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Growing demand for bioenergy, biofuels, and bioproducts has increased interests in the utilization of biomass residues from forest treatments as feedstock. In areas with limited history of industrial biomass utilization, uncertainties in the quantity, distribution, and cost of biomass production and logistics can hinder the development of new bio-based industries. This paper introduces a new methodology to quantify and spatially describe delivered feedstock volumes and costs across landscapes of arbitrary size in ways that characterize operational and annual management decision-making. Using National Agricultural Imagery Program (NAIP) imagery, the forest is segmented into operational-level treatment units. A remote sensing model based on NAIP imagery and Forest Inventory and Analysis plot data are used to attribute treatment units with stand-level estimates of basal area, tree density, aboveground biomass, and quadratic mean diameter. These methods are applied to a study site in southwestern Colorado to assess the quantity and distribution of treatment residue for use in bioenergy production. Results from the case study demonstrate how this generalized approach can be used in the analysis and decision-making process when establishing new bioenergy industries that use forest residue as feedstock. Key words: forest biomass, stand characteristics, treatment residue, bioenergy, stand delineation. La demande grandissante pour la bioenergie, les biocarburants et les bioproduits a augmente l'attrait pour l'utilisation comme matiere premiere de la biomasse residuelle generee par les traitements sylvicoles. Dans les regions qui ont une experience limitee de l'utilisation industrielle de la biomasse, les incertitudes concernant la quantite, la distribution ainsi que le cout de production et la logistique de la biomasse peuvent nuire au developpement de nouvelles bio-industries. Cet article presente une nouvelle methodologie pour quantifier et decrire spatialement les volumes et les couts de la matiere premiere livree dans un paysage aux dimensions arbitraires et d'une facon qui caracterise le processus de prise de decision operationnelle et annuelle d'amenagement. A l'aide des images du Programme national d'imagerie agricole (NAIP), la foret a ete segmentee en unites de traitement sur la base des contraintes spatiales definies par les utilisateurs. Un modele de teledetection fonde sur les images du NAIP et sur les donnees des places echantillons du Programme d'analyse et d'inventaire forestiers est utilise pour attribuer les unites de traitement avec des estimations a l'echelle du peuplement de la surface terriere, de la densite des arbres, de la biomasse aerienne et du diametre de la tige de surface terriere moyenne. Ces methodes sont appliquees a une station experimentale dans le sud-ouest du Colorado pour evaluer la quantite et la distribution des residus de traitement pour la production de bioenergie. Les resultats de cette etude de cas demontrent comment cette approche generalisee peut etre utilisee dans le processus d'analyse et de prise de decision lors de l'etablissement de nouvelles industries bioenergetiques qui utilisent les residus de la foret comme matiere premiere. [Traduit par la Redaction] Mots-cles: biomasse forestiere, caracteristiques des peuplements, residus de traitement, bioenergie, delimitation des peuplements., 1. Introduction The interior western United States (US) has experienced growing interest in using forest biomass as a renewable source of energy. Historically, the use of forest biomass has been [...]

Charles Elton introduced the 'pyramid of numbers' in the late 1920s, but this remarkable insight into body-size dependent patterns in natural communities lay fallow until the theory of the biomass size spectrum was introduced by aquatic ecologists in the mid-1960s. They noticed that the summed biomass concentration of individual aquatic organisms was roughly constant across equal logarithmic intervals of body size from bacteria to the largest predators. These observations formed the basis for a theory of aquatic ecosystems, based on the body size of individual organisms, that revealed new insights into constraints on the structure of biological communities. In this review, we discuss the history of the biomass spectrum and the development of underlying theories. We indicate how to construct biomass spectra from sample data, explain the mathematical relations among them, show empirical examples of their various forms, and give details on how to statistically fit the most robust linear and nonlinear models to biomass spectra. We finish by giving examples of biomass spectrum applications to production and fisheries ecology and offering recommendations to help standardize use of the biomass spectrum in aquatic ecology. Charles Elton a introduit le concept de la <> vers la fin des annees 1920, mais cette avancee remarquable dans la comprehension des motifs dependant de la taille du corps dans les communautes naturelles est demeuree lettre morte jusqu'a l'introduction de la theorie du spectre de taille de la biomasse par des ecologistes aquatiques, au milieu des annees 1960. Ces derniers avaient remarque que la somme des concentrations de biomasse d'organismes aquatiques individuels etait generalement constante pour des intervalles logarithmiques egaux de tailles du corps, des bacteries jusqu'aux plus grands predateurs. Ces observations constituaient le fondement d'une theorie des ecosystemes aquatiques reposant sur la taille du corps des organismes individuels, qui mettait en lumiere des facteurs agissant sur la structure des communautes biologiques. Dans la presente synthese, nous abordons l'histoire du spectre de biomasse et le developpement des theories sous-jacentes. Nous decrivons comment batir des spectres de biomasse a partir d'un echantillon de donnees, en expliquons les relations mathematiques et presentons des exemples empiriques de leurs diverses formes, ainsi que des details sur la maniere de caler les modeles lineaires et non lineaires les plus robustes sur des spectres de biomasse. Enfin, nous presentons des exemples d'applications des spectres de biomasse a la production et a l'ecologie des ressources halieutiques et formulons des recommandations pour aider a normaliser l'utilisation des spectres de biomasse en ecologie aquatique. [Traduit par la Redaction], Introduction The abundance of organisms in nature has been of interest to science since ecology emerged as a formal discipline of study. Elton (1927) introduced the 'pyramid of numbers' to [...]

Surplus production represents the processes that affect sustainable fishery harvest and is central to the ecology and management of marine fishes. Taxonomy and life history influence the ratio of spawning biomass at maximum sustainable yield to average unfished spawning biomass ([SB.sub.MSY]/[SB.sub.0]), and estimating this ratio for individual stocks is notoriously difficult. We use a database of published landings data and stock assessment biomass estimates and determine that process errors predominate in this data set by fitting a state-space model to data from each stock individually. We then fit multispecies process-error models while treating [SB.sub.MSY]/[SB.sub.0] as a random effect that varies by taxonomic order and maximum length. The estimated [SB.sub.MSY]/[SB.sub.0] = 0.40 for all 147 stocks is intermediate between the values assumed by the Fox and the Schaefer models, although Clupeiformes and Perciformes have lower and Gadiformes and Scorpaeniformes have higher [SB.sub.MSY]/[SB.sub.0] values. Model selection supports the hypothesis that large-bodied fishes for a given taxonomic order have relatively higher [SB.sub.MSY]/[SB.sub.0]. Results can be used to define reference points for data-poor fisheries or as input in emerging assessment methods. La production excedentaire represente les processus qui ont une incidence sur la recolte de poissons durable et est un element cle de l'ecologie et de la gestion des poissons marins. La taxonomie et le cycle biologique influencent le rapport entre la biomasse feconde correspondant au rendement maximum durable et la biomasse feconde non exploitee moyenne ([SB.sub.MSY]/[SB.sub.0]), l'estimation de ce rapport pour des stocks donnes etant particulierement difficile. Nous utilisons une base de donnees sur les debarquements publiees et des estimations de la biomasse reposant sur des evaluations des stocks et determinons, en ajustant un modele d'espace d'etats aux donnees pour chaque stock pris individuellement, que les erreurs de traitement dominent dans cette base de donnees. Nous ajustons ensuite des modeles multi-especes d'erreur de traitement en traitant le rapport [SB.sub.MSY]/[SB.sub.0] comme s'il s'agissait d'un effet aleatoire qui varie selon l'ordre taxonomique et la longueur maximum. La valeur de [SB.sub.MSY]/[SB.sub.0] = 0,40 estimee pour les 147 stocks est intermediaire entre les valeurs implicites dans les modeles de Fox et de Schaefer, bien que les [SB.sub.MSY]/[SB.sub.0] des Clupeiformes et les Perciformes soient plus faibles et ceux des Gadiformes et des Scorpaeniformes, plus grands. La selection de modele appuie l'hypothese voulant que les poissons a grands corps d' un ordre taxonomique donne presentent un [SB.sub.MSY]/[SB.sub.0] relativement plus eleve. Ces resultats peuvent servir a definir des points de reference pour les peches pour lesquelles peu de donnees sont disponibles ou comme intrants pour de nouvelles methodes d' evaluation. [Traduit par la Redaction], Introduction Surplus production (i.e., production of biomass above what is needed to replace individuals lost to natural mortality) incorporates the combined effects of individual growth, recruitment, predation, and disease (Hilborn [...]

: Understanding of the natural factors that lead to complex changes in forest ecosystems is limited. Worldwide, there are only a few forests as pristine and isolated as the Sierra de La Laguna in the southernmost range of the arid Baja California, Mexico. Its outstanding trait as a model system is that anthropogenic stressors are notably absent, which facilitates the study of natural ecological processes of the forest because separating human-induced ecological changes from natural ones is not a simple matter. In this study, we sampled sites and defined vegetation units on the basis of dominance of the canopy by the main tree species. We identified three forest types: the pine and encino forests that occupy the higher areas and the roble forest at lower elevations. For each living tree in the sampling plots, we measured height, canopy coverage per tree, diameter at breast height, as well as the amount of deadwood, leaf litter, and abundance of young trees. A succesional competition occurs between Pinus and Quercus sensu lato; we conclude that the encino forest represents a climax condition, the pine type represents an early succesional stage, and the roble forest type is a simple climax community. Resume: La comprehension des facteurs naturels qui entrainent des changements complexes dans les ecosystemes forestiers est limitee. A travers le monde, il y a tres peu de forets aussi parfaitement isolees que la Sierra de La Laguna dans la chaine de montagne la plus meridionale de la region aride de Basse-Californie. En tant que systeme modele, sa caracteristique exceptionnelle est le fait que les facteurs de stress anthropiques sont notamment absents, ce qui facilite l'etude des processus ecologiques naturels de la foret etant donne qu'il n'est pas facile de distinguer les changements ecologiques d'origine humaine de ceux dont l'origine est naturelle. Dans cette etude, nous avons d'abord echantillonne des stations pour definir des unites de vegetation sur la base de la dominance des principales especes d'arbre dans le couvert. Nous avons identifie trois types forestiers: la foret de pin et la foret de chene de la Californie occupent les zones plus elevees tandis que la foret de chene blanc de Californie occupe les zones les plus basses. Pour chaque arbre vivant present dans les placettes echantillons, nous avons mesure la hauteur, l'etendue du couvert attribuable a chaque arbre, le diametre a hauteur de poitrine et la quantite de bois mort et de litiere ainsi que l'abondance de jeunes arbres. Il existe une competition successionnelle entre Pinus et Quercus sensu lato; nous concluons que la foret de chene de la Californie represente une situation climacique, la foret de pin represente un stade de debut de succession tandis que la foret de chene blanc de Californie est representative d'une communaute climacique simple. [Traduit par la Redaction], Introduction The Sierra de La Laguna Biosphere Reserve was created in 1994 and encompasses an isolated mountain range located near the southern end of the arid Baja California peninsula. The [...]

Problem statement: World energy consumption is forecasted to grow significantly for the foreseeable future with fossil fuel remains the governing energy source. The demand in the need to explore alternative fuel source was further triggered by the overwhelmingly inconsistent cost of gasoline. Bio-oil is an alternative energy source produced from pyrolysis of biomass. However it is undesirable as a ready alternative transportation fuel due to its unfavorable nature i.e., highly oxygenated and low octane number. To overcome these physicochemical issues, hydrodeoxygenation reaction is a possible upgrading method i.e., by partial or total elimination of oxygen and hydrogenation of chemical structures. Hence, this study aimed to investigate feasible routes and to develop the process route to upgrade the pyrolytic bio-oil from biomass into value-added chemicals for the production of transportation fuel, i.e., benzene and cyclohexane, via hydrodeoxygenation process via simulation in PETRONAS iCON software. Approach: In this study, hydrodeoxygenation of phenols and substituted phenols was used to represent the hydrodeoxygenation of the major oxygen compound in bio-oil due to their low reactivity in HDO. Results: By assuming the feedstock used was 1% of the total palm shell available in Malaysia, i.e., 2,587 kg [h.sup.-1] bio-oil, the simulation predicted the production of 226 kg [h.sup.-1] benzene, 236 kg [h.sup.-1] cyclohexane and 7 kg [h.sup.-1] cyclohexene, with the yield of 34, 81 and 3% respectively. The preliminary economic potential was calculated to be positive. It was also observed that hydrogen was the limiting reactant in the hydrogenation reaction. Conclusion/Recommendations: The simulation study indicated positive technical and economic feasibility of hydrodeoxygenation of pyrolytic bio-oil from biomass into benzene and cyclohexane for the transportation fuel industry. This potential can be explored in more details and further findings can promote the prospect of co-processing bio-oil in standard refinery units to produce chemicals and fuels. Key words: Bio-oil, simulation, hydrodeoxygenation, flowsheet design, biomass, INTRODUCTION World energy consumption is predicted to grow significantly and continuously close with the global population. Contributing approximately 79% (US Energy Information Administration, 2009) of the worldwide energy demand, fossil [...]

Plant diversity has been shown to increase community biomass in experimental communities, but the mechanisms resulting in such positive biodiversity effects have remained largely unknown. We used a large-scale six-year biodiversity experiment near Jena, Germany, to examine how aboveground community biomass in grasslands is affected by different components of plant diversity and thereby infer the mechanisms that may underlie positive biodiversity effects. As components of diversity we defined the number of species (1-16), number of functional groups (1-4), presence of functional groups (legumes, tall herbs, small herbs, and grasses) and proportional abundance of functional groups. Using linear models, replacement series on the level of functional groups, and additive partitioning on the level of species, we explored whether the observed biodiversity effects originated from disproportionate effects of single functional groups or species or from positive interactions between them. Aboveground community biomass was positively related to the number of species measured across functional groups as well as to the number of functional groups measured across different levels of species richness. Furthermore, increasing the number of species within functional groups increased aboveground community biomass, indicating that species within functional groups were not redundant with respect to biomass production. A positive relationship between the number of functional groups and aboveground community biomass within a particular level of species richness suggested that complementarity was larger between species belonging to different rather than to the same functional groups. The presence of legumes or tall herbs had a strong positive impact on aboveground community biomass whereas the presence of small herbs or grasses had on average no significant effect. Two- and three-way interactions between functional group presences were weak, suggesting that their main effects were largely additive. Replacement series analyses on the level of functional groups revealed strong transgressive overyielding and relative yields >1, indicating facilitation. On the species level, we found strong complementarity effects that increased over time while selection effects due to disproportionate contributions of particular species decreased over time. We conclude that transgressive overyielding between functional groups and species richness effects within functional groups caused the positive biodiversity effects on aboveground community biomass in our experiment. Key words: biodiversity; community biomass; complementarity; ecosystem functioning; functional groups; Jena Experiment; replacement series; transgressive overyielding.

Increased biomass productivity could be achieved through double-cropping if extended growth duration could be realized with minimal reductions in growth efficiency relative to solecropping. To test this hypothesis, functional growth analysis was used to assess the relative importance of photosynthetic duration and efficiency in determining biomass production by sole-crop corn (Zea mays L.; SC) and double-crop triticale (xTriticosecale Wittmack)--double-crop corn (DT-DC). Aboveground dry matter and leaf area were measured weekly, and net dry matter production was assessed for each crop at harvest. Over 2 yr, average harvested dry matter was 25% greater for DT-DC (22.7 Mg [ha.sup.-1]) than for SC (18.2 Mg [ha.sup.-1]), despite greater maximum leaf area index and greater maximum crop growth rate for SC relative to DT-DC. Leaf area duration was increased by 23% for DT-DC compared with SC, while maximum net assimilation rate and seasonal net assimilation rate did not differ between cropping systems. Across systems, variation in yield was positively related to maximum crop growth rate, maximum leaf area index, and leaf area duration but was not associated with maximum or seasonal netassimilation rate. Therefore, leaf duration was more important than leaf efficiency in determining productivity in both cropping systems, and greater biomass yield for DT-DC was the outcome of photosynthesis occurring over an extended duration. These results suggest that potential exists to increase biomass productivity by expanding the seasonal interval of photosynthesis, and that in the case of double-cropping, expansion of leaf duration is not necessarily associated with reductions in leaf efficiency. doi: 10.2135/cropsci2008.12.07009

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized. Eucalyptus regnans | climate mitigation | primary forest | deforestation and degradation | temperate moist forest biome

We conducted 28 dilution experiments during August September 2007 to investigate the coupling of growth and microzooplankton grazing rates among ultraphytoplankton populations and the phytoplankton community and their responses to habitat variability (open-ocean oligotrophy, eddy-induced upwelling, and the Mekong River plume) in the western South China Sea. At the community level, standing stocks, growth, and grazing rates were strongly and positively correlated, and were related to the higher abundance of larger phytoplankton cells (diatoms) at stations with elevated chlorophyll concentration. Phytoplankton growth rates were highest (>2 [d.sup.-I]) within an eastward offshore jet at 13[degrees]N and at a station influenced by the river plume. Among ultraphytoplankton populations, Prochlorococcus dominated the more oceanic and oligotrophic stations characterized by generally lower biomass and phytoplankton community growth, whereas Synechococcus became more important in mesotrophic areas (eddies, offshore jet, and river plume). The shift to Synechococcus dominance reflected, in part, its higher growth rates (0.87 [+ or -] 0.45 [d.sup.-1]) compared to Prochlorococcus (0.65 [+ or -] 0.29 [d.sup.-l]) or picophytoeukaryotes (0.54 [+ or -] 0.50 [d.sup.-1]. However, close coupling of microbial mortality rates via common predators is seen to play a major role in driving the dominance transition as a replacement of Prochlorococcus, rather than an overprinting of its steady-state standing stock.

We develop an age-structured model for two krill populations near the Antarctic Peninsula and estimate the relative recruitment events that reproduce observed trends in krill abundance and age structure. Estimates of recruitment in both regions show a nonlinear relationship between recruitment and sea ice area in the combined Bellingshausen and Amundsen Seas from the previous winter and spring, with large recruitment events occurring over a narrow range of ice area, and minimal recruitment otherwise. This finding may allow for an adaptive approach in which future catch limits are adjusted based on predictions of biomass. This result also suggests that the ecosystem may change dramatically once average ice area drops below the recruitment threshold.

Application of organic manure (OM) to arable lands improves soil tilth. The objectives of this study were to: (i) simulate the effect of OM application rates (0, 168, 336, and 672 kg total N [ha.sup.-1]) and types (chicken [Gallus domesticus] and dairy manures) on soil organic C (SOC) and C[O.sub.2] emissions from a Hawaiian highly weathered tropical soil; and (ii) correlate SOC, C[O.sub.2] emissions, and two major soil properties: bulk density ([p.sub.b]) and saturated hydraulic conductivity ([K.sub.sat]). Measurements of SOC and [p.sub.b] were conducted on samples collected from the top 10 cm of soil tilled before and after manure application, cultivated with sweet corn ('Super Sweet 10,' Zea mays L. ssp. mays), and drip irrigated for two consecutive growing seasons. The [K.sub.sat] values were calculated from infiltration data measured with a tension infiltrometer. The Rothamsted C turnover model was used to simulate SOC and C[O.sub.2] emissions. The simulated and measured SOC agreed reasonably during model calibration ([r.sup.2] = 0.93) and validation ([r.sup.2] = 0.90). Results revealed that SOC, C[O.sub.2] emissions, and [K.sub.sat] increased while [p.sub.b] decreased with increasing OM rates. There was no significant effect of OM type. There was a highly significant (P < 0.01) correlation between the measured and simulated SOC and between the measured SOC and the simulated C[O.sub.2] emissions. The [K.sub.sat] values significantly correlated (P < 0.05) with the measured and simulated SOC and the simulated C[O.sub.2] emissions. A significant inverse relationship between [p.sub.b] and [K.sub.sat] was observed. We concluded that, in addition to improving soil aggregation, decreasing [p.sub.b], and increasing [K.sub.sat], OM application to this tropical soil increases SOC pools that contribute to atmospheric C[O.sub.2] following tillage and other agricultural practices. Abbreviations: BIO, microbial biomass; DPM, decomposable plant material; HUM, humified organic matter; IOM, inert organic matter; OM, organic manure; RothC, Rothamsted carbon model; RPM, resistant plant material; SOC, soil organic carbon; SOM, soil organic matter.

During January and February 2003, drought conditions led to major bushfires across southeast Australia, causing considerable damage. We have examined aerosol optical depth (AOD) data recorded by a sunphotometer at Wagga Wagga. Although this site lies to the northeast of the fires, periodic changes in wind direction brought smoke plumes over our instrument (AOD in excess of 1.0), sometimes via circuitous routes. By examining the hourly AOD spectra and, specifically, the Angstrom exponent derived from our two shortest wavelengths, we have observed clear evidence of a shift in the peak radius of the fine mode, most likely as a result of particle coagulation. Selected data sets were inverted to obtain the aerosol size distribution, confirming this conclusion. This was particularly clear on 25 January, when the wind changed during the day so that the afternoon observations were of smoke that had traveled on a more circuitous route to the north of Wagga Wagga before returning. OCIS codes: 010.1110, 010.1310, 010.0280, 010.5630.

The whole metazoan community inhabiting macrophyte stands and gravel beds of the English chalk stream River Lambourn were sampled for 1 yr. Secondary production estimates for specific taxa of macrofauna and meiofauna, usually at species of genus level, were made using the size-frequency method. Annual standing biomass and production to biomass ratios were also estimated. Total annual secondary production was as high as 64.99 g [m.sup.-2] [yr.sup.-1] in the macrophyte stands while within the gravel beds total annual secondary production was 22.55 g [m.sup.-2] [yr.sup.-1]. Macrofauna contributed >91% to secondary production in both habitats. A corresponding standing biomass of 11.87 g [m.sup.-2] in the macrophyte stands was also higher than within gravel beds of 5.13 g [m.sup.-2]. Macrofauna contributed >97% to standing biomass in both habitats. A large number of meiofauna and some macrofauna species displayed annual production-to-biomass (P:B) values in both habitats significantly higher than 9 of 10. Despite higher densities and turnover rates within the benthos of the River Lambourn, there was a minimal contribution of the meiofauna to total secondary production dominated by the macrofauna.

The development of more efficient utilization of biomass has received increased attention in recent years. Cellulases play an important role in processing biomass through advanced biotechnological approaches. Both the development and the application of cellulases require an understanding of the activities of these enzymes. A new method to determine the activity of cellulase has been developed using a quartz crystal microbalance (QCM) technique. We compare the results from this technique with those from the IUPAC (International Union of Pure and Applied Chemistry) dinitrosalicylic acid (DNS) standard method and also from biccinchoninic acid and ion chromatography methods. It is shown that the QCM technique provides results closer to those obtained by measuring the actual reducing sugars. The elimination of the use of color development in the standard redox methods makes the QCM platform easier to implement; it also allows more flexibility in terms of the nature of the substrate. Finally, validation of the proposed method was carded out by relating the crystallinity of different substrates to the cellulase activity. Numerical values of cellulase activities measured with the QCM method showed that celluloses with higher crystallinity indices were hydrolyzed slower and to a lower extent than those of lower crystallinity indices for the cellulase mixtures examined.

Carbon sequestration in reclaimed mine soils (RMSs) could partly mitigate C emissions associated with coal mining, but our knowledge of C storage in RMSs is derived almost exclusively from studies conducted in restored grasslands and forests. Limited information exists regarding intensively managed RMSs under agricultural land use. A study was conducted to assess the impact of tillage on recent soil organic C (SOC, total organic C minus geogenic C), total microbial biomass C (t-MBC) and active microbial biomass C (a-MBC) in RMSs under no-till (NT, 13 yr) and moldboard plowing (MR 9 and 13 yr). An undisturbed second-growth forest and a newly reclaimed (NR, 1 yr) grassland were also included. Significant effects (P < 0.01) of tillage on SOC, t-MBC, a-MBC, and metabolic quotient ([q.sub.CO2]) were detected in the 0- to 5-cm soil layer. These soil properties were strongly ([r.sup.2] > 0.66) correlated with recent SOC, but moderately ([r.sup.2] = 0.21-0.60) with geogenic C. Rates of C sequestration were estimated from the temporal trend in the recent SOC pool (0-40 cm in NR (23.2 Mg C [ha.sup.-l]), 9-yr MP (32.9 Mg C [ha.sup.-1]) and 13-yr MP (33 Mg C [ha.sup.-1]), and ranged between 0.8 and 0.25 Mg C [ha.sup.-1] [yr.sup.-1] during the first and second decades of restoration. Despite a similar amount of crop residue returned (2.8 Mg C [ha.sup.-1] [ha.sup.-1]), recent SOC under 13-yr NT (36.8 Mg C [ha.sup.-1]) exceeded that under 13-yr MP by 3.8 Mg C [ha.sup.-1]. This finding, in conjunction with the lower [q.sub.CO2] in the surface soil layer of NT, suggests a more efficient C utilization by soil microbes under NT than under MP. These results illustrate the benefits of NT to the restoration of SOC stocks and biological properties of severely disturbed soil systems. Abbreviations: a-MBC, active microbial biomass carbon; HWF, hardwood forest; MBC, microbial biomass carbon; MP, moldboard plowing; NR, newly reclaimed; NT, no-till; RMS, reclaimed mine soil; SOC, soil organic carbon; t-MBC, total microbial biomass carbon; TOC, total organic carbon.

The 'fundamental niche' is the range of conditions under which an organism can survive and reproduce, measured in the absence of biotic interactions. Niche measurements are often based on statistical relationships between species presence and measured environmental variables, or inferred from measured responses of species along hypothesized niche axes. In this study, we use novel, process-based models of how irradiance and gas diffusion influence photosynthesis and respiration to predict niche dimensions for three coral species: Acropora nasuta, Montipora foliosa, and Leptoria phrygia. We use a combination of mathematical modeling, laboratory experiments, and field observations to establish the link between energy acquisition and the dominant environmental gradients on reefs: light intensity and water flow velocity. Our approach allows us to quantify how the shape of the niche varies in response to light and flow conditions. The model predicts that, due to its higher photosynthetic capacity, the branching coral A. nasuta has a positive energy balance over a wider range of conditions than both a massive species (L. phrygia) and a foliose species (M. foliosa). Moreover, colony size influences niche width, with larger colonies of all three species achieving a positive energy balance over a broader range of conditions than small colonies. Comparison of model predictions with field data demonstrated that tissue biomass and reproductive output are significantly and positively correlated with predicted energy acquisition. These results show how interactions between light and flow determine organism performance along environmental gradients on coral reefs. In addition, this study demonstrates the utility of process-based models for quantifying how physiology influences ecology, and for predicting the ecological consequences of varying environmental conditions. Key words: Acropora nasuta; carbon acquisition; fundamental niche; Leptoria phrygia; light intensity; mass transfer coefficient; Montipora foliosa; photosynthesis; physiological model; scleractinian corals; water flow velocity.

Size-selective mortality inevitably leads to a decrease in population density and exerts a direct negative effect on targeted size classes. But density and population size structure are also shaped by food-dependent processes, such as individual growth, maturation, and reproduction. Mortality relaxes competition and thereby alters the dynamic interplay among these processes. As shown by the recently developed size-structured theory, which can account for food-dependent individual performance, this altered interplay can lead to overcompensatory responses in size class-specific biomass, with increasing mortality. We experimentally tested this theory by subjecting laboratory fish populations to a range of size-selective mortality rates. Overall, the results were in agreement with theoretical predictions. Biomass of the juvenile size class increased above control levels at intermediate adult mortality rates and thereafter declined at high mortality rates. Juvenile biomass also increased when juveniles themselves were subjected to intermediate mortality rates. Biomass in other size classes decreased with mortality. Such biomass overcompensation can have wide-ranging implications for communities and food webs, including a high sensitivity of top predators to irreversible catastrophic collapses, the establishment of alternative stable community states, and the promotion of coexistence and biodiversity. alternative stable states | food-dependent growth | harvesting | physiologically structured model | size structure

Biomass gasification by the use of metallic nickel as active metal on dolomite support has been chosen as catalyst because of its activity in biomass steam gasification and tar reduction. The purpose of this study is to study the effects of critical parameters on product gas compositions such as temperature, steam to carbon ratio (S/C) and oxygen input. The results showed the increasing carbon conversion to gas from 44.13-78.43% whereas tar was decreased from 19.55-1.4% at temperature of 800[degrees]C and S/C 0.95. It is found that Nickel-dolomite is effective for tar reduction and for improving the quality of syngas derived from biomass which is a renewable energy source. Key words: Tar, biomass, gasification, Ni/dolomite, coconut shell, INTRODUCTION Gasification of biomass is a potential source of renewable energy to produce useful gases such as syn gas or pure hydrogen. One of the major issues in biomass gasification [...]

Transport time scales such as flushing time and residence time are often used to explain variability in phytoplankton biomass. In many cases, empirical data are consistent with a positive phytoplankton-transport time relationship (i.e., phytoplankton biomass increases as transport time increases). However, negative relationships, varying relationships, or no significant relationship may also be observed. We present a simple conceptual model, in both mathematical and graphical form, to help explain why phytoplankton may have a range of relationships with transport time, and we apply it to several real systems. The phytoplankton growth-loss balance determines whether phytoplankton biomass increases with, decreases with, or is insensitive to transport time. If algal growth is faster than loss (e.g., grazing, sedimentation), then phytoplankton biomass increases with increasing transport time. If loss is faster than growth, phytoplankton biomass decreases with increasing transport time. If growth and loss are approximately balanced, then phytoplankton biomass is relatively insensitive to transport time. In analyses of several systems, portions of an individual system, or time periods, apparent insensitivity of phytoplankton biomass to changes in transport time could arise due to the superposition of cases with different phytoplankton--transport time relationships. Thus, in order to understand or predict responses of phytoplankton biomass to changes in transport time, the relative rates of algal growth and loss must be known.

Pearl millet [Pennisetum glaucum (L.) R. Br.] single cross hybrids, bred from high-yielding parental lines in favorable environments, are not well adapted to northwest India's arid zone. The objectives of these experiments were (i) to measure grain and stover yield heterosis in testcrosses of six landrace-based restorer populations and (ii) to understand how heterosis for biomass and harvest index (HI) affects heterosis for grain and stover yields in crosses of these populations. Six restorer populations and their testcrosses on 10 to 13 A1 male-sterile lines were evaluated at two arid zone locations of northwest India. Heterosis was calculated as percentage advantage of testcross hybrids over parental restorer population. The range in individual testcross heterosis varied from -3% to +39% for grain yield and from -22% to +17% for stover yield. Variation in biomass heterosis accounted for 55% of the variation in grain yield heterosis and 84% of the variation in stover yield heterosis. Harvest index heterosis accounted for 38% of variation in grain yield heterosis and 13% of stover yield heterosis with a positive heterosis in HI resulting in negative heterosis in stover yield. The testcrosses with the highest biomass heterosis for each restorer population achieved 20% biomass heterosis level (combined with a mean 12% heterosis in HI), resulting in 32% grain yield heterosis and 18% stover yield heterosis. We concluded that heterosis for biomass was the major determinant of grain and stover yield heterosis in pearl millet.

Banana is considered as one of the most important agricultural products of Northern Thailand. A large amount of banana peel has been left as garbage after industrial processes. The raw material is plentiful and has low economic value. Therefore, the characteristics of banana-peel briquettes including banana peel properties were investigated. The briquettes were produced with pressures ranging from 3 to 11 MPa. Molasses was used as the binder. According to some standard tests, it was found that briquettes produced with compaction pressure over 7 MPa passed both impact resistance and compressive strength tests. The density-pressure relationship and strength-pressure relationship over studied range were also developed and validated. Key words: Banana peel, briquette, agricultural residue, biomass densification, INTRODUCTION For most developing countries, it appears that biomass, particularly agricultural wastes, has become one of their most promising energy sources. The idea of utilizing the residues from agricultural sectors [...]

Auricularia polytricha (Mont) Saccardo, were found growing on decaying logs of wood in their large numbers within the marshy riverine ecosystem area of Wilberforce Island, Bayelsa State, Nigeria. The sporophores of this edible mushroom were tissue cultured and biomass production in submerged liquid medium was assessed. This fungus produced best mycelial biomass (340 mg [cm.sup.-3]) at 25[degrees]C after 15 days of incubation while no biomass was produced at 5, 45 and 50[degrees]C after 20 days. Likewise, very good biomass was produced at pH 6.5 after 10 days of incubation. Among the carbohydrate sources tested, glucose stimulated highest biomass yield of 375 mg [cm.sup.-3] at 1.6% concentration closely followed by fructose (350 mg [cm.sup.-3]) at 1.8% concentration. All the nitrogen compounds investigated enhanced significant biomass production (p[less than or equal to]0.05). However, 0.8% of peptone stimulated the best biomass yield (320 mg [cm.sup.-3]) followed by tryptophan (300 mg [cm.sup.-3]) at 0.9% concentration. The volume of inoculum of A. polytricha that produced highest biomass of this fungus in liquid culture was 7.0 [cm.sup.-3]. The implications of these findings were discussed. Keywords: Biomass, Auricularia polytricha, Wilberforce Island, collection, submerged culture, INTRODUCTION Previous work have been carried out on collection, identification and isolation of indigenous Nigerian mushrooms (1), (2), (3), (4), (5) .Investigations were carried out on these fungi basically, to [...]

BACKGROUND: Biomass smoke is an important source of particulate matter (PM), and much remains to be discovered with respect to the human health effects associated with this specific PM source. [...]

Many methods of microbial proteome characterizations require large quantifies of cellular biomass (> 1-2 g) for sample preparation and protein identification. Our experimental approach differs from traditional techniques by providing the ability to identify the proteomic state of a microbe from a few milligrams of starting cellular material. The small-scale, guanidine lysis method minimizes sample loss by achieving cellular lysis and protein digestion in a single-tube experiment. For this experimental approach, the freshwater microbe Shewanella oneidensis MR-1 and the purple non-sulfur bacterium Rhodopseudomonas palustris CGA0010 were used as model organisms for technology development and evaluation. A 2-D LC-MS/MS comparison between a standard sonication lysis method and the small-scale guanidine lysis techniques demonstrates that the guanidine lysis method is more efficient with smaller sample amounts of cell pellet (i.e., down to 1 mg). The described methodology enables deeper proteome measurements from a few milliliters of confluent bacterial cultures. We also report a new protocol for efficient lysis from small amounts of natural biofilm samples for deep proteome measurements, which should greatly enhance the emerging field of environmental microbial community proteomics. This straightforward sample boiling protocol is complementary to the small-scale guanidine lysis technique, is amenable for small sample quantifies, and requires no special reagents that might complicate the MS measurements.

The objective of this paper is to carry out a systematic investigation about the sensitivity of radar to maize crop growth and soil moisture by considering a wide range of frequencies and angles and all linear polarizations. We show the results of a correlation study carried out on the data collected on a maize field at Suberg, in the Swiss region named Central Plain, by the multifrequency RAdio ScAtteroMeter (RASAM). This agricultural field was monitored over a long period of time at a wide range of frequencies and observation angles so that the correlation between the backscattering and crop height and the biomass and soil moisture was studied under several plant and observation conditions. Moreover, we describe some recent refinements applied to the vegetation scattering model developed at Tor Vergata University, Rome, Italy, and we evaluate the accuracy of extended comparisons between model outputs and RASAM signatures. The Tor Vergata model is finally applied to give a theoretical basis to the experimental correlation findings. Index Terms--Biomass, crops, modeling, radar, soil moisture.

Debate on the relationship between diversity and stability has been driven by the recognition that species loss may influence ecosystem properties and processes. We conducted a litterbag experiment in the Scottish Highlands, United Kingdom, to examine the effects of altering plant litter diversity on decomposition, microbial biomass, and microfaunal abundance. The design of treatments was fully factorial and included five species from an upland plant community (silver birch, Betula pendula; Scots' pine, Pinus sylvestris; heather, Calluna vulgaris; bilberry, Vaccinium myrtillus; wavy-hair grass, Deschampsia flexuosa); species richness ranged from one to five species. We tested the effects of litter species richness and composition on variable means, whether increasing litter species richness reduced variability in the decomposer system, and whether any richness--variability relationships were maintained over time (196 vs. 564 days). While litter species composition effects controlled variable means, we revealed reductions in variability with increasing litter species richness, even after accounting for differences between litter types. These findings suggest that higher plant species richness per se may result in more stable ecosystem processes (e.g., decomposition) and decomposer communities. Negative richness-variation relationships generally relaxed over time, presumably because properties of litter mixtures became more homogeneous. However, given that plant litter inputs continue to enter the belowground system over time, we conclude that variation in ecosystem properties may be buffered by greater litter species richness. Key words: biodiversity; decomposition; ecosystem variability; litter identity; microbial biomass; nematodes; stability.

Net primary production (NPP) is influenced by disturbance-driven fluctuations in foliar standing crop (FSC) and resource-driven fluctuations in rates of recruitment and growth, yet most studies of NPP have focused primarily on factors influencing growth. We quantified NPP, FSC, recruitment, and growth rate for the giant kelp, Macrocystis pyrifera, at three kelp forests in southern California, USA, over a 54-month period and determined the relative roles of FSC, recruitment, and growth rate in contributing to variation in annual NPP. Net primary production averaged between 0.42 and 2.38 kg dry mass*[m.sup.-2]* [yr.sup.-1] at the three sites. The initial FSC present at the beginning of the growth year and the recruitment of new plants during the year explained 63% and 21% of the interannual variation observed in NPP, respectively. The previous year's NPP and disturbance from waves collectively accounted for 80% of the interannual variation in initial FSC. No correlation was found between annual growth rate (i.e., the amount of new kelp mass produced per unit of existing kelp mass) and annual NPP (i.e., the amount of new kelp mass produced per unit area of ocean bottom), largely because annual growth rate was consistent compared to initial FSC and recruitment, which fluctuated greatly among years and sites. Although growth rate was a poor predictor of variation in annual NPP, it was principally responsible for the high mean values observed for NPP by Macrocvstis. These high mean values reflected rapid growth (average of ~2% per day) of a relatively small standing crop (maximum annual mean = 444 g dry mass/[m.sup.2]) that replaced itself approximately seven times per year. Disturbance-driven variability in FSC may be generally important in explaining variation in NPP, yet it is rarely examined because cycles of disturbance and recovery occur over timescales of decades or more in many systems. Considerable insight into how variation in FSC drives variation in NPP may be gained by studying systems such as giant kelp forests that are characterized by frequent disturbance and rapid rates of growth and recruitment. Key words: biomass; disturbance; giant kelp; growth; Macrocystis pyrifera; net primary production; nutrients; recruitment; resource supply; standing crop.

Strip tillage results in soil disturbance levels similar to those of conventional tillage systems in the row locations (strip) and properties of no-till in the interrow (between-row) locations. In this study, biological and physical soil properties in the region spanning the row to interrow were investigated and results were compared among strip-tillage systems utilizing different inputs (conventional fertilizer and pesticides vs. USDA-approved organic inputs) and rotation regimes (continuous tomato [Lycopersicon esculentum Mill.] vs. a 3-yr vegetable rotation). Bulk density was significantly greater in the interrow locations. Soil respiration potential was greatest in the interrow and least in the row locations, and greater in treatments receiving organic inputs relative to synthetic inputs. No differences in soil N mineralization potential were determined. Microbial biomass C and N were greatest in interrow and least in row locations. Total soil C and N values did not vary from row to interrow locations or as a result of synthetic vs. organic inputs. The data suggest that organically managed production systems are less biologically stratified than conventional input systems under strip-tillage management. Although net C mineralization was similar between chemical and organically managed systems, greater microbial biomass values in the organic treatment systems may have been the result of continuous additions of weed biomass during the summer. The hypothesis of a gradient effect for biological activity in strip-tillage systems from row to interrow appears to be true in systems managed with synthetic fertilizers and pesticides, but not true of organically managed systems. Abbreviations: MBC, microbial biomass carbon; MBN, microbial biomass nitrogen.

Switchgrass (Panicum virgatum L.) has potential as a lignocellulosic feedstock for biofuel production. However, switchgrass yields need to be increased to make dedicated biomass feedstock economically competitive with conventional crops. Objectives of this study were to determine the importance of tiller density, number of phytomers per tiller, and mass per phytomer as: (i) determinants of biomass yield in swards of switchgrass in the northern Great Plains, and (ii) potential indirect criteria for selection for biomass. Swards of 'Cave-ln-Rock', 'Nebraska 28', and 'Sunburst' were sampled from June through November during 2005 and 2006. Partial regression coefficients were greater than 0.0 for 93, 87, and 44% of the samples for tiller density, mass per phytomer, and number of phytomers per tiller, respectively. Path coefficient analysis indicated that tiller density and mass per phytomer had consistently large positive direct effects on biomass yield; whereas, number of phytomers per tiller had smaller and less consistent, albeit positive, direct effects on biomass yield. All three of the yield components have potential as indirect selection criteria for improving biomass in switchgrass. However, progress for biomass production in swards from selection for any of the yield components will depend on heritabilities of the yield components and genetic correlations between the components and biomass.

Abstract. Flood-irrigation, to the extent that outwash (runoff from border-check bays) occurs, is a major cause of P loss from grazed pastures and has potential to harm surface water quality. [...]

Abstract: We looked for empirical relationships between periphyton biomass and recreational development in the Laurentian lakes of Quebec (Canada). We compared the response of periphyton (as chlorophyll a) on rocks [...]

Byline: Jiangwen Fan (1), Huaping Zhong (1), Warwick Harris (2), Guirui Yu (1), Shaoqiang Wang (1), Zhongmin Hu (1), Yanzhen Yue (1) Keywords: China; Carbon storage; Grassland communities; Biomass components Abstract: Above- and below-ground biomass values for 17 types of grassland communities in China as classified by the Chinese Grasslands Resources Survey were obtained from systematic replicated sampling at 78 sites and from published records from 146 sites. Most of the systematic samples were along a 5,000-km-long transect from Hailar, Inner Mongolia (49deg15 N, 119deg15 E), to Pulan, Tibet (30deg15 N, 81deg10 E). Above-ground biomass was separated into stem, leaf, flower and fruit, standing dead matter, and litter. Below-ground biomass was measured in 10-cm soil layers to a depth of 30 cm for herbs and to 50 cm for woody plants. Grassland type mean total biomass carbon densities ranged from 2.400 kg m.sup.-2 for swamp to 0.149 kg m.sup.-2 for alpine desert grasslands. Ratios of below- to above-ground carbon density varied widely from 0.99 for tropical tussock grassland to 52.28 for alpine meadow. Most below-ground biomass was in the 0--10 cm soil depth layer and there were large differences between grassland types in the proportions of living and dead matter and stem and leaf. Differences between grassland types in the amount and allocation of biomass showed patterns related to environments, especially aridity gradients. Comparisons of our estimates with other studies indicated that above-ground biomass, particularly forage-yield biomass, is a poor predictor of total vegetation carbon density. Our estimate for total carbon storage in the biomass of the grasslands of China was 3.32 Pg C, with 56.4% contained in the grasslands of the Tibet-Qinghai plateau and 17.9% in the northern temperate grasslands. The need for further standardized and systematic measurements of vegetation biomass to validate global carbon cycles is emphasised. Author Affiliation: (1) Key Laboratory of Ecosystem Network Observation and Modeling, CERN Center for Synthesis Research, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Datun Road, Anwai, Beijing, 100101, China (2) Landcare Research, P.O. Box 40, Lincoln, 7640, New Zealand Article History: Registration Date: 26/07/2007 Received Date: 17/01/2006 Accepted Date: 10/05/2007 Online Date: 06/09/2007

The presence of consumers not only alters the mean biomass of the prey assemblage, but also affects the spatial heterogeneity of biomass distribution. Whereas the mean prey biomass is generally reduced by consumer presence, the effect on spatial heterogeneity is less clear-cut. A meta-analysis of almost 600 field experiments manipulating the presence of benthic invertebrate or vertebrate grazers was conducted to analyze the effect of grazers on both the absolute spatial variability of periphyton biomass and the relative variability, which was standardized to the mean. Effects on absolute variability were measured as the log response ratio Of the standard deviation of biomass (LR-SD), whereas effects on relative variability were measured as the log response ratio of the coefficient of variation of biomass (LR-CV). The overall magnitude and range of LR-SD and LR-CV indicated that grazers not only reduced periphyton biomass, but also substantially altered their spatial distribution. However, grazer effects differed strongly for absolute and relative variability. On average, grazers reduced the absolute spatial variability in prey biomass by 50% (average LRSD =-0.68) but increased the relative variability by 24% (average LR-CV = 0.22). The magnitude of LR-SD strongly depended on the efficiency of grazing, with strong biomass removal leading to strong homogenization. Moreover, LR-CV and LR-SD were significantly affected by habitat type (freshwater vs. coastal) and substrata. Given the importance of spatial heterogeneity for resource uptake, competition and the maintenance of diversity, grazer presence has potentially strong indirect effects on the interactions within prey assemblages. Key words: coefficient of variation; grazer efficiency; meta-analysis; periphyton biomass; spatial heterogeneity; standard deviations.

Species diversity can increase natural grasslands productivity but the effect of diversity in agricultural systems is not well understood. Our objective was to measure the effects of species composition, species richness, and harvest management on crop and weed biomass in perennial herbaceous polycultures. In 2003, 49 combinations of seven species (legumes, [C.sub.3] and [C.sub.4] grasses) including all monocultures and selected two to six species polycultures were sown in small plots at two Iowa, USA, locations in a replicated field design. Plots were split in half and managed with either one or three harvests in each of 2004 and 2005. Biomass increased log-linearly with species richness in all location-management environments and the response was not different between managements. Polycultures outyielded monocultures on average by 73%. The most productive species in monoculture for each management best explained the variation in biomass productivity. The biomass of plots containing this species did not increase with richness in most environments but biomass of plots without this species increased log-linearly in all cases. Weed biomass decreased exponentially with richness in all environments. On average, increasing species richness in perennial herbaceous polycultures increased productivity and weed suppression, but well-adapted species produced high biomass yield regardless of richness.

Understanding how complex food webs assemble through time is fundamental both for ecological theory and for the development of sustainable strategies of ecosystem conservation and restoration. The build-up of complexity [...]

Alfalfa (Medicago sativa L.) has been proposed as a biofuel feedstock in which the stems would be processed to produce ethanol and the leaves sold separately as a livestock feed. Our objectives were to evaluate the effects of management strategy on leaf crude protein (CP), and stem carbohydrate concentrations and yields of alfalfa germplasms differing in genetic background. Two hay-type and two biomass-type alfalfas were established at 450 plants [m.sup.-2] and harvested at early bud (hay management system) and at 180 plants [m.sup.-2] and harvested at green pod (biomass management system) in three environments. The biomass-type alfalfas under the biomass management had lower leaf CP, higher stem cell wall polysaccharide, and higher stem lignin concentrations, comparable leaf CP yield, and 37% greater stem cell wall polysaccharide yields compared to the hay-type alfalfas under the hay management treatment. The impact of altered stem cell wall composition and increased stem dry matter yield of a biomass-type alfalfa under the biomass system compared to a hay-type alfalfa under the hay system increased the theoretical potential ethanol yield by 99%.

Emerging markets for fuels and energy from crop biomass are creating new opportunities for redesigning agricultural systems for improved ecological function and energy-use efficiency. Innovative bioconversion processes configured to recover key plant nutrients from biomass will allow recycling nutrients to crop fields, thereby closing nutrient cycles and reducing the energetic and economic costs of fertilization. Such advanced bioconversion matched with complementary biomass production may promote the development of highly productive agricultural--industrial systems that protect environmental quality. A generally representative example of nutrient recovery from an integrated biological and thermochemical conversion process designed to produce ethanol and synthetic fuels from switchgrass (Panicum virgatum L.) indicates that approximately 111 kg [ha.sup.-1] [yr.sup.-1] of N can be recovered. This is equivalent to 78% of the N-fertilizer input required. This example illustrates that N recovery and cycling could significantly improve the sustainability of biomass production as well as the overall energy balance of ethanol production from lignocellulosic biomass. Demand for lignocellulosic biomass as an industrial feedstock may also allow the introduction of new crops and cropping systems. In addition to perennial grasses, double-crop sequences and systems incorporating greater use of legumes, cover crops, and living mulch may be able to produce large amounts of biomass while improving resource use efficiency and reducing environmental impact.

Growth and distribution of coarse roots in time and space represent a gap in our understanding of belowground ecology. Large roots may play a critical role in carbon sequestration belowground. Using ground-penetrating radar (GPR), we quantified coarseroot biomass from an open-top chamber experiment in a scrub-oak ecosystem at Kennedy Space Center, Florida, USA. GPR propagates electromagnetic waves directly into the soil and reflects a portion of the energy when a buried object is contacted. In our study, we utilized a 1500 MHz antenna to establish correlations between GPR signals and root biomass. A significant relationship was found between GPR signal reflectance and biomass ([R.sup.2]= 0.68). This correlation was applied to multiple GPR scans taken from each open-top chamber (elevated and ambient C[O.sub.2]). Our results showed that plots receiving elevated C[O.sub.2] had significantly (P = 0.049) greater coarse-root biomass compared to ambient plots, suggesting that coarse roots may play a large role in carbon sequestration in scrub-oak ecosystems. This nondestructive method holds much promise for rapid and repeatable quantification of coarse roots, which are currently the most elusive aspect of long-term belowground studies. Key words: carbon dioxide; coarse-root biomass; ground-penetrating radar; roots; scrub oak.

Measuring root biomass is time consuming and prone to sampling error. We compared three different methods of measuring root biomass in six northern hardwood stands at the Bartlett Experimental Forest. We found that root coring, the most common method of root sampling, yields estimates of fine root biomass about 27% greater than the estimates based on roots sampled in soil pits. Soil compaction contributes about 10% to this difference; the other contributing factor is that cores cannot be taken through obstructions such as rocks and coarse roots. Pits are the only method allowing characterization of root distribution by depth in rocky soil. If the depth and diameter distribution of roots are not required, allometric equations, if available, provide the easiest method of estimating total root biomass. Equations developed at the nearby Hubbard Brook Experimental Forest predicted root mass measured in soil pits with a mean absolute error of 32%. Allometric equations systematically underpredicted observed soil pit root mass in the young stands, presumably because of mature root systems remaining from the previous cohort, and systematically overpredicted observed root mass in the oldest stands. Soil pits can accurately characterize roots up to about 2 cm; coarser roots are encountered too rarely to be estimated by this method. Soil cores sample only fine roots (up to 1-2-mm diameter) but are much less work than excavating soil pits. Root mass estimates made using cores are more accurate if larger diameter corers are used (5 cm rather than 2.5 cm); subsampling before picking roots can help to control labor costs in the face of larger sample sizes. Abbreviations: dbh, diameter at breast height.