Faculty Research Impacts
Forest Harvest Leads to Decade-Scale Alterations in Soil Fungal Communities
Forestlands provide a multitude of ecosystem services, and sustainable management is crucial to maintain these services. Intensive organic matter removal (OMR) of logging residues and litter during forest harvest may result in long-term alterations to soil properties and processes. Because soil fungal activity regulates essential biogeochemical processes in forestlands, changes in fungal community structure following OMR may translate into altered soil function. Using a long-term field experiment in pine forest in eastern Texas, USA, Dr. Tom Boutton and his students sampled soil to a depth of 1 m to assess the impact of intensive OMR on soil fungal communities. Soils were collected from replicated loblolly pine (Pinus taeda L.) stands subjected to 3 different harvest intensities (unharvested old growth controls, bole-only harvest, and whole-tree harvest + forest floor removal) in 1997. Nearly two decades after trees were harvested and replanted, next generation sequencing of the fungal internal transcribed spacer showed the diversity and community structure of the entire fungal community was altered relative to the unharvested stands. The relative abundance of Ascomycetes increased as OMR intensity increased and was positively correlated with concurrent changes in soil pH. The community composition of fungal functional groups (e.g., ecto- and arbuscular mycorrhizal, saprophytic fungi) was also altered by OMR. Results demonstrate strong linkage between anthropogenically-induced aboveground perturbation, edaphic factors, and soil fungal communities of southern pine forests. These results also indicate that tree harvesting effects on soil fungal communities can persist for decades post-harvest, with potential implications for ecosystem function.
Promoting ecosystem restoration by operationalizing resilience, experimentally testing ecological theory, and identifying sociopolitical constraints influencing effective management
Dr. William E. Rogers and collaborators have conducted numerous studies assessing the causes and consequences of both native and non-native woody plant encroachment into a variety of ecosystems throughout Texas and the southeastern United States. In addition to gaining insights into the biophysical mechanisms and evolutionary drivers contributing to these ecologically and economically costly ecosystem alterations, his research team has been a leader in developing and evaluating the effectiveness of novel intervention strategies that can be used to manage degraded landscapes. They have also developed a number of theoretical and conceptual models that allow for expanded spatial and temporal projections of these impacts under a variety of different environmental conditions and potential future climate scenarios. Moreover, his group has sought to integrate these ecological processes with various human dimensions by identifying sociopolitical constraints, economic concerns, and legal barriers that may lead to different stakeholder groups developing different risk-benefit assessments (e.g., conducting prescribed fires vs. chemical or mechanical control) in ways that likely influence the decision making of landowners and land managers seeking to promote ecosystem restoration.
Three-Dimensional Spatial Patterns of Fine Roots at the Landscape-Scale in a Subtropical Savanna
Grasslands and savannas in arid and semi-arid regions of the world have experienced proliferation of woody plants during the past century. In these resource-limited areas, the distribution and abundance of fine roots play an important role in acquiring essential resources and structuring communities. However, little is known regarding the depth distribution of fine root biomass at the landscape scale. Drs. Tom Boutton, Ben Wu, and their students quantified spatial patterns of fine root biomass across soil depths in a subtropical savanna landscape in southern Texas by intensively sampling to a depth of 1.2 m in a 160 m × 100 m georeferenced plot subdivided into 10 m × 10 m cells. Fine root biomass decreased with soil depth and differed significantly among plant communities. Kriged maps showed fine root biomass was highest at the center of woody patches, decreasing towards the canopy edges of woody patches, and reaching lowest values within the grassland matrix across all soil depths. These spatial patterns were further supported by strong positive correlations between fine root biomass and NDVI as an index of aboveground biomass. Spatial heterogeneity of fine root biomass across this landscape, quantified by lacunarity analysis, decreased continuously to a depth of 50 cm and then increased. This inconsistency is related to the presence/absence of an argillic horizon across this landscape. Anisotropic autocorrelation analyses showed fine root biomass distribution was strongly directional and perpendicular to the slope of this landscape. The greater abundance of fine root biomass beneath woody plants in both upper and lower soil layers suggests an ability to acquire disproportionately more resources than herbaceous species, which may facilitate the encroachment of woody plants across this landscape.
Restoration of Coastal Wetlands
Dr. Rusty Feagin restored over 5 miles of tidal network, 700 acres of wetland habitat, and built new oyster reefs in Magnolia Beach and Indianola, Texas. He and his PhD student Thomas Huff were awarded the Texas Environmental Excellence Award, the highest environmental award in the state, for their civic work with the local community. Feagin was recognized by Texas State Senate Proclamation No. 355, authored by Representative Schwertner, for his environmental work in general.
Wetland Carbon Database for the USA
Dr. Rusty Feagin, Dr. Marian Eriksson, and their students saw their Wetland Carbon Database used by the US National Greenhouse Gas Inventory to account for wetland carbon as part of international treaty obligations. Their work is an integral part of an initiative headed by President Obama’s office to include wetland-based carbon in greenhouse gas accounting.
Research Collaboration along Gulf of Mexico in Spanish-speaking Countries and Communities
Dr. Rusty Feagin hosted several students from the state of Yucatan and Veracruz, Mexico in his laboratory as part of a cross-college initiative. Work by Feagin and several Mexican colleagues, funded by multiple sources in the US and Mexico, has allowed students and faculty to facilitate cross-country exchanges. Their work focuses on reducing erosion, by mixing engineering and ecological principles.
History Matters - Conservation Paleobiology
In our efforts to conserve species, habitats, and ecosystem services, history matters. Dr. Michelle Lawing is assessing past distributions of species and their evolutionary relationships to reveal how species responded to past climatic changes and to help inform our predictions of how species, communities, and ecosystems will respond to impending climate change. She published two papers recently covering these topics. One paper in American Naturalist is titled, “Including fossils in phylogenetic climate reconstructions: a deep time perspective on the climatic niche evolution and diversification of spiny lizards (Sceloporus)” and the other paper in Ecography is titled, “Community functional trait composition at the continental scale: the effects of non-ecological processes.”
Genome Evolution and Cytogenetics in Conifers
Pine trees and other conifers fulfill essential ecological roles in a variety of ecosystems and represent a major source of timber and other wood products. Improved management strategies of conifer resources for both conservation and economic purposes increasingly depend on a better understanding of the genetic and genomic makeup of these trees. To this aim, Dr. Claudio Casola has continued his collaboration with Dr. Nurul Faridi to develop improved genetic markers for the characterization of single chromosomes in loblolly pine, the most common pine tree species in Southeastern United States, including Texas. Both Texas A&M AgriLife Research and the USDA Forest Service supported this research. As a result of another research project, Dr. Casola, his graduate student Xuan Lin and Dr. Faridi have published an article in the scientific journal Genome Biology and Evolution describing the first case of natural horizontal DNA transfer between animals and plants by characterizing a group of DNA sequences that invaded a common ancestor of all conifers from a parasitic insect approximately 340 million years ago. Unveiling the origin and function of DNA sequences in conifer genomes is instrumental to understand the genetic basis of adaptation and evolution of conifer trees, and it has been a primary focus of the research in Dr. Casola laboratory.
Rangeland Systems: Processes, Management and Challenges
Dr. David D. Briske has edited a book that provides an unprecedented synthesis of the current status of scientific and management knowledge regarding global rangelands and the major challenges that confront them. It has been organized around three major themes. The first summarizes the conceptual advances that have occurred in the rangeland profession. The second addresses the implications of these conceptual advances to management and policy. The third assesses several major challenges confronting global rangelands in the 21st century. The content is founded on the collective experience, knowledge and commitment of 80 authors who have worked in rangelands throughout the world. Their collective contributions indicate that a more comprehensive framework is necessary to address the complex challenges confronting global rangelands. Rangelands represent adaptive social-ecological systems, in which societal values, organizations and capacities are of equal importance to, and interact with, those of ecological processes. A more comprehensive framework for rangeland systems may enable management agencies, and educational, research and policy making organizations to more effectively assess complex problems and develop appropriate solutions. The book is titled ‘Rangeland Systems: Processes, Management and Challenges’ and it will be published by Springer. A November 2016 release date has been scheduled.
Coupled Human and Natural Systems in the Southern Great Plains
Dr. Bradford Wilcox is the PI on a National Science Foundation-Coupled Human and Natural Systems grant that is focusing on understanding woody plant encroachment in the southern Great Plains as a social-ecological system. The project is highly interdisciplinary involving hydrologists, ecologists, social scientists, remote sensing specialists, and system modelers from four universities including Texas A&M, Oklahoma State University, University of Arizona, and Virginia Tech. Dr. Project activities have focused on better understanding how woody plants are altering the water cycle in the Rolling Plains of Oklahoma, documenting the extent of the expansion of woody plants in the Southern Great Plains, and understanding how land owners view the expanding woodlands in the Southern Great Plains. Urs Kreuter is a Co-PI on the project. The project is funded for 3 years and was awarded at a level of $1.4 M.
Land Use Effects on Biogeochemistry and Hydrology of Caatinga Shrublands in Brazil
Drs. Bradford Wilcox and Jason West are using a TAMU-CAPES grant to build strong collaborative research ties with colleagues in northeastern Brazil. This collaborative project is focusing on understanding biogeochemical and water cycles as affected by land use in the caatinga shrublands in northeastern Brazil. The project is providing research support for graduate students from Texas A&M and Brazil and is resulting in considerable cross institutional collaborations. In the past year, students have completed their analysis of how plants and fauna affect infiltration dynamics in the region.
Ecohydrology of South Texas Shrublands
Dr. Bradford Wilcox and students have initiated a new project examining water dynamics in South Texas and how it is affected by changes in vegetation. This project has involved the establishment of long term runoff plots and soil moisture measurement points. In addition, micrometeorological towers are being established at two locations to help evaluate how vegetation affects evapotranspiration dynamics.
Ecohydrology of Shrublands in Sonora Mexico
Dr. Bradford Wilcox is collaborating with colleagues from the University of Sonora to better understand how the establishment and spread of buffel grass alters water dynamics in the shrublands of the Sonora desert in Mexico.
Genetics of Tree Development and Physiology
Previously, Dr. Carol Loopstra discovered 2.8 million SNPs (single nucleotide polymorphisms in loblolly pine, the commercially most important tree species in the southeastern United States. The markers were used for association studies to identify genes involved in traits related to growth and adaptation. Using very stringent conditions, 36 associations were identified between the SNPs and phenotypic traits. Eleven SNP-SNP interactions were identified that explain additional variation between trees. In addition, ~1700 associations were identified with gene expression levels and ~200 with metabolite levels. These findings will help us identify genes and alleles associated with tree development and physiology. The SNP discovery data has been shared with other researchers working on loblolly pine and they have been incorporated into university and industrial genotyping chips.
Characterizing Vegetation Canopy Heights with Icesat -2 Satellite Lidar Data
One of the main research accomplishments of Dr. Sorin Popescu included being one of two vegetation scientists on the NASA Science Definition Team (SDT) for the ICESat 2 satellite mission to be launched in 2018. Research responsibilities involved the development of algorithms to characterize terrain elevation and vegetation canopy heights using photon counting lidar data. In addition, SDT members define the science goals and provide guidance and advice to the ICESat-2 mission project to ensure the mission meets its science requirements.
Monitoring Crop And Vegetation Canopy With Unmanned Aerial Systems (UAS)
Dr. Sorin Popescu and his lab team collaborated with AgriLife soil and crop scientists to develop Unmanned Aerial Systems, sensors, and methodologies to reliably monitor and characterize crop and vegetation biophysical parameters for high throughput phenotyping applications. These research efforts are part of the AgriLife-funded Brazos Bottom Farm UAS project that involves AgriLife scientists and researchers, the TAMU GeoSAT Center, and the TAMU CANVASS Center.
Tropical Forest Ecology at the Soltis Center, Costa Rica
Dr. Georgianne Moore operates a carbon and water flux tower at the Soltis Center in Costa Rica with real-time data streaming via the internet. This tower is collecting critical data for use in global circulation models, is part of a global network of flux tower sites, and serves as a springboard for related undergraduate and graduate research at the Soltis Center. This effort was funded by a $871,841 grant from the US Department of Energy. Results from this work contribute to the DOE Next Generation Ecosystem Experiment in the tropics (NGEE Tropics) effort run by the national laboratories and is being used to study ENSO climate anomalies in tropical forests.
The Texas Water Observatory
Dr. Georgianne Moore is one of six lead investigators on a new initiative, the Texas Water Observatory (TWO), which encompasses a network of state-of-the-art monitoring sites throughout the Brazos Valley, with plans to expand to a statewide initiative in the future. This agricultural region sits at the ecotone between eastern deciduous forest and semiarid savannas along a strong east-to-west precipitation gradient. Our research promotes understanding of threshold vegetation responses to soil moisture variation at pedon to regional scale and how these dynamics govern exports of carbon, water, and nutrients to the Gulf of Mexico. The TWO leadership team is leveraging this effort to a larger team of TAMU researchers and land managers to address questions such as drought, water-energy-food nexus, coastal hazards, and extreme events.
Forest Recovery Following Wildfire at Bastrop State Park
Dr. Georgianne Moore is working in partnership with Texas Parks and Wildlife to characterizing the variability in soil properties and the interacting effects of water availability and burn severity on vegetation recovery following the Bastrop fire. The major goals of this project are to a) Determine the impact of burn severity on resource availability; b) Evaluate the impact of resource availability on vegetation (type, abundance, and growth rates), and c) Predict areas where pine forest recovery is (and is not) optimal. Partners on the project include Cristine Morgan, Jim Muir, and Jim Heilman from the Department of Soil and Crop Sciences.
Prescribed Burning in the Southern Great Plains
Dr. Urs Kreuter was funded ($360,000) by the Joint Fire Sciences Program to conduct a study entitled “Fighting wildlife with prescribed burning in the Southern Great Plains — Social and Regulatory barriers and facilitators". The project is a collaborative effort including researchers from Texas A&M University, Oklahoma State University, and University of Nebraska. Additionally, five peer reviewed journal articles were produced from research focusing on the human dimensions of prescribed fire and conservation easements on private land in Texas. I was also invited to present a keynote talk at the International Rangeland Congress held in Saskatoon, Canada in July; the talk was entitled “Energy Extraction Effects on North American Rangelands: Impacts on the Delivery of Ecosystem Services.” Finally, I was invited to serve on the Texas Academy for Medicine, Engineering and Science (TAMEST) Task Force on Environmental and Community Impacts of Shale Development in Texas.
Professional Ecological Knowledge: An Unrecognized Knowledge Domain Within Natural Resource Management
Drs. David Briske and Forrest Fleischman (Univ. of Minnesota) published a paper in Ecology and Society drawing on years of research and engagement with public natural resource agencies in the United States and India. This paper argues that when these agencies are insulated from political and ecological feedbacks, they develop a type of knowledge Fleischman and Briske term "professional ecological knowledge." This knowledge is based on established agency routines and protocols, but may have little relationship with ecological science or with an awareness of local conditions, and thus can be a significant factor in environmental mismanagement.