Loblolly pine (Pinus taeda L.) occupies 13 million hectares in the United States and represents a critical component of the global carbon (C) cycle. Forest management alters C dynamics, affecting the C sequestration capacity of a site. Identifying drivers that influence C cycling, quantifying C fluxes, and determining how management alters processes involved in C cycling will allow for an understanding of C sequestration capacity in managed forests. Objectives of the first study included (1) investigating environmental, soil C, root, and stand influences on soil CO2 efflux on the South Carolina coastal plain and (2) quantifying soil CO2 efflux over a rotation in loblolly pine stands located on the South Carolina coastal plain and the Virginia piedmont. In relation to the first objective, temporal variation in soil CO2 efflux was most highly related to soil temperature. Spatial and temporal variability in soil CO2 efflux was weakly related to soil C and root biomass, and not related to coarse woody debris, stand age, stand volume, or site index [Chapter 2]. Soil CO2 efflux was not related to stand age on the South Carolina sites while efflux was positively related to age on the Virginia sites. Cumulative soil C efflux on the South Carolina sites over 20 years is an estimated 278.6 Mg C/ha compared with an estimated 210.9 Mg C/ha on the Virginia sites [Chapter 3]. Objectives of the second study were (1) to investigate short-term effects of fertilization on processes permitting enhanced growth in loblolly pine and (2) to determine the short-term effects of fertilization on autotrophic, heterotrophic, and soil respiration. Major results from the study include the finding that fertilization caused a transient rise in photosynthetic capacity, which paralleled changes in foliar nitrogen. Leaf area accumulation and enhanced growth following fertilization was partly due to enhanced C fixation capacity [Chapter 4]. Fertilization altered the contribution of autotrophic and heterotrophic respiration to total soil CO2 efflux. Enhanced specific root respiration was short-lived while suppressed microbial respiration following fertilization was maintained over the course of the nearly 200-day study. Respiring root biomass growth increased total soil respiration over time [Chapter 5]. / Ph. D.

Soils are a major component of the global carbon budget and may serve an important role in mitigating increasing atmospheric CO2 through their capacity to store carbon. In this regard, it is important to evaluate the implications of forest management on changes in carbon cycling and sequestration and to determine the magnitude by which the efflux of CO2 from the soil surface can vary in time and space. For this study, soil CO2 efflux was measured in 5 replicate blocks of naturally regenerated and planted loblolly pine (Pinus taeda), shortleaf pine (Pinus echinata), and eastern white pine (Pinus strobus) in a 50-acre clear-cut on the Virginia Piedmont. Rates of CO2 efflux were measured every 2 weeks immediately adjacent and away (1m) from newly planted seedlings and cut stumps using a dynamic, closed-chamber infrared gas analyzer system. For each measurement date, volumetric water content was taken in the top 17cm, using time domain reflectometry (TDR) and soil-surface temperature was recorded in the top 7cm, using a temperature probe. For the October measurement a 12cm depth soil core (7cm diameter) was collected for each location. Carbon, nitrogen, coarse fragments, roots, surface litter and coarse woody debris were measured separately for each core. Position (near and away from seedling) had a strong effect on soil CO2 efflux rates. For the first measurement date, rates were higher near the newly planted seedlings (3.09μmol/m2/s) than those taken away from the seedlings (2.29 μmol/m2/s).. The same trend was maintained for the CO2 efflux rates measured near a cut stumps (3.51μmol/m2/s) and those taken away from the stump base (2.56μmol/m2/s). Species proved to have no significant effect on respiration rates for any date and no interaction between species and position was observed. Regression analysis was used to model the influence of soil and plant factors on efflux rates. Temperature (29.2%), position (near and away from the seedlings and stumps base)* temperature, (7.7%), soil carbon (4.1%), organic matter (1.6%), and soil moisture (0.7%) proved to be the major drivers for soil respiration (R2 = 0.4329). When only data near seedlings or stumps were modeled, species had a significant effect on soil CO2 efflux rates. The largest seedlings, loblolly pine (100 cm3 seedling value), had on average the highest rates followed by shortleaf pine (30 cm3 seedling value) and eastern white pine, which were the smallest (9 cm3 seedling value). Stumps had the highest efflux rates. The mean soil respiration rate measured over a seven month sampling period was 2.58 μmol/m2/s,, while the calculated carbon loss from the soil over the same period added up to 575 g C/ m2. The annual carbon loss was estimated to be 675 g C/ m2. / Master of Science

Managed loblolly pine forests comprise an important pool in the global carbon cycle. Understanding the influences upon inputs and outputs of this pool, including the effects of management activities, will allow landowners to understand how carbon can be sequestered in their stands. Specific to this study, we sought to create multivariate models of the output of carbon from the soil in the form of soil CO2 efflux (Rs) and a component of that total efflux, heterotrophic respiration index (Rh), from data collected across the managed range of loblolly pine in the Southeastern U.S. We also performed tests of significance on controlled subsets of these data for the effects of fertilization and of thinning. Finally, we sought a connection between stand leaf area index (LAI) and total soil CO2 efflux or heterotrophic respiration. Our models indicated variability in both Rs and Rh across latitude and physiographic province, respectively, within this range. The Rs (R2 = 0.56) model included temperature, latitude, a soil moisture by temperature effect, soil nitrogen, and bulk density variables. The Rh (R2 = 0.50) model included soil moisture, a temperature by moisture interaction, and physiographic province. Rs was not significantly affected by either fertilization or thinning, yet Rh was influenced by both (negatively and positively, respectively). This indicates a shift in relative contributions of heterotrophic respiration and root respiration components to Rs in response to these treatments. Heterotrophic respiration was shown to have a weak negative response (R2 = 0.04) to increasing stand LAI. / Master of Science

Soil carbon dioxide efflux resulting from microbial and root respiration is a major component of the forest carbon cycle. We undertook this investigation to better understand the nature of soil carbon dioxide efflux of plantation loblolly pine, an important ecological and economical resource in the southeastern United States. Specifically, we hoped to learn how soil carbon dioxide efflux differs both spatially and temporally for four age classes of plantation loblolly pine on the Virginia piedmont. During a 12-month period, soil carbon dioxide efflux was repeatedly measured for four age classes of plantation loblolly pine using a dynamic, closed-chamber infrared gas analyzer. The age classes examined were 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands. Mean soil carbon dioxide efflux rates measured during the 12-month study were 1.72, 2.58, 2.84, and 2.90 micromole/sq m/s for 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands, respectively. Stand age had a significant effect on efflux rate during 10 of the 12 monthly sampling sessions. Additionally, mean efflux rates were consistently higher near the tree and a significant positional difference was detected during 8 of the 12 monthly sampling sessions. Mean soil carbon dioxide efflux rates, by position, for the 12-month study were 2.72 and 2.28 micromole/sq m/s for the near and away measurement positions, respectively. Based on monthly mean soil carbon dioxide efflux rates, annual carbon losses were estimated at 651, 976, 1074, and 1082 g C/sq m/yr for 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands, respectively. Regression analysis was used to examine the influence of soil and climatic factors on seasonal changes in soil carbon dioxide efflux. The most influential factors affecting soil carbon dioxide efflux during the 12-month study were soil temperature, soil moisture, stand age, and measurement position. We believe respiring roots significantly influence soil carbon dioxide efflux of plantation loblolly pine and account for differences observed between stands of different ages as well as spatial differences observed within a given stand. / Master of Science

Soil respiration is an important source of atmospheric CO2, with the potential for large positive feedbacks with global warming. The size of these feedbacks will depend on the relative sensitivity to temperature of very large global pools of highly stable soil organic matter (SOM), with residence times of centuries or longer. Conflicting evidence exists as to the relationships between temperature sensitivity of respiration and stability of SOM, as well as the temperature sensitivity of individual stabilisation mechanisms. This PhD considers the relationship between different stabilisation mechanisms and the temperature sensitivity of SOM decomposition. I used physical fractionation to isolate SOM pools with a variety of turnover rates, from decadal to centennially cycling SOM, in a peaty gley topsoil from Harwood Forest. Mean residence times of SOM as determined by 14C dating was most strongly affected by depth, providing stability on a millienial scale, while OM-mineral associations and physical protection of aggregates provided stability to around 500 years. Chemical characteristics of organic material in these fractions and whole soils (13C CP-MAS NMR spectroscopy, mass spectrometry, FTIR spectroscopy, thermogravimetric analysis, ICP-OES) indicated the relative contribution of different stabilisation mechanisms to the longevity of each of these fractions. Two long-term incubations of isolated physical fractions and soil horizons at different temperatures provided information about the actual resistance to decomposition in each SOM pool, as well as the temperature sensitivity of respiration from different pools. Naturally 13C-labelled labile substrate additions to the mineral and organic horizons compared the resistance to priming by labile and recalcitrant substrates. Manipulation of soil pore water was investigated as a method for isolating the respiration of SOM from physically occluded positions within the soil architecture. Contadictory lines of evidence emerged on the relative stability of different SOM pools from 14C dating, incubation experiments and chemical characterisation of indicators of stability. This led to the interpretation that physical aggregate protection primarily controls SOM stability within topsoils, while mineral and Fe oxide stability provides more lasting stability in the mineral horizon. Less humified and younger SOM was found to have a higher sensitivity to temperature than respiration from well-humified pools, in contrast to predictions from thermodynamics.

Thesis (MScConEcol)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Soil respiration (Rs) is a major component of CO2 emissions and the global carbon balance. In the context of global change it of interest to understand seasonal patterns of RS in fynbos riparian ecosystems, particularly in invaded-riparian ecotones of these Mediterranean type ecosystems (MTE's) in the Western Cape, South Africa. Riparian ecotones are three dimensional transitional zones that provide multiple ecosystem services and functions and they act as the linkage between terrestrial and aquatic ecosystems where key ecological and geomorphological processes occur. Riparian ecotones are highly prone to disturbance, and because of this reason are also vulnerable to invasion by invasive alien plants (IAPs), notably Acacia species. Invasion by IAPs is considered one of the major threats to global change and biodiversity causing extensive ecological, economical, and social impacts. In south-western Cape, more than two thirds of the riparian environment is invaded to some extent, IAPs replacing the well adapted native species along river systems. In particular, impact of IAPs on soil respiration (Rs) may be relevant, with consequences for ecosystem function and services. Clearing of invaded riparian zones initiated by the Working for Water program has been a successful in eradicating alien plants within riparian areas even though recovery after alien clearing is lagging at many sites, and knowledge on repair of ecosystem function is lacking. Various studies have generated knowledge on carbon cycling and Rs in forests, savanna, grasslands, tundra and Mediterranean shrublands, but little is known about Rs in riparian zones, and even less about soil CO2 efflux in invaded riparian fynbos riparian ecotones. The objective of this study was to contribute to a better understanding and quantifying the effect and impact of IAPs on carbon cycling between and across riparian ecotones with different invasion status: natural, invaded, and cleared. The study areas were located in the south-western Cape and measurements of Rs, soil temperature, soil moisture, root mass, litter mass, and soil properties were carried out in riparian soils of the mountain and transitional stream longitudinal river sections, and uplands fynbos areas of six different perennial river systems. In each site, four to five transects were laid out with one sampling site of each landscape position (wet bank, dry bank, and terrestrial areas) giving a total of 12 to 15 samples per site. Soil respiration measurements were taken over a period of two years, and were done seasonally. Results from this study showed that Rs was different among seasons with highest soil respiration rates in summer. Soil CO2 efflux increased in response to warm and dry conditions during summer, while seasonal soil CO2 efflux declined in autumn and winter in response to wet and cold soil conditions. The large increase in soil CO2 efflux response to warm and dry periods when temperature was 25 to 30 °C over all riparian sites and was highest in invaded sites compared to the natural and cleared sites. A significant difference was found between sites with different statuses with invaded sites leading seasonal Rs rates. Natural and cleared sites did not differ significantly in their CO2 efflux rates, suggesting that clearing of IAPs may put invaded ecosystems on a trajectory of restoration. There were also differences in terms of landscape positions; dry banks zones of the invaded sites had higher rates compared to wet banks and the uplands areas. Our results further suggest that roots are the most important component of overall Rs rates, rather than microbial respiration. When we incubated soils minus roots, little difference was evident, either when viewing the results by invasion status or by landscape position, which suggest that inherent soil differences in terms of microbial respiration were not different. We also use a trenching approach to further investigate this, and though we found Rs to decline significantly, trends later suggest that decomposition of fine and course roots likely obscured the decline in overall Rs due to root respiration. Overall, our results showed that clearing of invaded riparian zones will likely lead to successful restoration of soil functioning in terms of C cycling. Clearing of Acacia-invaded riparian ecotones will likely lead to a decline in root density, and which removes a major component of overall Rs. These results make the investigation of the C balance of invaded riparian ecotones and terrestrial areas critical in order to assess their contribution to regional C cycles. / AFRIKAANSE OPSOMMING: Grondrespirasie (Rs) is 'n belangrike komponent van CO2 uitstroming en die globale koolstofbalans. Binne die konteks van globale verandering is dit van groot belang om die seisoenale patrone van Rs in fynbos oewer ekosisteme, veral in indringer-oewer ekotone, in die Meditereense tipe ekosisteme (MTE's) in die Wes- Kaap, Suid- Afrika te verstaan. Oewerekotone is drie-dimensioneel oorgangssones wat veelvuldige ekosisteem dienste en funksies verskaf. Hulle dien as die verbinding tussen terrestriële en water-ekosisteme waar kern ekologiese en geomorfologiese prosesse plaasvind. Oewerekotone is hoogs vatbaar vir versteuringe, en as gevolg van hierdie rede, is hul ook kwesbaar vir indringing deur indringer plante (IAPs), veral Acacia spesies. Indringing deur IAPs word beskou as een van die groot bedreigings tot en met globale verandering en biodiversiteit, wat ekstensiewe ekologiese, ekonomiese, en sosiale impakte veroorsaak. In die suid- westelike Kaap word meer as twee derdes van die oeweromgewing tot 'n mate binnegedring. IAPs vervang die goed aangepaste inheemse spesies langs riviersisteme. Die impak van IAPs, spesifiek op grondrespirasie mag substansieël wees, met gevolge vir ekosisteem funksies en dienste. Opruiming van hierdie spesifieke oewer sones, geinisieer deur die Working for Water program, was suksesvol in die uitroeing van indringer plante binne oewer areas. Alhoewel herstel na indringer opruiming op baie terreine agter is, is kennis oor die herstel van ekosisteemfunksies gebrekkig. Verskeie studies het kennis ontwikkel oor koolstofsiklisering en Rs in woude, savanna, graslande, tundra en Meditereense struiklande, maar daar is minimale informasie oor oewersones,en nog minder oor grond CO2 uitstroming in indringer oewer fynbos en oewer ekotone. Die doel van hierdie studie is om 'n bydrae te lewer koolstofsiklisering beter te verstaan, en die impak van IAPs op koolstofsiklisering te kwantifiseer tussen en oor oewerekotone met verkillende indringer statusse: natuurlik, binnegedring en skoongemaak. Die studie areas was geleë in die suid- westelike Kaap, en maatstawe van Rs, grond temperature, grondvogtigheid, wortelmassa, plantafvalmassa, en grondeienskappe is uitgevoer in oewergrond van die berg en transisionele stroom longitudinale rivier seksies, asook terrestriële fynbos areas van ses verskillende standhoudende riviersisteme. In elke area is vier tot vyf transekte uitgelê met een monsternemingsarea van elke landskapsposisie (nat bank, droë bank en terrestriële areas) met 'n totaal van 12 tot 15 monsters per area. Grondrespirasie maatstawe is geneem oor 'n periode van twee jaar, en is seisoenaal uitgevoer. Resultate van die studie het getoon dat Rs verkil het tussen seisoene, met die hoogste grondrespirasietempo in die somer. Grond CO2 uitstroming het toegeneem in reaksie op warm en droë kondisies gedurende somer, terwyl seisoenale grond CO2 uitstroming afgeneem het in herfs en winter in reaksie op nat en koue grond kondisies. Die grootste toename in grond CO2 uitstroming was in reaksie op warm en droë periodes wanneer temperature gewissel het tussen 25 tot 30˚C oor alle oewersones, en was die hoogste in binnegedringde sones, vergeleke met die natuurlike en skoongemaakte terreine. 'n Beduidende verskil is gevind tussen terreine met verskillende statusse in CO2 uitstromingskoerse‚ 'n aanduiding dat opruiming van IAPs binnegedringde ekosisteme op 'n trajek van restorasie plaas. Daar was ook verskille in terme van landskapsposisies; droë bank sones van die binnegedringde terreine het hoër tempos gehad, vergeleke met die nat bank en die hoogland areas. Ons resultate dui verder aan dat wortels, eerder as mikrobiologiese respirasie, die mees belangrike komponente van Rs koerse uitmaak. Toe ons grond minus wortels inkubeer, is min verskille opgemerk, as gekyk word na die resultate deur indringer status of landskapsposisie, wat toon dit dat inherente grondveskille in terme van mikrobiologiese respirasie nie verskillend is nie. Ons het verder ook 'n sloot-benadering gebruik om verdere ondersoek hierop in te stel, en alhoewel ons bevind dat Rs aansienlik afgeneem het, dui neigings later aan dat afbraak van fyn en growwe wortels die afname in gehele Rs as gevolg van wortel respirasie waarskynlik verdoesel. Ons resultate dui daarop dat opruiming van binngedringde oewers klaarblyklik sal lei tot suksesvolle restorasie van grondfunksionering in terme van C siklisering. Opruiming van Acacia- binnegedringde oewer ekotone sal vermoedelik lei tot 'n afname in worteldigtheid, en wat 'n belangrike komponent van die gehele Rs kan verwyder. Hierdie resultate maak die ondersoek van die C balans van binngedringde oewer ekotone en terrestriële areas krities, om sodoende hulle bydrae tot streeksgewyse C siklusse te asseseer.

Within the field of ecosystem science, substantial progress has been made towards our knowledge of the factors which shape the global distribution of vegetation. However, factors which control the biogeography of belowground vegetation structure and function remain less understood than their aboveground counterpart. Vegetation types can differ substantially in terms of belowground processes such as root growth, root turnover, and resulting vertical root distributions. Fine roots provide an exchange surface, allowing transport of water and nutrients to the leaves. On the other hand they also represent a significant sink for photosynthetically fixed carbon to the soil in terms of maintenance and growth. Overall, root processes have a major influence on fluxes of water, carbon and nutrients within ecosystems. In this thesis, an electrical impedance method was used to determine the area of ‘active’ root in contact with the soil for the purpose of absorption. These measurements were compared to the leaf area of the trees, for the first time allowing the aboveground and the belowground resource exchange areas of plant to be contrasted. This approach was first developed to compare the exchange surface areas of leaves and roots within a Sitka spruce (Picea sitchensis) managed forest, making measurements in adjacent stands of differing tree density, but identical in age. Stem density was found to significantly influence the proportion of absorbing root area relative to leaves. Following the successful test of the method, it was used to compare the resource exchange areas of eight stands of forest and savanna vegetation in central Brazil. Across a broad gradient of vegetation structure, the results showed progressively more investment in fine root area relative to leaf area across the transition from dense forest to open savanna. However, a contrasting result showed that the forests had a higher absorbing root area to leaf area ratio than savannas. Furthermore, these measured ratios were strongly correlated with tree height across the eight structurally contrasting stands. It appears that absorbing root area index provides a physiologically meaningful way of characterising belowground water uptake ability, it is possible that excessive investment in fine root area, relative to leaf area, may reflect differences in the requirement for nutrient uptake in poor soils. Complementary to the analysis of root absorbing area, measurements of root activity and belowground carbon cycling were made by focussing on two of the eight tropical study sites. Here, the carbon costs of root growth and respiration were quantified to develop a belowground carbon budget for two structurally contrasting Brazilian savannas, using soil respiration measurements and a root presence/absence manipulation experiment. Annual estimates showed that at least 60% of the total CO2 efflux from the soil was contributed by autotrophic processes, with this value rising to 80% during the dry season. Seasonal fluctuations of soil respiration were strongly correlated with soil moisture for both the autotrophic (R2=0.79, pvalue< 0.05) and heterotrophic (R2=0.90, p-value<0.05) components, with maximum flux rates corresponding with 16.4 and 17.7% soil moisture content respectively. Furthermore, autotrophic respiration was found to varied with phonological patterns of fine root growth (R2=0.80, p-value<0.05). It follows that, the way in which phenological processes respond to a changing climate is of potential importance within seasonally dry regions. Diurnal fluctuations of heterotrophic CO2 efflux were correlated with soil temperature (R2=0.74, p-value<0.05), demonstrating a Q10 value of 1.6 across both sites. In contrast, total soil CO2 efflux was not correlated with temperature (p-value=0.31), suggesting that autotrophic respiration is predominantly limited by substrate supply.

Soil CO2 efflux (F-soil) represents a significant source of ecosystem CO2 emissions that is rarely quantified with high-temporal-resolution data in carbon flux studies. F-soil estimates can be obtained by the low-cost gradient method (GM), but the utility of the method is hindered by uncertainties in the application of published models for the diffusion coefficient. Therefore, to address and resolve these uncertainties, we compared F-soil measured by 2 soil CO2 efflux chambers and F-soil estimated by 16 gas transport models using the GM across 1year. We used 14 published empirical gas diffusion models and 2 in situ models: (1) a gas transfer model called Chamber model obtained using a calibration between the chamber and the gradient method and (2) a diffusion model called SF6 model obtained through an interwell conservative tracer experiment. Most of the published models using the GM underestimated cumulative annual F-soil by 55% to 361%, while the Chamber model closely approximated cumulative F-soil (0.6% error). Surprisingly, the SF6 model combined with the GM underestimated F-soil by 32%. Differences between in situ models could stem from the Chamber model implicitly accounting for production of soil CO2, while the conservative tracer model does not. Therefore, we recommend using the GM only after calibration with chamber measurements to generate reliable long-term ecosystem F-soil measurements. Accurate estimates of F-soil will improve our understanding of soil respiration's contribution to ecosystem fluxes.

Forest soil is an important source of atmospheric CO2. Emission of CO2 from soil is the result of respiration of plant roots and soil organisms (Autotrophic and Heterotrophic respiration). This soil CO2 emission has a variation throughout the year with maximum emissions being in the summer. However, the seasonal variation affected by the external factors is not fully known. The aim of this thesis is to analyze a relationship between concentration of CO2 in the soil-atmosphere and CO2 emissions to the aboveground atmosphere. When knowing the relationship between CO2 concentration in the soil-atmosphere and the emission of CO2 from the soil atmosphere, a function (equation) can be established. Usually, the best fit is considered to establish the relationship. With the equations obtained, it is possible to calculate CO2 emissions using data different projects, where only soil-atmosphere CO2 concentrations were determined. Using the relationships, emissions rates in different soil types and in forest transect have been analyzed for a large number of samples. The effect of nitrogen deposition on CO2 emissions and seasonal variation of CO2 emission has also been studied. The sampled sites chosen for this study were located in different parts of Southern Scandinavia and Germany. A closed chamber was used to measure CO2 emission from soil. Soil CO2 concentrations were measured at every station and the equations were established. Finally, these relationships were used for analyses and comparison of the sites. An equation (best fit) obtained was used to calculate the emission values of CO2. The soil texture had a great influence on the CO2 from the soil besides the atmospheric pressure and temperature variations during the seasons. It is concluded that, therefore the soil texture and had a great influence on the CO2 emission from the soil besides the atmospheric pressure and temperature variations during the season. When knowing the equation between CO2 concentration and emission for a special type of soil, it is possible to estimate emissions based on CO2 concentrations. Therefore large scale sampling of CO2 concentrations could be done and this will facilitate the inventories carried out in e.g. global change studies.

Orientador: Alan Rodrigo Panosso / Resumo: O dióxido de carbono (CO2) é um dos principais gases do efeito estufa adicional, sendo a agricultura uma grande contribuinte para a emissão do mesmo no Brasil. Para melhor modelar a perda de carbono do solo via CO2, deve-se considerar a variação espacial dessa variável, bem como dos atributos do solo, atento ao uso do solo agrícola e manejo. O presente estudo objetivou caracterizar a anisotropia espacial de FCO2 e atributos físicos e químicos do solo por meio da dimensão fractal (DF), na região do Cerrado no Mato Grosso do Sul. Para o estudo da anisotropia e geração de mapas de padrões espaciais foi utilizado uma malha regular amostral constituída de 102 pontos nas duas áreas. Para a FCO2 foram observados valores de DF 2,51 ± 0,41 para cana-de-açúcar e 2,61 ± 0,18 para eucalipto. A DF de FCO2 e dos atributos do solo estudadas por meio do gráfico de rosas mostrou que o fluxo de CO2 do solo apresenta variação espacial associada a diferentes atributos químicos e físicos do solo. Foram observados ganhos de precisão quando comparados os mapas de padrões espaciais isotrópico e anisotrópico para as variáveis FCO2, matéria orgânica do solo (MO) e a densidade do solo (Ds) nas duas áreas, indicados pela validação cruzada, com os valores de coeficiente de determinação entre 0,82 e 0,99 para área de cana-de-açúcar e 0,94 e 0,98 para áreas de eucalipto. FCO2 é um fenômeno de natureza complexa, sendo sua anisotropia espacial associada às variações espaciais dos demais atributos do solo e s... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Carbon dioxide (CO2) is one of principal greenhouse gases, being the agriculture one of the contributor major to emission specially in Brazil. To better understands this phenomenon, it is necessary to consider the spatial variation of this variable, as well as the attributes of the soil, considering the type of agricultural land use and management. The present study objective of characterizing the spatial anisotropy of FCO2 and other soil physical and chemical attributes, through the fractal dimension (DF), in Cerrado region, Mato Grosso do Sul. For the study of anisotropy and maps generation of spatial patterns, a regular sample consisting of 102 points in both areas was used. To FCO2 anisotropy values of DF were observed for 2.51 ± 0.41 for sugarcane and 2.61 ± 0.18 for eucalyptus areas. DF of FCO2 and other soil attributes studied through the rose graphics showed that the FCO2 presents spatial variation associated with different soil chemical and physical attributes. Precision and accuracy gains were observed when comparing spatial patterns generated from isotropic and anisotropic modeling for FCO2, soil organic matter (MO) and soil density (Ds) in the two study areas, as indicated by cross-validation, with values of determination coefficient varying between 0.82 and 0.99 for sugarcane and 0.94 and 0.98 for eucalyptus areas. The spatial pattern indicated that the spatial variability of FCO2, soil organic matter (MO) and soil density (Ds) that obtained gains in the two stud... (Complete abstract click electronic access below) / Mestre