Assessing the effect of natural controls and land use change on sediment yield in a major Andean River: the Magdalena drainage basin, Colombia

The Magdalena River, a major fluvial system draining most of the Colombian Andes, is a world-class river, in the top 10 in terms of sediment load (approximately 150 MT/yr). In this study, we explore the major natural factors and anthropogenic influences behind the patterns in sediment yield on the Magdalena basin and reconstruct the spatial and temporal pattern of deforestation and agricultural intensification across the basin to test the relationships between land use change and trends in sediment yield. Our results show that sediment yield for the whole Magdalena catchment can be explained by natural variables, including runoff and maximum water discharge. These two estimators explain 58% of variance in sediment yield. Temporal analyses of sediment discharges and land use show that the extent of erosion within the catchment has increased over the last 10 to 20 years. Many anthropogenic influences, including a forest decrease by 40% in a 20-year period, an agriculture and pasture increase by 65%, poor soil conservation and mining practices, and increasing rates of urbanization, may have accounted for the overall increasing trends in sediment yield on a regional scale.     

Forest cover of insular Southeast Asia mapped from recent satellite images of coarse spatial resolution

The study provides an example of mapping tropical forest cover from SPOT-Vegetation satellite images of coarse spatial resolution (1 km) for the subregion of insular Southeast Asia. A satellite image mosaic has been generated from satellite images acquired for the period 1998 to 2000. Forest cover has been mapped by unsupervised digital classification. The mapping result has then been compared to selected forest maps from the subregion, demonstrating the potential to provide basic information on forest area extent and distribution, but also on massive forest cover change in the subregional context. Forest area estimates derived from the map for the subregion have been found comparable to those compiled by FAO. The results indicate that many of the remaining tropical forests in Southeast Asia, rich in timber resources and biodiversity, may be lost in the near future if deforestation continues at present or previous rates.     

Impacts of Surface Gold Mining on Land Use Systems in Western Ghana

Land use conflicts are becoming increasingly apparent from local to global scales. Surface gold mining is an extreme source of such a conflict, but mining impacts on local livelihoods often remain unclear. Our goal here was to assess land cover change due to gold surface mining in Western Ghana, one of the world’s leading gold mining regions, and to study how these changes affected land use systems. We used Landsat satellite images from 1986–2002 to map land cover change and field interviews with farmers to understand the livelihood implications of mining-related land cover change. Our results showed that surface mining resulted in deforestation (58%), a substantial loss of farmland (45%) within mining concessions, and widespread spill-over effects as relocated farmers expand farmland into forests. This points to rapidly eroding livelihood foundations, suggesting that the environmental and social costs of Ghana’s gold boom may be much higher than previously thought.     

Thirty years of land-cover change in Bolivia

Land-cover change in eastern lowland Bolivia was documented using Landsat images from five epochs for all landscapes situated below the montane tree line at approximately 3000 m, including humid forest, inundated forest, seasonally dry forest, and cloud forest, as well as scrublands and grasslands. Deforestation in eastern Bolivia in 2004 covered 45,411 km2, representing approximately 9% of the original forest cover, with an additional conversion of 9042 km2 of scrub and savanna habitats representing 17% of total historical land-cover change. Annual rates of land-cover change increased from approximately 400 km2 y(-1) in the 1960s to approximately 2900 km2 y(-1) in the last epoch spanning 2001 to 2004. This study provides Bolivia with a spatially explicit information resource to monitor future land-cover change, a prerequisite for proposed mechanisms to compensate countries for reducing carbon emissions as a result of deforestation. A comparison of the most recent epoch with previous periods shows that policies enacted in the late 1990s to promote forest conservation had no observable impact on reducing deforestation and that deforestation actually increased in some protected areas. The rate of land-cover change continues to increase linearly nationwide, but is growing faster in the Santa Cruz department because of the expansion of mechanized agriculture and cattle farms.     

Linking national agrarian policy to deforestation in the Peruvian Amazon: a case study of Tambopata, 1986-1997

Amazonian deforestation rates vary regionally, and ebb and flow according to macroeconomic policy and local social factors. We used remote sensing and field interviews to investigate deforestation patterns and drivers at a Peruvian frontier during 1986-1991, when rural credit and guaranteed markets were available; and 1991-1997, when structural adjustment measures were imposed. The highest rate of clearing (1.5% gross) was observed along roads during 1986-1991. Roadside deforestation slowed in 1991-1997 (0.7% gross) and extensive regrowth yielded a net increase in forest cover (0.5%). Deforestation along rivers was relatively constant. Riverside farms today retain more land in both crops and forest than do roadside farms where pasture and successional growth predominate. Long-term residents maintain more forest on their farms than do recent colonists, but proximity to urban markets is the strongest predictor of forest cover. Future credit programs must reflect spatial patterns of development and ecological vulnerability, and support the recuperation of fallow lands and secondary forest.     

Using satellite imagery to locate innovative forest management practices in Nepal

There is a critical need to locate innovative forest management institutions that significantly impact forest cover change. This research presents an initial "proof of concept" methodology which combines deforestation theory with satellite image change analysis to identify forested areas that, theoretically, should probably not be there. Ten such "forest anomalies" are identified using temporal analysis of Landsat TM imagery of the Chitwan district in Nepal, linked with a GIS database on roads and a visual estimation of topography. A rapid field reconnaissance is undertaken to determine which of these anomalies exhibit interesting forest management innovations. Based on this information, one case is selected for detailed field study: this turns out to be a major case of community forestry and a premier ecotourism initiative that we were not aware of until we undertook this analysis. The utility and limitations of the method are described for monitoring trends in forest cover change.     

Impact of impoldering and lake restoration on land-cover changes in Dongting Lake area, Central Yangtze

Human activities can have a remarkable effect on land-cover patterns over time. This study characterized long-term (1930s-1998) land-cover changes in Dongting Lake area in the Central Yangtze River, China, by digitalizing historical topographical maps for the 1930s and 1950s and interpreting satellite remote sensing data for 1978, 1989, and 1998. The study indicates that land-cover patterns in Dongting Lake area have been greatly altered by impoldering and subsequent lake restoration activities in the past 70 years. There are two distinct periods of change characterized by impoldering (1930s-1978) and lake restoration (1978-1998). In the former period, cropland increased sharply at the cost of a drop in other land-cover types, which had resulted in significant negative consequences, while the pattern of land-cover changes reversed in the later period.     

Drivers of Forest Cover Dynamics in Smallholder Farming Systems: The Case of Northwestern Vietnam

The national-scale forest recovery of Vietnam started in the early 1990s and is associated with a shift from net deforestation to net reforestation. Large disparities in forest cover dynamics are, however, observed at the local scale. This study aims to unravel the mechanisms driving forest cover change for a mountainous region located in northwest Vietnam. Statistical analyses were used to explore the association between forest cover change and household characteristics. In Sa Pa district, deforestation rates are decreasing, but forest degradation continues at similar rates. Deforestation is not necessarily associated with impoverished ethnic communities or high levels of subsistence farming, and the largest forest cover dynamics are found in villages with the best socio-economic conditions. Our empirical study does not provide strong evidence of a dominant role of agriculture in forest cover dynamics. It shows that empirical studies on local-scale forest dynamics remain important to unravel the complexity of human–environment interactions.     

Climate Warming and the Recent Treeline Shift in the European Alps: The Role of Geomorphological Factors in High-Altitude Sites

Global warming and the stronger regional temperature trends recently recorded over the European Alps have triggered several biological and physical dynamics in high-altitude environments. We defined the present treeline altitude in three valleys of a region in the western Italian Alps and reconstructed the past treeline position for the last three centuries in a nearly undisturbed site by means of a dendrochronological approach. We found that the treeline altitude in this region is mainly controlled by human impacts and geomorphological factors. The reconstruction of the altitudinal dynamics at the study site reveals that the treeline shifted upwards of 115 m over the period 1901–2000, reaching the altitude of 2505 m in 2000 and 2515 m in 2008. The recent treeline shift and the acceleration of tree colonization rates in the alpine belt can be mainly ascribed to the climatic input. However, we point out the increasing role of geomorphological factors in controlling the future treeline position and colonization patterns in high mountains.     

Recolonization and succession of subtidal macrobenthic infauna in sediments contaminated with cadmium

Recolonization and succession of macrobenthic infauna in defaunated sediment contaminated with Cd were studied over a period of 14 months. Trays with defaunated sediment contaminated with cadmium, and trays with defaunated (control) sediment, were exposed at the subtidal in a subtropical environment. Macrobenthic succession exhibited different patterns in Cd-contaminated and control sediments. Abundance and species number were significantly higher in Cd-contaminated sediment during early succession, suggesting that cadmium may facilitate recolonization of certain species of macrobenthos. Cadmium also led to a significant change in species composition in initial colonization and subsequent succession. No significant difference in abundance, species number, diversity and species composition was found between Cd-contaminated and control sediments at the end of experiment, suggesting a stable benthic community was arrived within 14 months.     

Deforestation control in Mato Grosso: a new model for slowing the loss of Brazil's Amazon forest

Controlling deforestation in Brazil's Amazon region has long been illusive despite repeated efforts of government authorities to slow the process. From 1997 to 2000, deforestation rates in Brazil's 9-state "Legal Amazon" region continually crept upward. Now, a licensing and enforcement program for clearing by large farmers and ranchers in the state of Mato Grosso appears to be having an effect. The deforestation rate in Mato Grosso was already beginning to slacken before initiation of the program in 1999, but examination of county-level data suggests that deforestation in already heavily cleared areas was falling due to lack of suitable uncleared land, while little-cleared areas were experiencing rapid deforestation. Following initiation of the program, the clearing rates declined in the recent frontiers. Areas with greater enforcement effort also appear to have experienced greater declines. Demonstration of government ability to enforce regulations and influence trends is important to domestic and international debates regarding use of avoided deforestation to mitigate global warming.     

Influence of enumeration time periods on analyzing colonization features and taxonomic relatedness of periphytic ciliate communities using an artificial substratum for marine bioassessment

Colonization features and taxonomic relatedness measures of ciliate communities have been used as useful indicators for marine bioassessment. The influence of enumeration time periods on analyzing colonization features measures of periphytic ciliate communities was studied in coastal waters of the Yellow Sea, northern China, during the period of May-June 2010. Ciliated protozoan samples were collected at depths of 1 m using an artificial substratum and were analyzed with different enumeration schemes. The ciliate species were identified using living observation and silver impregnation. Data analyses were conducted using a range of multivariate statistical routines. Enumeration time periods represented a strong influence on analyzing both colonization and taxonomic relatedness features of periphytic ciliate communities, although no significant changes occurred in colonization patterns between two enumeration schemes (within 24 and 24-48 h after sampling). The delayed enumeration (within 24-48 h) may result in the species richness, individual abundance, colonization rate decreasing to standard errors of >10 % in samples with almost all colonization ages, and in the similarities of the communities being reduced to 11-38 %. However, the species biodiversity (e.g., species diversity and evenness, except species richness) and taxonomic relatedness (taxonomic diversity, taxonomic distinctness and average taxonomic distinctness, except variation in taxonomic distinctness) measures of periphytic ciliate communities were weakly sensitive to disturbance from the delayed enumeration, achieving standard errors of <10 and <5 % during the colonization periods, respectively. These results suggest that the enumeration should be completed as soon as possible within 24 h after sampling to analyze colonization and taxonomic relatedness features of periphytic ciliate communities, and that the species diversity and taxonomic distinctness measures can be used on a robust bioindicator with weak dependence on enumeration time limits for monitoring programs and ecological investigations in marine ecosystems.     

Epiphytic Algae and Lichen Cover in Boreal Forests—A Long-Term Study Along a N and S Deposition Gradient in Sweden

The aim was to describe spatiotemporal patterns of colonization of spruce branches by algae and lichens and the relationship with decreasing deposition of N and S. Coverage was estimated annually over 10 years for four Swedish Integrated Monitoring catchments with varying deposition levels. Initial hypotheses were that algal coverage would be positively correlated with deposition and that lichen coverage would be negatively correlated with S and positively with N deposition. Data were analyzed using regression, ANOVA, and partial least square regression. The results showed a temporal decrease in the coverage of algae but an increase in colonization rates, while lichens showed less uniform patterns. Within catchments, algae and lichen coverages were positively correlated with mainly S deposition. Across catchments, coverage of algae increased, while the coverage of lichens decreased with increasing N and S deposition. Colonization rates of both algae and lichens showed weak correlations with both spatial and temporal trends in N and S deposition. Thus, while N and S deposition had an effect on the colonization and coverage of algae and lichens, other factors are also important.     

Plant species affect colonization patterns and metabolic activity of associated endophytes during phytoremediation of crude oil-contaminated soil

Plants coupled with endophytic bacteria hold great potential for the remediation of polluted environment. The colonization patterns and activity of inoculated endophytes in rhizosphere and endosphere of host plant are among the primary factors that may influence the phytoremediation process. However, these colonization patterns and metabolic activity of the inoculated endophytes are in turn controlled by none other than the host plant itself. The present study aims to determine such an interaction specifically for plant-endophyte systems remediating crude oil-contaminated soil. A consortium (AP) of two oil-degrading endophytic bacteria (Acinetobacter sp. strain BRSI56 and Pseudomonas aeruginosa strain BRRI54) was inoculated to two grasses, Brachiaria mutica and Leptochloa fusca, vegetated in crude oil-contaminated soil. Colonization patterns and metabolic activity of the endophytes were monitored in the rhizosphere and endosphere of the plants. Bacterial augmentation enhanced plant growth and crude oil degradation. Maximum crude oil degradation (78 %) was achieved with B. mutica plants inoculated with AP consortium. This degradation was significantly higher than those treatments, where plants and bacteria were used individually or L. fusca and endophytes were used in combination. Moreover, colonization and metabolic activity of the endophytes were higher in the rhizosphere and endosphere of B. mutica than L. fusca. The plant species affected not only colonization pattern and biofilm formation of the inoculated bacteria in the rhizosphere and endosphere of the host plant but also affected the expression of alkane hydroxylase gene, alkB. Hence, the investigation revealed that plant species can affect colonization patterns and metabolic activity of inoculated endophytic bacteria and ultimately the phytoremediation process.     

Ozone dynamics and deposition processes at a deforested site in the Amazon basin

The goal of this study is to investigate the impact of deforestation on ozone dynamics and deposition in the Brazilian Amazon basin. This goal is accomplished through i) analyses of ozone levels and deposition rates at a deforested site during the rainy season; and ii) comparisons of these data with similar information derived at a forest. At the pasture site maximum ozone mixing ratios reach 20 parts per billion on a volume basis (ppbv) but about 6 ppbv prevail over the forest. Maximum ozone deposition velocities for pastures can reach 0.7 cm s-1, which is about threefold lower than values derived for forests. Combining ozone abundance and deposition velocities, pasture maximum ozone fluxes reach approximately 0.2 microgram (ozone) m-2 s-1. This flux represents approximately 70% of the deposition rates measured over the forest. Hence, this study suggests that conversion of rainforests to pastures could lead to a net reduction (30%) in the ozone sink in the Amazon.     

Drivers of deforestation and degradation for 28 tropical conservation landscapes

Analysing the drivers of deforestation and forest degradation in conservation landscapes can provide crucial information for conservation management. While rates of forest loss can be measured through remote sensing, on the ground information is needed to confirm the commodities and actors behind deforestation. We administered a questionnaire to Wildlife Conservation Society’s landscape managers to assess the deforestation drivers in 28 tropical conservation landscapes. Commercial and subsistence agriculture were the main drivers of deforestation, followed by settlement expansion and infrastructure development. Rice, rubber, cassava and maize were the crops most frequently cited as drivers of deforestation in these emblematic conservation landscapes. Landscape managers expected deforestation trends to continue at similar or greater magnitude in the future, calling for urgent measures to mitigate these trends.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01325-9) contains supplementary material, which is available to authorized users.     

Implications of Rural–Urban Migration for Conservation of the Atlantic Forest and Urban Growth in Misiones,Argentina (1970–2030)

Global trends of increasing rural–urban migration and population urbanization could provide opportunities for nature conservation, particularly in regions where deforestation is driven by subsistence agriculture. We analyzed the role of rural population as a driver of deforestation and its contribution to urban population growth from 1970 to the present in the Atlantic Forest of Argentina, a global conservation priority. We created future land-use-cover scenarios based on human demographic parameters and the relationship between rural population and land-cover change between 1970 and 2006. In 2006, native forest covered 50% of the province, but by 2030 all scenarios predicted a decrease that ranged from 18 to 39% forest cover. Between 1970 and 2001, rural migrants represented 20% of urban population growth and are expected to represent less than 10% by 2030. This modeling approach shows how rural–urban migration and land-use planning can favor nature conservation with little impact on urban areas.     

Intensive land use in the Swedish mountains between AD 800 and 1200 led to deforestation and ecosystem transformation with long-lasting effects

Anthropogenic deforestation has shaped ecosystems worldwide. In subarctic ecosystems, primarily inhabited by native peoples, deforestation is generally considered to be mainly associated with the industrial period. Here we examined mechanisms underlying deforestation a thousand years ago in a high-mountain valley with settlement artifacts located in subarctic Scandinavia. Using the Heureka Forestry Decision Support System, we modeled pre-settlement conditions and effects of tree cutting on forest cover. To examine lack of regeneration and present nutrient status, we analyzed soil nitrogen. We found that tree cutting could have deforested the valley within some hundred years. Overexploitation left the soil depleted beyond the capacity of re-establishment of trees. We suggest that pre-historical deforestation has occurred also in subarctic ecosystems and that ecosystem boundaries were especially vulnerable to this process. This study improves our understanding of mechanisms behind human-induced ecosystem transformations and tree-line changes, and of the concept of wilderness in the Scandinavian mountain range.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0634-z) contains supplementary material, which is available to authorized users.     

Increasing concentrations of CO and O3 rising deforestation rates and increasing troposheric carbon monoxide and ozone in Amazonia

Increasing carbon monoxide and ozone concentrations have been observed in the lower troposphere of the Brazilian Amazon region in recent years (1989–1995). Carbon monoxide and ozone have been measured in the region continuously; from observations at a single site and many sporadic field missions, there is a clear indication that the chemical activity in the troposphere is growing, with increasing concentrations especially during the dry season. On the other hand, the most recent deforestation assessment by the Brazilian Government, performed by the Instituto Nacional de Pesquisas Espaciais (INPE) using Landsat data, shows yearly rates rising from the 11,130 km² year^?1 minimum of the 1990/91 survey, to 13,786 km² year^?1 for the 1991/92 period, and 14,896 km² year^?1 for the period 1992/94. It is argued that the increase in deforestation/biomass burning activities in “Amazonia” have produced larger carbon monoxide and ozone concentrations in the lower atmosphere.     

Psychosocial drivers of land management behaviour: How threats,norms, and context influence deforestation intentions

Understanding how private landholders make deforestation decisions is of paramount importance for conservation. Behavioural frameworks from the social sciences have a lot to offer researchers and practitioners, yet these insights remain underutilised in describing what drives landholders’ deforestation intentions under important political, social, and management contexts. Using survey data of private landholders in Queensland, Australia, we compare the ability of two popular behavioural models to predict future deforestation intentions, and propose a more integrated behavioural model of deforestation intentions. We found that the integrated model outperformed other models, revealing the importance of threat perceptions, attitudes, and social norms for predicting landholders’ deforestation intentions. Social capital, policy uncertainty, and years of experience are important contextual moderators of these psychological factors. We conclude with recommendations for promoting behaviour change in this deforestation hotspot and highlight how others can adopt similar approaches to illuminate more proximate drivers of environmental behaviours in other contexts.Supplementary informationThe online version of this article (10.1007/s13280-020-01491-w) contains supplementary material, which is available to authorized users.