Prosopis laevigata and Mimosa biuncifera (Leguminosae), jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem

Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.

Prosopis laevigata y Mimosa biuncifera coexisten en los matorrales semiáridos; sin embargo, se desconoce su influencia sobre la diversidad de la comunidad vegetal y el suelo. Este estudio evaluó el efecto de P. laevigata y M. biuncifera sobre la estructura, diversidad vegetal y nutrimentos del suelo, en tres matorrales del Valle del Mezquital, México. Los sitios difieren en la especie dominante: Sitio 1, P. laevigata; Sitio 2, M. biuncifera y Sitio 3, ambas leguminosas. En cada sitio se recolectó suelo, tanto abajo y fuera del dosel de las leguminosas, además, se realizaron transectos para medir e identificar las plantas arbóreas y arbustivas, se calculó el índice de valor de importancia y la diversidad del matorral. Asimismo, se registró mayor riqueza y diversidad en el Sitio 3 (ICE 29 spp. y H’ 2.7), en comparación con el Sitio 1 (24 spp. y 2.4) y Sitio 2 (26 spp. y 2.1). La materia orgánica y el carbono orgánico del suelo, así como el N total, el P-Olsen y la mineralización de C fueron mayores en el suelo bajo dosel de ambas leguminosas. La abundancia de esporas de hongos micorrizógenos arbusculares fue favorecida por M. biunficera. La influencia de P. laevigata para crear islas más ricas en recursos fue mayor que en M. biunficera, lo anterior sugiere que cada leguminosa modifica de una forma diferente el microambiente, sin embargo, juntas aumentan la disponibilidad de nichos para el establecimiento de otras especies, lo queayuda a comprender el papel de P. laevigata y M. biuncifera sobre la colonización vegetal en ecosistemas semiáridos.

Abelhas generalistas (Meliponina) e o sucesso reprodutivo de Stryphnodendron pulcherrimum (Fabales: Mimosaceae) com florada em massa na Mata Atlântica, BA / Generalist bees (Meliponina) and the reproductive success of the mass flowering tree Stryphnodendron pulcherrimum (Fabales: Mimosaceae) in the Atlantic Rainforest, Bahia

It is controversial the role played by Meliponina bees in the pollination of mass flowering trees with small generalized flowers (FMPG), very common group of trees in the tropical forest canopy. The species richness and relative abundance of flower visiting insects of the mass flowering tree Stryphnodendron pulcherrimum were measured to test the hypothesis of tight ecological association between these generalist bees and FMPG and to evaluate the effect of this relationship upon the reproductive success variation among tree crowns. The flower visiting insects were sampled on 10 flowering tree crowns at the Atlantic Rainforest in southern Bahia. Altogether, 553 visiting insects were collected during the flowering period of S. pulcherrimum: 293 (52 percent) Meliponina bees out of 438 bees (79.4 percent). All tree crowns were visited by Meliponina, with the proportion of these bees ranging from 27 percent to 87 percent. The tight ecological association between FMPG trees and Meliponina bees is supported by the observed pattern of spatial relationship. Both the relationship between variation of fruit set among tree crowns and species richness (r = 0.3579; P = 0.3098) or relative abundance (r = 0.3070; P = 0.3881) of Meliponina were not statistically significant. Likely a threshold of minimum relative abundance combined with the absolute abundance of these bees explain the fruit set variation among tree crowns of S. pulcherrimum, even by self-pollination. We tested this assumption with a preliminary analysis of Melipona bee genera distribution among the tree crowns.

Use and management of Mimosa species in the Tehuacán-Cuicatlán Valley, a tropical semi-arid region in Mexico (Fabaceae-Mimosoideae)

We report on the use of 15 Mimosa species within the Tehucán-Cuicatlán Valley,south-central Mexico.Seven of these species are endemic to Mexico,and four species and one variety are endemic to the Valley.We reviewed historical,ethnobotanical and floristic manuscripts,and conducted field studies.Several herbaria were consulted,as well as the BADEPLAM data base.Field work in the Valley has been done from 1994 to date.Most of the Mimosa species occur in the arid tropical scrub and the tropical deciduous forest,which are considered the most endangered vegetation types of the Valley.Our findings show that Mimosa species are used as fodder (45%),fuel (31%),living fences (14%)and construction material (7%).Only one species is used as medicine.Mimosa species are "multipurpose "shrubs/trees of the agrosilvopastoral system of this region

En este trabajo se informa el uso de 15 especies del género Mimosa dentro de la Reserva de la Biósfera del Valle de Tehuacán-Cuicatlán,en la región centro-sur de México.De las 15 especies de Mimosa estudiadas,siete de ellas son endémicas de México y cuatro especies y una variedad son endémicas del Valle.Se revisaron manuscritos y documentos históricos,etnobotánicos y florísticos,y se llevó a cabo trabajo de campo.Se consultaron varios herbarios,así como la base de datos BADEPLAM.El trabajo de campo en el Valle se está realizando desde 1994 hasta la fecha.La mayoría de las especies de Mimosa se establecen en el matorral xerófilo,el cual está considerado como el tipo de vegetación que está más en peligro de todos los que se encuentran en la Reserva.Los resultados muestran que la mayoría de las especies de Mimosa se usan como forraje (45%)y como combustible (31%),así como en la formación de cercas vivas (14%)y como material para construcción (7%);mientras que sólo una especie presenta un uso medicinal.Las especies de Mimosa son arbustos y/o árboles "multipropósito "en los sistemas agrosilvopastoriles practicados en el Valle de Tehuacán-Cuicatlán