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Two research projects were established to foster Brazilian-German collaboration and inter- and transdisciplinary research in the southern Amazon region. In the scope of the German BMBF-FONA program (Federal Ministry for Education and Research?Research for Sustainable Development), the Carbiocial consortium (www.carbiocial.de) investigated C stock changes, greenhouse gas (GHG) emissions, erosion, catchment hydrology, agricultural production, land cover, socio-economic drivers, policy impact and actor networks using experiments, monitoring, surveys, remote sensing and dynamic simulation modelling. In Brazil, the corresponding research project Carbioma focused more specifically on the political programs which were established to mitigate environmental problems arising from inappropriate land use, such as Brazil?s Sector Plan for the Mitigation and Adaptation to Climate Change for the Consolidation of Low Carbon Emission Agricuture (ABC Plan; Plano Setorial de Mitigação e de Adaptação às Mudanças Climáticas para a Consolidação de uma Economia de Baixa Emissão de Carbono na Agricultura; MAPA?MDA 2012), the Nationally Appropriate Mitigation Actions (NAMAS) and the intended Nationally Determined Contributions (iNDC; Brazil 2015). For this, Carbioma performed field experiments at the different experimental field stations of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa). The main objective of both project consortia was to investigate viable, carbon-optimised land management strategies for this hotspot of global change research. Together with its Brazilian partners, collaborators and local stakeholders, Carbiocial concentrated on obtaining parameters for simulation models, which are then used to test and improve carbonoptimised land use management strategies Made available in DSpace on 2018-01-03T23:19:37Z (GMT). No. of bitstreams: 1 CNPAF2018recp1.pdf: 764290 bytes, checksum: a9c95ac8ad5e4d9cd58d70ae2ff20965 (MD5) Previous issue date: 2017-12-14

We analyzed changes in water quantity and quality at different spatial scales within the Tapajós River basin (Amazon) based on experimental fieldwork, hydrological modelling, and statistical time-trend analysis. At a small scale, we compared the river discharge (Q) and suspended-sediment concentrations (SSC) of two adjacent micro-catchments ( 2) with similar characteristics but contrasting land uses (forest vs. pasture) using empirical data from field measurements. At an intermediary scale, we simulated the hydrological responses of a sub-basin of the Tapajós (Jamanxim River basin, 37 400 km2), using a hydrological model (SWAT) and land-use change scenario in order to quantify the changes in the water balance components due to deforestation. At the Tapajós' River basin scale, we investigated trends in Q, sediments, hydrochemistry, and geochemistry in the river using available data from the HYBAM Observation Service. The results in the micro-catchments showed a higher runoff coefficient in the pasture (0.67) than in the forest catchment (0.28). At this scale, the SSC were also significantly greater during stormflows in the pasture than in the forest catchment. At the Jamanxim watershed scale, the hydrological modelling results showed a 2 % increase in Q and a 5 % reduction of baseflow contribution to total Q after a conversion of 22 % of forest to pasture. In the Tapajós River, however, trend analysis did not show any significant trend in discharge and sediment concentration. However, we found upward trends in dissolved organic carbon and NO3− over the last 20 years. Although the magnitude of anthropogenic impact has shown be scale-dependent, we were able to find changes in the Tapajós River basin in streamflow, sediment concentration, and water quality across all studied scales.

This article describes the design of a new model-based assessment framework to identify and analyse possible future trajectories of agricultural development and their environmental consequences within the states of Mato Grosso and Para in Southern Amazonia, Brazil. The objective is to provide a tool for improving the information basis for scientists and policy makers regarding the effects of global change and national environmental policies on land-use change and the resulting impacts on the loss of natural vegetation, greenhouse gas emissions, hydrological processes, and soil erosion within the region. For this purpose, the framework combines the regional land-use models, LandSHIFT and alucR, the farm-level model, MPMAS, and the MONICA crop model, with a set of environmental impact models that are operating at the regional and watershed levels. As a first application of the framework, four scenarios with the time horizon 2030 were specified and analysed. Future land-use change will strongly depend on the interplay between the production of agricultural commodities, the agricultural intensification in terms of increasing crop yields and pasture biomass productivity, and the enforcement of environmental laws and policies. On the regional level, the scenarios with the highest increase in agricultural production in combination with weak law enforcement (Trend and Illegal Intensification) generated the highest losses in natural vegetation due to the expansion of agricultural area as well as the highest greenhouse gas emissions. Also, at the watershed level, these scenarios are characterised by the highest changes in river discharge and soil erosion that might lead to a further decline in soil fertility in the long term. Moreover, the analysis of the Sustainable Development scenario indicates that a shift in agricultural production patterns from livestock to crop cultivation, together with effective law enforcement, can effectively reduce land-use change and its negative effects on the environment. With the scenario analysis, we could illustrate that our assessment framework is capable to provide a large variety of valuable information to support the development of future land-use strategies in the study region.

Cocoa beans are produced all across the humid tropics under different environmental conditions provided by the region but also by the season and the type of production system. Agroforestry systems compared to monocultures buffer climate extremes and therefore provide a less stressful environment for the understory cocoa, especially under seasonally varying conditions. We measured the element concentration as well as abiotic stress indicators (polyamines and total phenolic content) in beans derived from five different production systems comparing monocultures and agroforestry systems and from two harvesting seasons. Concentrations of N, Mg, S, Fe, Mn, Na, and Zn were higher in beans produced in agroforestry systems with high stem density and leaf area index. In the dry season, the N, Fe, and Cu concentration of the beans increased. The total phenolic content increased with proceeding of the dry season while other abiotic stress indicators like spermine decreased, implying an effect of the water availability on the chemical composition of the beans. Agroforestry systems did not buffer the variability of stress indicators over the seasons compared to monocultures. The effect of environmental growing conditions on bean chemical composition was not strong but can contribute to variations in cocoa bean quality.

Ecuador is currently completing the readiness phase for the implementation of the Reducing Emissions from Deforestation and forest Degradation (REDD+) mechanism at the national level. Many challenges regarding rights, multilayered governance and land tenure remain open in this country where Indigenous Peoples (IPs) occupy 68% of the Ecuadorian Amazon. We focused on the Yasuni Biosphere Reserve to exemplify obstacles and answers found in the last years. In a REDD+ pilot project, six communities of the most widespread ethnicities (Shuar, Kichwa and Colonists) living in the buffer zone of the Yasuni National Park (YNP), were chosen. We used literature research, analysis of international and national agendas, as well as primary data on REDD+ perception obtained through semi-structured household interviews and personal observations. First, we reconstruct the historical development of territorial configuration and present the actual land tenure arrangements. And then, we analyze persistent management conflicts within institutional, planning and normative instruments. Finally we explore legal frameworks with a focus on participation and consultation. Our results show that insecure and overlapping land rights, as well as unclear and contradictory institutional responsibilities are major problems for REDD+ implementation. Despite great advancements that have been made, establishing equitable mechanisms to engage IPs and forest owners and stakeholders across many sectors in REDD+ is required. Especially in Ecuador where oil extraction is a priority and the central government has an exclusive competence over ecosystem services including carbon rights. Implementing fair methods for participation, benefit sharing and transfer of knowledge remains a challenge.

Since the 1980s, the state of Mato Grosso, Brazil, exhibits high rates of Cerrado conversion in favour of soybean expansion and cattle ranching. This conversion process becomes obvious in the upper Rio das Mortes macro-catchment. The objective of this study was to assess the influence of future land use changes on the discharge dynamics of the Rio das Mortes River. A single catchment approach was applied with the physically-based water balance simulation model WaSiM 8.5.0 (Schulla and jaSper 2007) to simulate land use scenarios. In Scenario 1, only small pasture sites (< 1 km²) were converted into the respective land use type surrounding them (i.e. cropland or Cerrado vegetation), whereas in Scenario 2 all pasture sites were converted into cropland and all Cerrado patches were then transformed into pastures. The WaSiM model was calibrated and validated based on discharge data measured at two gauging stations, achieving Nash-Sutcliffe coeffcients of 0.81 calibration) and 0.68 (validation). Main problems in modelling arise because of scarce spatial distributed data on subsurface parameter and vegetation parameter (Cerrado biome). Therefore, the use of the numerical groundwater model and manifold calibration runs were essential in this modelling approach to allow the simulation of the high levels of baseflow during the dry season and the transition from the dry to the wet season. The immediate rise of the baseflow in response to the increasing precipitation at beginning of the rainy season is a result of high soil hydraulic conductivity and groundwater recharge. These soil characteristics apparently persist on newly-created pasture and cropland sites, which still exhibit high ksat values after deforestation. Simulated evapotranspiration is comparable to literature values (Eddy flux measurements, MODIS-EVI calculation) and recently done paired micro-catchment studies in this catchment. The scenario analysis indicates that there are only small differences in runoff \ud volume, which is directly related to the precipitation changes. In the scenario 2, groundwater recharge and base flow increase, whereas surface runoff does not. Therefore, the ongoing land use intensification with pasture conversion to cropland, remaining high infiltration and slight increase of evapotranspiration may not change runoff volume and discharge characteristics.

Mapping vegetation types through remote sensing images has proved to be effective, especially in large biomes, such as the Brazilian Cerrado, which plays an important role in the context of management and conservation at the agricultural frontier of the Amazon. We tested several combinations of optical and radar images to identify the four dominant vegetation types that are prevalent in the Cerrado area (i.e., cerrado denso, cerradão, gallery forest, and secondary forest). We extracted features from both sources of data such as intensity, grey level co-occurrence matrix, coherence, and polarimetric decompositions using Sentinel 2A, Sentinel 1A, ALOS-PALSAR 2 dual/full polarimetric, and TanDEM-X images during the dry and rainy season of 2017. In order to normalize the analysis of these features, we used principal component analysis and subsequently applied the Random Forest algorithm to evaluate the classification of vegetation types. During the dry season, the overall accuracy ranged from 48 to 83%, and during the dry and rainy seasons it ranged from 41 up to 82%. The classification using Sentinel 2A images during the dry season resulted in the highest overall accuracy and kappa values, followed by the classification that used images from all sensors during the dry and rainy season. Optical images during the dry season were sufficient to map the different types of vegetation in our study area.

Studies on the impacts of land-use and land-cover change on stream hydrochemistry in active deforestation zones of the Amazon agricultural frontier are limited and have often used low-temporal-resolution datasets. Moreover, these impacts are not concurrently assessed in well-established agricultural areas and new deforestations hotspots. We aimed to identify these impacts using an experimental setup to collect high-temporal-resolution hydrological and hydrochemical data in two pairs of low-order streams in catchments under contrasting land use and land cover (native vegetation vs. pasture) in the Amazon and Cerrado biomes. Our results indicate that the conversion of natural landscapes to pastures increases carbon and nutrient fluxes via streamflow in both biomes. These changes were the greatest in total inorganic carbon in the Amazon and in potassium in the Cerrado, representing a 5.0- and 5.5-fold increase in the fluxes of each biome, respectively. We found that stormflow, which is often neglected in studies on stream hydrochemistry in the tropics, plays a substantial role in the carbon and nutrient fluxes, especially in the Amazon biome, as its contributions to hydrochemical fluxes are mostly greater than the volumetric contribution to the total streamflow. These findings demonstrate that assessments of the impacts of deforestation in the Amazon and Cerrado biomes should also take into account rapid hydrological pathways; however, this can only be achieved through collection of high-temporal-resolution data.

This study presents the setup, calibration, validation and scenario application of the soil and water assessment tool for two contrasting macro-catchments along the Amazon agricultural frontier in the federal states of Para and Mato Grosso, Brazil. Calibration and validation of the model are realised for the periods of the most intensive deforestation and agricultural expansion. In order to give consideration to the rapid, however gradual nature of land use change, the model implements an annual land use update combined with a land use dependent soil parameterization of the upper most soil layer. The comparison of these results with the results of a setup with a steady land use distribution shows distinct improvements of the prediction quality. Discharge prediction improves through the application of gradual land use change in the model by 12 % for a 1.8 % deforestation rate per year and 1.2 % for a deforestation rate of 0.7 % per year. Consequently, the validated models are applied to four land use scenarios for the period 2026–2035. Scenario simulation results show effects on the water balance proportional to land use change. Further, the changes in the water balance follow clear seasonal patterns with highest hydrological effects due to land use change during the rainy season in both catchments. Overall, with continuous deforestation, peak discharge increases. Further, the conversion of native vegetation to pasture has the highest impact on the water balance. For example, monthly discharge in the rainy season increases by up to 24 % for a 13 % conversion of Cerrado savannah into pasture.

SUMMARYAgroforestry systems (AFS) can serve to decrease ecosystem carbon (C) losses caused by deforestation and inadequate soil management. Because of their shade tolerance, cacao plants are suitable to be grown in AFS, since they can be combined with other kinds of trees and shrubs. The potential for C sequestration in cacao farming systems depends on various factors, such as management practices, stand structure and plantation age. We compared conventionally and organically managed cacao monoculture systems (MCS) and AFS in Sara Ana (Bolivia) with respect to C stocks in plant biomass and to amounts of litterfall and pruning residues. The total aboveground C stocks of the AFS (26 Mg C ha−1) considerably exceeded those of the MCS (~7 Mg C ha−1), although the biomass of cacao trees was greater in the MCS compared to the AFS. Due to higher tree density, annual litterfall in the AFS (2.2 Mg C ha−1 year−1) substantially exceeded that in the MCS (1.2 Mg C ha−1 year−1). The amounts of C in pruning residues (2.6 Mg C ha−1 year−1 in MCS to 4.3 Mg C ha−1 year−1 in AFS) was more than twice those in the litterfall. Annual nitrogen (N) inputs to the soil through pruning residues of cacao and N-fixing trees were up to 10 times higher than the N inputs through external fertiliser application. We conclude that appropriate management of cacao AFS, involving the pruning of leguminous trees, will lead to increases in biomass, litter quantity and quality as well as soil C and N stocks. Thus, we recommend stimulating the expansion of well-managed AFS to improve soil fertility and enhance C sequestration in soils.

International audience; AbstractKey messageShade trees in agroforestry systems protect the understory cocoa from climate extremes. Shade tree pruning manages microclimatic conditions in favor of cocoa production while tree diversity is maintained. Adaptation of pruning has to consider seasonal changes in temperature and precipitation to protect the understory cocoa.ContextStructural characteristics of tree stands such as species diversity, tree density, and stratification can affect throughfall and microclimate. Pruning changes the canopy and may therefore modulate internal conditions.AimsThe aim of this study is to assess the environmental growing conditions of cocoa trees.MethodsWe monitored canopy openness and the impact of stand structure on throughfall and microclimate in three cocoa production systems (monoculture, agroforestry, and successional agroforestry) and a natural regrowth in a long-term trial in Bolivia from 2013 to 2015. We further focused on the effect of annual shade tree and cocoa pruning on these variables to evaluate the potential impact of this activity.ResultsAgroforestry systems buffered extreme climate events like temperature fluctuations compared to monocultures but reduced light and throughfall drastically. Spatial variability of throughfall and transmitted light were low under a high and closed shade tree canopy. Shade tree pruning resulted in higher canopy openness, light transmittance, and throughfall, while the buffer function of the agroforestry systems concerning temperature and humidity fluctuations was reduced.ConclusionDifferences between cocoa production systems regarding throughfall and microclimate were overlain by pruning activities. Cocoa agroforestry systems are temporal dynamic systems. Pruning timing and intensity is pivotal for balancing light and water availability under seasonally varying environmental conditions to conserve micro-environments for cocoa production with less exposure to unfavorable climate.

Reducing Emissions from Deforestation and Forest Degradation (REDD+) is considered a promising strategy to slow down deforestation rates, promote sustainable forest use, and support rural livelihoods under the umbrella of climate change mitigation. However, so far there is only little field-based knowledge on how REDD+ can go along with subsistence-based production systems and livelihoods of forest-dependent communities. We addressed this research gap by analyzing the income generation of three widespread ethnic groups (Colonists, Shuar, Kichwa) in the buffer zone of the Yasuni National Park in Ecuador to better understand their livelihoods and possible engagement in REDD+. We selected two communities of each ethnic group (close-to and far-from markets) and used household surveys to (a) calculate household incomes, (b) assess the degree of forest-dependency, and (c) discuss how REDD+ schemes can be designed along with traditional subsistence-based production systems. We found that the studied indigenous communities have a higher degree of forest-dependency and higher environmental income compared to Colonists. However, our assumption that close-to-market communities have a lower degree of forest dependency and higher cash income due to better market access and labor opportunities applies only to the Colonists and Shuar, but must be rejected for the Kichwas who gain income from timber sale. Despite these differences, all communities receive high off-farm revenues from unskilled labor provided by oil-companies and external aid. Therefore, dependency on agriculture and forestry is temporarily reduced. Under these circumstances, REDD+ provides only weak financial incentives so that the willingness to participate in REDD+ is low.

Terrestrial herbs are important elements of tropical forests; however, there is a lack of research on their diversity patterns and how they respond to different intensities of forest-use. The aim of this study was to analyze the diversity of herbaceous angiosperms along gradients of elevation (50 m to 3500 m) and forest-use intensity on the eastern slopes of the Cofre de Perote, Veracruz, Mexico. We recorded the occurrence of all herbaceous angiosperm species within 120 plots of 20 m x 20 m each. The plots were located at eight study locations separated by ~500 m in elevation and within three different habitats that differ in forest-use intensity: old-growth, degraded, and secondary forest. We analyzed species richness and floristic composition of herb communities among different elevations and habitats. Of the 264 plant species recorded, 31 are endemic to Mexico. Both α- and γ-diversity display a hump-shaped relation to elevation peaking at 2500 m and 3000 m, respectively. The relative contribution of between-habitat β-diversity to γ-diversity also showed a unimodal hump whereas within-habitat β-diversity declined with elevation. Forest-use intensity did not affect α-diversity, but β-diversity was high between old-growth and secondary forests. Overall, γ-diversity peaked at 2500 m (72 species), driven mainly by high within- and among-habitat β-diversity. We infer that this belt is highly sensitive to anthropogenic disturbance and forest-use intensification. At 3100 m, high γ-diversity (50 species) was driven by high α- and within-habitat β-diversity. There, losing a specific forest area might be compensated if similar assemblages occur in nearby areas. The high β-diversity and endemism suggest that mixes of different habitats are needed to sustain high γ-richness of terrestrial herbs along this elevational gradient., Open-Access-Publikationsfonds 2017

Soil moisture has high spatial and temporal variability, depending on topography, soil texture, vegetation and meteorological conditions. It influences many processes in the soil and supplies water to the vegetation. This is often a limiting factor in agricultural production. Over an 18-month period, we measured soil moisture dynamics down to a depth of 70 cm in a long-term trial in Bolivia comprising six different land-use systems, i.e. cocoa monocultures and agroforestry systems, both under organic and conventional management, successional cocoa agroforestry systems and a natural fallow. Soil was heterogeneous over the area and in depth. We identified and separated two soil groups which differed in both, texture and soil water retention capacity. Considering the two groups, we assessed the effect of the different land-use systems on soil moisture dynamics and plant available water on the one hand, and how different soil moisture conditions affect growth and production of cocoa on the other. In monocultures with shallow rooting cocoa only, soil moisture decreased mainly in the uppermost soil layer during the dry season and the lower layers kept more moisture year round. In agroforestry systems soil moisture decreased homogeneously over the soil profile, implying a complementarity in water use of cocoa and deeper rooting trees. The uppermost soil layer in the agroforestry systems had higher soil moisture than in the monoculture, demonstrating the role of shade trees to reduce water loss from top soil by evaporation and transpiration of the cocoa. Even though one soil group had continuously higher water availability than the other group, we did not find an effect on the cocoa yield. Cocoa relies on sufficient water supply, but beside information on the precipitation it is important to know the soil structure and soil water retention capacity when discussing water availability for cocoa production and to consider the heterogeneity of the soil even over small area.

On the basis of interactions between landscape characteristics and precipitation inputs, watersheds respond differently to different climatic inputs. The objective of this study was to quantitatively characterize controls on runoff generation from two first order micro-catchments in the Amazonia region. The study investigated the variation of hydrological signatures at micro-catchment scale and related these to landscape and land cover differences and weather descriptors that control the observed responses. One catchment is a pasture cleared of all natural vegetation in the early 1980s, and the second catchment is a primary tropical forest with minor signs of disturbance. Water levels and meteorological variables were continuously monitored during the study period (December 2012–May 2013). Water level measurements were converted to discharge, evapotranspiration was quantified using Penman–Monteith equation and catchment pedohydrological properties were also determined. During the study period, mean total rainfall was 1200 mm, and direct runoff ratios were 0.29 and 0.12 for the pasture and forest catchments, respectively. Baseflow index was relatively high in the forest catchment (0.76) compared with pasture catchment (0.63). Results from this study showed that the pasture catchment had a 35% higher mean stream flow. Analysis of selected individual rainstorm events also showed peak discharges, which were attained much faster in the pasture catchment compared with the forest catchment. At both sites, rainfall-runoff responses were highly dependent on surface and subsurface flow generation. Overland flow was observed in the pasture site during intense rainfall events. The pasture catchment exhibited higher event water contribution than the forest catchment. Findings from this research suggest that shallow lateral pathways play a significant role in controlling runoff generation processes in the forest catchment, whereas infiltration excess runoff generation processes dominate in the pasture catchment. The findings in this study suggest that the conversion of forest to pasture may lead to important changes in runoff generation processes and water storage in these head water catchments.

Predicting potential habitats of endemic species is a suitable method for biodiversity conservation and rehabilitation of rangeland ecosystems. The present study was conducted to estimate the geographic distribution of Artemisia sieberi ( A. sieberi ) and Artemisia aucheri ( A. aucheri ), find the most important environmental predictor variables and seek for similarities and differences in habitat preferences between the two species for Poshtkouh rangelands in Central Iran. Maps of environmental variables were created by means of geographic information system (GIS) and geostatistics. Then predictive distribution maps of both species were produced using the maximum entropy modeling technique (Maxent) and presence-only data. Model accuracy is evaluated by using the area under the curve (AUC). Lime1, gravel1, lime 2 and elevation most significantly affect habitat distribution of A. aucheri , while habitat distribution of A. sieberi is affected by elevation, lime1, am1, lime2, and om2. For both species, elevation has an influence on their potential distributions. However, A. aucheri depends more on elevation, and consequently climate in comparison to A. sieberi . Finally, it is revealed that the potential distribution of A. aucheri is limited mostly to mountainous landscapes while A. sieberi is present in wide ranges of environmental conditions.

The global importance of wetlands in the carbon and nitrogen cycles is well documented, but the specific greenhouse gas characteristics of South African wetlands are less well known. These wetlands most likely differ from more prominent wetlands from continuously humid climate zone (boreal, temperate and tropics). Particular wetlands in the southern Drakensberg are adapted to the seasonal drying during the winter months. Greenhouse gas emissions were measured during natural rewetting at two wetlands. A rapid reaction and significant positive correlation between greenhouse gas fluxes and ground water level were determined. Methane emissions were observed after two days of rewetting at one of the wetlands, and nitrous oxide emissions started within a day of rewetting at the other wetland. The high nitrous oxide emissions may be caused by the recent winter burning of vegetation, which most likely resulted in a greater availability of nitrogen in the soil. High nitrous oxide emissions following natural rewett...

The best method for determining soil organic carbon (SOC) in carbonate-containing samples is still open to debate. The objective of this work was to evaluate a thermal gradient method (ThG), which can determine simultaneously inorganic carbon (SIC) and SOC in a wide range of soil samples. The determination of SOC by ThG (SOCThG) was compared to the following widespread standard methods: (1) acidification (ACI) as pretreatment and subsequent dry combustion (SOCACI) and (2) volumetric quantification of SIC by a calcimeter (CALC) and subtraction of the total carbon content as determined by dry combustion (SOCCALC). Precision (F test) and bias (t test) were tested on a subset of seven samples (n = 3). Comparison of the ThG and CALC methods was performed by regression analysis (n = 76) on samples representing a wide range of SOC (5.5 to 212.0 g kg−1) and SIC (0 to 59.2 g kg−1) contents. Tests on the replicated subset showed that the precision of ThG was not significantly different from ACI or CALC (F values

The reduction of tropical deforestation is of crucial importance for mitigating climate change and curbing the loss of biodiversity. In light of the current international efforts to reduce deforestation associated to REDD+, effective and efficient country-specific policy options need to be identified to make progress on the ground. Taking lowland Bolivia as an example, we propose a systematic approach to identify and discuss such policy options; this systematic approach can be applied to other tropical contexts with ongoing conversion of forests to agricultural uses. We begin with the distinction of three land use categories associated with the main proximate causes of deforestation in lowland Bolivia, viz. mechanized agriculture, small-scale agriculture and cattle ranching, each of them linked to typical agents. Based on a systematic analysis of spatial and socioeconomic criteria, we then estimate the potential of land use expansion and the likely costs of deforestation reduction in order to formulate suitable policy options for each of the three proximate causes of deforestation. Although mechanized agriculture caused more than half of deforestation in lowland Bolivia, we argue that cattle ranching activities, which contributed to 27% of deforestation between 1992 and 2004, should be targeted as a priority since its expansion threatens forests in many different locations and improvements could be achieved at relatively low costs. In this light, enforcing land use legislation, accompanied by strengthening institutions on national and local levels, constitute tasks of utmost importance.

Effects 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 ha− 1) 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 STR treatments (1–10%). Effect of N-rate was not significant. The observed relation between change of SOC and C-input was quadratic (YO = − 13.4 + 7.5x − 0.9x2; R2 = 0.74, p ≤ 0.001), which contrasted the linear relationship predicted by RothC (YP = − 12.9 + 5.5x; R2 = 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-saturation 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.

Forests in lowland Bolivia suffer from severe deforestation caused by different types of agents and land use activities. We identify three major proximate causes of deforestation. The largest share of deforestation is attributable to the expansion of mechanized agriculture, followed by cattle ranching and small-scale agriculture. We utilize a spatially explicit multinomial logit model to analyze the determinants of each of these proximate causes of deforestation between 1992 and 2004. We substantiate the quantitative insights with a qualitative analysis of historical processes that have shaped land use patterns in the Bolivian lowlands to date. Our results suggest that the expansion of mechanized agriculture occurs mainly in response to good access to export markets, fertile soil, and intermediate rainfall conditions. Increases in small-scale agriculture are mainly associated with a humid climate, fertile soil, and proximity to local markets. Forest conversion into pastures for cattle ranching occurs mostly irrespective of environmental determinants and can mainly be explained by access to local markets. Land use restrictions, such as protected areas, seem to prevent the expansion of mechanized agriculture but have little impact on the expansion of small-scale agriculture and cattle ranching. The analysis of future deforestation trends reveals possible hotspots of future expansion for each proximate cause and specifically highlights the possible opening of new frontiers for deforestation due to mechanized agriculture. Whereas the quantitative analysis effectively elucidates the spatial patterns of recent agricultural expansion, the interpretation of long-term historic drivers reveals that the timing and quantity of forest conversion are often triggered by political interventions and historical legacies. peerReviewed

Since the 1980s, mechanized soybean production in Bolivia has caused extensive deforestation in the northeast of Santa Cruz de la Sierra in the eastern Bolivian lowlands. We analyze the spatial and temporal dynamics of deforestation due to mechanized agriculture with spatially explicit logistic regression models. Deforestation patterns are derived from the classification of Landsat imagery by Killeen et al. (2007) and include five time steps (1976, 1986, 1992, 2001 and 2005). We associate deforestation with geophysical and socioeconomic determinants. Our model controls for spatial autocorrelation and temporal dependencies, and we assess the robustness of the results for several model formulations. The expansion of mechanized agriculture is concentrated in areas with favorable environmental conditions, good market access and close proximity to prior deforestation. While overall dynamics remained relatively stable over time, the expansion of mechanized agriculture between 2001 and 2005 became more tolerant to excessive rainfall and less dependent on fertile soils. This mirrors the increasing penetration of mechanized agriculture into humid and less fertile Amazonian rainforests in the northern portion of the study area. The map of deforestation probability substantiates these patterns and shows the highest propensities for future deforestation in the north. Our study demonstrates the value of spatial regression models to better understand the development of deforestation dynamics over a 30-year time span, and contributes to the formulation of policies that aim to reduce deforestation. Yet the results are sensitive to hidden correlations between independent variables, and we therefore advocate a careful evaluation of regression results for different model formulations.

Deforestation and fragmentation are threats to the conservation of species and have consequences for ecosystem functions. The focus of this study was to elucidate forest cover change in the period of 1993 to 2014. Our study area is in the central region of Veracruz, Mexico. Land cover and land use classes for the Years 1993, 2000, and 2014 were derived from Landsat images applying supervised classification. Then, we quantified the net change in forest area, the loss of original forest area, and evaluated forest fragmentation using landscape metrics. Our results showed that the area covered by remnant forests decreased 57%. The annual net forest cover change rate for 1993 to 2000 was −0.44%; since then forest cover increased at a rate of 0.11% from 2000 to 2014. The decreasing total edge density and the mean proximity index during the entire period of the study indicate decreasing irregularity in the shape of remnant forest patches and a slight decrease of vulnerability to edge effects. Forest patches augm...

In the densely settled Bragantina region, northern Brazil, smallholder cattle pastures start into compulsory degradation processes indicated, among other factors by the woody encroachment of the resprouting secondary vegetation, nationally called "capoeira". By means of Landsat and QuickBird satellite imagery techniques different stages of treedominated pastures were identified and the distribution of degraded pastures quantified. This was tested in a supervised Landsat classification from 2006 and 2007, taking QuickBird imageries from 2004 and 2005 as additional ground checks. We found that 42% of the rural Bragantinian landscape has already converted into pastures, 28% in advanced stages of above ground pasture degradation. Our reclassification means that the region is still confronted with a serious ecological pasture problem and that conventional land use classifications, climatological models and carbon calculations, based on Landsat imageries only, underestimate pasture distribution and thus lead to inaccurate extrapolations. As the resprouting shrubs of the capoeira are a permanent problem on tropical lowland pastures but, on the other hand, are also the ecological basis of the sustainable slash-and-burn systems of smallholders, we tested some innovative strategies to tolerate various useful woody components of the capoeira on pastures to stabilise them ecologically: first, a buffet trial shows that the ten tested capoeira and some other common domesticated tree species obtain a comparable palatability as well-known woody forage legumes. Thus, Cecropia palmata and Tithonia diversifolia, among others, were as palatable for cattle as the well-known multi-purpose legume Cratylia argentea. As a consequence, these freely accessible tree species should not be slashed but fostered on pastures, like supplementary forage plants. Secondly, it is demonstrated that the multi-purpose forage legumes C. argentea and Flemingia macrophylla perform better under smallholder management than under large scaled farming or even intense management due to the associated prolonged restoration times. In sum, we could demonstrate that woody components (capoeira and/ or woody legumes) are more appropriate for the humid tropics than pure grass-monocultures. Based on these experiences, we modified the model of a grass-capoeira-legume pasture, incorporating pastures just as an interim stage of the slash-andburn system. Forage production could be enhanced in that system by selective slashing of the capoeira (palatable species are tolerated) and by incorporating woody forage legumes. As this biome is known to restore its ecosystem fertility rather in its above-ground biomass than in its poor soils, woody components on pastures are recommended for ecologically sustainable production systems. Furthermore, they might be requisite to mitigate the proclaimed climatic change in the Amazon.

Economic problems generate large secondary tropical forests due to crop abandonment; lianas (woody vines climbing upon trees) proliferate there. Lianas generally retard the growth and carbon capture of trees, potentially enhancing global change. It is not known whether all liana species play such a role and which land-use disturbances determined the cur rent species composition of liana communities. We surveyed all lianas >lcm diameter at ground level and all trees > 3.16 cm diameter at 1.3 m above ground in twelve plots 20 x 20-m each in semi-evergreen tropical forests in Northeastern Yucatan Peninsula, Mexico, re-measuring the trees 15 mo later. Lianas were classified into two anatomic types: "hard" (typical stem with compact xylem masses) and "soft" (with much parenchyma and wide xylem vessels). History, archaeology, anthropol ogy, and remote sensing studies, as well as non-formal interviews were used to determine the land-use history of each stand. Increasing densities of the hard liana Dalbergia glabra (Leguminosae), but not of soft lianas ?Arrabidaea spp, Cydista sp, Melloa spp (Bignoniaceae) and Serjania sp (Sapindaceae), were related to more rapid relative growth rates of trees (Linear regression, R2 = 0.680, P = 0.001). Where D. glabra dominated, the trees hosting it grew more rapidly, but trees with large liana-tangles grew more slowly where soft lianas were dominant (Kruskall Wallis, P > 0.01 in both cases). The anatomy of soft lianas sug gests that they are less able to survive burn after slash during shifting cultivation than D. glabra the previous land use where D. glabra dominated. Soft-liana dominated stands were not burnt but subjected to liana-cut during logging and extraction of lianas, palm leaves and latex from Manilkara %apota trees. Our results suggest that some lianas enhance carbon capture mitigating global change, whereas others do not and that the dominance of one liana species is a legacy of previous land use, which is better understood by combining natural and social sciences.