Co-Directors: John Davis, Eric Jokela, Tim Martin
The Forest Biology Research Cooperative (FBRC) is a forest industry - University cooperative that provides a forum for UF/IFAS, government agencies, and eight national / international forest products companies to work together to further the FBRC's mission of understanding the biological mechanisms controlling productivity and resistance to insects and disease in managed southern pine ecosystems Since its founding in 1996, the FBRC has been effective at building infrastructure for pine productivity research in the southeastern United States. Metrics of FBRC infrastructure building include:
• Involvement of approximately 20 Ph.D.-level scientists from UF, Texas A&M University, University of Georgia, North Carolina State University, Virginia Polytechnic and State University, and U.S. Forest Service;
• $1.2 million in direct industry funding since 2000;
• In-kind industry support for installation and measurement of experiments approximately equal to the $1.2 million of direct support;
• $3.7 million in extramural grant funding for research projects in support of the FBRC mission;
• Two series of large field experiments installed between 2000 and 2003, occupying more than 300 acres on industry lands from Texas to South Carolina. Consisting of over 20 genetic block plot and single-tree clonal trial installations, these studies represent the "state of the art" in southern pine production biology research. The studies serve as outdoor laboratories in which scientists from UF and other institutions investigate the interactions among genetics, silviculture, and environment at scales ranging from the molecular to the stand level.
• Currently, 10 graduate students base their research projects on FBRC study installations or genetic material; and
• 30 peer-reviewed publications and 32 internal publications reporting FBRC-related research.
Field experiment weather station
Photo: Brian Roth
Photo: Brian Roth
PIs: Tim Martin, Gregory Starr, Wendell Cropper, Henry Gholz, Ken Clark
A program initiated by Henry Gholz in the mid-1990s to elucidate the interacting influences of forest structure, forest function, climate, and management on the net exchange of carbon, water and energy from Florida forest ecosystems. The Florida AmeriFlux program is a part of the AmeriFlux network, a continent-wide system of studies in representative ecosystems designed to improve our understanding of the controls over terrestrial carbon balance. The Florida AmeriFlux sites are located in three contrasting southern pine ecosystems in Alachua County, FL: a young slash pine plantation, a mid-rotation slash pine plantation, and an older, naturally-regenerated slash pine / longleaf pine stand. Eddy covariance (EC) instrumentation located on towers at each site provides continuous, ecosystem-scale measurements of carbon, water and energy fluxes on a half-hourly time step. The EC data are complemented by detailed physiological and ecological measurements at the sub-ecosystem level. This project has proven to be an excellent platform for generating collaboration:
• There are over a dozen scientists and collaborators from seven institutions associated with the UF AmeriFlux project (UF, FSU, UGA, Univ. NH, Woods Hole, USDA Forest Service, Smithsonian Institution), including four departments at UF (SFRC, Botany, Geography, Agricultural and Biological Engineering).
• These collaborating scientists are responsible for additional extramurally funded projects totaling approximately $5,000,000 that directly or indirectly utilize the Florida AmeriFlux and related project infrastructure and data streams.
Austin Cary Memorial Forest flux tower
Photo: Tom Powell
Photo: Tom Powell
PIs: Maureen Conte, Jeff Chanton, Tim Martin, Wendell Cropper
Temporal and spatial variations in the concentration and isotopic composition of atmospheric carbon dioxide can be used to estimate the relative magnitudes of the terrestrial and oceanic carbon sinks. Although a powerful approach, sizeable uncertainties in model-derived estimates exist because of our relative lack of understanding of the extent and causes of variability in isotopic fractionation by terrestrial photosynthesis and respiration. Two important model parameters are photosynthetic discrimination (∆) and the d13C of ecosystem-respired CO2 (dCr), yet no satisfactory method exists to measure or model either terms on large spatial scales. The extent to which these parameters vary can significantly alter model conclusions. For example, variations in ∆ and dCr as a result of water or nutrient stress, or changes in C3/C4 productivity, result in variations in atmospheric 13CO2 that could be erroneously interpreted as a shift in the magnitude of the terrestrial sink.
Both ∆ and dCr reflect the consequences of environmental and physiological factors on photosynthetic and respiratory processes, but little is known about how these factors influence the magnitude of ecosystem level variations in ∆ and dCr, nor the extent to which ∆ and dCr are coupled. The d13C of recently assimilated CO2 reflects the modern atmospheric 13C-CO2 offset by photosynthetic discrimination (∆), while the d13C of respired CO2 (dCr) reflects both the modern signal of assimilated CO2 as well as a past signal due to heterotrophically respired "old" carbon.
Southern pine forests appear to be among the largest North American carbon sinks. The research is conducted at the Florida AmeriFlux mid-rotation pine plantation site.
The first objective is to determine, how climatic variables, operating by affecting plant physiological status, influence photosynthetic discrimination (∆) and the isotopic composition of total ecosystem respired carbon dioxide (dCr). This is important because global models do not take into account interannual variability of these parameters yet their variability may affect model results, particularly in predicting the balance between terrestrial and oceanic carbon sinks.
The second objective is to further develop a novel technique based upon the isotopic composition of ablated leaf waxes in aerosols that may be able to uniquely provide direct data on ∆ and its temporal variation on large spatial scales (Conte and Weber 2002a). Direct data on the large spatial and temporal scale variations in ∆ are critically needed to accurately model the magnitude and geographical pattern of the terrestrial carbon sink using variations in [CO2] and d13CO2
Measuring net photosynthesis rate in a Pinus palustris
tree.
PIs: Matias Kirst, Gary Peter, Tim Martin
The goal of this project is to identify the molecular basis of natural variation in carbon allocation (C translocation from source to sink organs) and partitioning (C distribution into chemical structures) in poplar. Identification of these molecular mechanisms can lead to rational strategies for using genetic approaches to increase terrestrial C sequestration by enhancing C flow into sink organs and chemical forms that are favored for long term storage.
In this project, we merge genetic markers, transcript abundance, and quantitative carbon allocation and partitioning phenotypes, collected from a segregating interspecific Populus pedigree, with the sequence of the Populus genome. We will carry out:
1. Genome-based carbon partitioning and allocation QTL characterization. Quantitative trait loci for carbon partitioning and allocation traits, under limiting and luxuriant nitrogen availability, will be identified and candidate genes underlying these QTLs will be defined based on the genome sequence.
2. Genomic regulation of transcription for carbon allocation/partitioning. Genome sequence will be applied to design and construct a QTL/C-metabolism targeted long oligonucleotide DNA chip, to contrast transcript abundance between progeny sets that inherited alternative alleles for target QTLs.
3. Genome identification of target genes for functional characterization. Differentially regulated genes in target organs, located in the QTL interval (cis-regulated) whose predicted function and expression are correlated with carbon allocation and partitioning will be candidates for direct functional analysis. Genes will be down regulated in transgenic poplars by gene silencing and unregulated with select tissue specific promoters.
Matias Kirst, Gary Peter, and John Davis examine a seedling population of Populus derived from a pseudo-backcrossed hybrid pedigree. (IFAS file photo)
PIs: Tim Martin, Gary Peter
This research aims to improve wood quality in managed southern pine forests through a better understanding of the relationships among tree xylem cell structure, tree water relations, and wood quality characteristics such as specific gravity and latewood: earlywood ratio (LW:EW). In brief, we hypothesize that genetic variation in LW:EW will alter xylem hydraulic properties, which will in turn cause variation in physiological characteristics related to water relations, such as foliar stable carbon isotope discrimination (∆13C). Understanding these relationships should lead to increased understanding of adaptive structure-function relationships, as well as the development of practical tools for screening breeding populations for wood quality characteristics. We will also test hypotheses regarding the relationships between water stress and latewood formation, and attempt to corroborate previously-documented correlations between foliar ∆13C and growth rate.
Carlos Gonzalez prepares the wiring for a soil moisture probe.
Replicate cores from a clone showing typical growth
ring formation (left) and a clone showing a tendency for the formation
of false rings (right).
Photo: Xiaobo Li
Photo: Xiaobo Li
PIs: Tim Martin, Tim White
Research into the physiology of southern pines has given us considerable insight into how physiological processes, such as transpiration, photosynthesis and respiration respond to environmental influences and stresses. Unfortunately, the ability to relate this information in a realistic way to the growth of trees and stands in the field remains elusive. In other words, we are still unable to quantitatively explain clonal, family or even species growth differences of southern pines in terms of physiological processes. This shortcoming hampers our ability to predict the outcomes of management actions such as genetic deployment, site preparation treatments or fertilization.
One explanation for this shortcoming may be that physiological studies have usually been carried out on individual plant organs, with little attention given to how organ-level processes are integrated into the function of the entire organism. In other words, the spatial scale of most physiological investigations (the organ) and the spatial scales of primary interest to land managers (whole trees and stands) are not directly compatible. There is also the additional issue of temporal scale. Most physiological investigations, in addition to taking place at small spatial scales, are also confined to relatively small time scales (seconds to hours or days). In order to address larger-scale questions, we need physiological investigations which either operate directly at the appropriate scale for the questions being asked, or which endeavor to relate small-scale physiological measurements to the larger spatial and temporal scales faced by land managers. This project utilizes a suite of physiological, architectural and growth measurements which are intended to quantify processes or surrogates of processes at larger spatial and temporal scales which are potentially more informative for understanding the controllers of growth in different genotypes in the field.
Wires in the woods: Hub for sap flow cable routing