Carl Trettin - Academia.edu (original) (raw)

Papers by Carl Trettin

Many forestry and agricultural agencies and organizations worldwide have developed soil monitorin... more Many forestry and agricultural agencies and organizations worldwide have developed soil monitoring and quality standards and guidelines to ensure future sustainability of land management. These soil monitoring standards are typically developed in response to international initiatives such as the Montreal Process, the Helsinki Ministerial Conference, or in support of Best Management Practices program development and Code of Forest Practices regulations. This paper describes international (Australia, New Zealand, Canada, and the European Union) and U.S. efforts and perspectives on soil quality monitoring, and offers suggestions on how to use the existing USDA Forest Service standards and modify them for future relevance.

Potential evapotranspiration (PET) is a driving factor behind the estimates of ecosystem evapotra... more Potential evapotranspiration (PET) is a driving factor behind the estimates of ecosystem evapotranspiration (ET). Most of the PET methods with varying levels of complexity have been developed for a standard grass reference with unlimited soil moisture. There is only limited information examining the difference between the PET for a standard grass reference (REF-ET) and for a forest vegetation and their potential effects in water balance. Data being measured at three long-term complete weather stations located within < 10 km distance from each other on the USDA Forest Service Santee Experimental Forest (SEF) in coastal South Carolina are used in this study. The first two stations on grass reference are located at SEF headquarters (SHQ) and on Turkey Creek watershed (TC), and a third one is on a 27-m tall tower above the canopy of a pine/mixed hardwood forest on a control watershed (WS 80). In this study we evaluated (a) the observed micro-climatic conditions at those three stations and (b) the monthly and annual PET estimated by three methods with varying complexities (Penman-Monteith (P-M), Turc, and Thornthwaite (THORN)) using daily climatic data for a recent two-year (2011-2012) period. Average daily wind speed was observed to vary substantially (as much as 3 times) among the three locations, and average daily net radiation (R n) on the WS 80 forest canopy was ~ 14% higher than the nearby SEF grass site. The effects of these differences were reflected in the PET results by the P-M method with much higher PET for the forest than the nearby grass site where the Turc method provided similar results with another grass site. Where possible and data were available, the results from these three methods were compared with pan evaporation estimates at SHQ. Results indicated that the PET estimates derived by these three methods for a single site and/or the estimates for nearby sites using a single method can vary greatly because of differences in their complexity of describing PET process, climatic factors and their interaction with site vegetation types. These differences should be considered when selecting a PET method and interpreting the results in hydrologic and water balance studies, especially for forested sites with much taller vegetation than the grass reference assumed in most PET methods in the literature.

This workshop was developed to determine the state-of-the-science for soil monitoring on National... more This workshop was developed to determine the state-of-the-science for soil monitoring on National Forests and Rangelands. We asked international experts in the field of soil monitoring, soil monitoring indicators, and basic forest soil properties to describe the limits of our knowledge and the ongoing studies that are providing new information. This workshop and the proceedings are particularly important as National Forests wrestle with determining how (or if) to modify their existing soil quality standards and guidelines.

The objective of this chapter is to characterize the distribution of carbon stocks and fluxes in ... more The objective of this chapter is to characterize the distribution of carbon stocks and fluxes in terrestrial wetlands within North America. The approach was to synthesize available literature from field measurements with analyses of resource inventory data to estimate wetland area, carbon stocks, and net ecosystem exchange (NEE) of carbon and methane (CH 4) fluxes of terrestrial wetlands (see Appendices 13A, p. 547, and 13B, p. 557, for details 1). Then, the findings employed from large-scale simulation studies provided additional context, with consideration given to the effects of disturbance regimes, restoration and creation of terrestrial wetlands, and the 1 The assessment described in this chapter required additional background and parallel analyses of recently published and accessible databases. These analyses pertain only to Ch. 13 and are presented in Appendices 13A and 13B, beginning on p. 547. KEY FINDINGS 1. The assessment of terrestrial wetland carbon stocks has improved greatly since the First State of the Carbon Cycle Report (CCSP 2007) because of recent national inventories and the development of a U.S. soils database. Terrestrial wetlands in North America encompass an estimated 2.2 million km 2 , which constitutes about 37% of the global wetland area, with a soil and vegetation carbon pool of about 161 petagrams of carbon that represents approximately 36% of global wetland carbon stock. Forested wetlands compose 55% of the total terrestrial wetland area, with the vast majority occurring in Canada. Organic soil wetlands or peatlands contain 58% of the total terrestrial wetland area and 80% of the carbon (high confidence, likely). 2. North American terrestrial wetlands currently are a carbon dioxide sink of about 123 teragrams of carbon (Tg C) per year, with approximately 53% occurring in forested systems. However, North American terrestrial wetlands are a natural source of methane (CH 4), with mineral soil wetlands emitting 56% of the estimated total of 45 Tg C as CH 4 (CH 4-C) per year (medium confidence, likely). 3. The current rate of terrestrial wetland loss is much less than historical rates (about 0.06% of the wetland area from 2004 to 2009), with restoration and creation nearly offsetting losses of natural wetlands. Although area losses are nearly offset, there is considerable uncertainty about the functional equivalence of disturbed, created, and restored wetlands when comparing them to undisturbed natural wetlands. Correspondingly, there remains considerable uncertainty about the effects of disturbance regimes on carbon stocks and greenhouse gas (GHG) fluxes. For this reason, studies and monitoring systems are needed that compare carbon pools, rates of carbon accumulation, and GHG fluxes across disturbance gradients, including restored and created wetlands. Those studies will produce data that are needed for model applications (high confidence, likely). Note: Confidence levels are provided as appropriate for quantitative, but not qualitative, Key Findings and statements. application of modeling tools to assess the carbon cycle of terrestrial wetlands. Chapter 13 | Terrestrial Wetlands Second State of the Carbon Cycle Report (SOCCR2) November 2018 using remote-sensing data (Federal Geographic Data Committee 2013). Soils are also indicative of wetland conditions; two major soil types useful for assessing carbon stocks and fluxes recognized here are mineral soils and organic soils. Wetland ecosystems with organic soils, also known as peatlands, are classified as Histosols by the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey (Soil Survey Staff 2010). The Histosol order represents soils with a thick (>40-cm) accumulation of organic matter on top of mineral sediments or rock. Most Histosols are formed under wet conditions (e.g., peat soils), but some of these soils form under aerated conditions. Not considered a wetland, aerated Histosols are distinctly recognized (e.g., suborder Folists) and thus are not considered here. However, all peatlands are formed under wet conditions (Joosten and Clarke 2002), and they are classified as wetlands in Canada (Zoltai and Vitt 1995) and throughout North America (Gorham et al., 2012). The amount and distribution of accumulated soil organic matter reflect the balance between inputs from vegetative production and losses from decomposition or overland transport (e.g., erosion or drainage). While the depth for defining organic soils (Histosols) or peatlands ranges from 10 to 50 cm among different countries, the USDA Soil Survey uses the top 40 cm in the upper 80 cm of soil, which is the definition used here (Soil Survey Staff 2010). Mineral soil wetlands vary widely in the composition and depth of the surface organic layer, varying from a few centimeters to nearly 40 cm in histic-mineral soil wetlands ("histic" refers to soils with a 20-to 40-cm organic horizon, differentiating them from Histosols). 13.1.2 Relationship to Other Chapters and SOCCR1 For this chapter, assessments were made of terrestrial wetlands that occur in boreal, temperate, and tropical climatic zones in Canada, the United States, Mexico, and Puerto Rico. Tidally influenced saltwater and freshwater wetlands are assessed in Ch. 15: Tidal Wetlands and Estuaries, p. 596. Terrestrial wetlands, including peatlands, occurring in Description of evidence base Key Finding 1 is supported by an extensive analysis of the most current wetland soil and vegetation information available across the conterminous United States (CONUS),

Hydrology and Water Resources in Arizona and the Southwest, Apr 14, 2012

The authors have requested that this preprint be removed from Research Square.

Annual Meeting of the American Geophysical Union (AGU), Dec 1, 2019

Conclusion Tidal freshwater wetlands are the interface between marine and terrestrial ecosystems;... more Conclusion Tidal freshwater wetlands are the interface between marine and terrestrial ecosystems; hence they are directly impacted by sea level rise and climate change (James & Callahan, 2012). Little is known about the hydro-ecological functions and ecosystem services provided by these important and widely-distributed ecosystems. These wetlands are common in the urbanizing landscape of the southeastern Atlantic coastal plain, as well as other coastal areas. Tidal freshwater forested wetlands (TFFW) occur in floodplains situated near the coastal zone along freshwater rivers that are subject to tides. They are most prominent along the Southeastern Atlantic lower Coastal Plain, where it is estimated that 200,000 ha of TFFW exist. The majority of TFFW are concentrated along the coasts of the South Carolina, Georgia, Florida, Virginia and Maryland, with other areas along the Gulf coast and upper portions of the Atlantic Coastal Plain. South Carolina is considered to have the most land a...

WETLAND-DNDC, a process-based model that integrates soil, vegetation and hydrology, was developed... more WETLAND-DNDC, a process-based model that integrates soil, vegetation and hydrology, was developed to represent unique biogeochemical properties and processes of wetland ecosystems. Recent studies have demonstrated great potential of the model by applying it to different wetland sites, from Minnesota to Florida. However, to have a broad application of the model to more systems and at larger scales, a full uncertainty analysis is needed to understand its behaviors and determine its critical variables and parameters. With a wetland in Florida as the test site, we used the Monte Carlo method to run WETLAND-DNDC, simulating carbon (C) and nitrogen pools/fluxes driven by a combination of various input parameters (e.g., climate variables, soil properties, forest characteristics, hydrological conditions) and determining impacts of varying parameter values on C dynamics in wetland ecosystems. Input variables included daily maximum air temperature, total organic carbon content, soil saturated...

This study considered the effects on carbon pools in a forested mire following whole-tree harvest... more This study considered the effects on carbon pools in a forested mire following whole-tree harvesting and two site preparation treatments; bed ding and trenching. Whole-tree harvesting, which resulted in complete removal of the overstory biomass, and bedding exhibited the greatest loss of carbon from the site. Removal of the overstory biomass and in creased decomposition of organic matter were the major causes of carbon loss. Measurement of the soil carbon pools in the tree planting zone did not provide an accurate assessment of the treatment effect. Renewal of carbon accumulation will depend on the productivity and composition of the regenerating plant community and on the rate of decomposition of organic matter.

Citation for proceedings: Stringer, Christina E.; Krauss, Ken W.; Latimer, James S., eds. 2016. H... more Citation for proceedings: Stringer, Christina E.; Krauss, Ken W.; Latimer, James S., eds. 2016. Headwaters to estuaries: advances in watershed science and management—Proceedings of the Fifth Interagency Conference on Research in the Watersheds. March 2-5, 2015, North Charleston, South Carolina. e-Gen. Tech. Rep. SRS-211. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 302 p. DESIGNING A MANGROVE RESEARCH AND DEMONSTRATION FOREST IN THE RUFIJI DELTA, TANZANIA

KEY FINDINGS The assessment of terrestrial wetland carbon stocks has improved greatly since the F... more KEY FINDINGS The assessment of terrestrial wetland carbon stocks has improved greatly since the First State of the Carbon Cycle Report (CCSP 2007) because of recent national inventories and the development of a U.S. soils database. Terrestrial wetlands in North America encompass an estimated 2.2 million km2, which constitutes about 37% of the global wetland area, with a soil and vegetation carbon pool of about 161 petagrams of carbon that represents approximately 36% of global wetland carbon stock. Forested wetlands compose 55% of the total terrestrial wetland area, with the vast majority occurring in Canada. Organic soil wetlands or peatlands contain 58% of the total terrestrial wetland area and 80% of the carbon (high confidence, likely). North American terrestrial wetlands currently are a carbon dioxide sink of about 123 teragrams of carbon (Tg C) per year, with approximately 53% occurring in forested systems. However, North American terrestrial wetlands are a natural source of methane (CH4), with mineral soil wetlands emitting 56% of the estimated total of 45 Tg C as CH4 (CH4–C) per year (medium confidence, likely). The current rate of terrestrial wetland loss is much less than historical rates (about 0.06% of the wetland area from 2004 to 2009), with restoration and creation nearly offsetting losses of natural wetlands. Although area losses are nearly offset, there is considerable uncertainty about the functional equivalence of disturbed, created, and restored wetlands when comparing them to undisturbed natural wetlands. Correspondingly, there remains considerable uncertainty about the effects of disturbance regimes on carbon stocks and greenhouse gas (GHG) fluxes. For this reason, studies and monitoring systems are needed that compare carbon pools, rates of carbon accumulation, and GHG fluxes across disturbance gradients, including restored and created wetlands. Those studies will produce data that are needed for model applications (high confidence, likely). Note: Confidence levels are provided as appropriate for quantitative, but not qualitative, Key Findings and statements

Soil Science Society of America Journal, 2019

Bedding of Wetland Soil: Effects of Bed Height and Termite Activity on Wood Decomposition Microor... more Bedding of Wetland Soil: Effects of Bed Height and Termite Activity on Wood Decomposition Microorganisms and termites are the primary wood decay agents in forests of the southeastern United States, whose activity can be affected by forest management practices. Bedding establishes raised planting beds on poorly-drained soils, but little is known about the effect of bedding or soil bed height on wood decomposition. Therefore, a four height bedding study was conducted on a wetland soil in eastern South Carolina: flat (no bedding), half (7.5 cm), single (20 cm), and double (30 cm) above the original soil surface. Aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.) wood stakes were inserted to 30-cm soil depth, sampled over 23 mo, and decomposition (mass loss) by soil microorganisms and termites assessed. Microbial decay of both aspen and pine stakes increased as bed height increased, approaching 50% mass loss in double beds at the end of the study. Termites were not present in the flat (unbedded) soil, only damaged <1% of stakes in half beds, but were very active in single and double beds. Termites damaged or consumed 43% of aspen stakes in the double beds, which increased aspen mass loss by 30%. In contrast, termites attacked only 11% of pine stakes in double beds, and had little impact on mass loss. Stake decomposition was highest at the 5-cm soil depth and was affected by soil microsite variability among soil bed heights. Soil bedding increased wood decomposition by both soil microorganisms and termites, and their impact on soil organic matter content and productivity deserves more attention. Abbreviations: OM, organic matter. C oarse woody debris is an important structural and functional component of forest ecosystems, and is considered an important terrestrial carbon (C) sink because of its slow decomposition rate (Harmon et al., 1986; Woodall et al., 2013). Many factors control the rate at which coarse woody debris decomposes, such as wood species, size, and location (Edmonds and Vogt, 1986). Forest management can also impact soil properties, which subsequently could alter organic matter (OM) decomposition (Grigal and Vance, 2000; Page-Dumroese et al., 2006). Therefore, land managers and climate-change modelers need to understand how wood decomposition rates and subsequent soil C sequestration are affected by various forestry operations. There have been numerous studies on wood decomposition in which fungi are the main biological drivers of the decay process (e.g., Rayner and Boddy, 1988; van der Wal et al., 2015). However, in many ecosystems termites have an important role in soil processes, such as OM decomposition, methane production, and pedogenesis (Sugimoto et al., 2000; Ulyshen 2016). Considerable information is available on species richness, abundance, and biomass consumption by moundbuilding termites in tropical and subtropical ecosystems (e.g., Bignell and Eggleton, 2000; Takamura 2001), but much less is known on the distribution and activity

Estuarine, Coastal and Shelf Science, 2018

It is important to have the capability to assess carbon (C) dynamics in mangrove forests and esti... more It is important to have the capability to assess carbon (C) dynamics in mangrove forests and estimate their role in mitigating climate change because of their high carbon density, the threats to their integrity from land-use change and sea-level rise, and functional linkages of the many goods and services. A process-based model for mangroves was developed by integrating new features with existing biogeochemical processes in Forest-DNDC for simulating C sequestration and turnover in mangrove ecosystems. The new model is used to assess (1) the dynamics of C, nitrogen and phosphorous in mangrove ecosystems, including above-and below-ground C in saline wetlands, (2) the impacts of ecological drivers, including climate, soil nitrogen and phosphorous deficit and salt stress, on mangrove production, (3) the production of methane, and aerobic and anaerobic oxidation of methane with sulfate, nitrate and nitrite reductions, (4) the contributions of dissolved inorganic C (DIC), dissolved organic C (DOC), particulate organic C (POC) and burial C (BC) to blue C, and (5) impacts of natural and anthropogenic disturbances on C sequestration in mangrove ecosystems. Model sensitivity analysis showed that C sequestration in mangrove ecosystems was highly sensitive to multiple ecological factors, including climate, soil phosphorus, salinity and sulfate, as well as latitude. The responses of different C components to these factors were distinct. The responses of gross and net primary productivity and aboveground biomass to alterations of mean daily temperature (MDT) were quadratic, or increasing or decreasing non-linearly with an increment or decrement in MDT, but leaf production was linear. Similarly, other mangrove C components, such as BC, DIC, DOC and POC, respond substantially to variations of the ecological drivers. The combined effects of the driving factors are complex due to their intricate interactions. For example, while mangrove productivity is sensitive to available phosphorous, phosphorous cannot mitigate the stress imposed by high salinity. These results highlight the value of a tool to assess C dynamics in mangroves, especially for regional or large mangrove forests.

Agricultural and Forest Meteorology, 2017

Wetlands store a disproportionately large fraction of organic carbon relative to their areal cove... more Wetlands store a disproportionately large fraction of organic carbon relative to their areal coverage, and thus play an important role in global climate mitigation. As destabilization of these stores through land use or environmental change represents a significant climate feedback, it is important to understand the functional regulation of respiratory processes that catabolize them. In this study, we established an eddy covariance flux tower project in a coastal plain forested wetland in North Carolina, USA, and measured total ecosystem respiration (R e) over three years (2009-2011). We evaluated the magnitude and variability of three respiration componentsbelowground (R s), coarse woody debris (R CWD), and aboveground plant (R agp) respiration at the ecosystem scale, by accounting microtopographic variation for upscaling and constraining the mass balance with R e. Strong hydrologic control was detected for R s and R CWD , whereas R agp and R e were relatively insensitive to water table fluctuations. In a relatively dry year (2010), this forested wetland respired a total of about 2000 g CO 2-C m-2 y-1 annually, 51% as Rs, 37% as R agp , and 12% as R CWD. During non-flooded periods R s contributed up to 57% of R e and during flooded periods R agp contributed up to 69%. The contribution of R s to R e increased by 2.4% for every cm of decrease in water level at intermediate water table level, and was nearly constant when flooded or when the water level more than 15 cm below ground. The contrasting sensitivity of different respiration components highlights the need for explicit consideration of this dynamic in ecosystem and Earth System Models.

Hydrology and Management of Forested Wetlands, Proceedings of the International Conference, April 8-12, 2006, New Bern, North Carolina

Prescribed burning of understory vegetation is one of the widely accepted silvicultural treatment... more Prescribed burning of understory vegetation is one of the widely accepted silvicultural treatments for reducing fire hazards in forests and for the restoration of both the vegetative species and wildlife habitat. In some parts of Francis Marion National Forest (FMNF) in Coastal South Carolina, prescribed burning is generally conducted in 2-3 year intervals for the restoration of longleaf pine and management of Red-Cockaded Woodpecker (RCW) habitat. This study evaluates the effects on outflow process of a 160 ha forested watershed (WS 77), located at Santee Experimental Forest within the FMNF, after a prescribed understory burning treatment in about 80% of its area on May 10, 2003. The evaluation was performed using a classic paired watershed approach with data from a similar adjacent 160 ha watershed (WS 80) as a control. Yield during a pre-burning period yielded approximately 10% higher total outflow from the control (WS 80) as compared to the treatment (WS 77) watershed. Outflow from the treatment watershed for a storm soon after the burning was about 90% higher than the control. However, low flow rates were generally higher on the control than the treatment watershed possibly due to its higher depressional storage than the treatment, which yielded higher peak flow rates than the control most of the time. Assuming uniform rainfall across the watersheds, the treatment watershed yielded 45% and 40% higher outflows in 2004 and 2005, respectively, than its expected outflow obtained using measured data from the control and their pre-treatment relationship. Among other factors, spatial variability in rainfall, especially during the summer-fall periods somewhat complicated the accurate quantification of effects.

A forest biogeochemical model, Forest-DNDC, was developed to quantrfy carbon sequestration in and... more A forest biogeochemical model, Forest-DNDC, was developed to quantrfy carbon sequestration in and trace gas emissions h m forest ecosystems. Forest-DNDC was constructed by integrating two existing models, PnET and DNDC, with several new features including nitrification, forest litter layer, soil &zing and thawing etc, PnET is a forest physiological model predicting forest photosynthesis, respiration, C allocation, and litter production. DNDC is a soil biogeochemical model pmlicting soil organic matter turnover, trace gas emissions and N leaching. The two models were linked to each other by exchanging i d i o n of litter production, plant demand I for water and N, and availability of water and N in soil. Input parameters required by Forest-DNDC are daily i meteorological data, forest type and age, soil properties, and forest management practices (e. g., harvest, thinning, fire, reforestation, chinage, wetland restoration etc.). For wetland applications, observed or modeled water table data are r e q M to drive the soil redox potential dynamics. Forest-DNDC runs at daily time step, and produces 1 1 daily and annual results of forest growth, net ecosystem C exchange, fluxes of C02, a , N20, NO, N2, and NH3 ! emissions, and N leaching h m the rooting m e. The modeled C and N fluxes can be compared with the observations gained with static chamber, automated chamber, or Eddy tower facilities. Actually, Forest-DNDC has been tested against measured fluxes of CO,, a , N20, and NO at about 20 forested sites in North America,

In: Stringer, Christina E.; Krauss, Ken W.; Latimer, James S., eds. 2016. Headwaters to estuaries: advances in watershed science and management -Proceedings of the Fifth Interagency Conference on Research in the Watersheds. March 2-5, 2015, North Charleston, South Carolina. e-General Technical R..., 2016

Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes ... more Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes in forested wetlands. However, the consequences of tidally mediated hydrology are seldom considered within forested wetlands that occur along tidal water bodies. These tidal water bodies may be either fresh or brackish, and the tidal streams function as a reservoir to sustain a shallow water table depth as compared to nontidal stream reaches. Accordingly, both the hydrology and water chemistry are expected to affect the forest carbon cycle; however, there are few studies to support this assertion. Hypotheses that are suggested by this hydrogeomorphic setting include greater net primary productivity and greenhouse gas emissions. However, given the persistent and dynamic high water table, it is important to consider micro-topography in quantifying greenhouse gas emissions, a functionality similar to boreal peatlands. A major constraint to assessing carbon cycle dynamics in tidally influenced forested wetlands is the lack of an accepted classification system and reliable spatial data base to indicate their spatial extent; this is particularly important for the upper tidal reaches where there is not a threat of changes in salinity associated with sea level rise. Advancing research to address this important part of the landscape is fundamental to addressing issues associated with sea level rise and the interaction of coastal development on estuaries.

Hydrology and Water Resources in Arizona and the Southwest, Apr 14, 2012

The authors have requested that this preprint be removed from Research Square.

Annual Meeting of the American Geophysical Union (AGU), Dec 1, 2019

Soil Science Society of America Journal, 2019

Estuarine, Coastal and Shelf Science, 2018

Agricultural and Forest Meteorology, 2017

Hydrology and Management of Forested Wetlands, Proceedings of the International Conference, April 8-12, 2006, New Bern, North Carolina