Mean Patch Edge Research Articles

The relationship between forest fragmentation and the potential geographical distribution of psittacids (Psittaciformes: Psittacidae) in the Yucatan Peninsula, Mexico

Parrots are a seriously threatened group because of the illegal pet trade, their habitat fragmentation and the destruction of tropical forests. This study aimed to determine the relationship between forest fragmentation and the geographic potential distribution of parrot species in the Yucatan Peninsula, Mexico. The research was carried out in the Mexican portion of the Yucatan Peninsula Biotic region, which includes the states of Campeche, Quintana Roo and Yucatan. We worked with the eight species of psittacids that inhabit the selected areas: Eupsittula nana, Amazona albifrons, Amazona xantholora, Amazona autumnalis, Pionus senilis, Pyrilia haematotis, Amazona oratrix and Amazona farinosa. For these species, we used the potential geographical distribution maps that were obtained through the Maximum Entropy algorithm, published in 2014. To measure the levels of forest fragmentation in the Peninsula, we employed the land use and vegetation maps from series IV (2007-2010) of the National Institute of Statistics and Geography. We calculated different landscape metrics at 100 sites randomly distributed within the predicted presence and absence areas for the species. Multivariate methods were used to shorten dimensionality in the analysis, as well as to explore the observed patterns. We did not find any pattern regarding the number of variables that contribute to the logistic regression models (LR) and the size of the parrots’ potential geographical distribution area within the Peninsula. For Pyrilia haematotis and Amazona oratrix, the fragmentation variables used did not seem to have any relationship with their potential geographical distribution in the Peninsula (intersection, Pr < 0.0001). Only for Eupsittula nana, Amazona xantholora and Pionus senilis, we found that the mean patch edge, the mean shape index and the mean perimeter-area ratio were important to determine their potential distribution patterns, respectively; and, in general, the variables indicated the preferences of these parrots to occupy larger habitat patches. Parrots must be given a special care and protection within the states of Campeche and Quintana Roo, since there are areas with high parrot diversity and are importantly affected by human activities. The best recommendation for managers and users of protected areas within the Yucatan Peninsula is that extensive areas of forest should be maintained in order to guarantee the suvival of psittacid populations.

Spatiotemporal changes and fragmentation of mangroves and its effects on fish diversity in Ca Mau Province (Vietnam)

Mangroves are important economically and ecologically, however mangrove cover has declined dramatically leading to habitat fragmentation and biodiversity loss. Information on mangrove cover change, fragmentation and impacts on fish diversity is poorly understood. The aims of this study are to detect spatiotemporal changes and mangrove status, examine fragmentation changes and associated effects on fish diversity. Landsat images in 1989, 2000, and 2013 were used to classify mangrove cover in Ca Mau Province (Vietnam) and validated against high resolution Pleiades imagery. Fragmentation changes in mangrove cover were examined using series of landscape metrics evaluated against fish diversity indices (Simpson’s index, Jaccard’s coefficient and relative abundance). Results show that mangrove cover has declined 24.6% in the province. Currently, high and moderately dense mangroves distribute in southern half of the region while the low density mangroves occurs in the northern half. Over the 24 year study periods, the number of patches and edge density has increased 58% and 53.9%, respectively, while the mean patch size and mean patch edge has decreased 52.3% and 26.6%. Fish diversity in the more highly fragmented mangrove area was 1.78 times lower than the less fragmented mangrove. The study illustrates the applicability of using Landsat satellite imagery for use in mangrove fragmentation studies as well as the impact of fragmentation.

Ecología del paisaje y caracterización de la cobertura forestal de la microcuenca del Río La Balsa, Costa Rica

Se evaluó la ecología del paisaje, el cual está dominado por tres coberturas: bosques, pastos y cultivos. Las principales métricas de paisaje obtenidas: a) Bosque: Área de la clase (CA): 11447,72 ha; Número de Parches (NumP): 16344; Tamaño promedio de parches (MPS): 0,70 ± 10,73 ha; Borde Total (TE): 5245378,35 m; Borde promedio de parche (MPE): 320,94 m/ha; Índice de forma promedio (MSI): 1,47. b) Pastos: CA: 10467,63 ha; NumP: 13930; MPS: 0,75 ± 23,93 ha; TE: 4432678,19 m; MPE: 318,21 m/ha; MSI: 1,47. c) Cultivos: CA: 3603,76 ha; NumP: 636; MPS: 5,67 ± 63,59 ha; TE: 7666342,78 m; MPE: 1204,94 m/ha; MSI: 1,93. Se obtuvo además un índice de diversidad de Shannon para el paisaje de 1,32. La composición florística y estructura se evaluaron en tres pisos altitudinales y para las principales coberturas forestales presentes. Se establecieron 68 parcelas temporales de 2000 m2 (20 x 100 m), identificándose las especies, la altura total y el diámetro de todos los árboles mayores a 10 cm de diámetro presentes en las parcelas de medición. Los valores promedio obtenidos: a) Basal: bosques<br />intervenidos, d: 23,3 cm; Ht: 24 m; N ha-1: 458 y G/ha: 22,8 m2. b) Premontano: bosques intervenidos, d: 22,6 cm; Ht: 27,3 m; N ha-1: 423 y G/ha: 20,6 m2, potreros arbolados, d: 24,3 cm; Ht: 18,9 m; N ha-1: 121 y G/ha: 6,6 m2. c) Montano bajo: bosques de altura, d: 26,6 cm; Ht: 27,5 m; N ha-1: 380 y G/ha: 27,2 m2, bosques intervenidos, d: 22,9 cm; Ht: 27 m; N ha-1: 318 y G/ha: 15,8 m2, potreros arbolados, d: 24,5 cm; Ht: 25 m; N ha-1: 118 y G/ha: 6,9 m2. La composición florística y las variables estructurales sugieren que los hábitats presentes en la microcuenca se encuentran en estado de recuperación.

The relationship between landscape patterns and human-caused fire occurrence in Spain

Aim of study: Human settlements and activities have completely modified landscape structure in the Mediterranean region. Vegetation patterns show the interactions between human activities and natural processes on the territory, and allow understanding historical ecological processes and socioeconomic factors. The arrangement of land uses in the rural landscape can be perceived as a proxy for human activities that often lead to the use, and escape, of fire, the most important disturbance in our forest landscapes. In this context, we tried to predict human-caused fire occurrence in a 5-year period by quantifying landscape patterns.Area of study: This study analyses the Spanish territory included in the Iberian Peninsula and Balearic Islands (497,166 km2).Material and Methods: We evaluated spatial pattern applying a set of commonly used landscape ecology metrics to landscape windows of 10x10 sq km (4751 units in the UTM grid) overlaid on the Forest Map of Spain, MFE200.Main results: The best logistic regression model obtained included Shannon’s Diversity Index, Mean Patch Edge and Mean Shape Index as explicative variables and the global percentage of correct predictions was 66.3 %.Research highlights: Our results suggested that the highest probability of fire occurrence at that time was associated with areas with a greater diversity of land uses and with more compact patches with fewer edges.Keywords: human-caused wildfires; landscape ecology; logistic regression.