The origin of the forest-grassland mosaic of central Cameroon: What we learn from the isotopic geochemistry of soil organic matter

The Holocene ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 1391-1399
Author(s):  
Thierry Desjardins ◽  
Bruno Turcq ◽  
Anne-Marie Lézine ◽  
Jean-Pierre Nguetnkam ◽  
Magloire Mandeng-Yogo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Large Scale ◽  
Forest Cover ◽  
Central Africa ◽  
Environmental Crisis ◽  
Forest Expansion ◽  
The Holocene ◽  
Forest Sites ◽  
Forest Mosaic

The end of the Holocene Humid Period was characterized by the massive collapse of forest ecosystems in central Africa. Was this large-scale environmental crisis dated between 3300 and 2500 years BP at the origin of the present-day wooded-grassland/forest mosaic of central Cameroon? Here we present carbon isotope data on soil organic matter collected from 29 sites from this area, including the Grassfield plateaus, with the aim of characterizing this environmental crisis and discussing the origin of the present-day landscape. 14C data on total soil organic matter and charcoal fragments show that the organic matter in these soils originates from the Holocene. In our forest sites, the δ13C profiles do not show any marked alteration of the forest cover throughout the Holocene. Discrete traces of forest expansion or retreat are observed only punctually at the forest margins. In the wooded-grassland/forest mosaic zone, the environmental crisis was of reduced amplitude. In the present grassland and wooded grassland areas, there was no true forest during the lower to middle Holocene, but a markedly more tree-covered landscape. The timing of this crisis revealed by our 14C measurements, although only indicative at this stage, suggests that it occurred earlier at higher altitudes than in the lowlands due to marked topographic relief favoring drainage along the slopes. These results fit a climatic rather than anthropogenic origin of the vegetation opening in this region.

Accumulation patterns of soil organic matter in forests as a legacy of historical charcoal burning

2021 ◽  
Author(s):  
Anna Schneider ◽  
Alexander Bonhage ◽  
Florian Hirsch ◽  
Alexandra Raab ◽  
Thomas Raab
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Large Scale ◽  
Soil Surface ◽  
Landscape Scale ◽  
Legacy Effects ◽  
Charcoal Production ◽  
Study Region ◽  
Land Use Legacies

<p>Human land use and occupation often lead to a high heterogeneity of soil stratigraphy and properties in landscapes within small, clearly delimited areas. Legacy effects of past land use also are also abundant in recent forest areas. Although such land use legacies can occur on considerable fractions of the soil surface, they are hardly considered in soil mapping and inventories. The heterogenous spatial distribution of land use legacy soils challenges the quantification of their impacts on the landscape scale. Relict charcoal hearths (RCH) are a widespread example for the long-lasting effect of historical land use on soil landscapes in forests of many European countries and also northeastern USA. Soils on RCH clearly differ from surrounding forest soils in their stratigraphy and properties, and are most prominently characterized by a technogenic substrate layer with high contents of charcoal. The properties of RCH soils have recently been studied for several regions, but their relevance on the landscape scale has hardly been quantified.</p><p>We analyse and discuss the distribution and ecological relevance of land use legacy soils across scales for RCH in the state of Brandenburg, Germany, with a focus on soil organic matter (SOM) stocks. Our analysis is based on a large-scale mapping of RCH from digital elevation models (DEM), combined with modelled SOM stocks in RCH soils. The distribution of RCH soils in the study region shows heterogeneity at different scales. The large-scale variation is related to the concentration of charcoal production to specific forest areas and the small-scale accumulation pattern is related to the irregular distribution of single RCH within the charcoal production fields. Considerable fractions of the surface area are covered by RCH soils in the major charcoal production areas within the study region. The results also show that RCH can significantly contribute to the soil organic matter stocks of forests, even for areas where they cover only a small fraction of the soil surface. The study highlights that considering land use legacy effects can be relevant for the results of soil mapping and inventories; and that prospecting and mapping land use legacies from DEM can contribute to improving such approaches.</p>

scholarly journals Large-scale genome sequencing of mycorrhizal fungi provides insights into the early evolution of symbiotic traits

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Shingo Miyauchi ◽  
Enikő Kiss ◽  
Alan Kuo ◽  
Elodie Drula ◽  
Annegret Kohler ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Transposable Elements ◽  
Genome Sequencing ◽  
Mycorrhizal Fungi ◽  
Large Scale ◽  
Terrestrial Ecosystems ◽  
Pathogenic Species ◽  
Fungal Genomes ◽  
Induced Genes

Abstract Mycorrhizal fungi are mutualists that play crucial roles in nutrient acquisition in terrestrial ecosystems. Mycorrhizal symbioses arose repeatedly across multiple lineages of Mucoromycotina, Ascomycota, and Basidiomycota. Considerable variation exists in the capacity of mycorrhizal fungi to acquire carbon from soil organic matter. Here, we present a combined analysis of 135 fungal genomes from 73 saprotrophic, endophytic and pathogenic species, and 62 mycorrhizal species, including 29 new mycorrhizal genomes. This study samples ecologically dominant fungal guilds for which there were previously no symbiotic genomes available, including ectomycorrhizal Russulales, Thelephorales and Cantharellales. Our analyses show that transitions from saprotrophy to symbiosis involve (1) widespread losses of degrading enzymes acting on lignin and cellulose, (2) co-option of genes present in saprotrophic ancestors to fulfill new symbiotic functions, (3) diversification of novel, lineage-specific symbiosis-induced genes, (4) proliferation of transposable elements and (5) divergent genetic innovations underlying the convergent origins of the ectomycorrhizal guild.

Soil organic matter dynamics in changing forests: linking ecosystem manipulation experiments with soil inventories across Switzerland

2020 ◽  
Author(s):  
Frank Hagedorn ◽  
Sia Gosheva ◽  
Stephan Zimmermann ◽  
Konstantin Gavazov
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soils ◽  
Dry Forest ◽  
Soil Profiles ◽  
Forest Age ◽  
Forest Expansion ◽  
Soil C ◽  
Ecosystem Manipulation

<p>Forest soils are storing large quantities of carbon, but their quantitative role in sequestering C is less certain. In principal, soils developed over millennia are assumed to be ‘in equilibrium’ with minimal C stock changes. This concept is challenged by forest soil inventories (in Germany and France) indicate a substantial increase in soil C storage. However, soil organic matter (SOM) storage is susceptible to recent changes in forests - climate warming and droughts, increasing forest disturbances, and a more intensive forest management are all potentially increasing SOM turnover which may turn forest soils into C sources. Here, I will critically discuss the role in Swiss forest soils as C sinks by presenting data from 1000 soil profiles across environmental gradients and from flux measurements in large scale ecosystem manipulation experiments.</p><p>Swiss forests soils are among the C-richest soils in Europe storing on average 140 t C/ha. Analysis of 1000 forest soils show that these SOM stocks are caused by their high contents in potential SOM sorbents (pH, Al+Fe-oxides, Ca, clay), but also by the cool temperatures and high amounts of precipitation. Climate manipulation experiments suggest Swiss forest soils are vulnerable to loose C with expected climatic changes. A six year long soil warming experiment at treeline revealed soil C losses, while a 15 year long irrigation experiment in a dry forest induced C gains in the mineral soil, implying that a warmer and more frequent droughts will lead to C losses.</p><p>Switzerland - as other European mountainous areas – is currently experiencing a major change in land-use due to land abandonment, with the forests expanding by 3 to 4% per decade. Forest expansion affects a multitude of factors driving SOM cycling and storage, including the quantity and quality of organic matter inputs above and below the ground, a cooler and drier microclimate, and change in microbial diversity and activity. In contrast to the intuitive assumption that forests expansion leads to C gains in soils, measurements along an afforestation chronosequence of alpine grassland show that forest expansion leads to minimal changes in SOM stocks but a strong change in SOM quality. Soils gains in particulate organic matter with increasing forest age but lose C in mineral-associated organic matter. In support, reconstructing forest cover ages of 850 soil profiles showed that forest age and hence time since conversion into forest (predominantly from grasslands) did not significantly affect total SOM stocks, while other factors, especially physico-chemical soil characteristics and climate were more important. Overall, these results show that the inherently C rich forest soils in Switzerland are unlikely to gain additional C but rather loose it in response to the ongoing changes in climate and land-use. </p>

scholarly journals 14C Dating and Stable Carbon Isotopes of Soil Organic Matter in Forest–Savanna Boundary Areas in the Southern Brazilian Amazon Region

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 1013-1022 ◽  
Author(s):  
L. C. R. Pessenda ◽  
S. E. M. Gouveia ◽  
Ramon Aravena ◽  
B. M. Gomes ◽  
Rene Boulet ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Stable Carbon Isotopes ◽  
Brazilian Amazon ◽  
Amazon Region ◽  
Published Data ◽  
Forest Site ◽  
The Holocene ◽  
Savanna Vegetation ◽  
Brazilian Amazon Region

This study, which was carried out in the southern Brazilian Amazon region (Rondônia state and Humaitá, Southern Amazon state), presents and discusses the significance of carbon isotope data measured in soil profiles collected across natural boundaries of forest to savanna vegetation. The main objective of this study was to evaluate the expansion-regression dynamics of these vegetation units in relation to climate changes during the Holocene. 14C data from charcoal, soil organic matter (SOM) and its component humin fraction indicate that the organic matter in the studied soils is essentially Holocene in origin. 13C data indicate that C3 type plants were the dominant vegetation at all study areas in the early Holocene, and during the entire Holocene, in the forest sites of Central Rondônia state and in the forest site 50 km from the city of Humaitá. 13C data also indicate that C4 plants have influenced significantly the vegetation at the transitional forest and the Cerrado (wooded savanna) sites of Southern Rondônia state and the forest ecosystem located 20 km from the Humaitá city. These typical C4 type isotopic signatures probably reflect a drier climate during the mid-Holocene. The 13C records representing probably the last 3000 yr show an expansion of the forest, due to a climatic improvement, in areas previously occupied by savanna vegetation. These results and other published data for the Amazon region indicate that the areas representing today's forest-savanna boundaries have been determined by significant vegetation changes during the Holocene. The boundary between forest and savanna vegetation seems to be quite sensitive to climatic change and should be the focus of more extensive research to correlate climate and past vegetation dynamics in the Amazon region.

δ13C variation of soil organic matter as an indicator of vegetation change during the Holocene in central Cameroon

2013 ◽  
Vol 345 (7-8) ◽  
pp. 266-271 ◽  
Author(s):  
Thierry Desjardins ◽  
Bruno Turcq ◽  
Jean-Pierre Nguetnkam ◽  
Gaston Achoundong ◽  
Magloire Mandeng-Yogo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Vegetation Change ◽  
The Holocene

Large-scale mapping of soil organic matter content by regression kriging in Zala County

2013 ◽  
Vol 62 (2) ◽  
pp. 219-234 ◽  
Author(s):  
Gábor Szatmári ◽  
Annamária Laborczi ◽  
Gábor Illés ◽  
László Pásztor
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Large Scale ◽  
Mean Absolute Error ◽  
Organic Matter Content ◽  
Absolute Error ◽  
Matter Content ◽  
Mean Square ◽  
Regression Kriging ◽  
Soil Organic Matter Content

Dolgozatunkban Zala megye feltalajainak szervesanyag-tartalmát kívántuk digitálisan térképezni regresszió krigeléssel a rendelkezésünkre álló Digitális Kreybig Talajinformációs Rendszer (DKTIR) adataira, illetve környezeti segédváltozókra alapozva. A térbeli kiterjesztések során különböző kombinációkban használtuk fel a talajképződési tényezőket, illetve DKTIR talajtérképi egységeit. Munkánk célja volt, hogy a regresszió krigelés modelljébe vont segédváltozó kombinációk minőségi hatását vizsgáljuk a becslő eljárás alapját jelentő többszörös lineáris regresszió modellre, illetve a becsült térkép pontosságára vonatkozóan.A szervesanyag-tartalom térbeli kiterjesztéséhez szükséges segédváltozókat a szakirodalom alapján választottuk ki. Segédadatként használtuk fel Zala megye digitális domborzatmodelljét, a 2009 és 2011 között készült MODIS műholdképekből származtatott vegetációs index állományokat, két klímaparaméter fedvényét, illetve a DKTIR talajtérképi egységeit. A regresszió krigeléssel becsült humusztartalom térképeket a DKTIR talajszelvény adataiból előzetesen leválogatott, a becslési eljárástól független kontroll adatpontokkal értékeltük. A validációhoz származtattuk a ME (Mean Error), a MAE (Mean Absolute Error), az RMSE (Root Mean Square Error), illetve az RIi(%) (Relative Improvement) paraméterek értékeit, ahol utóbbi az egyes térképek pontosságának relatív növekedését fejezi ki egy viszonyítási alapnak választott térképhez képest.A vizsgalati eredmenyek alapjan a terbeli talajinformaciok segedadatkent torten. felhasznalasa jelentősen novelte a regresszio modellek determinacios koefficienseinek erteket, illetve a becsult humuszterkepek pontossagat. A talajtani segedinformaciokat is figyelembe vevő regresszio modellek R2 ertekei — ket eset kivetelevel — joval meghaladtak a 30%-ot, vagyis a szervesanyag-tartalom terbeli valtozekonysaganak tobb mint egyharmadat voltak kepesek determinalni. A validacios mutatok alapjan azon terkepek bizonyultak pontosabbnak, melyekben a DKTIR talajok textura es vizgazdalkodasi tulajdonsagait (DKTIR-F) hasznaltuk fel talajtani segedvaltozokent. A legalacsonyabb MAE ertekkel (0,747) a domborzati es eghajlati talajkepző tenyezőket, illetve a DKTIR-F talajterkepi egyseget segedvaltozokent alkalmazo humuszterkep rendelkezett, ezen terkep eseten az RIi(%) parameter erteke 21%-nak adodott. A mutatok alapjan ezen terkep adta a legpontosabb becslest a mintaterulet szervesanyag-tartalmara, hisz a felhasznalt segedvaltozokon keresztul figyelembe veszi a mintaterulet szervesanyag-tartalmat alapvetően befolyasolo eroziot es akkumulaciot, illetve a talajok fizikai feleseget, mely utobbi hatassal van a vizhaztartasra, a beszivargasra, a kilugozasra es ezeken keresztul a humuszkepződes folyamatara. A biologiai talajkepző tenyezőt reprezentalo MODIS vegetacios index allomanyok eseteben megfigyelhető volt, hogy segedadatkent tortenő alkalmazasuk eseten kevesbe pontos becsleseket kaptunk osszevetve az ezen segedadatokat mellőző becslesekkel.Munkánkat a K105167 számú OTKA, illetve a TÁMOP-4.2.2.A-11/1/KONV-2012-0013. pályázatok támogatják.

Integrated Crop-Livestock-Forest Systems: Soil Carbon Sequestration and Organic Matter stabilization as detected by laser-based spectroscopies

2020 ◽  
Author(s):  
Amanda Maria Tadini ◽  
Alfredo Augusto Pereira Xavier ◽  
Ladislau Martin-Neto ◽  
Débora Marcondes Bastos Pereira Milori ◽  
Alberto Carlos de Campos Bernardi
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Fluorescence Spectroscopy ◽  
Soil Carbon ◽  
Chemical Structure ◽  
Large Scale ◽  
Laser Induced Fluorescence ◽  
Sustainable Intensification ◽  
Carbon Accumulation ◽  
Soil C

<p>The Integrated Crop-Livestock-Forest Systems (CLF) have been able to capture and store the carbon (C) in the form of Soil Organic Matter (SOM), in different regions in Brazil, thereby contributing to mitigate agricultural greenhouse gases emission. This is an eligible practice in Low Carbon Emission Agriculture Plan in Brazil, and currently has around 15 million hectares under use, a very positive and important trend in soil land use in Brazil. SOM is considered a relevant indicator of soil quality due to its direct relationship with biological, chemical, and physical properties, allowing it to evaluate the impacts of agricultural management. Laser-based spectroscopies as Laser-Induced Fluorescence Spectroscopy (LIFS) and Laser-Induced Breakdown Spectroscopy (LIBS) have become promising tools in the evaluation of the SOM in agricultural soils. LIBS can measure soil C, and LIFS can infer about the chemical structure of SOM, mainly aromaticity. The standard protocol for measuring soil C changes involves soil sampling at the field and chemical sample preparation for laboratory analysis. Although this procedure produces precise results, it takes time, generates chemical residues, and the costs restrict its routine for large scale use in agricultural projects. Thus, there is a need to develop clean (green chemistry), rapid, precise, and cost-efficient methods for measuring soil C changes in the field. Also, information about the chemical structure of SOM usually is done through spectroscopic techniques, such as <sup>13</sup>C NMR, EPR, and fluorescence of humic acid, which are not applied for large scale measurement and mapping. LIFS can be applied in whole soil and can be used to evaluate the aromaticity of SOM, and consequently, its chemical stability.  The objectives of this study were to evaluatethe soil C stock and SOM Stability of some Brazilian soils under different integrated systems, such as,Crop-Livestock-Forest (CLF), Crop-Livestock (CL) and Livestock-Forest(LF). The results showed the combination of soil carbon accumulation, and an increase of SOM aromaticity for CLF, which can be promising for sustainable intensification in agriculture.</p><p><strong>Keywords: </strong>Sustainable Intensification; Soil Organic Matter; Carbon stock; Laser-Induced Fluorescence Spectroscopy; Integrated Crop-Livestock-Forest Systems</p>

Historical C3-C4 vegetation pattern on forested mountain slopes: its implication for ecological rehabilitation of degraded highlands of Ethiopia by afforestation

2002 ◽  
Vol 18 (5) ◽  
pp. 743-758 ◽  
Author(s):  
Zewdu Eshetu
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Conservation ◽  
Forest Cover ◽  
Vegetation Pattern ◽  
Soil Conditions ◽  
Tree Leaves ◽  
Ecological Rehabilitation ◽  
Exotic Tree ◽  
Rotation Age

In Ethiopia, plantation forestry for soil conservation and wood supply is mainly based on exotic tree species harvested at 12–25-y rotation age. To evaluate if these forests truly represent ecological rehabilitation of degraded areas through the build-up of soil organic matter before harvest, relative abundances of C3 vs. C4 carbon in soils under a 25-y-old forest on Mt. Yegof have been studied based on changes in soil δ13C values due to vegetation cover changes by afforestation. At Yegof, shrub and tree leaves had δ13C value of −28.7 ± 0.4‰. The grasses showed a value of −30.7 ± 0.6‰ at 2700–3000 m asl (typical C3) and of −13.6 ± 0.3‰ at 2520 m asl (typical C4). Soil δ13C values were −21.7 ± 0.9‰ in soil at 0–5 cm and −20.7 ± 0.6‰ in soil at 30–50 cm indicating a long history of C4-dominated grass or cropland over the elevations sampled. The shifts towards lower δ13C values in soil at 0–5 cm coincide with 25 y of C3 vegetation. Carbon content in topsoil was 3.4–9.2% and in tree leaves was 45–56%. However, an estimate of new C3 carbon (54%) in 0–5 cm soil was low as compared with tropical rain-forest and savanna ecosystems suggesting a slow rate of carbon turnover at Yegof. The results suggest that degraded sites at Yegof may need further duration of forest cover longer than current rotation times of the forests to improve soil conditions and restore soil organic matter and carbon, which have been lost during the past land use. It is encouraging from the perspectives of ecological rehabilitation and soil conservation that a shift in the dominance from C4 vegetation types of agricultural and grassland ecosystems to C3 forest ecosystems could be established in less than 25 y on these highly degraded slopes of Mt. Yegof.

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