Article

Preliminary study of prairies forested with Eucalyptus sp. at the northwestern Uruguayan soils

January 2004
Environmental Pollution 127(1):49-55

DOI:10.1016/S0269-7491(03)00258-6

Source
PubMed

Authors:

Leonidas Carrasco-Letelier

National Institute of Agricultural Research of Uruguay

Gabriela Eguren

Universidad de la República de Uruguay

Carola Castiñeira Latorre

CONICET - Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" y Museo de La Plata

Oscar Parra

University of Concepción

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The land cover change of Uruguayan Forestal Plan provoked biogeochemical changes on horizon Au(1) of Argiudols; in native prairies which were replaced by monoculture Eucalyptus sp. plantation with 20 year rotations as trees. Five fields forested and six natural prairies were compared. The results not only show a statistical significant soil acidification, diminution of soil organic carbon, increase of aliphaticity degree of humic substances, and increase of affinity and capacity of hydrolytic activity from soil microbial communities for forested sites with Eucalyptus sp. but also, a tendency of podzolization and/or mineralization by this kind of land cover changes, with a net soil organic lost of 16.6 tons ha(_1) in the horizon Au(1) of soil under Eucalyptus sp. plantation compared with prairie. Besides, these results point out the necessity of correction of the methodology used by assigned Uruguayan commission to assess the national net emission of greenhouse gases, since the mineralization and/or podzolization process detected in forested soil imply a overestimation of soil organic carbon. The biochemical parameters show a statistical significant correlation between the soil organic carbon sink.

Soil Organic Carbon vs. Bulk Density Following Temperate Grassland Afforestation

Article

Full-text available

Mar 2017

Afforestation is part of a worldwide strategy to mitigate CO2 emissions. However, afforestation in grassland soils may have the opposite effect by promoting the loss of native carbon. Potential effects of this land use change on the flow of organic carbon to and from the soil can be described through bulk density (Db). Nowadays the suitability of Db for this purpose is being questioned. In order to bring new elements to the discussion, we carried out a comparative study of soil in the western region of Uruguay. Based on the background information and our own data, collected for over a decade, we evaluated the fitness of Db as proxy soil organic carbon (SOC) stocks in grassland converted to tree afforestation. These data were also related to soil pH values. The sampling consisted of five plots afforested with Eucalyptus grandis paired with control plots under grassland. All samples were taken at depth (0-10 cm and 10-20 cm) except for Db samples (0-10 cm). In afforested sites, Db increased (1.62 vs 1.53 g/cm3; p≤0.01) and SOC decreased (0-10 cm: 0.90 vs. 1.22%; p≤0.08). Db values were not significantly correlated with SOC content. As with SOC, pH values decreased after afforestation at both depths (0-10 cm: 4.92 vs. 5.62; p≤0.01; 10-20 cm: 4.76 vs. 5.54; p≤0.01). The high acidity generated in soils following afforestation, is enough to affect the interaction between mineral and organic fractions and, with them, the original Db values. According to a previous study in the same location, there is a change in the predominance of different clay minerals in the topsoil (0-20 cm). This qualitative change in the mineral fraction can affect the ability of the soil to retain organic carbon, and not be reflected in the recorded Db values. The non-reciprocity recorded between Db and SOC values warns about the need for restriction of the generic use of Db in calculation of SOC stocks estimation. In view of these results, we present a discussion of possible causes that explain the disparity between Db values and SOC measurements.

Dinámica de la materia orgánica y de algunos parámetros fisicoquímicos en Molisoles, en la conversión de una pradera a cultivo forestal en la región de Piedras Coloradas-Algorta (URUGUAY)

Thesis

Full-text available

Nov 2008

Carlos Céspedes-Payret

Dinámica de la materia orgánica y de algunos parámetros fisicoquímicos en Molisoles, en la conversión de una pradera a cultivo forestal en la región de Piedras Coloradas-Algorta (URUGUAY)

Article

Mar 2014

Carlos Céspedes-Payret

La récente expansion de la foresterie, en tant que politique à l’échelle mondiale, a atteint aussi l’Uruguay, situé dans une zone de sols de prairie. Afin d’évaluer les effets des cultures d’eucalyptus sur les sols de prairie, quelques paramètres pédologiques ont été étudiés comparativement avant et après l’implantation des cultures. La zone d’étude se situe au nord –ouest de l’Uruguay (Piedras Coloradas-Algorta), elle est caractérisée par la prédominance de Mollisols associés à une végétation herbacée de type C4. L’étude a été réalisée en deux temps ; dans un premier temps (Eude t25) une seule culture a été considérée (Eucalyptus grandis), un total de huit paramètres pédologiques analysés (matières organiques, pH, capacité d’échange des cations (CEC), Ca2+, Mg2+, Na+, Fe libre et Fe amorphe) et les échantillonnages ont été effectués sur deux horizons (A et B). Dans un deuxième temps (Eude t10-30) le nombre de parcelles a été augmentée, ainsi que l’intervalle des âges des cultures, et les échantillonnages ont été effectués à deux profondeurs (0-10 et 10- 20 cm). En même temps, le nombre de paramètres étudiés a été diminué : teneur en matières organiques, pH, et densité apparente (DA). Les résultats ont montré 1) qu’il y a une perte effective du carbone organique des sols cultivés avec les eucalyptus ; 2) que cette perte de carbone affecte principalement le CC3 apporté par les eucalyptus. Cette perte de carbone est associée à l’âge des plantations d’eucalyptus et est indépendante du passé cultural des sols avant plantation. Dans tous les cas étudiés, cette perte est clairement associée à un changement significatif des paramètres analysés (pH, CEC, Ca2+, Mg2+ et DA). Conclusions : 1) les Eucalyptus affectent de façon négative –et significative- le bilan du carbone du sol, 2) ceci est expliqué par une augmentation du turnover. ABSTRACT. Afforestation of prairie regions has rapidly reached, as a recent world-wide policy, countries like Uruguay, but little is known about the effects of eucalyptus plantation on soil organic matter (SOM) dynamics. In order to evaluate their possible effects in a prairie soil, some soil parameters were compared, before and after forestation. The zone of study was located 200 km from the Rio Uruguay mouth (Piedras Coloradas-Algorta) in a 1200-mm temperate gently undulated sandy lowland dominated by Mollisols with an herbaceous vegetation of photosynthetic pathway C4 type. The study included two stages; in the first one, a 25-year old C3 type cultivation (Eucalyptus grandis) and eight soil parameters (organic matter, pH, cation exchange capacity (CIC) Ca2+, Mg2+, Na+, free and amorphous Fe) are considered. The soil samples were taken also by horizons (A and B). The data obtained was statistically evaluated by t-tests and analysis of variance (ANOVA). In the second stage the cultivation time and parcel number were increased and the sampling was made on the less resilient (0-20cm) depths. Here, the key parameters were restricted to C (TOC and δ13C) pH and apparent density. From the overall 30 years data set it arises that there is an effective loss of total organic carbon (TOC) in soils cultivated with eucalyptus and that the lower mean residence time of C derived from the eucalyptus is responsive of the total soil carbon decline. The TOC decline was related with the age of the plantation for most of previous land uses and with a change in other parameters (pH, apparent density, CIC, Ca2+, Mg2+, Fe3+ and 1:1/2:1 clay balance). Eucalyptus affects the C balance of soil and it is explained by an increase of its turnover. The soil C sequestration in afforestation projects appears questionable in Uruguayan mollisols

Evaluation of a 20–40 year old gold mine tailings rehabilitation project on the Witwatersrand, South Africa

Conference Paper

Jan 2009

Experimental model of a Eucalyptus grandis plantation in Concordia, Entre Ríos

Article

Full-text available

Jan 2016

The Argentinian Mesopotamia is the core of fast-growing tree species plantations of the country. Eucalyptus grandis plantations constitute 90 % of the forested area with Eucalyptus spp. in NE Entre Rios. Based on previous studies on structural and functional features, a comprehensive model is here proposed on emergence of new properties linked to matter and ecosystem processes. Data from different plantations at harvest time were used: biomass, net primary productivity, water flows, nutrient flows, nutrient content in biomass, necromass and soil. Aboveground biomass, productivity and nutrient requirements were higher than belowground ones. Nutrient requirements, except phosphorus, were provided mostly by the absorption rather than by retranslocation whilst the opposite situation was observed in phosphorus. Litter fall and roots mortality were the main ways of nutrient return, except for potassium, which returned mainly by water flows. The high productivity of the plantation was supported by an important water and nutrients use efficiency. The importance of an appropriate harvest residue management is highlighted, since export of total aboveground biomass and its nutrients content involves a high distribution, compared with belowground storages. Compared with nitrogen, high phosphorus retranslocation efficiency would allow plantation to be more independent of mineralization and immobilization edaphic processes.

Evaluation of a 20–40 year old gold mine tailings rehabilitation project on the Witwatersrand, South Africa

Conference Paper

Full-text available

Jan 2009

This paper describes the rehabilitation status of a gold tailings storage facility (TSF) on the Witwatersrand,South Africa. The aim of the rehabilitation was to effect surface stability and dust control, rather than ecological restoration and closure. However, the contribution that this approach is making towards TSF rehabilitation needs to be assessed against current site closure objectives and regulations. The site (Fleurhof) is representative of TSFs that were constructed from the 1950s to 1990s using the all-sliming process and paddock method of construction. Fleurhof is considered by vegetation practitioners to have well-grassed slopes by comparison with other Witwatersrand TSFs, and was therefore chosen as a site representative of best practice using the historical methods. The top was vegetated using irrigation in 1969–1970 with a mixture of Australian and European shrubs, trees and grasses. The slopes were leached, then ameliorated and grassed using irrigation in the 1970s to 1980s, followed by some repair at a later date.Vegetation monitoring and landscape function analysis (LFA – an index-based method of evaluating the retention of resources by surfaces) requires repeated measures in order for trends and patterns to beidentified. Evaluations of plant aerial cover and species composition were conducted in 1975 in a priorstudy, and again in mid-summer 2009 (for this study) together with the first LFA survey to investigate the contribution of vegetation overall, including discrete plant functional groups to landscape functionality,i.e. for derived LFA indices of infiltration, stability and nutrient cycling. Our evaluation of the plant coverand diversity 20–40 years after the first assessment shows an overall decline in the number of speciesinitially planted on the top surface, but with natural colonisation by a few perennial grasses and forbs.A total of 35 species was observed, 50% being alien. Vegetation aerial cover is higher on all natural analogue slopes (90%) than on the TSF slopes (53%). Overall, the TSF relative indices for infiltration (30%)are similar, and stability (58%) and nutrient cycling (20%) are lower, than those of the analogue (30, 65 and23% respectively). Perennial patch types make the largest contribution to the LFA and soil surface assessment (SSA) indicators on the TSF. Although percentage aerial vegetation cover on the TSF is only one-third that of the analogue, it appears to makes a disproportionately high contribution to the stability, infiltration and nutrient-cycling indices on the TSF.LFA, with measures of plant functional groupings, provides a useful approach to evaluating TSF rehabilitation, as the outcomes can be used for practical site management actions. This LFA assessment indicated that although the TSF vegetation is contributing to the control of dust, the site surface compares poorly in terms of ecological criteria to a natural analogue hill and other TSF site; and is therefore unlikelyto meet closure criteria. However, the monitoring requires repeated measures over longer time periods to identify trends. The results of this study support previous findings which demonstrate that cryptogams and some plant functional groups (perennial tussock grasses and semi-woody to woody species) contribute more than others (mat-forming grasses and weeds) to patches with more favourable indices of stability, infiltration and nutrient-cycling. Taken as a whole, these results can assist in the design of vegetation for more ecologically-meaningful rehabilitation practices, and support mine and regulatory authorities in reaching decisions on TSF closure.

Grassland afforestation impact on primary productivity: A remote sensing approach

Article

Full-text available

Jul 2013

QuestionHow is the magnitude and seasonality of carbon uptake affected by the replacement of native grasslands by eucalyptus plantations? LocationRío de la Plata Grasslands in Argentina and Uruguay. MethodsA total of 115 paired sites of fast‐growing Eucalyptus grandis plantations and adjacent grasslands were used to characterize the magnitude and seasonality of (1) radiation interception by canopies and (2) above‐ground net primary productivity based on a time series of MODIS‐derived normalized difference vegetation index (NDVI). The response of NDVI to precipitation was explored across temporal scales. ResultsNDVI in afforested vs. grassland plots presented higher annual averages (1.3‐fold), lower seasonal ranges (average relative range of 0.11 vs. 0.29) and delayed growing seasons (2‐month shift). Temporally, NDVI was positively associated with precipitation input, showing a correlation with longer periods of precipitation accumulation in tree plantations compared to grasslands (> 7 vs. 2–3 months). Estimated average annual above‐ground net primary productivity (ANPP) almost quadrupled as a consequence of replacing grasslands by tree plantations (∼4 vs. ∼17 Mg dry matter. ha−1·yr−1), and this difference was evidenced throughout the whole study period. Conclusions Afforested grasslands intercept more radiation and have higher and more stable ANPP throughout the year, probably as a result of major changes in leaf phenology and root distribution patterns, which in turn allowed better access to water. Changes in carbon uptake can influence climate/biosphere feedbacks and should be considered in land‐use planning, especially when grassland afforestation is recommended as a tool to mitigate global warming.

The irruption of new agro-industrial technologies in Uruguay and their environmental impacts on soil, water supply and biodiversity: A review

Article

Full-text available

Jan 2009
Int J Environ Health

In recent years, economic growth has produced a global change in the demand for food, fibre and energy supply. This has gone together with the globalisation of the agro-industrial production systems, leading to a qualitative change in land use because of intensive use of technological inputs. Uruguay, just as the other countries of the region, is part of this phenomenon. The massive introduction of forest crops has been made over native grassland ecosystems, replacing traditional productive activities of the post-colonial period. Research on eucalyptus afforestation shows depletion of the ecosystem services associated with grassland and loss of the resilience capacity of the system. Impacts on soil organic matter, soil physicochemical properties, the hydrological cycle and on biodiversity are analysed. This review (with emphasis on Uruguay and the River Plata Basin) tries to contribute to an integrated vision of the environmental consequences of current land-use change. 176 C. Céspedes-Payret et al., D. (2009) 'The irruption of new agro-industrial technologies in Uruguay and their environmental impacts on soil, water supply and biodiversity: a review', Int. international journals, books and chapters of books and papers in national and international conference proceedings. His research interests include fields such as environmental topics, physical geography, natural resources and edaphology.

Land use change in a temperate grassland soil: Afforestation effects on chemical properties and their ecological and mineralogical implications

Article

Full-text available

Oct 2012

The current change in land use of grassland in the temperate region of South America is a process associated with the worldwide expansion of annual crops and afforestation with fast growing exotic species. This last cultivation has particularly been the subject of numerous studies showing its negative effects on soil (acidification, loss of organic matter and base cations, among others). However its effects on the mineral fraction are not yet known, as it is generally considered as one of the slowest responses to changes. This stimulated the present study in order to assess whether the composition of clay minerals could be altered together with some of the physicochemical parameters affected by afforestation. This study compares the mineralogical composition of clays by X-ray diffraction (XRD) in a grassland soil (Argiudolls) under natural coverage and under Eucalyptus grandis cultivation implanted 25years ago in a sector of the same grassland. The tendency of some physicochemical parameters, common to other studies was also compared. XRD results showed, as a most noticeable difference in A(11) and A(12) subhorizons (~20cm) under eucalyptus, the fall of the 10Å spectrum minerals (illite-like minerals), which are the main reservoir of K in the soil. Meanwhile, the physicochemical parameters showed significant changes (p<0.01) to highly significant ones under eucalyptus, particularly in these subhorizons, where on average soil organic matter decreased by 43%; K(+) by 34%; Ca(2+) by 44%, while the pH dropped to this level by half a point. Our results show that the exportation of some nutrients is not compensated due to the turnover of organic forestry debris; the process of soil acidification was not directly associated with the redistribution of cations, but with an incipient podzolization process; the loss of potassium together with soil acidification, leads to a drastic change in clay mineralogy, which would be irreversible.

Extractivismo agrario en América Latina

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Nov 2022

Extractivismo Forestal - Uruguay

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Jan 2022

La purga agroextractivista en Guatemala.: ¿Hacia un futuro renovable pero insufrible?

Chapter

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Jan 2022

Alberto Alonso-Fradejas

ANÁLISE DE IMAGEM APLICADA AO MONITORAMENTO DA FERRUGEM DA SOJA

Chapter

Jun 2022

The global standard bearers of soil governance

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Feb 2022

Lewis Ross Peake

The need for effective governance of soil resources is critical. This article outlines five levels of national soil governance against which states may assess themselves and highlights those the authors consider to be in the top category. Responding to the question Which countries or political states can be viewed as ‘global standard bearers of soil governance?’ it describes exemplars of national and subnational best practice that, if widely emulated, could significantly improve the condition of land and soil globally.

Temperate Grassland Afforestation Dynamics in the Aguapey Valuable Grassland Area between 1999 and 2020: Identifying the Need for Protection

Article

Full-text available

Dec 2021

Temperate grasslands are considered the most endangered terrestrial ecosystem worldwide; the existent areas play a key role in biodiversity conservation. The Aguapey Valuable Grassland Area (VGA), one of the most well-preserved temperate grassland areas within Argentina, is currently threatened by the anthropogenic expansion of exotic tree plantations. Little is known about the impacts of afforestation over temperate grassland landscape structures; therefore, the aim of this study is to characterize Aguapey VGA landscape structural changes between 1999 and 2020 based on remotely sensed data. This involves the generation of land cover maps for four annual periods based on unsupervised classification of Landsat 5 TM and 8 OLI images, the estimation of landscape metrics, and the transition analysis between land cover types and annual periods. The area covered by temperate grassland is shown to have decreased by almost 22% over the 20 year-period studied, due to the expansion of tree plantation cover. The afforestation process took place mainly between 1999 and 2007 in the northern region of the Aguapey VGA, which led first to grassland perforation and subsequently to grassland attrition; however, Aguapey’s cultural tradition of cattle ranching could have partially inhibited the expansion of exotic trees over the final years of the study. The evidence of grassland loss and fragmentation within the Aguapey VGA should be considered as an early warning to promote the development of sustainable land use policies, mainly focused towards the Aguapey VGA’s southern region where temperate grassland remains the predominant land cover type.

Life purging agrarian extractivism in Guatemala

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Apr 2021

Alberto Alonso-Fradejas

Agrarian extractivism in the Brazilian Cerrado

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Apr 2021

Influence of land use on distribution of soil n -alkane δD and brGDGTs along an altitudinal transect in Ethiopia: Implications for (paleo)environmental studies

Article

Jun 2018
ORG GEOCHEM

The combined use of plant wax n-alkane δD values and branched glycerol dialkyl glycerol tetraether lipid (brGDGT) distributions provides a novel approach for paleoaltitude reconstruction. Studies from East Africa revealed, however, inconsistent results between the proxy estimates and altitudinal parameters. Here, we explore these proxies in soils of different land use (forest, cropland and pasture) along an altitudinal transect in the Jimma zone of the southwest Ethiopian highlands to better understand environmental and plant-specific factors controlling the isotopic composition and distribution of n-alkanes and brGDGTs. The hydrogen isotope composition of individual n-alkanes does not unambiguously reflect the altitude effect on precipitation δD, but seems largely influenced by the specific land use. Only forest soil-derived n-C27 and n-C29 alkane δD values exhibit a significant linear relationship with altitude (r −0.87, p < 0.05), likely reflecting the most stable ecosystem. The resulting lapse rate of −17‰/1000 m is comparable with that of local precipitation in the southwest Ethiopian highlands. In addition, the linear correlation of the average chain length (ACL) and δ¹³C values of forest soil n-alkanes suggests a physiological adaptation of the specific plant type waxes to altitude-induced environmental changes in the study area. The distribution of brGDGTs also reveals a significant linear correlation with altitude (r −0.97, p < 0.01), reflecting the decrease in temperature with higher elevation, independent of land use. In addition, brGDGT-based mean annual air temperature (MAT) estimates of 19.5–14.0 °C and temperature lapse rate of −6 °C/1000 m are in good agreement with direct measurements in the Jimma zone. In contrast to previous studies from East Africa, our results show that both soil n-alkane δD values and brGDGT-based MAT distributions track present day altitude effects on local environmental gradients in the southwest Ethiopian highlands.

Riparian reforestation with a single exotic species restores soil aggregation and porosity but not humic substances

Article

Mar 2018

A degraded riparian area in the Uberaba River basin (Brazil) was restored by local landowners using a monoculture of the exotic species Syzygium cumini (L.) Skeels over 15 years. To assess this riparian restoration, we compared this experimental site (ES) with a disturbed site (DS) and a preserved site (PS) with regard to soil organic matter, humic and fulvic acids (HA and FA), glomalin, soil aggregation and porosity. The results did not show significant differences between ES and PS with regard to soil aggregation and porosity. The cation exchange capacity and the HA and FA contents of ES were significantly different from those in PS and DS. Whereas the HA content of ES was less than that in PS, FA was significantly increased. The order of aromatic composition of humic substances by site was PS > ES > DS and contrasted with the aliphatic composition, which was DS > ES > PS. A principal component analysis based on all variables demonstrated that ES was closer to PS than to DS but that there was no overlap among sites, as PS was driven by humic aromatic substances and the experimental site by fulvic and aliphatic compounds. We concluded that there was a functional recovery of ecosystem services related to soil aggregation and porosity, but the qualitative differences in organic matter formation between the restored and preserved sites were not consistent with ES being fully restored.

Empowering Small Farmers in India through Organic Agriculture and Biodiversity Conservation

Article

Full-text available

Jan 2012

Anna Marie Nicolaysen

"Empowering Small Farmers in India through Organic Agriculture and Biodiversity Conservation" investigates how, through conversion to organic agriculture, with its postulated socioeconomic, environmental and health benefits, and through biodiversity conservation, by, for example, creating community seed banks, local farming organizations enable and empower small farmers to become independent and self-sufficient. Local farming organizations are defined as movements to improve the economic, health, and social status of independent farmers in the face of global agribusiness through the adoption of sustainable agriculture. I explore the philosophy of these organizations; the agricultural and political ideas they transmit; the challenges they face in involving small farmers; and how farmers who become involved assess this experience. ^ Fieldwork for this study was carried out during 2007 and 2008 in the Indian states of Punjab, Uttarakhand, Tamil Nadu, and West Bengal. Living in villages in these states—approximately three months per state—I completed 89 in-depth and 16 focus group interviews with female and male farmers, and with the farming organizations' staff, for a total of 250 participants. Interviews and field observations, primarily those carried out in Punjab and Uttarakhand, constitute the data for this dissertation. ^ I found that farmers who get involved with these organizations do perceive that their food security is improved through conservation and the revival of traditional crops. Additionally their economic situation is strengthened with less expenditure on inputs such as seed, chemical pesticides, or mineral fertilizers. Finally, it is argued, training provided by these organizations prepares farmers, many of whom become more self-reliant and confident individuals, to stand up for their democratic rights in the midst of the formidable power of globalized corporate agriculture. ^ This study contributes to a growing understanding among small farmers, researchers and international human rights and farming-focused organizations (e.g., the United Nations Human Rights Council and the Food and Agriculture Organization), of how reinvestment in sustainable agriculture is vital to the realization of the right to food, and to rural economic development, issues that were accentuated by the 2008 global food price crisis and current return to a pattern of rising food prices that are reaching 2008 levels.

The Effect of Earthworms on the Physiological State of the Microbial Community at Vermicomposting

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Full-text available

Jul 2009
Mikrobiologiya

Floristic of the ecosystems of Campus Carreiros, Rio Grande, Rio Grande do Sul, Brazil

Article

Full-text available

Jun 2013

The Campus Carreiros of the Rio Grande Federal University is an area of 227 hectares and vegetation is distributed in natural and anthropized ecosystems. We conducted a survey of vegetation taking into account the classification of the species as their origin and their distribution in different ecosystems found on this Campus. The flora was composed of 392 species distributed in 286 genera and 101 families. Families with the highest number of species were Asteraceae, Poaceae, Fabaceae and Cyperaceae. The predominant life form was herbaceous presenting a relationship with the field which was the area's prevailing ecosystems. Concerning the origin, 266 (68%) native and 126 (32%) exotic species were recorded. The ecosystems presented differentiat richness, regarding the species number the garden areas (128), swamps (110), fields (103), anthropized fields (95), lakes (63), dunes (58) and exotic tree monocultures (31). Among these eight threatened species were found, mainly in the swamp ecosystems. The survey has shown greater richness of native species in swamp ecosystems and in fields.

Forestry

Chapter

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Jan 2007

Does Acacia dealbata express shade tolerance in Mediterranean forest ecosystem of South America?

Article

Full-text available

Jul 2015

The distribution of Acacia dealbata Link (Fabaceae) in its non-native range is associated with disturbed areas. However, the possibility that it can penetrate the native forest during the invasion process cannot be ruled out. This state- ment is supported by the fact that this species has been experimentally estab- lished successfully under the canopy of native forest. Nonetheless, it is unknown whether A. dealbata can express shade tolerance traits to help increase its invasive potential. We investigated the shade tolerance of A. dealbata under the canopy of two native forests and one non-native for three consecutive years, as well as its early growth and photosynthetic performance at low light intensi- ties (9, 30, and 70 lmol m!2sec!1) under controlled conditions. We found many A. dealbata plants surviving and growing under the canopy of native and non-native forests. The number of plants of this invasive species remained almost constant under the canopy of native forests during the years of study. However, the largest number of A. dealbata plants was found under the canopy of non-native forest. In every case, the distribution pattern varied with a highest density of plants in forest edges decreasing progressively toward the inside. Ger- mination and early growth of A. dealbata were slow but successful at three low light intensities tested under controlled conditions. For all tested light regimes, we observed that in this species, most of the energy was dissipated by photo- chemical processes, in accordance with the high photosynthetic rates that this plant showed, despite the really low light intensities under which it was grown. Our study reveals that A. dealbata expressed shade tolerance traits under the canopy of native and non-native forests. This behavior is supported by the effi- cient photosynthetic performance that A. dealbata showed at low light intensi- ties. Therefore, these results suggest that Mediterranean forest ecosystems of South America can become progressively invaded by A. dealbata and provide a basis for estimating the possible impacts that this invasive species can cause in these ecosystems in a timescale.

Forestry

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Jan 2007

Above-ground carbon absorption in young Eucalyptus globulus plantations in Uruguay

Article

Full-text available

Mar 2014

Absorção aérea de carbono em plantações jovens de Eucalyptus globulus no Uruguai Resumo Carbon absorption in young Eucalyptus globulus Labill plantations was quantified in four sites in the western region of Uruguay: Algorta, Bequeló, Quebracho and Tres Bocas. Plantation densities varied from 733 to 1300 trees ha -1 , and ages ranged from three to nine years. We selected 132 trees from twenty 300 m² circular plots. Each tree was divided into four components: tree bole, live branches, dead branches, and leaves, and carbon content was determined for each component. Total above-ground carbon content was calculated by adding the carbon content of the four components. We evaluated 20 allometric function types to predict carbon absorption: one function per site, eight global functions for all sites combined, and eight global functions including a dummy variable to implicitly identify sites. For all components, carbon absorption functions that included diameter at breast height (dbh) and tree height as explanatory variables provided the smallest standard error of estimate (SEE) on all sites. The mean SEE of all sites was 3.89 Kg C for total above-ground carbon absorption, and 3.84, 1.06, 1.26, and 0.59 Kg C for tree bole, leaves, live branches and dead branches respectively. An ANOVA test indicated significant differences in the mean annual increment (MAI) of carbon absorption among the four sites, with Bequeló and Tres Bocas having the largest carbon absorption rates followed by Quebracho and Algorta. The ANOVA test included plantation density as a covariate, which was significant only for the tree bole and total above-ground. Abstract O objetivo do presente trabalho foi quantificar a absorção de carbono em plantações de Eucalyptus glo-bulus em quarto zonas localizadas no litoral oeste da República Oriental do Uruguai (Algorta, Bequeló, Quebracho e Tres Bocas), as densidades de plantação variavam de 733 a 1.300 árvores ha

Saltmarsh soil evolution after land reclamation in Atlantic estuaries (Bay of Biscay, North coast of Spain)

Article

Feb 2010
GEOMORPHOLOGY

Tidal wetland soils exhibit particular physical–chemical properties governed mainly by tidal dynamics. On the Atlantic seaboard of the Iberian Peninsula a great swath of tidal wetlands, which correspond to semi-confined estuaries, represents land reclaimed from the 18th century to the first half of the 20th century and used for urban development or agricultural production. These interventions led to the end of tidal flooding in extensive areas of salt marshes, causing a drop in the water table that triggered pyrite oxidization processes, leaching of cations and salts and soil acidification. In many cases, these transformations have given rise to environmental problems such as the development of acid sulphate soils, a resulting decrease in pH, and the leaching of carbonates. The organic carbon storage capacity has also been altered, and the release of metal cations from sediments has caused toxic waters to appear.In order to investigate the alterations caused by the historic reclamation of estuarine soils on the north coast of Spain, natural and reclaimed lands were mapped in two estuaries (Villaviciosa and San Vicente de la Barquera) and zoned in accordance with flood frequency.The different evolutionary paths of the two studied estuarine sites after reclamation can be assessed through the description and analysis of their soils despite reclamation, some parts (i.e. lower areas) of the reclaimed lands do not remain fully isolated from tidal dynamics, whose influence varies throughout the soil profiles that have developed since. The strength of the morphological (e.g. genetic horizons), chemical (pH, metal cation concentration) and functional (balance of the carbon budget) changes suffered by the original soils seem to depend strongly on the remaining tidal influence as well as the land use of the area.

Environmental management tools for basins with forest plantations: advances and proposals (Chapter: 3.9)

Conference Paper

Full-text available

Mar 2010

Carbon Stocks and Fluxes in Rangelands of the Río de la Plata Basin

Article

Jan 2010

Los pastizales son uno de los ecosistemas terrestres que más modificaciones han sufrido. Los cambios en el uso del suelo han tenido un gran impacto sobre los depósitos y flujos de C. Comprender el impacto de los cambios en uso y cobertura del suelo es crítico a la hora de evaluar el potencial de los pastizales de retener C. En este trabajo analizamos los flujos y depósitos de C a lo largo de los gradientes ambientales de una de las áreas de pastizales templados más extendidas: los Pastizales del Río de la Plata en Sudamérica. El análisis resume la información provista por estudios de campo, teledetección y simulaciones con modelos. La Productividad Primaria Neta Aérea (PPNA) varió entre 240 y 316 g C · m−2 · año−1. La PPN subterránea fue más variable que la PPNA, cubriendo un rango de valores entre 264 y 568 g C · m−2 · año−1. El C total varió entre 5 004 y 15 008 g C · m−2. En promedio, un 13% de ese C correspondió a biomasa vegetal. La contribución de la biomasa vegetal varió entre 9.5% y 27%. El depósito de C vegetal más importante fue el subterráneo. La biomasa verde aérea representó menos de un 7% del C vegetal. El C orgánico del suelo (COS) se concentró en los compartimentos pasivos y de dinámica lenta. El depósito activo de la materia orgánica edáfica representó sólo el 6.7% del COS. El conocimiento de la dinámica y los depósitos de C en la región es aún parcial e incompleto. Las estimaciones de PPNA y PPNB son escasas y no se basan en un protocolo de medición común. Las técnicas de teledetección tienen el potencial para generar una base de datos de PPNA consistente y espacialmente explícita. Sin embargo, es necesario mejorar las estimaciones de la variabilidad espacial y temporal de la eficiencia en el uso de la radiación. La falta de una red de torres de medición de flujos restringe la posibilidad de monitorear cambios estacionales en las ganancias de C y de entender los controles de la dinámica del C a escala detallada.

The effect of earthworms on the physiological state of the microbial community at vermicomposting

Article

Full-text available

Aug 2009

The effect of earthworms on the microbial community of composts and vermicomposts was assayed by the following parameters: mineralization activity, the levels of physiologically active and growing microbial biomass, the requirement for growth factors, and the spectrum of assimilation of organic substrates by the microbial community. The substrate affinities of microbial enzyme systems in vermicompost were found to be lower than in compost without earthworms, which is evidence of a higher amount of r-strategists in the microbial community of vermicomposts. Physiologically active biomass of microorganisms is higher in peat-based vermicompost than in compost. The microorganisms of vermicomposts and composts experience deficiency in growth factors to a lesser extent than the microorganisms in soil. The presence of earthworms influences the physiological diversity: the Shannon index increases or decreases depending on the type of composted substrate and incubation time. The growth rate of microorganisms increases on various test substrates in the presence of worms.

Действие дождевых червей на физиологическое состояние микробного сообщества при вермикомпостировании

Article

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Jan 2009

Contribution of Working Group I to the Fourth Assessment Report of the IPCC

Article

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Jan 2007

Forestry

Article

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Jan 2007

Method for determining microbial activity (hydrolysis of fluorescein diacetate (FDA), 490 nm)

Article

Full-text available

Sep 2022

Fluorescein diacetate (FDA) is used to determine microbial activity. The determination of this activity can be carried out within the frame of various study objects using soil, litter, peat, etc. This method is based on a hydrolysis reaction of converting fluorescein diacetate (FDA) to fluorescein. The concentration is usually determined using a spectrophotometer in the UV range. This article discusses the possible concentration of fluorescence in the visible spectrum (490 nm). The activity of microorganisms was determined in the Chernozem typical arable horizon. The work used two methods for determining the concentration of fluorescence by optical density. The first option is to use a calibration concentration (the dependence of optical density on the concentration of fluorescein). In this case two options were used: with heating (60 °C) and without it (25 °C). The second option is to use the Bouguer-Lambert-Beer equation and the extinction coefficient. The results were used for calculating the Michaelis-Menten constants ( K m) and the maximum reaction rate ( V m). While determining the microbial activity with FDA, the concentration of fluorescein can be determined in the visible range. The more preferable way of determining the concentration of fluorescein is by using the extinction coefficient of fluorescein, rather than by plotting a calibration graph based on matrix solutions.

Cuantificación de los cambios en el contenido y distribución de carbono orgánico del suelo por efecto del cambio de uso pastoril a forestal en plantaciones de Eucalyptus grandis Hill ex Maiden y Pinus taeda L. Free download at: https://hdl.handle.net/20.500.12008/8769

Thesis

Full-text available

Dec 2014

Fabián Del Giorgio

The global concern about the increase of greenhouse gases blamed for global warming has focused interest in the study of forest systems. There’s few information about the ability of forest plantations in Uruguay to sequester carbon in soil organic matter (SOM). In order to assess such changes, two studies were performed: i) in five plantations of Eucalyptus grandis Hill ex Maiden of 17-18 years old at the west coast soils, at Caja Bancaria’s field; and ii) a stand density experiment (816, 1111 and 2066 plants ha-1) of E. grandis Hill ex Maiden and Pinus taeda L. 8 years old, in northeastern soils at Los Moros´s field. At each site a stratified sampling soil 0-5, 5-10, 10-15, 15-20 and 20-30 cm was performed in forest plantation and in the ground with native grass. It was also sampled from 30 to 50 cm in Caja Bancaria’s site. Soil organic carbon (SOC) isotopic ratios 13C/12C was performed. SOC concentration (g C kg-1) and total SOC stock (Mg C ha-1) of each soil management and soil sampled stratum was calculated. Based on the relationships 13C/12C the proportion of SOC from forest vegetation was calculated. There were no significant differences between afforested soils and native pasture soils managements in SOC concentrations or stocks at Caja Bancaria’s site. However, at 0-5 and 30-50 soil stratums, a trend toward higher values of SOC under forest management was observed. δ13C values of afforested soil at Caja Bancaria’s place were significantly more negative at the depths of 0-5 and 5-10 cm, showing the contribution of E. grandis mulch (C3) to SOC from pasture soils. α(%) values showed a contribution from E. grandis vegetation to SOC of 37,3 % in the first 5 cm (5,66 Mg C ha-1), having replacement and gain on the total SOC. At Los Moros there was a trend to minor concentrations of SOC on afforested soils than under native pasture soils. As to the C input of new vegetation (δ13C) in the layer of 0 to 5 cm, there were significant differences for EU2066 (E. grandis 2066), but PI816 (P. taeda 816) was different at all depths. No significant differences between afforested and grazing management for total SOC stock were found. For comparison between the three pine and eucalyptus densities at the three measured variables, significant differences for E. grandis with different planting densities (tree spacing) were found at different dephts. After 17 years the new vegetation (E. grandis) compensates the loss of SOC from the original vegetation of the site, occurred during the early years of the plantation system. As in the experiment of plantation densities of pine and eucalyptus, statistical differences between E. grandis forest soils at different plantation densities and the originally pastoral land for the SOC stock were found, it can be concluded that the equilibrium level of this parameter will depend upon the afforested soil rotation time, the planting density, and the tree species.

Study of the Site Class Index Chart of Larch Plantation Based on the Mitscherlich Model1

Article

Full-text available

Feb 2021

In this paper, 196 plots and 460 larches were selected as the material, and analyzed the oriented exponential order site class index curve model of larches located at Wangyedian in Chifeng City, Inner Mongolia. The forestal statistical analysis software (SPSS 18.0) was used to data fitting and analytic comparison of larch plantation data. The results showed that: the oriented Mitstcherlich curvilinear function was the more appropriate model of oriented larch plantation site class index curve after comprehensive considering of fitting accuracy, curve trend, distribution trend of sampling points and residual distribution. Based on regressive Mitstcherlich model, the paper selected 30a larches planted and operating level confirmed the exponential distance is 2m with 12 exponential orders, and then drew the site class curve cluster. Furthermore, the 12 exponential orders site class index table of larches located in Wangyedian, Chifeng City, Inner Mongolia was worked out.

Eucalyptus viminalis L. EN EL ÁREA DE VENTANIA: EFECTOS SOBRE ALGUNAS PROPIEDADES EDAFICAS SUPERFICIALES Eucalyptus viminalis L. IN VENTANIA: EFFECTS ON SOME SURFACE SOIL PROPERTIES

Article

Full-text available

Jul 2019

La implantación de especies forestales en ambientes carentes de árboles contribuye a la mitigación del cambio climático global, debido a que constituye un método efectivo de captura de CO2. Sin embargo, también puede tener un impacto ambiental negativo generando una pérdida de calidad del suelo. Los objetivos de este trabajo fueron: i) evaluar algunas propiedades físicas y químicas de los horizontes minerales superficiales de los suelos (0-20 cm) del área de Ventania bajo montes de Eucalyptus viminalis L. (EV) y vegetación natural graminosa (situación de referencia, PN), y ii) determinar si las variaciones en las propiedades del suelo dentro de los rodales se asocian a la influencia circular de los árboles individuales. Bajo EV se observaron valores de 30,0 g kg-1 y 12,1 g kg-1 de carbono orgánico total (COT) y particulado grueso (COPg), mientras que en PN los mismos fueron 12,0 g kg-1 y 3,6 g kg-1, respectivamente. Por otra parte, en relación a los valores obtenidos para PN, bajo los árboles se produjo una disminución significativa de pH (5,8 vs 6,4) y aumentos de fósforo extractable (Pe) (37,7 vs 2,7 mg kg-1). No se detectaron efectos de la forestación sobre la estabilidad estructural del suelo. Además, en esta investigación se observó que los árboles individuales dentro del monte forestal dan lugar a una variabilidad espacial de las propiedades del horizonte superficial del suelo, con un aumento progresivo y significativo en los contenidos de COT y Pe desde los 2 m hacia el eje de los árboles, y disminuciones en el pH y en las relaciones COT/COPg en la misma dirección. En la región, la forestación con eucaliptos tuvo un impacto positivo sobre el secuestro de C en los suelos en el mediano-largo plazo. Sin embargo, las alteraciones del pH observadas en los horizontes superficiales señalan la necesidad de continuar con el monitoreo de los efectos negativos de su implantación sobre el recurso suelo.

Prioridades Geográficas para la Conservación de la Biodiversidad Terrestre de Uruguay

Book

Full-text available

Jul 2008

Brazeiro Alejandro

Se realiza un estudio de priorización espacial para la conservación de la biodiversidad terrestre de Uruguay, en el marco de la aproximación ecoregional. Se analiza la distribución de la riqueza de especies (plantas leñosas y vertebrados terrestres), especies amenazadas, regiones biológicas, grado de pérdida de ecosistemas naturales, y la distribución de las áreas protegidas implementadas, para generar un propuesta de áreas prioritarias para la conservación.

Implementación de un complejo forestal Industrial, ¿una política de Estado? Estudio de caso: Uruguay

Technical Report

Full-text available

Jan 2014

La forestación con fines industriales en Uruguay, ha tenido un desarrollo explosivo a partir de la década de 1990, y más recientemente se ha asociado a la producción de celulosa y al mercado de “bonos de carbono”. En el presente artículo, se analizan, las condicionantes históricas del país, tanto culturales, como socio‐políticas y ambientales, tanto nacionales como supranacionales que las promovieron, así como los impactos ecológicos y económicos en el corto y mediano plazo, analizados desde la perspectiva de los servicios ecosistémicos y de bienes transables. Lo que a todas luces parecía ser una política de Estado persistente en el tiempo, para el desarrollo de una cadena productiva agrícola, que atraviesa varios gobiernos democráticos y una dictadura; a través de este trabajo se explícita, que en realidad el proceso es el resultado de una transferencia de políticas de las agencias multilaterales y bilaterales de cooperación y crédito, en el marco de sus estrategias para abaratar costos de materia primas, cuya producción involucra una alta externalidad ambiental.

Potenciales impactos del cambio de uso de suelo sobre la biodiversidad terrestre de Uruguay

Chapter

Full-text available

Jan 2008

One of the major global challenges facing the modern Man, is the colossal loss of biodiversity that has been hit the planet. There are no doubts that land use and land 8 cover change (LULC), the most important component of global change, is primarily responsible for the current crisis of biodiversity. In South America, while deforestation in tropical and subtropical forests is the most studied LULC type, in the temperate region the rate of substitution of natural prairies by crops is alarming. Uruguay, with exponential growth of the soybean and forestry areas, was not immune to this regional reality. The purpose of this study was to assess the potential impact of LULC derived from agricultural expansion, on terrestrial biodiversity of Uruguay, especially on "hot spots" of tetrapods diversity (i.e., sites of greater diversity by bioregion). Analyzing satellite images, we found in some regions, reduction of natural areas in "hot spots" of about 50%. According to the simulation of a potential LULC scenario, based on the maximum expansion of soybean cultivation and forestry, four of the six bioregions of the country would register significant impacts on habitat loss in "hot spots". At these sites, just a remnant of 36-50% of the original natural surface would persist. As economic pressures to expand the agroforestry border remain and might even increase, it is urgent to take measures to conserve the prairie ecosystem in Uruguay and the region, where the representation of these environments in national systems of protected areas is highly insufficient.

Geoarqueología y biogeografía: el registro de cuevas en Pali Aike

Chapter

Full-text available

Oct 2007

INTRODUCCIÓN En este trabajo exploramos el aporte de la geoarqueología para discusiones sobre biogeografía humana a par-tir de un caso procedente del campo volcánico Pali Aike (CVPA), localizado en Patagonia meridional. Los temas biogeográfi cos generales con los cuales se vincula nuestro trabajo geoarqueológico específi co incluyen los patrones de circulación e instalación humana entre espacios costeros e interiores, la jerarquización del espacio, que está re-lacionada con la distribución espacial de los nodos demográfi cos o de asentamiento humano, y el cambio temporal en estas variables (Borrero 2002; Borrero y Barberena 2006). Un enfoque biogeográfi co sobre la conducta humana implica integrar evidencias procedentes de distintos sec-tores del espacio, en contextos geomorfológicos variables que condicionan modos tafonómicos particulares para la depositación y preservación de restos orgánicos e inorgánicos. En este proyecto, el aporte de la geoarqueología a los temas mencionados se cristaliza a partir del trabajo en dos líneas de evidencias geoarqueológicas. La primera de ellas, que no es profundizada aquí, se dirige al análisis del registro de superfi cie y estratigrafía procedente de contextos a cielo abierto (Barberena 2006; Barberena y Borrero en prep.). El trabajo en espacios abiertos se articula a partir del estudio del registro pedogenético en contextos de la costa (p.e. Cabo Vírgenes, ver Favier Dubois y Manzi 2002; Favier Dubois 2003; Barberena y Borrero en prep.) y el interior, como el CVPA (Bar-berena 2006). Esto permite evaluar la estabilidad de diferentes sectores del paisaje y aporta parámetros cronológicos y formacionales para la interpretación del registro estratifi cado y en superfi cie. Provee, a su vez, una medida de gran utilidad para correlacionar con la tafonomía regional de los espacios litorales y del interior del continente. El segundo nivel de trabajo se relaciona con las evidencias recuperadas en reparos rocosos, como cuevas y ale-ros. El CVPA constituye un paisaje de cuevas (Martin y Borrero 2004), que aportan condiciones adecuadas para la formación de secuencias estratifi cadas. Estas secuencias son importantes tanto desde una perspectiva biogeográfi ca como geoarqueológica. El nexo entre el registro de estas secuencias y las preguntas biogeográfi cas está dado por la intensidad ocupacional humana. Al evaluar la intensidad de las ocupaciones en localidades con propiedades geográfi cas diferentes, comen-zamos a comprender la jerarquía de diferentes espacios en términos de circulación e instalación de las poblaciones humanas (ver Bailey y Davidson 1983). Un paisaje arqueológico de señales variables de intensidad ocupacional puede ser traducido en términos de nodos demográfi cos y zonas marginales (Borrero 2004). Sin embargo, los restos materiales no pueden interpretarse directamente en términos de intensidad de ocupaciones. Para evaluar la intensidad de presencia humana que denota un conjunto se debe estimar el tiempo implicado en la formación del depósito que lo contiene, o su resolución temporal (Farrand 1993; Otte et al. 2003). Esto se realiza a partir de análisis cronológicos y formacionales y en nuestro caso implica el estudio de los procesos de sedimentación predominantes en diferentes sectores del campo volcánico. Por la amplia variabilidad de reparos que contiene, Pali Aike constituye un 'laboratorio' apropiado para el análisis de las condiciones que determinan la historia sedimentaria de diferentes sitios. A su vez, los estudios sedimentológicos aportan evidencias sobre las condiciones climáticas cualitativas imperantes en el momento de formación de un depósito. Desarrollamos estos argumentos a partir de un caso de estudio en escala de sitio que corresponde a la localidad Cóndor, ubicada en el sector meridional del CVPA. De aquí proceden conjuntos líticos y faunísticos que están siendo actualmente estudiados

Ecosystem services and tree plantations in Uruguay: A reply to Vihervaara et al. (2012)

Article

Sep 2012
FOREST POLICY ECON

José Paruelo

The expansion of industrial tree plantations in South America is a case of land transformation that has already generated conflicts at the local, national and international levels. In a recent article, Vihervaara et al. (2012) present a controversial analysis, mainly for the potential use of some of their results; they suggest that the general attitude among the local people toward an increment in tree plantations and toward the forest industry is positive. In this article I discuss the results and conclusions of the Vihervaara et al. article, particularly those related to the definition of the ecosystem services concept, the definition of stakeholders and the approaches to deriving their perception, and the available evidence on the impacts of grassland afforestation in Uruguay.

Hydrolase activity as an indicator of the state of microbial communities in vermicomposts

Article

Jun 2009

The hydrolase activity was studied using the fluorescein diacetate (FDA) hydrolysis assay in order to assess the microbial activity in composts and vermicomposts obtained with participation of Eisenia fetida andrei, Aporrectodea caliginosa, and A. rosea earthworms from cattle manure, leaves, and peat. The hydrolase activity (the Michaelis—Menten constant, K m ) was found to be lower in the vermicomposts than in the composts and correlated with a corresponding decrease in the length of fungal hyphae. The determination of the hydrolase activity according to the reaction of FDA hydrolysis may be recommended to control the process of vermicomposting and the quality of vermicomposts. Thus, the process of vermicomposting may be characterized with the use of the functional (hydrolase activity) and structural (microbial biomass, length of fungal hyphae) approaches.

Effects of gaseous emissions from the Namakwa Sands Mineral Separation Plant near Lutzville on the adjacent succulent Karoo vegetation : a pilot study

Article

Jan 2006

Beatice M. K. Lukama

A pilot study was conducted at the Namakwa Sands Mineral Separation Plant, to investigate the effects of acidic gaseous emissions from the Mineral Separation Plant on the adjacent Succulent Karoo vegetation. Sulphuric acid fumes, a major gaseous emission of the mineral processing, was the subject of investigation of the present study, due to the potential high negative impact of elevated concentrations thereof on vegetation in the ecosystem. Permanent sample plots along three transects radiating from the Mineral Separation Plant were laid out in the eastern, south-eastern and southern directions following the prevailing wind directions and practical consideration of land accessibility. The ecological components assessed as indicators of possible pollution levels in the environment included percentage plant mortality, foliar sulphur content of selected plant species, chemical composition of solubles in mist and dust samples, and soil pH. In addition, the vegetation was screened for plant species suitable to be used as potential bioindicators. Potential bioindicator plant species were selected on the basis of their relatively wide distribution in the study area and apparent sensitivity to the ambient air pollutants. The percentage of dead plants of each species that occurred on the sample plots was used as a criterion of the possible sensitivity of the plant species towards air pollution. The bioindicator plant species selected for potential monitoring purposes were: Galenia fruticosa, Lampranthus suavissimus, Lycium ferocissimum and a Ruschia sp. (SP 9). Plant mortality was greater nearer the emission source, with 28 + 5 % dead plants at 400 m, 19 + 6 % at 800 m and only 10 + 4 % at 1,200 m from the Mineral Separation Plant. Data summed for all species recorded and pooled for all three transects per sampling distance. With the methods used in this study, in the case of all sample plots on the three transects, no significant difference was found between the mean pH values of soil samples collected from open spaces without plant cover (8.01 + 0.46) and those collected underneath shrubs (8.91 + 0.96). Subsequently only the pH values of soil samples collected on open spaces were used to investigate the variation in soil acidity with distance and direction from the emission source. The means represent total number of samples from open space versus those collected from underneath shrubs. The pH of soil samples increased with distance from the emission source along the transects to the south and south-east of the emission source. Eastward of the emission source, soil pH values remained relatively low at all sample distances. This pilot study could not determine whether the continuous acidity of the soil along the eastern transect in the direction of the prevailing wind, was caused by increased deposition of gaseous emissions on the higher lying hilly terrain in this area, or by the underlying geology. Ion chromatographic analysis of mist and dust samples collected on each sample plot indicated the presence of several chemicals that had probably originated from the gaseous emissions from the Mineral Separation Plant as well as wind blown constituents from the adjacent surroundings of the sample plots. Of these chemicals, only the sulphate concentrations of the mist and dust samples were further evaluated, since that could be related to the emission of sulphuric acid fumes by the Mineral Separation Plant. Results indicated that the mean sulphate concentration of mist and dust samples collected from sample plots relatively close to the Mineral Separation Plant, 118.8 + 31.6 mg/litre (400 m), were higher than further afield, decreasing to 57 + 30.1 mg/litre at 800 m and 43.1 + 19.6 mg/litre at 1,200 m. These values, representing the mean sulphate concentrations of mist and dust samples at each sampling distance (data of the three transects pooled), differ significantly at the 85 % confidence level. Statistical evaluation of the data of the mist and dust pH measurements, pooled for the three transects on the basis of distance, indicated a gradual increase of the mean values from 400 m (7.3 + 0.26), through 800 m (7.7 + 0.34), to 1,200 m (8.2 + 0.83), although these values were not significantly different. A decreasing trend in accordance with that in the case of the sulphate concentrations of mist and dust samples with distance from the mineral processing plant, was also observed in the sulphur content of the leaves of selected plant species, with mean sulphur content higher at 400 m sampling distance (0.29 + 0.091 %) than at 800 m (0.264 + 0.086 %) and a further decline at 1,200 m (0.232 + 0.079 %), data of the three transects pooled. However, these values were also not significantly different. Although not significantly so, the decreasing trend in the results of the sulphate concentration of mist and dust samples, the sulphur content of plant leaf samples as well as plant mortality observed, and increasing soil pH values with distance from the Mineral Separation Plant, suggest that the gaseous emissions from the Mineral Separation Plant could probably have had a detrimental effect on the adjacent Succulent Karoo vegetation. A more detailed study is necessary to confirm this trend. In addition it is recommended that in order to clarify the soil pH measurements outcome along the eastern transect that were contradicted by the results of the mist and dust pH measurements, a more intensive survey over a greater distance (at least further than 1.2 km from the Mineral Separation Plant), be conducted to quantify vegetation damage and acid deposition to the east of the emission source. Thesis (MSc (Conservation Ecology and Entomology)--University of Stellenbosch, 2006.

Influence of mineral nutrients redistribution in eucalyptus plantations on soil properties

Article

Full-text available

Jan 1991

Manuel Madeira

The properties of Dystric Cambisols under Eucalyptus globulus plantations were studied and compared with those found in similar soils under native vegetation, e.g., Quercus suber. The E. globulus plantations accumulate greater quantities of Ca in the above ground biomass and in the organic horizons, and the sum of bases is lower in the soils, than under Q. suber. This is explained essentially by a decrease in the exchangeable Ca as a result of uptake by E. globulus followed by its immobilization in the biomass and organic horizons. These soils have a lower degree of base saturation and a lower pH than the soils under Q. suber. Magnesium follows a pattern similar to Ca in the soils but with less marked differences between the soils. The importance of changes in soils due to E. globulus plantations depends greatly on the intensity of biomass removal and the silvicultural practices. -from Author

Human Domination of Earth’s Ecosystems

Article

Full-text available

Jul 1997

Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial sources combined; more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species on Earth have been driven to extinction. By these and other standards, it is clear that we live on a human-dominated planet.

Changes in soil organic matter characteristics due to reforestation with Eucalyptus globulus, in Portugal

Article

Full-text available

Jun 1989
SCI TOTAL ENVIRON

In southern Portugal, two areas reforested with and a reference area under native vegetation dominated by , were selected. The distribution of humus carbon and nitrogen in these soils was compared by physical and chemical fractionation. All size fractions of soils under had higher C/N ratios than the corresponding fractions of the soil under The studied humic acids had similar elemental composition, except their nitrogen content that was lower in those from soils under . The differences in nitrogen content and aliphaticity were more pronounced when the humin fractions were considered.

Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future

Article

Full-text available

Jul 1999

In the past three centuries, human perturbations of the environment have affected the biogeochemical behavior of the global carbon cycle and that of the other three nutrient elements closely coupled to carbon: nitrogen, phosphorus, and sulfur. The partitioning of anthropogenic CO{sub 2} among its various sinks in the past, for the present, and for projections into the near future is controlled by the interactions of these four elemental cycles within the major environmental domains of the land, atmosphere, coastal oceanic zone, and open ocean. The authors analyze the past, present, and future behavior of the global carbon cycle using the Terrestrial-Ocean-aTmosphere Ecosystem Model (TOTEM), a unique process-based model of the four global coupled biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur. They find that during the past 300 yrs, anthropogenic CO{sub 2} was mainly stored in the atmosphere and in the open ocean. Human activities on land caused an enhanced loss of mass from the terrestrial organic matter reservoirs (phytomass and humus) mainly through deforestation and consequently increased humus remineralization, erosion, and transport to the coastal margins by rivers and runoff. Photosynthetic uptake by the terrestrial phytomass was enhanced owing to fertilization by increasing atmospheric CO{sub 2} concentrations and supported by nutrients remineralized from organic matter. TOTEM results indicate that through most of the past 300 yrs, the loss of C from deforestation and other land-use activities was greater than the gain from the enhanced photosynthetic uptake. Since pre-industrial time (since 1700), the net flux of CO{sub 2} from the coastal waters has decreased by 40%, from 0.20 Gt C/yr to 0.12 Gt C/yr. TOTEM analyses of atmospheric CO{sub 2} concentrations for the 21st century were based on the fossil-fuel emission projections of IPCC (business as usual scenario) and of the more restrictive UN 1997 Kyoto Protocol. By the mid-21st century, the projected atmospheric CO{sub 2} concentrations range from about 550 ppmv (TOTEM, based on IPCC projected emissions) to 510 ppmv (IPCC projection) and to 460 ppmv (TOTEM, based on the Kyoto Protocol reduced emissions).

Long‐term species change in a Uruguayan grassland

Article

Full-text available

Apr 1998
J VEG SCI

This paper reports on species changes which occurred in plots in a Uruguayan grassland after 55 yr of continuous grazing. The study was based on the pioneering work of B. Rosengurtt who sampled 10 plots in 1935; in 1990 we re-sampled five of them. Comparative studies were based on rank-frequency, diversity, evenness and multivariate analyses. Diversity was measured as species richness S, Shannon's index H and its exponential form N = eH, evenness E = N/S and Gini's coefficient of hierarchy G. Species-richness of the plots increased significantly. Species which entered the sites are mostly weedy species, while those that have decreased are mostly palatable forage species. Evenness, however, remained constant. Floristic change was chiefly associated with time, and secondarily with plot soil-type. During the 55 yr that elapsed between both observation periods, a dramatic floristic change has occurred in this grassland site.

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

Article

Full-text available

Apr 2000

As the largest pool of terrestrial organic carbon, soils interact strongly with atmospheric composition, climate, and land cover change. Our capacity to predict and ameliorate the consequences of global change depends in part on a better understanding of the distributions and controls of soil organic carbon (SOC) and how vegetation change may affect SOC distributions with depth. The goals of this paper are (1) to examine the association of SOC content with climate and soil texture at different soil depths; (2) to test the hypothesis that vegetation type, through patterns of allocation, is a dominant control on the vertical distribution of SOC; and (3) to estimate global SOC storage to 3 m, including an analysis of the potential effects of vegetation change on soil carbon storage. We based our analysis on .2700 soil profiles in three global databases supplemented with data for climate, vegetation, and land use. The analysis focused on mineral soil layers. Plant functional types significantly affected the vertical distribution of SOC. The per- centage of SOC in the top 20 cm (relative to the first meter) averaged 33%, 42%, and 50% for shrublands, grasslands, and forests, respectively. In shrublands, the amount of SOC in the second and third meters was 77% of that in the first meter; in forests and grasslands, the totals were 56% and 43%, respectively. Globally, the relative distribution of SOC with depth had a slightly stronger association with vegetation than with climate, but the opposite was true for the absolute amount of SOC. Total SOC content increased with precipitation and clay content and decreased with temperature. The importance of these controls switched with depth, climate dominating in shallow layers and clay content dominating in deeper layers, possibly due to increasing percentages of slowly cycling SOC fractions at depth. To control for the effects of climate on vegetation, we grouped soils within climatic ranges and compared distributions for vegetation types within each range. The percentage of SOC in the top 20 cm relative to the first meter varied from 29% in cold arid shrublands to 57% in cold humid forests and, for a given climate, was always deepest in shrublands, inter- mediate in grasslands, and shallowest in forests ( P , 0.05 in all cases). The effect of vegetation type was more important than the direct effect of precipitation in this analysis. These data suggest that shoot/root allocations combined with vertical root distributions, affect the distribution of SOC with depth. Global SOC storage in the to p3mo fsoil was 2344 Pg C, or 56% more than the 1502 Pg estimated for the first meter (which is similar to the total SOC estimates of 1500-1600 Pg made by other researchers). Global totals for the second and third meters were 491 and 351 Pg C, and the biomes with the most SOC at 1-3 m depth were tropical evergreen forests (158 Pg C) and tropical grasslands/savannas (146 Pg C). Our work suggests that plant functional types, through differences in allocation, help to control SOC distributions with depth in the soil. Our analysis also highlights the potential importance of vegetation change and SOC pools for carbon sequestration strategies.

Biocontrol Within the Context of Soil Microbial Communities: A Substrate-Dependent Phenomenon

Article

Full-text available

Feb 1999

Broad spectrum biological control of diseases caused by soilborne plant pathogens such as Pythium, Phytophthora, and Rhizoctonia solani requires the introduction into or presence of edaphic sources of organic nutrients in soil for sustenance of biocontrol agents. The decomposition level of organic matter critically affects the composition of bacterial taxa as well as the populations and activities of biocontrol agents. Competition, antibiosis, parasitism, and systemic induced resistance are all affected. Highly stabilized sources of Sphagnum peat consistently fail to support sustained biological control, even when inoculated with biocontrol agents. Composts, on the other hand, can serve as an ideal food base for biocontrol agents and offer an opportunity to introduce and establish specific biocontrol agents into soils, which in turn leads to sustained biological control based on the activities of microbial communities.

Fluorescein Diacetate Hydrolysis as a Measure of Total Microbial Activity in Soil and Litter

Article

Full-text available

Jul 1982

Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter. FDA hydrolysis was studied in soil and straw incubated for up to 3 h. Hydrolysis was found to increase linearly with soil addition. FDA hydrolysis by pure cultures of Fusarium culmorum increased linearly with mycelium addition both in shake cultures and after inoculation into sterile soil. FDA hydrolysis by Pseudomonas denitrificans increased linearly with biomass addition. The FDA hydrolytic activities in soil samples from different layers of an agricultural soil were correlated with respiration. Acetone was found to be suitable for terminating the reaction.

Humic Substances-Their Structure and Function in the Biosphere.

Article

Apr 1976

The dynamics of organic matter in a Latosol-Podzol toposequence in Amazonia (Brazil)

Article

Jan 1991

In the Brazilian Amazonia, near Manaus, Latosols and Podzols are associated in toposequences developed from the same Tertiary Barreiras sediment. Clayey Latisols occur on the plateau and are covered by dense forest, changing progressively downslope into sandy Podzols covered by a very sparse vegetation. In Latosols, biodegradation and mineralization are very active and release essentially small molecules of a fulvic nature which are stabilized early on mineral surfaces. In the soils of the middle part of the slope, the humic products are more easily extractable and less strongly adsorbed, characteristic of the progressive appearance of the podzolization process. At the foot of the slope redistribution of high C/N ratio of organic components and spatial redistribution of the products of humification (residual poorly extractable organic matter in the A1 horizons and very extractable and polycondensed organic matter in the Bh horizons) are characteristic of a strong podzolization process. -from Authors

The Dynamics of Organic Matter in a Latosol-Podzol Toposequence in Amazonia (Brazil)

Chapter

Dec 1991

In the Brazilian Amazonia, near Manaus, latosols and podzols are associated in toposequences which have developed from the same tertiary Barreiras sediment. Clayey latosols are located on the plateau and are covered by dense forest. Down the slope, they change progressively into sandy podzols covered by a very sparse vegetation. Study of the organic matter shows important changes in the dynamics of the humification along the toposequence. In latosols, biodegradation and mineralization are very active and release essentially small molecules of a fulvic nature which are stabilized early on mineral surfaces.

Soil Taxonomy: U.S. Department of Agriculture, Soil Conservation Service

Article

Jan 1975

Soil Survey Staff

Total Carbon, Organic Carbon, and Organic Matter

Chapter

Jan 1996

Total carbon (C) in soils is the sum of both organic and inorganic C. Organic C is present in the soil organic matter fraction, whereas inorganic C is largely found in carbonate minerals. The wet combustion analysis of soils by chromic acid digestion has long been a standard method for determining total C, giving results in good agreement with dry combustion. Methods for total C are basic for many of the procedures used to determine organic C in soils. In contrast to noncalcareous soils, inorganic C must be removed from calcareous or limed soils before the analysis if wet or dry combustion techniques are used to directly measure the organic C present. The organic matter content of soil may be indirectly estimated through multiplication of the organic C concentration by the ratio of organic matter to organic C commonly found in soils.

Soil enzyme activities as indicators of soil quality

Article

Jan 1994

R.P. Dick

After enumerating the groups of soil enzymes, their activity as potential biological/biochemical indicators is discussed, firstly with reference to the ecology and function of soil enyznmes and their activity in relation to soil microbial activities. Next, soil enzyme activities as indicators of perturbation are considered, particularly the long-term effects of soil management, temporal responsiveness of soil enzymes, and approaches to a biological index of soil fertility. The use of soil enzyme assays in research is reviewed, and conclusions are made on the potential for measuring enzyme activity as an indicator of soil quality. -J.W.Cooper

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation

Article

Apr 2000

Changes in soil organic matter characteristics due to reforestation with Eucalyptus globulus Labill

Article

Jan 1989
SCI TOTAL ENVIRON

Influence of Mineral Nutrients Redistribution in Eucalyptus Plantations on Soil Properties

Chapter

Dec 1991

Manuel Madeira

The properties of Dystric Cambisols under Eucalyptus globulus plantations were studied and compared with those found in similar soils under native vegetation, e.g., Quercus suber. The E. globulus plantations accumulate great quantities of calcium in the above ground biomass and in the organic horizons. These quantities are higher than in the case of the Q. suber. The sum of bases is lower in the soils under E. globulus than under Q. suber. This is explained essentially by a decrease in the exchangeable calcium as a result of uptake by E. globulus followed by its immobilization in the biomass and organic horizons. Actually, in some cases the level of exchangeable and total calcium in the soils under E. globulus does not change and even decreases from the weathering horizons to the upper soil horizons. These soils have a lower degree of base saturation and a lower pH than the soils under Q. suber. Magnesium follows a pattern similar to calcium in the soils but with less marked differences between the soils. The amounts and the distribution of potassium and phosphorus are not influenced by the vegetation. The importance of changes in soils due to E. globulus plantations depends greatly on the intensity of biomass removal and the silvicultural practices.

CLIMATE: The Terrestrial Carbon Cycle: Implications for the Kyoto Protocol

Article

May 1998

IGBP Terretrial Carbon Working Group

Fluorescein diacetate hydrolysis as an estimator of microbial biomass on coniferous needle surfaces

Article

Sep 1980

Estimating microbial standing crops and microbial production in natural habitats has been difficult for microbial ecologists. The present paper describes a simple spectrophotometric assay based on the hydrolysis of fluorescein diacetate which estimates well the standing crops of microbial cells on coniferous needles and twigs. A technique is also presented for correlating optical density readings with actual dry weights of microbial cells epiphytic on needles, and thus for standardizing the assay. The assay shows promise of broad applicability to other microbial habitats.

Brazos River Bar: A Study in the Significance of Grain Size Parameters

Article

Mar 1957
J Sediment Petrol

A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.

Soil pH and Lime requirement

Article

Jan 1986

E. O. Mclean

UV and visible spectroscopic investigations in relation to macromolecular characteristics of humic substances

Article

Jul 2006
EUR J SOIL SCI

Humic substances were investigated by both UV and visible absorption spectroscopic methods with special emphasis on their macromolecular characteristics. The spectral ranges examined were 200–350 nm and 350–700 nm. Conclusions were drawn on the basis of absorption intensities in optical density (O.D.) vs. wavelength (λ) curves, slopes of log O.D. vs. log λ plots, nature of shoulders in the 250–270 nm region, and E4/E6 ratios. As macromolecular characteristics are expected to be dependent on the medium, studies were carried out at different pH values as well as at different neutral salt concentrations, the two major parameters influencing the soil environment. It was noted that with increasing neutral electrolyte concentrations, the particle size decreased, probably due to the coiling of the macromolecule. On increasing the pH from 6.5 to 9.5, the particle size increased slightly, possibly because of partial association through homolytic bonding. At pH 3.5 (with FA only), the degree of association was greater than that at pH 9.5. However, here association occurred by a different mechanism, that of intermolecular hydrogen bonding. At pH 2.0 (with FA only), association was markedly pronounced because of the very dominant role played by intermolecular hydrogen bonding.

Enzyme activity and microbial biomass in a field soil amended with municipal refuse

Article

Sep 1992

P. Perucci

Changes in enzyme activity levels, in biomass-C content, and in the rate of fluorescein diacetate hydrolysis were measured in a loamy soil to which solid municipal refuse had been applied as compost over a 3-year period at two different rates. Addition of the compost caused significant increases in the activity of all enzymes tested. The increases were much higher at 90 t ha-1 year-1 than at 30 t ha-1 year-1. Significant increases were also observed in the biomass-C content and in the rate of fluorescein diacetate hydrolysis. Significant correlations among changes in biomass-C content and the rate of fluorescein diacetate hydrolysis and the changes in all enzymes tested were found. Two activity indices were calculated; a biological index of fertility and an enzyme activity number. No correlations were found between the biological index of fertility and the changes in the various enzyme activities. However, significant correlations were found either between enzyme activity number and most of the changes in enzyme activity, or between the enzyme activity number index and the biomass-C content (r=0.850). The use of a new activity index, the hydrolysis coefficient, is proposed. This coefficient was significantly correlated with biomass-C content (r=0.925) and with the enzyme activity number index (r=0.780).

Hydrolysis of fluorescein diacetate in sphagnum peat container media for predicting suppressiveness to damping-off caused by Pythium ultimum

Article

Dec 1991
SOIL BIOL BIOCHEM

Microbial activity, based on the rate of hydrolysis of fluorescein diacetate (PDA), accurately predicted supprcssivcness to Pythium damping-off of cucumber in media containing light-colored. relatively nondecomposed Canadian sphagnum peat. Suppressiveness was directly related to the quantity of FDA hydrolysed. Organic matter in container media adsorbed fluorescein. Adsorption was directly related to peat decomposition level. In media prepared with dark, decomposed sphagnum peats, that are H3-H4 or higher on the von Post scale, adsorption of fluorescein was strong enough to interfere with the assay. Since such decomposed peats were consistently conducive, the procedure did not yield false readings even here.

The effects of Eucalyptus globulus Labill. leaf letter on C and N mineralization in soils from pasture and native forest

Article

Oct 1999
SOIL BIOL BIOCHEM

The effects of addition of Eucalyptus globulus leaf litter on carbon and nitrogen mineralization in soils from a pasture and a native forest were evaluated using a long-term laboratory aerobic incubation assay (29 weeks at 20°C) in leaching microlysimeters. The amount of added leaf litter significantly influenced microbial respiration, microbial biomass and N turnover in both the native forest and pasture soils. Cumulative CO2-C respired increased with increasing rate of leaf litter addition when leaf litter was mixed through the soil or placed on the soil surface. These increases were associated with increases in microbial biomass C content. Cumulative net N mineralization declined in all treatments when litter was added and was lowest when leaf litter was mixed with soil. When leaf litter was added in increasing amounts to the soil surface, there was a concomitant increase in microbial biomass N content (r2=0.79, n=8), indicating that the reduction in net N mineralization was primarily due to immobilization of N in microbial tissues. In contrast, when litter was mixed with soil in increasing amounts, there was a decrease in microbial biomass N in forest soil and an increase in pasture soil. Consequently, changes in the rate of net N mineralization were not well related to changes in microbial biomass N content. It is suggested that this may be due to the greater activity and more rapid turnover of microorganisms where litter was incorporated resulting in more of the immobilized N being partitioned into metabolic products or dead microbial cells. Incorporation of litter may also have enhanced loss N through denitrification.

Development of a Sensitive and Rapid Method for Measurement of Total Microbial Activity Using Fluorescein Diacetate (FDA) in a Range of Soils

Article

Jun 2001
SOIL BIOL BIOCHEM

Fluorescein diacetate (FDA) hydrolysis is widely accepted as an accurate and simple method for measuring total microbial activity in a range of environmental samples, including soils. Colourless fluorescein diacetate is hydrolysed by both free and membrane bound enzymes, releasing a coloured end product fluorescein which can be measured by spectrophotometry. The current method for measuring FDA hydrolysis in soils is limited in its application. FDA activity was very low in sandy and clayey soils. The low activity observed for these soil types was made difficult to measure by the original authors’ choice of solvent for terminating the hydrolysis reaction. Acetone (50% v/v) was found to be most efficient at stopping the hydrolysis reaction. During this study acetone (50% v/v) was found to cause a decrease of approximately 37% in the absorbance of fluorescein produced by the soil samples measured. Although this colour loss is independent of initial fluorescein concentration, it makes the measurement of FDA hydrolytic activity extremely difficult in soils with low microbial activity i.e. sandy and/or clayey soils. Chloroform/methanol (2:1 v/v) was found to successfully stop the hydrolysis reaction for up to 50 min in a range of soil samples without causing the loss of colour observed with acetone. By changing the solvent used for terminating the hydrolysis reaction, low activity soils could be measured successfully. Other parameters of the hydrolysis reaction were optimised for the measurement of soil samples including effect of pH, optimum temperature of incubation, amount of soil, time of incubation, amount of substrate and preparation of suitable standards. A new, more sensitive method is proposed adapted from the original method, which provides a more accurate determination of FDA hydrolysis in a wide range of soils.

Plant Species Affect Acid Phosphatase, Ergosterol and Microbial P in a Jarrah (Eucalyptus marginata Donn ex Sm.) Forest in South-Western Australia

Article

Nov 2000
SOIL BIOL BIOCHEM

Dry sclerophyll forest dominated by Jarrah (Eucalyptus marginata Donn ex Sm.) covers about 1.6 Mha of south-western Australia and is, relative to other eucalypt forests, low in many nutrients, especially N and P. If fire is excluded from these forests, Banksia grandis Willd. (Proteaceae) often grows in dense thickets as the dominant understorey. Jarrah has an extensive surface (0–20 cm) system of fine lateral roots with ectomycorrhizal associations, while B. grandis produces a mat of cluster (proteoid) roots (0–20 cm) in the late winter and early spring. We measured seasonal changes in acid phosphatase activity and concentrations of ergosterol, microbial P and other P fractions (NaOH-extractable inorganic and organic P, Bray inorganic P) in soil from a forest where B. grandis was either present (Jarrah+Banksia) or absent (Jarrah). Acid phosphatase activity was between 30 and 40 μmol p-NP g−1 h−1 in the moist winter and spring, but declined to less than 10 μmol p-NP g−1 h−1 during the dry summer. Microbial P varied from less than 10 μg g−1 in the late summer to more than 50 μg g−1 during the wetter times of the year. Ergosterol also increased about four-fold as soil moisture content increased (P≤0.05). Acid phosphatase was significantly and positively related to both ergosterol and microbial P in both Jarrah+Banksia and Jarrah soils, but the intercepts and slopes of the regressions varied seasonally and were not significantly different (P≤0.05) between species composition. About 50% of the variation in phosphatase activity in Jarrah soils was explained by variation in fungal biomass (ergosterol), regardless of season, while in Jarrah+Banksia soils, 74% was explained by fungal biomass when soils were dry, decreasing to less than 10% as soil moisture increased. Linear regression models showed that ergosterol and microbial P are good predictors of acid phosphatase activity in soil, but their relative importance is dependent on plant species composition and season. We propose that the relative importance of fungal biomass as a determinant of phosphatase activity in the soil decreases as the seasonal flush of cluster roots dominate in the Jarrah+Banksia soils, while in Jarrah soils the phosphatase flush is primarily due to increased activity of the fungal biomass. Seasonal and spatial heterogeneity in microbial P, ergosterol and in the source of acid phosphatase in the soil are therefore a consequence of plant species composition and root type and will influence nutrient availability at the ecosystem scale.

The leaching of Eucalyptus hybrids and Acacia auriculiformis leaf litter: Laboratory experiments on early decomposition and ecological implications in congolese tree plantations

Article

Jul 1999
APPL SOIL ECOL

France Bernhard-Reversat

The first stage of leaf litter decomposition of two eucalyptus hybrids and Acacia auriculiformis was studied in laboratory experiments where the decaying leaves were leached with water. Although the litter of both the species were characterized by a high content of soluble compounds, little soluble organic matter of acacia litter was recovered in litter leachates. By contrast, soluble organic matter of eucalyptus litter was more resistant to degradation and was, therefore, recovered in leachates, where soluble carbon amounts and coloration varied with the age of decomposing litter. The pH of eucalyptus litter leachates decreased at the beginning of the experiment whereas the pH of acacia litter leachates increased. When added to savanna soil, litter leachates mobilized iron into soil solution, with greater effects observed from eucalyptus than from acacia. In bioassay, litter leachates were added to sand in which test plant seedlings were grown, and a strong allelopathic activity was observed with leachates from the first days of eucalyptus litter decomposition. Leachates from older litter did not show any effect. The possible ecological implications of the observed processes are discussed.

Human Domination of Earth's Ecosystems

Article

Jul 1997

P.Mooney Vitousek

The Terrestrial Carbon Cycle: Implications for the Kyoto Protocol

Article

Jan 1998

Relaciones agua-suelo-planta

Article

The terrestrial carbon cycle: Implications for the Kyoto Protocol

Article

May 1998

Chemistry of Soil Organic Matter

Article

Jan 1988

K. Kumada

Humus Chemistry—Genesis, Composition, Reactions

Article

Jan 1983

F.J. Stevenson

National-scale estimation of changes in soil C stocks on agricultural lands

Article

Feb 2002
ENVIRON POLLUT

Average annual net change in soil carbon stocks under past and current management is needed as part of national reporting of greenhouse gas emissions and to evaluate the potential for soils as sinks to mitigate increasing atmospheric CO2. We estimated net soil C stock changes for US agricultural soils during the period from 1982 to 1997 using the IPCC (Intergovernmental Panel on Climate Change) method for greenhouse gas inventories. Land use data from the NRI (National Resources Inventory; USDA-NRCS) were used as input along with ancillary data sets on climate, soils, and agricultural management. Our results show that, overall, changes in land use and agricultural management have resulted in a net gain of 21.2 MMT C year(-1) in US agricultural soils during this period. Cropped lands account for 15.1 MMT C year(-1), while grazing land soil C increased 6.1 MMT C year(-1). The land use and management changes that have contributed the most to increasing soil C during this period are (1) adoption of conservation tillage practices on cropland, (2) enrollment of cropland in the Conservation Reserve Program, and (3) cropping intensification that has resulted in reduced use of bare fallow.

Soil carbon dynamics and potential carbon sequestration by rangelands

Article

Feb 2002
ENVIRON POLLUT

The USA has about 336 Mha of grazing lands of which rangelands account for 48%. Changes in rangeland soil C can occur in response to a wide range of management and environmental factors. Grazing, fire, and fertilization have been shown to affect soil C storage in rangelands, as has converting marginal croplands into grasslands. Carbon losses due to soil erosion can influence soil C storage on rangelands both by reducing soil productivity in source areas and potentially increasing it in depositional areas, and by redistributing the C to areas where soil organic matter mineralization rates are different. Proper grazing management has been estimated to increase soil C storage on US rangelands from 0.1 to 0.3 Mg C ha(-1)year(-1) and new grasslands have been shown to store as much as 0.6 Mg C ha(-1)year(-1). Grazing lands are estimated to contain 10-30% of the world's soil organic carbon. Given the size of the C pool in grazing lands we need to better understand the current and potential effects of management on soil C storage.

Methodology for estimating soil carbon for the forest carbon budget model of the United States, 2001

Article

Feb 2002
ENVIRON POLLUT

The largest carbon (C) pool in United States forests is the soil C pool. We present methodology and soil C pool estimates used in the FORCARB model, which estimates and projects forest carbon budgets for the United States. The methodology balances knowledge, uncertainties, and ease of use. The estimates are calculated using the USDA Natural Resources Conservation Service STATSGO database, with soil dynamics following assumptions based on results of site-specific studies, and area estimates from the USDA Forest Service. Forest Inventory and Analysis data and national-level land cover data sets. Harvesting is assumed to have no effect on soil C. Land use change and forest type transitions affect soil C. We apply the methodology to the southeastern region of the United States as a case study.

Soil carbon dynamics in cropland and rangeland

Article

Feb 2002
ENVIRON POLLUT

Rattan Lal

Most soils in the Midwestern USA have lost 30 to 50% of their original pool, or 25 to 40 Mg C/ha, upon conversion from natural to agricultural ecosystems. About 60 to 70% of the C thus depleted can be resequestered through adoption of recommended soil and crop management practices. These practices include conversion from plow till to no till, frequent use of winter cover crops in the rotation cycle, elimination of summer fallow, integrated nutrient management along with liberal use of biosolids and biological nitrogen fixation, precision farming to minimize losses and enhance fertilizer use efficiency, and use of improved varieties with ability to produce large root biomass with high content of lignin and suberin. The gross rate of soil organic carbon (SOC) sequestration ranges from 500 to 800 kg/ha/year in cold and humid regions and 100 to 300 kg/ha/year in dry and warm regions. The rate of SOC sequestration can be measured with procedures that are cost effective and credible at soil pedon level, landscape level, regional or national scale. In addition to SOC, there is also a large potential to sequester soil inorganic carbon (SIC) in arid and semi-arid regions. Soil C sequestration has numerous ancillary benefits. It is truly a win-win situation: extremely cost-effective, and a bridge to the future until alternative energy options take effect.

Development of a protocol for monitoring status and trends in forest soil carbon at a national level

Article

Feb 2002
ENVIRON POLLUT

The national Forest Health Monitoring (FHM) program requires protocols for monitoring soil carbon contents. In a pilot study, 30 FHM plots loblolly shortleaf (Pinus taeda L./Pinus echinata Mill.) pine forests across Georgia were sampled by horizon and by depth increments. For total soil carbon, approximately 40% of the variance was between plots, 40% between subplots and 20% within subplots. Results by depth differed from those obtained by horizon primarily due to the rapid changes in carbon content from the top to the bottom of the A horizon. Published soil survey information overestimated bulk densities for these forest sites. The measurement of forest floor depths as a substitute to sampling did not provide reliable estimates of forest floor carbon. Precision of replicate samples was approximately 10-30% for field duplicates and 5-10% for laboratory duplicates. Based on national indicator evaluation criteria, sampling by depth using bulk density core samplers has been recommended for national implementation. Additional procedures are needed when sampling organic soils or soils with a high percentage of large rock fragments.

Effects of forest management on soil carbon: Results of some long-term resampling studies

Article

Feb 2002
ENVIRON POLLUT

The effects of harvest intensity (sawlog, SAW; whole tree, WTH; and complete tree, CTH) on biomass and soil C were studied in four forested sites in the southeastern US (mixed deciduous forests at Oak Ridge, TN and Coweeta, NC; Pinus taeda at Clemson, SC: and P. eliottii at Bradford, FL). In general, harvesting had no lasting effects on soil C. However, intensive temporal sampling at the NC and SC sites revealed short-term changes in soil C during the first few years after harvesting, and large, long-term increases in soil C were noted at the TN site in all treatments. Thus, changes in soil C were found even though lasting effects of harvest treatment were not. There were substantial differences in growth and biomass C responses to harvest treatments among sites. At the TN site, there were no differences in biomass at 15 years after harvest. At the SC site, greater biomass was found in the SAW than in the WTH treatment 16 years after harvest, and this effect is attributed to be due to both the N left on site in foliar residues and to the enhancement of soil physical and chemical properties by residues. At the FL site, greater biomass was found in the CTH than in the WTH treatment 15 years after harvest, and this effect is attributed to be due to differences in understory competition. Biomass data were not reported for NC. The effects of harvest treatment on ecosystem C are expected to magnify over time at the SC and FL sites as live biomass increases, whereas the current differences in ecosystem C at the TN site (which are due to the presence of undecomposed residues) are expected to lessen with time.

Desarrollo forestal y medio ambiente (com-pilation)

Pe
C Arrarte

Pe ´ rez-Arrarte, C., 1993. Desarrollo forestal y medio ambiente (com-pilation). CIEDUR Montevideo, Uruguay

Variabilite´ de quelques caracteristiques e´ des sols sableux sous Eucalyptus du littoral congolais. Me´ I The leaching of Eucalyptus hybrids and Acacia auriculiformis leaf litter: laboratory experiments on early decomposition and ecological implications in Congolese tree plan-tations

Jan 1993
251-261

J D R Bandzouzi
Universite´ Rennes
France
F Bernhard-Reversat

Bandzouzi, J., 1993. Variabilite´ de quelques caracteristiques e´ des sols sableux sous Eucalyptus du littoral congolais. Me´ I.D.R., Universite´ Rennes, France. Bernhard-Reversat, F., 1999. The leaching of Eucalyptus hybrids and Acacia auriculiformis leaf litter: laboratory experiments on early decomposition and ecological implications in Congolese tree plan-tations. Applied Soil Ecology 12, 251–261.

Etude comparative de quelques ele´ments du fonctionnement de deux peuplement do Eucalyptus au Congo

Jan 1990

E Loubelo

Loubelo, E., 1990. Etude comparative de quelques ele´ments du fonctionnement de deux peuplement do Eucalyptus au Congo. Uni-versite´de Rennes, France.

Superficie Forestada Bajo Proyecto 1975– 2000: Paysandu´ Paysandu´ıó Negro

Jan 1961

Direccio´

Direccio´, 2001. Superficie Forestada Bajo Proyecto 1975– 2000: Paysandu´ Paysandu´ıó Negro. Ministerio de Agricultura y Pesca, Montevideo, Uruguay. DNM, 1995. Normales Climatolo´ 1961–1990.

Global soil carbon resources

Jan 1995
27-43

H Eswaran
Van Den
E Berg
P Reich
J Kimble

Eswaran, H., Van den Berg, E., Reich, P., Kimble, J., 1995. Global soil carbon resources. In: Lal, R., Kimble, J., Levine, E., Stewart, B.A. (Eds.), Soil and Global Change. CRC Lewis Publishers, Boca Raton, USA, pp. 27-43.

Uruguay Forestal: antecedentes, legislacio´ , desarrollo actual y perspectives

Jan 1999

Uruguay
J Morales
C M Ribeiro

MGAP, 1999. Uruguay Forestal: antecedentes, legislacio´, desarrollo actual y perspectives. Ministerio de Agricultura y Pesca, Montevideo, Uruguay. Morales, J., Ribeiro, C.M., 1999. Tendencias y perspectivas de la economıá forestal de los paı´ del Conosur (Argentina, Brasil, Chile, Uruguay). Oficina Regional FAO para Ame´ Latina y el Caribe, Santiago, Chile.

Chemical, spectroscopic and thermal methods for the classification and characterization of humic substances

M Schnitzer

Schnitzer, M., 1972. Chemical, spectroscopic and thermal methods for the classification and characterization of humic substances. In: Humic Substances: Their Structure and Function in Biosphere. Nieuweslius, Pudoc Wageningen, TheNetherlands, pp. 293-310.

Influence of mineral nutrients redistribution in Eucalyptus plantation on soil properties Diversity of Environmental Biogeochemistry, Development in Geo-chemistry 6 The Neth-erlands

Jan 1992
485-494

M A V Madeira

Madeira, M.A.V., 1992. Influence of mineral nutrients redistribution in Eucalyptus plantation on soil properties. In: Berthelin, J. (Ed.), Diversity of Environmental Biogeochemistry, Development in Geo-chemistry 6. Elsevier Sciences Publications, Amsterdam, The Neth-erlands, pp. 485–494.

Desarrollo forestal y medio ambiente (com-pilation) CIEDUR Montevideo, Uruguay. Perucci, P., 1992. Enzyme activity and microbial biomass in a field soil amended with municipal refuse

Jan 1993
54-60

C Pe´-Arrarte

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Ecologıá polı´ del cambio clima´ . CLAES, Montevideo, Uruguay. IGBP, 1998. The terrestrial carbon cycle: implications for the Kyoto protocol

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G Honty

Honty, G., 2000. Ecologıá polı´ del cambio clima´. CLAES, Montevideo, Uruguay. IGBP, 1998. The terrestrial carbon cycle: implications for the Kyoto protocol. Science 280, 1393–1394.

Preliminary study of prairies forested with Eucalyptus sp. at the northwestern Uruguayan soils

Abstract

No full-text available

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