Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology.This is especially true in areas where topography is complex due to volcano elevational gradients and where forests are vulnerable to human activity.In this study we used a set of climatic(temperature,rainfall,and radiation solar),topographic(elevation,slope aspect,and slope orientation)and human disturbance variables to determine their effect on diversity and composition patterns of a tree community,considering three slope aspects of a tropical volcano in southeastern Mexico.We sampled trees in seventy 0.1-ha plots distributed on three slope aspects of the Tacaná volcano along an elevational gradient of 1500 to 2500 m.We determined diversity patterns(general tree richness,exponential of Shannon index,and pioneer species richness)with linear regression models,and for beta diversity,we used a dissimilarity index(within and between elevational bands 100 m wide).The effect of a set of environmental and human disturbance variables on tree diversity and community composition was analyzed with general linear models and multivariate analyses,respectively.We registered 2,949 individual trees belonging to 176 species and 58 families.The average species richness and alpha diversity per plot were 13(standard deviation±6)and 9(±5),respectively.General tree richness and alpha diversity increased in the middle part(unimodal patterns)of the elevational gradient,but pioneer species richness decreased linearly with elevation.The variance explained by general linear models was greater in richness(32％)than in alpha diversity(25.3％).The most important predictor variables were temperature(elevational gradient),which explained the unimodal pattern(richness and alpha diversity increase at intermediate levels of temperature),and slope orientation,which explained the increase in richness and alpha diversity toward the geographic north.Only temperature had a significant effect on pioneer species diversity(22％).For community composition,all the predictor variables evaluated had a significant effect,but the most important were slope aspect and temperature.Assemblages were almost completely different in plots that were farther apart along the elevation gradient and had different slope aspects.Finally,the forests at lower elevations(1500-1900 m)were those that had the most human disturbance.Our study reveals the importance of considering a set of environmental variables related to climate,topography(e.g.,slope aspect),and human disturbance to understand variation in diversity and composition of a tree community on a tropical volcano.With this information,we believe that it is important to implement conservation and restoration measures in the forests of the lower parts of the Tacaná volcano,complemented by studies that contribute to designing better conservation strategies.

Rubén MARTíNEZ-CAMILO;Manuel MARTíNEZ-MELéNDEZ;Nayely MARTíNEZ-MELéNDEZ;Derio Antonio JIMéNEZ-LóPEZ;Mauricio JOSé-RíOS

Unidad Villa Corzo,Facultad de Ingeniería,Universidad de Ciencias y Artes de Chiapas,30520 Villa Corzo,Chiapas,Mexico;Instituto de Ciencias Biológicas,Universidad de Ciencias y Artes de Chiapas,29039 Tuxtla Gutiérrez,Chiapas,Mexico;Eizia A.C.,29045 Tuxtla Gutiérrez,Chiapas,Mexico;Departamento de Conservación de la Biodiversidad,El Colegio de la Frontera Sur,29290 San Cristóbal de las Casas,Chiapas,Mexico;Orquidiario y Jardín Botánico de Comitán,Secretaría de Medio Ambiente e Historia Natural,30106 Comitán de Domínguez,Chiapas,Mexico;Instituto de Investigación en Gestión de Riesgos y Cambio Climático,Universidad de Ciencias y Artes de Chiapas,29039 Tuxtla Gutiérrez,Chiapas,Mexico

山地科学学报（英文版）

[1]Rubén MARTíNEZ-CAMILO;Manuel MARTíNEZ-MELéNDEZ;Nayely MARTíNEZ-MELéNDEZ;Derio Antonio JIMéNEZ-LóPEZ;Mauricio JOSé-RíOS-.Tropical tree community composition and diversity variation along a volcanic elevation gradient)[J].山地科学学报（英文版）,2022(12):3475-3486

Tacan

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