Pollinator Species at Risk from the Expansion of Avocado Monoculture in Central Mexico

The monoculture of avocado (Persea americana) has triggered the loss of large forested areas in central Mexico, including the habitat of threatened species. This study assessed the potential habitat loss of ten threatened pollinator species due to the expansion of avocado monoculture in Mexico. First, we modeled the distribution of avocado and pollinators. Then, we overlapped their suitable areas at a national level and within the Trans-Mexican Volcanic Belt (TMVB). We also identified the areas with more affected pollinators and coinciding with protected areas. As a result, 78% of the suitable areas for avocado coincided with the distribution of at least one pollinator. Although only two pollinators lost more than one-fifth of their distribution at a national level, the habitat loss increased to 41.6% on average, considering their distribution within the TMVB. The most affected pollinators were Bombus brachycephalus, B diligens, Danaus plexippus, and Tilmatura dupontii, losing more than 48% of their distribution within this ecoregion. The areas with a greater number of affected species pollinators were found in the states of Michoacán, Mexico, and Morelos, where most of the area is currently unprotected. Our results suggest that the expansion of the avocado monoculture will negatively affect the habitat of threatened pollinators in Mexico

Pollinator Species at Risk from the Expansion of Avocado Monoculture in Central Mexico

The monoculture of avocado (Persea americana) has triggered the loss of large forested areas in central Mexico, including the habitat of threatened species. This study assessed the potential habitat loss of ten threatened pollinator species due to the expansion of avocado monoculture in Mexico. First, we modeled the distribution of avocado and pollinators. Then, we overlapped their suitable areas at a national level and within the Trans-Mexican Volcanic Belt (TMVB). We also identified the areas with more affected pollinators and coinciding with protected areas. As a result, 78% of the suitable areas for avocado coincided with the distribution of at least one pollinator. Although only two pollinators lost more than one-fifth of their distribution at a national level, the habitat loss increased to 41.6% on average, considering their distribution within the TMVB. The most affected pollinators were Bombus brachycephalus, B diligens, Danaus plexippus, and Tilmatura dupontii, losing more than 48% of their distribution within this ecoregion. The areas with a greater number of affected species pollinators were found in the states of Michoacán, Mexico, and Morelos, where most of the area is currently unprotected. Our results suggest that the expansion of the avocado monoculture will negatively affect the habitat of threatened pollinators in Mexico

Allometric height-diameter equations for Pinus pseudostrobus Lindl

Silvicultural practices used for forest management in the Indigenous Community of Nuevo San Juan Parangaricutiro (CINSJP for its initials in Spanish), Michoacan, Mexico, are important for the sustainability of its woodlands. For this purpose, techniques that provide reliable and current quantitative estimates are required. The aim was to t an equation that describes the allometric relationship between total height and normal diameter (Th-nd) of Pinus pseudostrobus in the CINJSP forests. Data were obtained from P. pseudostrobus stands that have been managed with the Silvicultural Development Method (SDM) at dierent stages according to the current forest management program. The research area is between 2,200 and 2 500 masl, has a temperate type C (w2) climate, and is located at southwest of the Purhépecha Plateau within the Trans-Mexican Volcanic Belt region. The sample size consisted of 169 total height-normal diameter (Th-nd) data pairs. Ten allometric models to evaluate the goodness of t were tested, choosing three models based on the lowest values of the sum of square errors of prediction (SSE) and the root mean squared error (RMSE), the highest adjusted coecients of determination and the signicance of their parameters. The deviations of the models were smaller than 0.01 m. The three-parameter equation T h = K + 38.06004 1+6.033101exp(0.066439dn) , proved to be statistically more stable than the rest, and it also shows deviations of less than one meter per tree and less than 1% for the entire population