Veldkamp, Edzo

[["dc.bibliographiccitation.firstpage","2311"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Biogeosciences"],["dc.bibliographiccitation.lastpage","2325"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Koehler, B."],["dc.contributor.author","Zehe, E."],["dc.contributor.author","Corre, M. D."],["dc.contributor.author","Veldkamp, E."],["dc.date.accessioned","2017-09-07T11:43:41Z"],["dc.date.available","2017-09-07T11:43:41Z"],["dc.date.issued","2010"],["dc.description.abstract","Soil respiration is the second largest flux in the global carbon cycle, yet the underlying below-ground process, carbon dioxide (CO2) production, is not well understood because it can not be measured in the field. CO2 production has frequently been calculated from the vertical CO2 diffusive flux divergence, known as \"soil-CO2 profile method\". This relatively simple model requires knowledge of soil CO2 concentration profiles and soil diffusive properties. Application of the method for a tropical lowland forest soil in Panama gave inconsistent results when using diffusion coefficients (D) calculated based on relationships with soil porosity and moisture (\"physically modeled\" D). Our objective was to investigate whether these inconsistencies were related to (1) the applied interpolation and solution methods and/or (2) uncertainties in the physically modeled profile of D. First, we show that the calculated CO2 production strongly depends on the function used to interpolate between measured CO2 concentrations. Secondly, using an inverse analysis of the soil-CO2 profile method, we deduce which D would be required to explain the observed CO2 concentrations, assuming the model perception is valid. In the top soil, this inversely modeled D closely resembled the physically modeled D. In the deep soil, however, the inversely modeled D increased sharply while the physically modeled D did not. When imposing a constraint during the fit parameter optimization, a solution could be found where this deviation between the physically and inversely modeled D disappeared. A radon (Rn) mass balance model, in which diffusion was calculated based on the physically modeled or constrained inversely modeled D, simulated observed Rn profiles reasonably well. However, the CO2 concentrations which corresponded to the constrained inversely modeled D were too small compared to the measurements. We suggest that, in well-structured soils, a missing description of steady state CO2 exchange fluxes across water-filled pores causes the soil-CO2 profile method to fail. These fluxes are driven by the different diffusivities in inter- vs. intra-aggregate pores which create permanent CO2 gradients if separated by a \"diffusive water barrier\". These results corroborate other studies which have shown that the theory to treat gas diffusion as homogeneous process, a precondition for use of the soil-CO2 profile method, is inaccurate for pore networks which exhibit spatial separation between CO2 production and diffusion out of the soil."],["dc.identifier.doi","10.5194/bg-7-2311-2010"],["dc.identifier.fs","570252"],["dc.identifier.gro","3150209"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5240"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/6948"],["dc.language.iso","en"],["dc.notes.intern","Migrated from goescholar"],["dc.notes.status","final"],["dc.relation.issn","1726-4189"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.subject","CO2 production"],["dc.subject.ddc","570"],["dc.title","An inverse analysis reveals limitations of the soil-CO2 profile method to calculate CO2 production and efflux for well-structured soils"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","365"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","African Journal of Agricultural Research"],["dc.bibliographiccitation.lastpage","377"],["dc.bibliographiccitation.volume","4"],["dc.contributor.author","Mekuria, Wolde"],["dc.contributor.author","Veldkamp, Edzo"],["dc.contributor.author","Haile, Mitiku"],["dc.contributor.author","Gebrehiwot, Kindeya"],["dc.contributor.author","Muys, Bart"],["dc.contributor.author","Nyssen, Jan"],["dc.date.accessioned","2019-07-10T08:13:19Z"],["dc.date.available","2019-07-10T08:13:19Z"],["dc.date.issued","2009"],["dc.description.abstract","The study investigated how effective exclosures are in the fight against soil erosion and how they are perceived as a means to control soil erosion by the local community (farmers and local experts). The universal soil loss equation (USLE) used to estimate potential soil erosion. Data on local community perception obtained from a survey of 62 farm households and five local experts. In-depth interview, group discussion and non-participant field observation also carried out to obtain additional information. The USLE results agreed with the farmers’ (67%) and local experts’ opinion that erosion at study area is severe and affects the quality of lives of residents. Insignificant difference (p > 0.05) was observed in the estimated soil loss among treatments. However, the estimated soil loss from free grazing lands was higher by 47% than soil loss from exclosures which illustrated that exclosures are effective to control soil erosion. The majority of farmers (70%) also rated exclosures effectiveness to control soil erosion as high. Local communities were optimistic about the chances to rehabilitate degraded lands and make them productive. The majority of farmers (60%) did not consider population growth as a cause of soil erosion. For the majority of interviewed farmers, poor land management is more important. Efforts to create awareness within the rural communities should focus on the link between high population growth, environmental degradation and poverty. The optimistic view of local communities can be considered as an asset for the planning and development of degraded lands rehabilitation efforts."],["dc.identifier.fs","388891"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5856"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/61203"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.orgunit","Fakultät für Forstwissenschaften und Waldökologie"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.subject.ddc","570"],["dc.title","Effectiveness of exclosures to control soil erosion and local community perception on soil erosion in Tigray, Ethiopia"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","5131"],["dc.bibliographiccitation.issue","16"],["dc.bibliographiccitation.journal","Biogeosciences"],["dc.bibliographiccitation.lastpage","5154"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Kurniawan, Syahrul"],["dc.contributor.author","Corre, Marife D."],["dc.contributor.author","Matson, Amanda L."],["dc.contributor.author","Schulte-Bisping, Hubert"],["dc.contributor.author","Utami, Sri Rahayu"],["dc.contributor.author","van Straaten, Oliver"],["dc.contributor.author","Veldkamp, Edzo"],["dc.date.accessioned","2019-07-09T11:45:54Z"],["dc.date.available","2019-07-09T11:45:54Z"],["dc.date.issued","2018"],["dc.description.abstract","Conversion of forest to rubber and oil palm plantations is widespread in Sumatra, Indonesia, and it is largely unknown how such land-use conversion affects nutrient leaching losses. Our study aimed to quantify nutrient leaching and nutrient retention efficiency in the soil after land-use conversion to smallholder rubber and oil palm plantations. In Jambi province, Indonesia, we selected two landscapes on highly weathered Acrisol soils that mainly differed in texture: loam and clay. Within each soil type, we compared two reference land uses, lowland forest and jungle rubber (defined as rubber trees interspersed in secondary forest), with two converted land uses: smallholder rubber and oil palm plantations. Within each soil type, the first three land uses were represented by 4 replicate sites and the oil palm by three sites, totaling 30 sites. We measured leaching losses using suction cup lysimeters sampled biweekly to monthly from February to December 2013. Forests and jungle rubber had low solute concentrations in drainage water, suggesting low internal inputs of rock-derived nutrients and efficient internal cycling of nutrients. These reference land uses on the clay Acrisol soils had lower leaching of dissolved N and base cations (P D0.01–0.06) and higher N and base cation retention efficiency (P < 0.01–0.07) than those on the loam Acrisols. In the converted land uses, particularly on the loam Acrisol, the fertilized area of oil palm plantations showed higher leaching of dissolved N, organic C, and base cations (P < 0.01–0.08) and lower N and base cation retention efficiency compared to all the other land uses (P < 0.01–0.06). The unfertilized rubber plantations, particularly on the loam Acrisol, showed lower leaching of dissolved P (P D 0:08) and organic C (P < 0.01) compared to forest or jungle rubber, reflecting decreases in soil P stocks and C inputs to the soil. Our results suggest that land-use conversion to rubber and oil palm causes disruption of initially efficient nutrient cycling, which decreases nutrient availability. Over time, smallholders will likely be increasingly reliant on fertilization, with the risk of diminishing water quality due to increased nutrient leaching. Thus, there is a need to develop management practices to minimize leaching while sustaining productivity."],["dc.identifier.doi","10.5194/bg-15-5131-2018"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15340"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59333"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation","SFB 990: Ökologische und sozioökonomische Funktionen tropischer Tieflandregenwald-Transformationssysteme (Sumatra, Indonesien)"],["dc.relation","SFB 990 | A | A05: Optimierung des Nährstoffmanagements in Ölpalmplantagen und Hochrechnung plot-basierter Treibhausgasflüsse auf die Landschaftsebene transformierter Regenwälder"],["dc.relation.issn","1726-4189"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.ddc","570"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","Conversion of tropical forests to smallholder rubber and oil palm plantations impacts nutrient leaching losses and nutrient retention efficiency in highly weathered soils"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1223"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Biogeosciences"],["dc.bibliographiccitation.lastpage","1235"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","van Straaten, Oliver"],["dc.contributor.author","Veldkamp, Edzo"],["dc.contributor.author","Köhler, M."],["dc.contributor.author","Anas, Iswandi"],["dc.date.accessioned","2017-09-07T11:43:36Z"],["dc.date.available","2017-09-07T11:43:36Z"],["dc.date.issued","2010"],["dc.description.abstract","Climate change induced droughts pose a serious threat to ecosystems across the tropics and sub-tropics, particularly to those areas not adapted to natural dry periods. In order to study the vulnerability of cacao (Theobroma cacao) – Gliricidia sepium agroforestry plantations to droughts a large scale throughfall displacement roof was built in Central Sulawesi, Indonesia. In this 19-month experiment, we compared soil surface CO2 efflux (soil respiration) from three roof plots with three adjacent control plots. Soil respiration rates peaked at intermediate soil moisture conditions and decreased under increasingly dry conditions (drought induced), or increasingly wet conditions (as evidenced in control plots). The roof plots exhibited a slight decrease in soil respiration compared to the control plots (average 13% decrease). The strength of the drought effect was spatially variable – while some measurement chamber sites reacted strongly (responsive) to the decrease in soil water content (up to R2=0.70) (n=11), others did not react at all (non-responsive) (n=7). A significant correlation was measured between responsive soil respiration chamber sites and sap flux density ratios of cacao (R=0.61) and Gliricidia (R=0.65). Leaf litter CO2 respiration decreased as conditions became drier. The litter layer contributed approximately 3–4% of the total CO2 efflux during dry periods and up to 40% during wet periods. Within days of roof opening soil CO2 efflux rose to control plot levels. Thereafter, CO2 efflux remained comparable between roof and control plots. The cumulative effect on soil CO2 emissions over the duration of the experiment was not significantly different: the control plots respired 11.1±0.5 Mg C ha−1 yr−1, while roof plots respired 10.5±0.5 Mg C ha−1 yr−1. The relatively mild decrease measured in soil CO2 efflux indicates that this agroforestry ecosystem is capable of mitigating droughts with only minor stress symptoms."],["dc.identifier.doi","10.5194/bg-7-1223-2010"],["dc.identifier.fs","574214"],["dc.identifier.gro","3150173"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5733"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/6908"],["dc.language.iso","en"],["dc.notes.intern","Migrated from goescholar"],["dc.notes.status","final"],["dc.relation.issn","1726-4189"],["dc.rights","Goescholar"],["dc.rights.access","openAccess"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.subject","CO2"],["dc.subject.ddc","570"],["dc.title","Spatial and temporal effects of drought on soil CO2 efflux in a cacao agroforestry system in Sulawesi, Indonesia"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3509"],["dc.bibliographiccitation.issue","14"],["dc.bibliographiccitation.journal","Biogeosciences"],["dc.bibliographiccitation.lastpage","3524"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Matson, Amanda L."],["dc.contributor.author","Corre, Marife D."],["dc.contributor.author","Langs, Kerstin"],["dc.contributor.author","Veldkamp, Edzo"],["dc.date.accessioned","2019-07-09T11:44:36Z"],["dc.date.available","2019-07-09T11:44:36Z"],["dc.date.issued","2017"],["dc.description.abstract","Tropical lowland forest soils are significant sources and sinks of trace gases. In order to model soil trace gas flux for future climate scenarios, it is necessary to be able to predict changes in soil trace gas fluxes along natural gradients of soil fertility and climatic characteristics. We quantified trace gas fluxes in lowland forest soils at five locations in Panama, which encompassed orthogonal precipitation and soil fertility gradients. Soil trace gas fluxes were measured monthly for 1 (NO) or 2 (CO2, CH4, N2O) years (2010–2012) using vented dynamic (for NO only) or static chambers with permanent bases. Across the five sites, annual fluxes ranged from 8.0 to 10.2 Mg CO2-C, −2.0 to −0.3 kg CH4-C, 0.4 to 1.3 kg N2O-N and −0.82 to −0.03 kg NO-N ha−1 yr−1. Soil CO2 emissions did not differ across sites, but they did exhibit clear seasonal differences and a parabolic pattern with soil moisture across sites. All sites were CH4 sinks; within-site fluxes were largely controlled by soil moisture, whereas fluxes across sites were positively correlated with an integrated index of soil fertility. Soil N2O fluxes were low throughout the measurement years, but the highest emissions occurred at a mid-precipitation site with high soil N availability. Net negative NO fluxes at the soil surface occurred at all sites, with the most negative fluxes at the low-precipitation site closest to Panama City; this was likely due to high ambient NO concentrations from anthropogenic sources. Our study highlights the importance of both short-term (climatic) and long-term (soil and site characteristics) factors in predicting soil trace gas fluxes."],["dc.identifier.doi","10.5194/bg-14-3509-2017"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/14837"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59048"],["dc.language.iso","en"],["dc.relation.issn","1726-4189"],["dc.subject.ddc","570"],["dc.title","Soil trace gas fluxes along orthogonal precipitation and soil fertility gradients in tropical lowland forests of Panama"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]