1,721,092 research outputs found
Impacts of carbon-optimised land use management in Southern Amazonia – multi-disciplinary perspectives: An Introduction
No full textShort-term effects of an exceptionally hot and dry summer on decomposition of surface peat in a restored temperate bog
No full textThe restoration of drained peat bogs in Northwest (NW) Europe is an important task of soil protection, but needs to cope with warmer and drier summers. Our examination took place in the Pietzmoor bog (Schneverdingen, NW Germany) that had been drained for fuel peat extraction until the 1970s and rewetted since then. We determined carbon dioxide (CO2) efflux in situ and in laboratory incubations. Also, we analyzed pore water for dissolved organic carbon (DOC), total and dissolved organic N (DON), nitrate (NO3-) and ammonium, (NH4+) concentration. In Schneverdingen, the summer 2003 was record-breaking hot (mean temperature June to August elevated > 3 K compared to long-term average) and dry (precipitation during the same period 42 cm below the surface in July 2003,when in Situ Soil CO2 efflux was up to 23.4 g m(-2) d(-1) compared to 15.7 g m(-2) d(-1) in September. Prior to March 2003, DOC concentrations in pore water were < 180,mg l(-1) and NH4+ was the dominant fraction of mineral N. In July 2003, DOC concentration rose to 249 g l(-1), DON concentrations. more than doubled, and NO3- became the dominant fraction of mineral N. Due to the increased future likelihood of,hot and dry summers in NW Germany, peat bog restoration efforts need take care that a water table close to the surface is maintained. (c) 2006 Elsevier Masson SAS. All rights, reserved
Hydrometeorologic, Pedologic and Vegetation Patterns along an Elevational Transect in the Montane Forest of the Bolivian Yungas
No full textThe "Mountain Agenda" of the World Summit on Sustainable Development 2002 emphasised the global relevance of montane cloud forests for important ecosystem services like water resources and biodiversity hot spots. Serious concern about the fate of tropical mountain forests has recently triggered intensified research on the ecological complexity of these forests. However, in Latin America research was focused on the Caribbean, Costa Rica and Ecuador (DFG Research Unit 816), whereas studies in the Andes of Peru and Bolivia were missing. In the framework of an interdisciplinary project aiming at understanding the relationships between vegetation and abiotic factors in the montane forest belts of the humid Yungas of Bolivia, hydrometeorologic observations and research on the altitudinal change of soils along an elevational gradient were carried out. Results suggest that the floristic change of vegetation belts and the differences in forest stature are influenced by complex interactions of climatic and pedologic variables along an elevational transect from 1,700 to 3,400 m a.s.l
Hydrometeorologic, Pedologic and Vegetation Patterns along an Elevational Transect in the Montane Forest of the Bolivian Yungas
No full textThe "Mountain Agenda" of the World Summit on Sustainable Development 2002 emphasised the global relevance of montane cloud forests for important ecosystem services like water resources and biodiversity hot spots. Serious concern about the fate of tropical mountain forests has recently triggered intensified research on the ecological complexity of these forests. However, in Latin America research was focused on the Caribbean, Costa Rica and Ecuador (DFG Research Unit 816), whereas studies in the Andes of Peru and Bolivia were missing. In the framework of an interdisciplinary project aiming at understanding the relationships between vegetation and abiotic factors in the montane forest belts of the humid Yungas of Bolivia, hydrometeorologic observations and research on the altitudinal change of soils along an elevational gradient were carried out. Results suggest that the floristic change of vegetation belts and the differences in forest stature are influenced by complex interactions of climatic and pedologic variables along an elevational transect from 1,700 to 3,400 m a.s.l
Soil development along an altitudinal transect in a Bolivian tropical montane rainforest: Podzolization vs. hydromorphy
No full textKnowledge about soil formation in tropical montane rainforests is scarce and patchy. We examined the altitudinal change of soils in a Bolivian tropical montane rainforest, aiming to illuminate the contribution of podzolization and hydromorphic processes to soil formation. In three transects from 1700 in to 3400 in a.s.l. we determined the pH, exchangeable cation exchange capacity, carbon and nitrogen stocks, and iron and aluminium fractions from 26 soil profiles. Three zones of different dominant soil forming processes were found: In the lower montane forest (LMF, 1700-2200 in a.s.l.), Dystropepts with high nutrient concentration and acidity were common. The pronounced change to the upper montane cloud forest (UMCF, 2200-2700 m a.s.l.) coincided with the appearance of Placorthods with more acidic conditions, deep ectorganic horizons and increasing translocation of sesquioxides. In the sub-alpine forest (SCF, 2700 m-3400 in a.s.l.), hydromorphic processes dominated over podzolization, resulting in Placaquods with low mineralization rate and nutrient concentration. This shows that due to increasing wetness and colder temperatures at high altitudes, dominant soil forming processes change from podzolization to hydromorphism soils with increasing altitude. (c) 2006 Elsevier B.V. All rights reserved
LIANA-TREE RELATIONSHIPS: CONSEQUENCES FOR TREE COMMUNITIES AND TREE EVOLUTION
No full textLianas (woody vines) comprise 10-40% of the individuals and species of tropical forests. They proliferate in response to global change and differentially reduce the survival, growth and reproduction of tree species. Indeed, it has been proposed that lianas alter the competitive balance among tree species and even that there are trees with adaptations to avoid and shed lianas. However, many evidences suggest that lianas also have neutral and positive effects on trees, and thus a multiple linear regression model is formulated on the role of lianas on tree communities. Such a model is an expansion of the differential hypothesis on the effect of lianas on trees. Liana's role in structuring tree communities can be reduced and diffused among tree species due to the diffuse, non-predictable associations among species of lianas and trees and to the rapid switch of such associations in time and space. That is consistent with evolutionary studies showing that lianas are not a major selective pressure favoring adaptations of trees to avoid and shed them; such characteristics have other functions. Further studies combining both Ecology and Evolution may better explain the relationships between the two main components of the woody flora of tropical forests: lianas and trees
Spatial databases and GIS as tools for regional landslide susceptibility modeling
No full textThis study presents a regional landslide susceptibility model for the Federal State of Lower Saxony in the NW part of Central Europe. On the basis of a landslide database and a Geographical Information System (GIS), a modified information value approach is developed, which uses bivariate statistics to predict the spatial distribution and probability of mass movements. The input data of the susceptibility model include a spatial inventory of about 900 landslides and different data sets of geomorphometry, lithology and land use. A regional perspective puts specific requirements on the modeling, which is considered by a reformulation of the weighting function. The model estimates that about 2% of the Lower Saxon territory shows a predisposition to landslides. Most part of this land is concentrated on three key areas in the Lower Saxon Uplands. The spatial pattern of landslide susceptibility is directly correlated with the regional relief configuration and is characterized by specific clusters. In addition to slope gradient between 21 degrees and 49 degrees, Mesozoic sedimentary rock, especially sequences of lime- and claystone, are identified to be the most relevant predisposing factors. Like lithology, land use can be of stabilizing or destabilizing influence, but its significance, however, is less important. A special focus is on the identification of potential infrastructure exposure to landslides. This assessment reveals that in the Lower Saxon Uplands about 1% of the urban area and up to 4% of the road network is located in zones of significant hazard. Although the model is proven to be of good predictive power and high spatial accuracy, the study clarifies that susceptibility modeling often faces methodological shortcomings and a lack of plausibility. Some of these problems are discussed in this paper in detail
Implications of input estimation, residue quality and carbon saturation on the predictive power of the Rothamsted Carbon Model
No full textEffects of fertilisation and cropland management on soil organic carbon (SOC) dynamics can be assessed best in long-term experiments. Using data from the long-term fertilisation experiment in Puch, Germany (part of the series "Internationale Organische Stickstoff Dauerversuche", IOSDV), we tested the performance of the Rothamsted Carbon Model 26.3 (RothC). The objectives of this work were: (i) quantify the C-input and the efficiency of SOC stabilisation, (ii) test the performance of different input estimates on predictive power of the RothC and (iii) test implementations of residue quality and C-saturation on model predictions. The experiment is a full-factorial strip design, the factors being "organic amendment" and "level of N-fertiliser". Each treatment was replicated three times. The crop rotation is silage maize-winter wheat-winter barley. Five levels of the factor "organic amendment" were considered: (i) CON: no organic amendment; (ii) SLU: slurry application (on average 0.8 Mg C ha(-1) year(-1)); (iii) FYM: application of farmyard manure (30 to 40 Mg ha(-1) fresh mass every third year to maize, on average 1.0 Mg C ha(-1) year(-1)). (iv) STR: straw incorporation after harvest of wheat and barley (depending on straw yield on average 0.7 to 2.2 Mg C ha(-1) year(-1)): (v) STSL: slurry application plus straw incorporation (on average 1.1 to 2.4 Mg C ha(-1) year(-1)). All treatments (including CON) were combined with five different levels of N-fertilisation (N0 to N4), whereas N0 was nil N application and N4 averaged 177 kg N ha(-1) year(-1). N-rates increased gradually and differed depending on the crop. Starting values for SOC stocks (Mg hat) were measured in 1983 as a mean among N-rates for organic amendment treatments (CON: 42; SLU: 39.8; FYM: 40.5; STR 39.8; STSL: 40.5). SOC stocks (0-25 cm) in 2004 (35.5 to 46.6 Mg C ha(-1)) were in the order STSL> FYM = SLU > STR = CON (p <= 0.001). However, slightly different starting values indicated a higher loss of SOC after 21 years in the CON (11-14%) compared to the SIR treatments (1-10%). Effect of N-rate was not significant. The observed relation between change of SOC and C-input was quadratic (Y-O = -13.4 + 7.5x - 0.9x(2); R-2 = 0.74, p <= 0.001), which contrasted the linear relationship predicted by RothC (Y-P = -12.9 + 5.5x; R-2 = 0.97, p <= 0.0001). Serious deviation between observed and predicted relationship occurred above C-inputs of 2.5 Mg C ha(-1) year(-1). Mechanistic explanation (e.g. C-saturation or increased mineralisation by N-fertilisation) for the observation needs further exploration, but implication on regional estimates for C-accumulation for different cropland management scenarios is obvious: potential gain in SOC storage by increasing C-inputs may be overestimated, at least under conditions of the Puch site. Independent model predictions (i.e. no parameter adjustment and independent estimation and measurement of C-input) were successful for treatments without straw incorporation (CON, SLU, FYM). Using a regression between crop yields and crop residue input yielded better results than using a constant belowground-to-aboveground biomass ratio. SOC stocks of treatments STR and STSL were seriously overestimated by the model. Using a higher decomposability of crop residue improved result only marginally and required the change of a standard parameter. Using a simple implementation of C-saturtion improved predictions for STR and STSL but failed to simulate dynamics in all other treatments. Overall, our results showed that it is important to recognise that relation between SOC change and C-input is not necessarily linear. However, the RothC model predicted SOC dynamics well at lower input levels. Observation that a regression equation for input estimation is superior to a constant biomass ratio for modelling purposes has to be tested further. An implementation of residue quality or saturation capacity in the RothC model may be promising for a better mechanistic understanding of SOC dynamics. However, this requires careful calibration and will increase the number of parameters to be fitted. (C) 2011 Elsevier B.V. All rights reserved.Bayrische Landesanstalt fur Landwirtschaft, state of Bavaria, German
LIANA-TREE RELATIONSHIPS: CONSEQUENCES FOR TREE COMMUNITIES AND TREE EVOLUTION
No full textLianas (woody vines) comprise 10-40% of the individuals and species of tropical forests. They proliferate in response to global change and differentially reduce the survival, growth and reproduction of tree species. Indeed, it has been proposed that lianas alter the competitive balance among tree species and even that there are trees with adaptations to avoid and shed lianas. However, many evidences suggest that lianas also have neutral and positive effects on trees, and thus a multiple linear regression model is formulated on the role of lianas on tree communities. Such a model is an expansion of the differential hypothesis on the effect of lianas on trees. Liana's role in structuring tree communities can be reduced and diffused among tree species due to the diffuse, non-predictable associations among species of lianas and trees and to the rapid switch of such associations in time and space. That is consistent with evolutionary studies showing that lianas are not a major selective pressure favoring adaptations of trees to avoid and shed them; such characteristics have other functions. Further studies combining both Ecology and Evolution may better explain the relationships between the two main components of the woody flora of tropical forests: lianas and trees
AN IN SITU METHOD TO MEASURE AND MAP BARK PH
No full textBark pH is an essential parameter which partly governs the chemistry of the bark as well as its suitability as a microhabitat to a wide range of epiphytic organisms. Bark pH is known to vary with tree species, epiphytic cover, stemflow channelization, and anthropogenic influences. To date, reliable methods to quantify the spatial and temporal dimensions of bark pH have remained elusive. The aim of the present study was to develop and validate an in situ method to measure the surface pH of bark with high spatial resolution. Agar-agar panels, prepared with a pH indicator, were used to quantify and map the spatial variation of bark pH for cacao trees in Indonesia. Fine-scale changes of bark pH were clearly detectable and quantifiable with our bark pH mapping method. Bark pH was found to vary as a function of bark microrelief and the presence of epiphytes. The use of pH reference panels validated the bark pH measurements obtained from our method. The bark pH measurement method developed, described, and validated in this article is inexpensive and straightforward. It has the potential for wide adoption by scientists across disciplines who are interested in bark pH and its effect on life in the cortisphere. Unlike conventional methods to measure bark pH in deionized water or KCl extracts, our method is able to identify fine-scale spatial changes in bark pH that are relevant for the colonization of bark by organisms.German Research Foundation (DFG) [SFB 552.
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