Diversity of soil macro-arthropods correlates to the richness of plant species in traditional agroforestry systems in the humid tropics of Mexico

A change in land use from forest to livestock and agriculture is generally linked to a potentially devastating effect on communities of flora and fauna. Tabasco is a state with the highest deforestation rate in the humid tropics of Mexico; more than 66% of its territory is currently occupied by livestock farming. Here, we evaluated the diversity of soil macro-arthropods and plant species richness in eight different, traditional agroforestry systems (AFS): family garden (FG), shade trees in plantations (ShTP), scattered trees in pastures (ScTP), living fences (LF), alley farming (AF), taungya systems (TG), slash and burn agriculture (SBA) and grazing plantations (GP). First, we recorded the biophysical information of the AFS, age and management of the system, richness of the plant community, and other general characteristics. Then, we collected of macro-arthropods in 49 plots of land in five sub-regions of Tabasco. We established ten pitfall traps in each plot during the dry season (March-May 2009). To compare the diversity of soil macro-arthropods among the AFS, we computed the species accumulation curves and calculated the diversity indexes. We found that the total plant richness varied among the AFS and ordered as FG (108), ShTP (106), ScTP (32), LF (38), AF (30), TG (16), SBA (0) and GP (2). We collected 42,269 individuals of arthropods, belonging to 15 orders in the eight AFS. The most abundant orders were Hymenoptera and Coleoptera, while the least abundant was Dermaptera. The SBA, FG, ShTP, and ScTP systems presented the higher diversity of macro-arthropods as shown by Shannon-Wiener index (H') values. We also found a significant positive correlation (r(s)=0.84) between macro-arthropod order diversity (H') and plant species richness in the most common AFS. The study showed that the AFS with greater plant species richness are important agricultural production strategies that increase the diversity and conservation of soil macro-arthropods.