modeling will be used to relate spectra to analytical measures. Hybrid geospatial methods will be used to develop soil carbon prediction models.  In addition, soils collected from Hawaii and analyzed at the NRCS National Soil Characterization Lab in Lincoln, Nebraska will be scanned with VNIR DRS and chemometric models will be developed to relate DRS spectra to laboratory-measured soil properties for the Hawaiian soils.

 

Emerging Technologies for Soil and Water Conservation in Mixed-Use Watersheds of Hawaii and the Pacific Islands. CTAHR Hatch Project.

In the State of Hawai’i there is currently an increasing need for new monitoring techniques that are faster, cheaper, and more reliable than traditional measures.  The diffuse reflectance spectroscopy (DRS), global positioning system (GPS), and geographic information system (GIS) technologies tested, developed, and applied in this Hatch project will aid in more effective management of Hawaii’s natural resources and agricultural ecosystems.


VNIR

Caption: Here's a photo of the VNIR at work scanning a soil sample from Hawai'i.

Visible near infrared (VNIR)- and mid infrared (MIR)-DRS is an exciting new technology that has the potential to revolutionize soil characterization and monitoring by allowing for samples to be scanned rapidly, inexpensively, and non-destructively.  The spectra produced from these scans can be related to physical and chemical soil properties with the use of chemometric modeling.  For example, VNIR- and MIR-DRS has been used to provide robust estimates of total carbon (TC), organic carbon (OC), cation exchange capacity (CEC), pH, and texture.  Developing chemometric models with VNIR- and MIR-DRS will allow us to scan greater amounts of soil samples and better characterize the spatial and temporal variability of soil resources across different soil orders and land-uses.The data generated from DRS can then be incorporated into a GIS framework that will allow us to work over larger scales with greater resolution than has ever been previously possible.  Global positioning systems also allow the same site to be sampled repeatedly over time to investigate temporal changes in environmental properties such as soil carbon that occur over seasons and years.  The technologies also allow us to identify critical source areas of nutrient, pesticide, and sediment loss or to more strategically target areas for remediation.  Integrating the processing capabilities of DRS within the spatially-explicit GPS and GIS context has a tremendous potential to help growers, landowners, managers, and scientists characterize the status and degradation of soil and water quality at the watershed scale.  The data and results generated from this project will be critical in the effort to manage resources such that we can meet the food demands of future populations without compromising environmental quality.

Other Research Areas

I'm also working with Dr. Dharni Vasudevan of Bowdoin College to study the sorption of phamaceutical compounds such as oxytetracycline and ciprofloaxin to different soil orders. See the Publications page of this website to read more about this research.

 

Completed Projects

Innovations in Stream Phytoremediation and Erosion Control of Degraded Stream Banks. EPA/Hawaii DOH 319 Grant.

This project began in July 2007 and involves the use of coconut fiber coir logs as erosion control measures in windward Oahu streams.  These coir logs have been used extensively for erosion control in temperate stream systems in the continental U.S. but have not been tested in subtropical areas such as Hawaii.  We tested whether native riparian and wetland plant species could be grown on these coir logs to provide addition nutrient uptake and habitat quality benefits.  An experiment was conducted to test the survival, growth, and nutrient uptake rates of 4 species under three different nutrient treatments at the CTAHR Mauka Campus facility.  Based on the results of this experiment, coir logs were grown in local greenhouse and placed into two streams in Waimanalo to help provide erosion control, uptake of N, and reintroduce native and riparian plants to the stream bank and riparian zone.  See the Publications page of this website to read more about this research.

Experiment

Caption: Here's a photo of the coir log growth and nutrient uptake experiment.

 

An Assessment of the Water Quality and Habitat Functions of Restored, Created, and Natural Wetlands of the Hawaiian Islands. EPA Wetland Program Development Grant.

In Sept. 2006 myself, Dr. Rich MacKenzie (USFS), Ms. Christian McGuire (Hawaii DLNR), Ms. Adonia Henry (USFWS), and Ms. Connie Ramsey (ACoE) started a 3-year Wetland Program Development Grant Project funded by EPA Region IX. The objective of the project was to compare the functionality of restored and created wetlands to those of natural wetlands in Hawai'i. In Phase I of the project, we samped water quality, soils, vegetation, and fish community composition of 40 coastal lowland wetland sites on Kauai, Oahu, Molokai, Maui, and Hawaii. Phase II involved a quarterly sampling of water quality and fish community composition over the next two years of the project at a subset of 20 sites (4 sites per island). We started Phase II in Sept. 2007 and completed it in Sept. 2009. See the Publications page of this website to read more about this research.

Honuapo

Caption: Here's a photo of the EPA Phase I sampling team and site manager after finishing the sampling of one of the coastal wetland study sites on Hawaii Island.