Edge influence on diversity of orchids in Andean cloud forests

Cloud forests harbor high levels of orchid diversity. However, due to the high fragmentation of these forests in the Andes, combined with the pressure for new agricultural land, orchid diversity is highly threatened. Despite this worrying scenario, few studies have assessed the effects of habitat loss specifically on orchid assemblages in the Andes. The aim of this study was to analyze the edge effect on orchids in cloud forest fragments of varying size. We measured forest structure, neighboring land cover and edge effect on orchid abundance, species richness and beta-diversity, by sampling assemblages along edge-to-interior transects in six different sized Andean (southwest Colombia) forest remnants. We recorded 11,127 stem-individuals of orchids in 141 species. Within the forest, edges sustained equal or more species than interior plots. Our results revealed neither patch metrics nor forest structure showed any significant association to orchid diversity at any scale. Nonetheless, from our observations in composition, the type of neighboring cover, particularly pastures, negatively influences interior species (richness and composition) in larger reserves. This might be due to the fact that some species found in interior plots tend to be confined, with sporadic appearances in regeneration forest and are very scarce or absent in pastures. Species richness differed significantly between matrix types. Our results suggest that (1) orchid diversity shows spatial variability in response to disturbances, but the response is independent from forest structure, patch size and patch geometry; (2) orchid communities are negatively affected by covers, and this pattern is reflected in reduced richness and high species turnover; (3) orchid richness edge effect across a pasture-interior gradient. Two forest management implications can be discerned from our results: (1) management strategies aiming to reduce edge effects may focus on improvement regeneration conditions around pasture lands; and (2) local scale management and conservation activities of natural forests in cloud forests will favor small reserves that harbor high levels of richness

Dinámicas y causas de deforestación en bosques de latino américa: una revisión desde 1990

Over the past few years there have been a considerable number of studies on deforestation in Latin America. Deforestation rates reported up to the 2000s are generally lower in the region than in other tropical areas. The causes of deforestation in Latin America are similar to those identified in other regions. In general, studies of deforestation are regional or very localized and do not permit comparison of intraregional variability within the American tropics. In this paper we present results obtained from a meta-analysis of 283 articles on deforestation rates for different types of forests in Latin America (Atlantic, Montane , Dry, Lowland and others). Causes of deforestation identified in the literature and published at the national or subnational level since 1990 are also analyzed. There is an overall deforestation rate of -1.54 for the region, but results indicate a high variability of deforestation rates between countries and that there are even cases of forest cover gains, e.g. in El Salvador. The highest deforestation rates are in dry forest followed by montane forests. Most countries identify agricultural and livestock expansion as the main cause of deforestation.Durante los últimos años se han publicado varios estudios sobre deforestación en Latino América, donde las tasas de pérdida de bosques, hasta la década del año 2000 en la región, por lo general son inferiores a las de otras zonas tropicales. Regularmente, los estudios de deforestación son regionales o estatales o a nivel de cuenca o microcuenca, y no permiten observar la variabilidad intrarregional presente en los trópicos americanos. En este trabajo se presenta el resultado de un meta-análisis de 283 artículos indexados sobre pérdida de cobertura forestal para diferentes tipos de bosques en América Latina (Atlánticos, Montanos, Secos, de Tierras bajas y otros), desde el año 1990 hasta el 2012, así como los factores identificados como causantes de deforestación. Con una tasa general de deforestación de -1.54 para la región, los resultados indican que se presenta una alta variabilidad por países, e incluso se encuentran casos de ganancias de cobertura forestal como en El Salvador. Los bosques más afectados y con tasas de cambio mayores son los bosques secos, seguidos por los bosques montanos. La mayoría de los países identifica la expansión agrícola y ganadera como la principal causa de deforestación

A Preliminary Assessment Using Satellite Remote Sensing

The upper ranges of the northern Andes are characterized by unique Neotropical, high altitude ecosystems known as paramos. These tundra-like grasslands are widely recognized by the scientific community for their biodiversity and their important ecosystem services for the local human population. Despite their remoteness, limited accessibility for humans and waterlogged soils, paramos are highly flammable ecosystems. They are constantly under the influence of seasonal biomass burning mostly caused by humans. Nevertheless, little is known about the spatial extent of these fires, their regime and the resulting ecological impacts. This paper presents a thorough mapping and analysis of the fires in one of the world’s largest paramo, namely the “Complejo de Páramos” of Cruz Verde-Sumapaz in the Eastern mountain range of the Andes (Colombia). Landsat TM/ETM+ and MODIS imagery from 2001 to 2013 was used to map and analyze the spatial distribution of fires and their intra- and inter-annual variability. Moreover, a logistic regression model analysis was undertaken to test the hypothesis that the dynamics of the paramo fires can be related to human pressures. The resulting map shows that the burned paramo areas account for 57,179.8 hectares, of which 50% (28,604.3 hectares) are located within the Sumapaz National Park. The findings show that the fire season mainly occurs from January to March. The accuracy assessment carried out using a confusion matrix based on 20 reference burned areas shows values of 90.1% (producer accuracy) for the mapped burned areas with a Kappa Index of Agreement (KIA) of 0.746. The results of the logistic regression model suggest a significant predictive relevance of the variables road distance (0.55 ROC (receiver operating characteristic)) and slope gradient (0.53 ROC), indicating that the higher the probability of fire occurrence, the smaller the distance to the road and the higher the probability of more gentle slopes. The paper sheds light on fires in the Colombian paramos and provides a solid basis for further investigation of the impacts on the natural ecosystem functions and biodiversity. View Full-Tex

The implications of fire management in the Andean paramo: A preliminary assessment using satellite remote sensing

The upper ranges of the northern Andes are characterized by unique Neotropical, high altitude ecosystems known as paramos. These tundra-like grasslands are widely recognized by the scientific community for their biodiversity and their important ecosystem services for the local human population. Despite their remoteness, limited accessibility for humans and waterlogged soils, paramos are highly flammable ecosystems. They are constantly under the influence of seasonal biomass burning mostly caused by humans. Nevertheless, little is known about the spatial extent of these fires, their regime and the resulting ecological impacts. This paper presents a thorough mapping and analysis of the fires in one of the world’s largest paramo, namely, the ‘Complejo de Páramos’ of Cruz Verde – Sumapaz in the Eastern mountain range of the Andes (Colombia). Landsat TM/ETM+ and MODIS imagery from 2001 to 2013 were used to map and analyse the spatial distribution of fires and their intra- and inter-annual variability. Moreover, a logistic regression model analysis was undertaken to test the hypothesis that the dynamics of the paramo fires can be related to human pressures. The resulting map shows that the burned paramo areas account for 57,179.8 hectares of which 50% (28,604.3 hectares) are located within the Sumapaz National Park. The findings show that the fire season mainly occurs from January to March. The accuracy assessment carried out using a confusion matrix based on 20 reference burned areas shows values of 90.1% (producer accuracy) for the mapped burned areas with a Kappa Index of Agreement (KIA) of 0.746. The results of the logistic regression model suggest a significant predictive relevance of the variables road distance (0.55 ROC (Receiver Operating Characteristic)) and slope gradient (0.53 ROC), indicating that the higher the probability of fire occurrence the smaller the distance to the road and the higher the probability of more gentle slopes. The paper sheds light on fires in the Colombian paramos and provides a solid basis for further investigation of the impacts on the natural ecosystem functions and biodiversity.JRC.H.5-Land Resources Managemen

Uso del suelo y estructura de la vegetación en paisajes fragmentados en la Amazonia, Colombia

Monitoring land use and knowledge about the vegetation state in forests remnants which are in a rapid fragmentation process are essential to support decision-making on land planning. We undertook a multitemporal analysis of land use change and landscape configuration for the period 1990-2016. Vegetation sampling transects were established in three forest relicts. Our results indicate a loss of 56.34% of forest area, an increase in the patches number, area reduction and a distance increase between the forest fragments. In the sampled forests, the dominance of generalist heliophyte species from disturbed ecosystems was found. Also, we observed a structural complexity reduction of the forest associated with an individuals low density with a DBH ≥ 10 cm in the upper tree layer, showing that landscape fragmentation has led to the forest degradation.El seguimiento al uso del suelo y el conocimiento del estado de la vegetación en remanentes de bosques de paisajes representan una metodología fundamental para la planificación del territorio ante la acelerada fragmentación. Por ello, se realizó un análisis multitemporal de la composición y configuración del paisaje (1990-2016) y se establecieron transectos de muestreo de la vegetación. Se identificó una pérdida del 56.34% de áreas de bosque, aumento en el número de parches, reducción de su área y ampliación de la distancia entre relictos, lo que evidencia procesos activos de fragmentación. En los bosques muestreados se registró la dominancia de especies heliófitas generalistas de ecosistemas perturbados y se encontró una reducción en la complejidad estructural asociada a una baja densidad de individuos (DAP≥ 10 cm) en el estrato superior arbóreo, mostrando que la fragmentación del paisaje ha conllevado a la degradación de estos bosques

Distribución geográfica y temporal de incendios en colombia utilizando datos de anomalías térmicas

Patrones de distribución en el tiempo y en el espacio de las anomalías térmicasdetectadas por el sensor MODIS son analizadas para el territorio colombiano entrediciembre 2000 y Febrero 2009. Se presenta un estudio de la dinámica inter-anuale intra-anual de la superfi cie afectada por los incendios para distintas coberturasde vegetación. También se analiza los patrones al interior de áreas protegidas,reservas forestales, reservas indígenas y territorio de comunidades negras, con lafi nalidad de analizar el posible rol como barrera a los incendios de estas fi guras demanejo en Colombia. Adicionalmente se analiza la distribución temporal y espacialpor regiones naturales, Corporaciones Autónomas Regionales y Departamentos.La información proporcionada por este tipo de análisis puede ser de gran utilidadpara la toma de decisiones en el manejo de los recursos naturales en el país. Losresultados obtenidos indican que los Llanos de Colombia es el área más afectadaanualmente por los incendios, seguida del Caribe y de la zona Andina, en particularel piedemonte amazónico. Estos análisis muestran el potencial para identifi car ymodelar la distribución de los incendios en el país y la identifi cación de patronesen función tanto de las características de la vegetación como del manejo que se estérealizando en un lugar determinado y pueden ser de utilidad para mejorar la gestiónde riesgo de incendios en el país, así como para entender los cambios de uso que sehan dado en Colombia en la última década

Land use and vegetation structure in forest remnants of fragmented landscapes in Amazonia, Colombia

Monitoring land use and knowledge about the vegetation state in forests remnants which are in a rapid fragmentation process are essential to support decision-making on land planning. We undertook a multitemporal analysis of land use change and landscape configuration for the period 1990-2016. Vegetation sampling transects were established in three forest relicts. Our results indicate a loss of 56.34% of forest area, an increase in the patches number, area reduction and a distance increase between the forest fragments. In the sampled forests, the dominance of generalist heliophyte species from disturbed ecosystems was found. Also, we observed a structural complexity reduction of the forest associated with an individuals low density with a DBH ≥ 10 cm in the upper tree layer, showing that landscape fragmentation has led to the forest degradation

Changing patterns of fire occurrence in proximity to forest edges, roads and rivers between NW Amazonian countries

Tropical forests in NW Amazonia are highly threatened by the expansion of the agricultural frontier and subsequent deforestation. Fire is used, both directly and indirectly, in Brazilian Amazonia to propagate deforestation and increase forest accessibility. Forest fragmentation, a measure of forest degradation, is also attributed to fire occurrence in the tropics. However, outside the Brazilian Legal Amazonia the role of fire in increasing accessibility and forest fragmentation is less explored. In this study, we compared fire regimes in five countries that share this tropical biome in the most north-westerly part of the Amazon Basin (Venezuela, Colombia, Ecuador, Peru and Brazil). We analysed spatial differences in the timing of peak fire activity and in relation to proximity to roads and rivers using 12 years of MODIS active fire detections. We also distinguished patterns of fire in relation to forest fragmentation by analysing fire distance to the forest edge as a measure of fragmentation for each country. We found significant hemispheric differences in peak fire occurrence with the highest number of fires in the south in 2005 vs. 2007 in the north. Despite this, both hemispheres are equally affected by fire. We also found difference in peak fire occurrence by country. Fire peaked in February in Colombia and Venezuela, whereas it peaked in September in Brazil and Peru, and finally Ecuador presented two fire peaks in January and October. We confirmed the relationship between fires and forest fragmentation for all countries and also found significant differences in the distance between the fire and the forest edge for each country. Fires were associated with roads and rivers in most countries. These results can inform land use planning at the regional, national and subnational scales to minimize the contribution of road expansion and subsequent access to the Amazonian natural resources to fire occurrence and the associated deforestation and carbon emissions

Dinámica espacio temporal de ocurrencia de incendios en zonas con diferentes tipos de manejo en el noroeste de la Amazonia: ¿barrera efectiva?

La acción del hombre y la variabilidad climática asociada al calentamiento global está afectando la incidencia de fuegos en las regiones tropicales, aumentando tanto su intensidad como su frecuencia, particularmente en periodos de sequías. En este estudio se realizó un análisis espacio temporal para identificar la ocurrencia de fuegos dentro y fuera de áreas protegidas en el noroeste de la Amazonía. El objetivo fue analizar la efectividad de estas figuras de protección o manejo en los países de la región en términos de reducción de la afectación por incendios. Se utilizaron datos de focos activos de fuegos detectados por sensores remotos (MODIS) para el periodo comprendido entre diciembre del año 2000 hasta febrero del año 2015 en Brasil, Colombia, Ecuador, Perú y Venezuela. Se siguió la denominación asignada por La Unión Internacional para la Conservación de la Naturaleza (IUCN), las áreas protegidas presentes en la región se agruparon en tres categorías, y la dinámica de los incendios fue analizada a diferentes niveles de estudio. Los resultados indican que las áreas protegidas presentan en todos los casos una menor densidad de fuegos, a diferencia de territorios sin ningún tipo de protección. En términos de comparación de la efectividad, se presenta una mayor cantidad de fuegos en la categoría de resguardo indígena, mientras que la mayor densidad de fuegos por km2 ocurre en áreas tipo categorías II-III. Los resultados obtenidos mostraron que la presencia de áreas protegidas en el noroeste de la Amazonía es efectiva para mitigar la incidencia de fuegos forestales

Camera traps enable the estimation of herbaceous aboveground net primary production (ANPP) in an African savanna at high temporal resolution

Determining the drivers of aboveground net primary production (ANPP), a key ecosystem process, is an important goal of ecosystem ecology. However, accurate estimation of ANPP across larger areas remains challenging, especially for savanna ecosystems that are characterized by large spatiotemporal heterogeneity in ANPP. Satellite remote sensing methods are frequently used to estimate productivity at the landscape scale but generally lack the spatial and temporal resolution to capture the determinants of productivity variation. Here, we developed and tested methods for estimating herbaceous productivity as an alternative to labour-intensive repeated biomass clipping and caging of small plots. We compared measures of three spectral greenness indices, normalized difference vegetation index derived from Sentinel-2 (NDVIs) and a handheld radiometer (NDVIg), and green chromatic coordinate derived from digital repeat cameras (GCC) and tested their relationship to biweekly field-measured herbaceous ANPP using movable exclosures. We found that a satellite-based model including average NDVIs and its rate of change (ΔNDVIs) over the biweekly productivity measurement interval predicted herbaceous ANPP reasonably well (Jackknife R2 = 0.26). However, the predictive accuracy doubled (Jackknife R2 = 0.52) when including the sum of day to day increases in camera trap-derived vegetation greenness (tGCC). This result can be considered promising, given the current lack of productivity estimation methods at comparable spatiotemporal resolution. We furthermore found that the fine (daily) temporal resolution of GCC time series captured fast vegetation responses to rainfall events that were missed when using a coarser temporal resolution (>2 days). These findings demonstrate the importance of measuring at a fine temporal resolution for predicting herbaceous ANPP in savanna ecosystems. We conclude that camera traps are promising in offering a reliable and cost-effective method to estimate productivity in savannas and contribute to a better understanding of ecosystem functioning and its drivers