Análisis de la fragmentación del paisaje en el área protegida ¿Los Petenes¿, Campeche, México
Abstract
Los bosques tropicales sufren rápidas procesos de deforestación y de fragmentación que tienen, entre otras
consecuencias. la desaparición de numerosas especies vegetales y animales, es decir, una pérdida de biodiversidad. En
la región de "Los Petenes", estado de Campeche, México. la vegetación forestal se distribuye en islotes, llamados
pefenes, constituyendo un paisaje fragmentado de origen natural. Con base en el cálculo de indices matemáticos, se llevó
a cabo una caracterización de los patrones de fragmentación en esta zona y se clasificaron los petenes en diferentes
categorias. Se discutió la utilidad de los índices utilizados para el estudio del paisaje en la región. Se observó que los
petenes presentan una gran variedad en cuanto al tamaño, a la forma y al grado de aislamiento, por lo que constituyen
zonas particularmente interesantes para estudiar las relaciones entre fragmentación de los hábitats y biodiversidad.
... The study area also represents an islandmainland system that gave us the opportunity to test whether spatial variables of fragments, such as size and isolation, can affect genetic diversity or structure. Owing to the wide variation among the fragments, in terms of size and isolation (Mas & Correa 2000), this area also represents a useful model for a transversal study of the long-term effect of habitat loss and patch isolation on plant genetic diversity and structure. ...
... Vegetation in these forest fragments is characterized by taller and more diverse plant species dominated by Manilkara zapota, Metopium brownei, Bursera simaruba, Laguncularia racemosa and Avicennia germinans, compared with that of the matrix, which is dominated by salt-and flood-tolerant plant species, such as the shorter mangrove species (Rhizophora mangle, Conocarpus erectus), sedges (Eleocharis cellulosa, Cladium jamaicense) and cattails (Typha dominguensis) (Durán 1987, Rico-Gray 1982. Forest fragments are highly variable in size and degree of isolation (Mas & Correa 2000); however, toward the interior of the Peninsula the forest becomes continuous ). The adjacent continuous forest presents similar abiotic conditions, species composition and canopy openness to those of the forest fragments; canopy openness is also similar in the matrix, where trees are the dominant life form. ...
... While M. zapota is pollinated by bees (Salinas-Peba & Parra-Tabla 2007), and these pollinators cannot move large distances, mean distance to the nearest patches in the study area is less than one kilometre (Mas & Correa 2000), which thus falls within the dispersion range of bee species such as Apis mellifera (up to 6 km; Dick 2001, Hagler et al. 2011 and Scaptotrigona sp. (up to 1.7 km; León et al. 2015) that visit the flowers of M. zapota in the Yucatan Peninsula (Salinas-Peba & Parra-Tabla 2007). ...
Forest fragmentation, habitat loss and isolation may have a strong effect on biodiversity in tropical forests. This can include modification of the genetic diversity and structure of plant populations. In this study, we assessed the genetic diversity and structure of the tree Manilkara zapota in 15 naturally formed fragments of semi-evergreen tropical forest, as well as in an adjacent continuous forest for comparison. Forest fragments were scattered within a matrix of wetlands and were highly variable in terms of size and degree of isolation. The naturally fragmented populations of M . zapota had slightly less allelic diversity (Ar: 3.4) than those of the continuous forest (Ar: 3.6), when corrected for sample size. However, populations in the fragments and continuous forest had very similar heterozygosity levels (H E : 0.59 in both cases). Low levels of genetic differentiation were observed among populations (F ST : 0.026) and genetic structure was not consistent with isolation by distance, indicating high levels of gene flow. Genetic diversity was not explained by fragment size or degree of isolation. The relatively high genetic diversity and low inter-population genetic differentiation observed in M. zapota may be the result of long-distance pollen and seed dispersal, as well as the high proximity among patches.
... Es un proceso dinámico (6) en el que un área amplia e intacta de bosque es progresivamente subdividida en pequeños parches o fragmentos (8,10) geométricamente alterados y aislados (2,5,6,11) inscritos en otros usos del suelo distintos (12), rodeado por matrices generalmente antrópicas (13), lo que genera la modificación de las condiciones medioambientales y el funcionamiento de los ecosistemas (14), (15), provocando elevada mortalidad de árboles y plantas juveniles (13), caída acelerada de las hojas, alteración en el almacenamiento de carbono, y en otros procesos como la abundancia de algunas especies, en la productiva, formación de detritus, movimiento de agua y nutrientes, la sucesión y la competencias entre otros (16,17). Autores han descrito el proceso de fragmentación en cuatro etapas: i) la perforación, en la cual se crea un agujero o hueco en la cobertura original; ii) la subdivisión, en la cual las áreas de coberturas de la tierra más grandes se dividen en parches más pequeños; iii) la contracción, que es la etapa en la cual se pierde la conectividad entre los parches de cobertura original; y por último, iv) la etapa de desgaste, en la cual los parches originales del paisaje disminuyen gradualmente en tamaño hasta que finalmente desaparecen (18,19). ...
... Por otro lado, la fragmentación es un motor de cambio global muy variable en el tiempo y en el espacio (21), que se mani-fiesta no solamente como proceso, sino como patrón dentro del espacio geográfico (22). Si el grado de aislamiento de los fragmentos es muy alto, el movimiento de organismos entre ellos puede limitarse, de tal manera que se disminuye el intercambio y la diversidad genética de las poblaciones tanto de plantas como de animales (14,23). El conocimiento de este permite cierta inferencia sobre sus probables impactos, incluso sin un conocimiento detallado de todos los procesos que podrían verse afectados, posibilita identificar y priorizar regiones y organismos para la medición directa de los impactos (24). ...
El presente artículo de revisión busca describir la fragmentación de bosques desde un enfoque conceptual y explorar las metodologías implementadas para su estudio a nivel nacional e internacional, principalmente, orientadas al uso de sistemas de información geográfica y diferentes métricas para la caracterización del paisaje. Para ello se realizó la revisión de artículos científicos relacionados con la fragmentación de bosques, análisis espacial y multitemporal. Mostrando el valor único y eficacia en la evaluación de las dinámicas del proceso de fragmentación, que tienen el uso de Sistemas de Información Geográfica, junto con los índices y el análisis de factores económicos, políticos y sociales dentro de un área de estudio.
... Aunque existen diversas investigaciones sobre la temática, su aplicabilidad en escenarios tropicales es escaso. Se destaca el estudio realizado por Mass, J. y Correa, J. (2000), en el área protegida de Los Petenes, en el estado de Campeche (México), la cual es una investigación pionera que analiza las condiciones ecológicas e identifica grandes aplicabilidades de los índices de paisaje en procesos de conectividad y fragmentación de los ecosistemas tropicales, especialmente reconociendo patrones en el tiempo. ...
... Coincidiendo con lo planteado por Mass y Correa (2000), en una investigación sobre fragmentación del paisaje en México, los patrones de fragmentación son recientes y son dinámicos, por lo cual sus efectos sobre la biodiversidad son difíciles. Así, estos tipos de investigaciones permiten revisar algunos planteamientos teóricos, que se dan por probados, como los factores que determinan la fragmentación de los ecosistemas naturales. ...
... En la reserva el proceso de fragmentación por pérdida de cobertura es grande sobre todo en el sitio Calkiní por lo que la probabilidad de colonizar nuevos sitios es baja. De igual forma, en el sitio Hecelchakán se encontraron nidos en construcciones antiguas de asentamientos humanos lo que puede deberse al decremento de sustratos naturales para anidar, debido al incremento de la perturbación antropogénica que cada día se vuelve más frecuente en estos sitios (Mas y Correa-Sandoval, 2000). De modo que, la perturbación en la RBLP influyó negativamente en la densidad de nidos, ya que fue más baja a la reportada por Nates-Parra et al. (2008) en un bosque de Colombia (9,4 nidos/ha). ...
Las abejas sin aguijón (ASA) son organismos relevantes en los ecosistemas por su desempeño como polinizadores. En México, la mayor diversidad de ASA se encuentra en el sureste. En este estudio se determinaron las especies de ASA y densidad de nidos en dos sitios con diferente perturbación dentro de La Reserva de la Biosfera de los Petenes (RBLP) Campeche (México). Asimismo, se identificaron los sustratos y las especies arbóreas de nidificación. En total se realizaron diez muestreos en transectos entre los meses de enero a mayo de 2018. Se registraron 56 nidos pertenecientes a ocho especies diferentes de ASA (Cephalotrigona zexmeniae, Frieseomelitta nigra, Lestrimellita niitkib, Nannotrigona perilampoides, Partamona bilineata, Plebeia frontalis, Scaptotrigona pectoralis y Trigona fulviventris). Las especies con mayor número de nidos correspondieron a F. nigra (41,07 %) y S. pectoralis (28,57 %). No se encontraron diferencias significativas en la densidad de nidos entre los sitios Hecelchakán (2,15 nidos/ha) y Calkiní (0,19 nidos/ha). El sustrato preferido para anidación son las cavidades en árboles vivos (78,57 %). En total 15 especies arbóreas fueron identificadas como sustrato de nidificación y la especie más abundante correspondió a Crescentia cujete (n = 18, 40,9 %). El grado de perturbación tuvo poco efecto en el número y densidad de nidos de ASA, sin embargo, en general, la RBLP presentó una composición de especies y densidad de nidos reducida. Por lo tanto, este estudio permitió establecer las bases para futuros estudios sobre estrategias de manejo y conservación de estas especies para evitar su desaparición en la RBLP.
... Asimismo, se analizó la evolución espacial y temporal de tres índices vectoriales, el Indicador de Forma (SI), que adopta valores menores (cercanos a 1) cuando el fragmento es regular (en forma de círculo) mientras que los valores altos indican mayor irregularidad, la Relación Perímetro/Área (PAR) cuyos valores altos indican que los fragmentos presentes tienen mayor perímetro (son más irregulares) mientras que al fragmentarse disminuye su perímetro y adoptan una superficie cada vez más regular y la Dimensión Fractal (FD) que también expresa la complejidad mediante valores cercanos a 1 para fragmentos con perímetros simples mientras que los valores más altos de FD (cercanos a 2) representan fragmentos con perímetros complejos basados en su geometría. (Mas y Correa, 2000). ...
A pesar de la importancia que tienen los ecosistemas de la ecorregión Puna en la provisión de servicios ecosistémicos esenciales para el bienestar humano, al extremo sur del Perú no se implementan estrategias de conservación y restauración. Por el contrario, durante años se vienen degradando y transformando por la construcción de infraestructura gris de diversas actividades antropogénicas (viales, afianzamiento hídrico, depósitos materiales, crecimiento poblacional, etc.) generándose un evidente proceso de fragmentación cuyo nivel y efectos ecológicos se ignoran. Es por ello que utilizando los principios de la ecología del paisaje, software especializado, revisión de imágenes satelitales y viajes de campo elaboramos una base cartográfica completa de actividades antropogénicas de los años 1975, 2012 y 2050 para interceptarlos a los ecosistemas de la ecorregión Puna del Mapa Nacional y así calcular las métricas o índices de fragmentación. Los resultados indican que al año 2050 el 8,2% de la ecorregión Puna será transformada en infraestructura, triplicándose la cantidad de fragmentos, disminuyéndose gravemente su área (tamaño), complejidad, irregularidad (forma) y aumentando la distancia entre ellos (borde). A nivel de clase, los pajonales de puna serán los más fragmentados, luego la zona periglaciar, lagunas, bofedales, matorrales y bosques altoandinos, generándose efectos nocivos para la biodiversidad que no están siendo considerados en las políticas de gestión territorial. Esta información científica resulta útil para que las autoridades locales establezcan mecanismos de restauración de los ecosistemas proveedores de recurso hídrico, necesario para la agricultura, ganadería, población, minería, etc., a nivel departamental con miras al desarrollo sostenible.
... These fires are a frequent occurrence, including inside the natural protected areas of the peninsula. For example, in Reserva de la Biósfera Los Pentenes, Campeche, approximately 16% of the land is subjected to this practice (Mas and Correa-Sandoval, 2000). Many of the induced fires are associated with uncontrolled slash and burn practices, but many others are instigated to obtain a land use change permit in order to continue urban expansion or the construction of infrastructure for tourism; the latter likely is the primary motivator of induced fires in northern Quintana Roo (Ellis et al., 2015). ...
The herpetofauna of the Mexican Yucatan Peninsula is comprised of 145 species, including 22 anurans, three salamanders, two crocodylians, 102 squamates, and 16 turtles. We examined the state-level distribution of the herpetofauna of this region, which revealed that the largest number of amphibian species (24 of 25) is recorded for Campeche, followed by Quintana Roo (22), and then by Yucatán (17). The largest number of crocodylians, squamates, and turtles is reported for Quintana Roo (107 of 120), with the next highest number in Campeche (104) and then in Yucatán (88). We documented the distribution of the herpetofauna among the six physiographic regions recognized herein, including four mainland regions and two insular ones. The total number of species in these six regions ranges from 43 in the Gulf Islands region to 120 in the Karstic Hills and Plains of Campeche. The individual species inhabit from one to six regions (x– = 3.7). The largest number of single-region species (five) is restricted to the Yucatecan Karstic Plains. We constructed a Coefficient of Biogeographic Resemblance (CBR) matrix that demonstrates the number of shared species ranging from 26 between the Caribbean Islands and Gulf Islands to 104 between the Karstic Hills and Plains of Campeche and the Yucatecan Karstic Plains. The CBR values range from 0.44 between the Karstic Hills and Plains of Campeche and the Caribbean Islands to 0.88 between the Gulf Islands and the Karstic Hills and Plains of Campeche. Based on the CBR data we constructed an Unweighted Pair Group Method with Arithmetic mean (UPGMA) dendrogram, which indicates that the four mainland physiographic regions are fairly closely related to one another because they share a sizable number of broadly distributed species, and are fairly distantly related to the two insular groupings perhaps because of the dispersal ability bias seen among members of the mainland herpetofauna. Only about 24% of the herpetofauna is distributed in one or two of the six regions, demonstrating the relatively broad distribution of many species on the peninsula. We placed the members of the herpetofauna into four distributional categories, of which the largest number (127 of 145) is allocated to the non-endemic category; relatively small numbers are placed in the regional endemic category (11), followed by the non-native species (six) and the country endemic category (one). We identified the principal environmental threats as agriculture and deforestation, hurricanes and other tropical storms, forest fires, tourist development, infectious diseases, invasive species, climate change, illegal collecting, oil mining, killing on roads, and other forms of direct and incidental killing. We assessed the conservation status of the native species by employing the SEMARNAT (NOM-059), IUCN, and Environmental Vulnerability Score (EVS) systems, of which the EVS proved to be the most useful. The number of species in the three EVS categories decreased from low (57) through medium (51) to high (26). We also used the EVS rankings to determine how species in the IUCN Not Evaluated (NE) and Least Concern (LC) categories might be evaluated more informatively. In addition, we used a means of determining Relative Herpetofaunal Priority (RHP), a simple method for ascertaining the rank order of a physiographic regional herpetofauna based on the number of peninsular and national endemic species, as well as the number of high vulnerability EVS species. Using these measures, we concluded that the Yucatecan Karstic Plains ranked as the highest priority region, in both cases. Moreover, we discuss the capability of the protected areas of the Mexican Yucatan Peninsula to provide protection for members of the herpetofauna. Based on our analysis, we erected a set of conclusions and recommendation for the perpetual protection of the peninsular herpetofauna.
Land use/land cover change (LULCC) is a major threat that affects the viability of insect populations worldwide yet our estimates of such effects are usually poor. We analysed how LULCC affected the distribution of 49 species of dragonflies and damselflies in the south-central zone in Mexico during the period 2006-2012. For this, we mapped the potential species richness using ecological niche models in order to analyse predicted future changes and determined the effect of LULCC on the current and future habitats of Odonata. We also estimated current incidence of deforestation and projected its effect to 2050 using the Dinamica-EGO program. Having predicted the level of deforestation in the year 2050, we then compared current vs. expected species richness and the factors that determine it. First, roads and urban areas turned out to be the most important drivers of LULCC in our analysis. Second, deterioration occurred at all sites, but species richness remained high despite considerable habitat fragmentation. Third, there is likely to be a high species turnover rate (i.e. a high species richness, but composed of different species) even in areas where there are significant changes in the vegetation. Our work illustrates both a resilience of Odonata to LULCC and provides a useful method for measuring the effects of LULCC on insects.
Landscape analysis characterizes ecological structure and functioning to propose mitigation strategies for addressing environmental problems. The objective was to analyze the spatial configuration of landscape elements in the Los Tuxtlas Biosphere Reserve (LTBR), from 1995, 2006 and 2016 LANDSAT images. These were rectified and classified according to the land cover and use types; each one was analyzed with landscape metrics using FRAGSTATS 3.3 software. For 2016, 60% of the landscape corresponds to an agricultural profile, with 95% aggregation and a matrix density of 0.9; acahual (fallow land) constitutes 77.62% of the landscape and is composed of 6 242 fragments, with dispersed and disaggregated cover, with a density of 4.05; rainforest/cloud forest (CF) accounts for 27% of the landscape with 2 141 fragments, 94.9% aggregation and a matrix density of 1.38. The rainforest/CF is the cover with the highest connectivity index, so actions must be taken to conserve these areas and even increase them, while the acahuales are in processes of ecological succession and those that are transitioning to rainforest must be identified, to channel these properties as private conservation areas. The LTBR is increasing the rainforest/CF, acahual and mangrove cover and diminishing the agricultural matrix, which leads to the conservation of biodiversity.
Estimación de cobertura boscosa mediante el sistema TerraAmazon y análisis de fragmentación en los municipios de Viotá (Cundinamarca) y FuentedeOro (Meta), Colombia (2016). Abstract. The purpose of this study was to estimate the forest cover and areas with low or without vegetation have in the municipalities of Viota (Cundinamarca Department) and Fuentedeoro (Meta Department) in the year 2016. In order to, make decisions on priority areas to reforestation, through the use of the TerraAmazon System and in turn, to perform a spatial fragmentation analysis through SAGA software. The TerraAmazon System was configured by the building of a database Postgres SQL, the conceptual model, access control, control phases, project, rules control and categories, required to the posterior visual interpretation display of existing covers on a 456 composition Landsat 8 imagery. The results determined a greater existence of land with low vegetation or without vegetation in the Viota municipality with 53,904 km 2 (25,9 %) in contrast to Fuentedeoro municipality, this cover present 470,200 km 2 (74,5 %). With these results were proceeded to develop the fragmentation analysis, that indicates, a high fragmentation in Fuentedeoro represented for the patch (19,56%) and border (8,93%) categories, in contrast to Viota municipality when the mayor vegetation is localized in the border (53,08%) and nucleus (23,90%) categories, annotating in addition the absence the perforated category.
Compared point count census data from both short and tall second-growth sites with counts taken from a nearby undisturbed tropical deciduous forest in coastal Jalisco, Mexico. Each of the second-growth sites differed significantly from the undisturbed forest in its bird composition. Much of the change can be attributed to the improvement of conditions for some guild members (eg seedeaters) and the removal of adequate conditions for others (eg trunk-foragers, fruit-eaters), but there was a significant difference in the effect on migrant vs. resident species that was independent of foraging guild; long distance migratory species were significantly more likely to increase in abundance as a result of disturbance than were resident species. Thus, many migratory species in W Mexico may benefit from the human-caused creation of mid-successional habitats. -from Author
The Center for Remote Sensing and Mapping Science at The University of Georgia and the South Florida Natural Re-sources Center, Everglades National Park, have developed a detailed vegetation database in geographic information sys-tem (GIS) format and 1:15,000-scale vegetation maps keyed to 80 U.S. Geological Survey (USGS) 7.5-minute topographic quadrangles covering Everglades National Park, Big Cypress National Preserve, Biscayne National Park, and the Florida Panther National Wildlife Refuge in south Florida, an area of over 10,000 km2. National Aerial Photography Program (NAPP) color-infrared (cm) aerial photographs recorded in 1994/95 were the primary source material, supplemented by extensive GPS-assisted data collections from helicopter recon-naissance missions and field work. The ground control nec-essary to rectify the vegetation polygons and linear features extracted from the Cm photographs was obtained from geo-coded SPOT panchromatic images of 10-m resolution and from USGS 1:24,000-scale topographic line maps. A detailed three-tiered, hierarchical vegetation classification system, the Everglades Vegetation Classification System, was developed specifically for the project. In addition to the vegetation data-base, a digital database and map products were constructed for off-road vehicle (ORV) trails in Big Cypress National Pre-serve. The length of trails in the 2,950-km2 Preserve totaled over 47,900 km. The databases and maps, constructed through a combination of remote sensing, GIs, GPS, and field studies, provide Park and Preserve managers with detailed baseline information on the status of vegetation and ORV trails in 1995. It is anticipated that, with increased concern over environmental preservation, water demand and expan-sion of urban development, agricultural land utilization, and ORV use, the databases will prove valuable for a range of management and modeling tasks.
Research on fragmented ecosystems has focused mostly on the biogeograpbic consequences of the creation of habitat “islands” of different sizes and has provided little of practical value to managers. However, ecosystem fragmentation causes large changes in the physical environment as well as biogeograpbic changes. Fragmentation generally results in a landscape that consists of remnant areas of native vegetation surrounded by a matrix of agricultural or other developed land. As a result fluxes of radiation, momentum (La, wind), water, and nutrients across the landscape are altered significantly. These in turn can have important influences on biota within remnant areas, especially at or near the edge between the remnant and the surrounding matrix. The isolation of remnant areas by clearing also has important consequences for the biota. These consequences vary with the time since isolation distance from other remnants, and degree of connectivity with other remnants. The influences of physical and biogeographic changes are modified by the size, shape, and position in the landscape of individual remnant, with larger remnants being less adversely affected by the fragmentation process. The Dynamics of remnant areas are predominantly driven by factors arising in the surrounding landscape. Management of, and research on, fragmented ecosystems should be directed at understanding and controlling these external influences as much as at the biota of the remnants themselves. There is a strong need to develop an integrated approach to landscape management that places conservation reserves in the context of the overall landscape
The effects of landscape patchiness on the diversity of birds of the Georgia Piedmont were investigated during 1993. Birds were sampled along line transects within relatively large (10–13.25 ha) and small (less than 3.25 ha) forest patches located within nonforest agricultural landscapes. Patterns of habitat use in these patches were compared to those in contiguous forest patches larger than 13.25 ha. Analysis of variance revealed significant differences in diversity between large and small woodlots and between contiguous and fragmented landscapes, especially in terms of the numbers of edge and interior species and winter-resident, summer-resident, and year-round birds observed.
1. A review of the literature shows that in nearly all cases tropical rain forest fragmentation has led to a local loss of species. Isolated fragments suffer reductions in species richness with time after excision from continuous forest, and small fragments often have fewer species recorded for the same effort of observation than large fragments or areas of continuous forest. 2. Birds have been the most frequently studied taxonomic group with respect to the effects of tropical forest fragmentation. 3. The mechanisms of fragmentation-related extinction include the deleterious effects of human disturbance during and after deforestation, the reduction of population sizes, the reduction of immigration rates, forest edge effects, changes in community structure (second- and higher-order effects) and the immigration of exotic species. 4. The relative importance of these mechanisms remains obscure. 5. Animals that are large, sparsely or patchily distributed, or very specialized and intolerant of the vegetation surrounding fragments, are particularly prone to local extinction. 6. The large number of indigenous species that are very sparsely distributed and intolerant of conditions outside the forest make evergreen tropical rain forest particularly susceptible to species loss through fragmentation. 7. Much more research is needed to study what is probably the major threat to global biodiversity.
Following habitat alteration or fragmentation, competition, parasitism, and predation from species that live in the new habitats may reduce the survival and reproductive success of species living in the original habitats. Negative influences from species that live outside the remnant patches are expected to be greater in small rather than in large remnant patches because more “external” species are expected to move through the centers of small remnant patches. We surveyed birds within remnant patches of old‐growth montane forests on Vancouver Island, Canada, (1) to evaluate whether the richness and abundance of non‐old‐growth bird species were larger at the center of small rather than large patches and (2) to evaluate whether the opposite was true of old‐growth bird species. More non‐old‐growth bird species were present at the center of small remnant patches of old growth than in large old‐growth patches. We found no relationship, however, between patch size and richness or abundance of old‐growth bird species at the center of remnant patches of old growth. This was true for old‐growth species with open, cup‐shaped nests and cavity nests. Old‐growth birds may have been affected less in our study area than in other areas because they evolved within heterogeneous montane forests and interacted with non‐old‐growth species throughout their evolutionary histories or because the contrast between old‐growth forests and logged areas was less than that between the forests and agricultural/urban areas that were surveyed in other studies.
Efectos del tamaño de parches sobre las aves en bosques primarios de montaña