Xerophytic Shrubland Research Articles

Diversity of Diurnal Butterflies (Lepidoptera: Hesperioidea and Papilionoidea) of Laguna Potosí and Surrounding Area, Guerrero, Mexico

Abstract. The Mexican state of Guerrero is fourth in butterfly diversity in Mexico. However, little is known about the superfamily Hesperioidea and communities of butterflies that live in coastal ecosystems. Hesperioidea and Papilionoidea of Laguna Potosi and surrounding area were surveyed monthly for 1 year (December 2009-November 2010) in pre-established transects in tropical dry forest; xerophytic shrubland; mangrove; coconut palm crop; secondary vegetation of tropical dry forest; and mixed environment of acacia forest, coconut palm, and mango crops. In total, 188 species in two superfamilies, six families, 18 subfamilies, and 127 genera were identified; seven species were endemic to Mexico, three to the tropical dry forest, and 32 were new records for Guerrero. Most species of butterflies were found in the family Hesperiidae (73), followed by Nymphalidae (52), Pieridae (20), Lycaenidae (19), Riodinidae (15), and Papilionidae (nine species). Most species were found in xerophytic shrubland (114) and tro...

Diversidad de orquídeas de las diferentes formaciones vegetales de los Andes peruanos

Debido a la presencia de la Cordillera de los Andes y la Corriente de Humboldt, el Perú posee una gran diversidad de ecosistemas. Mientras que las regiones bajas al oeste de los Andes peruanos está caracterizada por ser una franja desértica-semidesértica, con bosques secos, matorrales y principalmente formaciones vegetales estacionales, las regiones del lado este de los Andes se caracterizan por estar formados de extensos bosques húmedos de gran biodiversidad. A lo largo de la cordillera; la vegetación de la zonas altoandinas y de los valles interandinos del norte, centro y sur del Perú no son tan contrastantes, aunque si existen diferencias en la composición florística debido a la humedad; las regiones del norte son mas húmedas que las del centro y sur. Las orquídeas que se encuentran en los bosques montanos de la vertiente oriental de los Andes peruanos son principalmente epífitas y han sido objeto de numerosos estudios con el propósito de conocer su diversidad. En cambio el estudio de las orquídeas terrestres no han recibido la misma atención, a pesar de que éstas se encuentra en casi todos los ecosistemas del país, desde los desiertos, matorrales xerofíticos, turberas altoandinas e incluso en áreas donde se ha introducido especies exóticas, como los bosques de Eucalyptus globulus. En la presente contribución se describen las formaciones vegetales del desierto costero, valles interandinos y zonas altoandinas del Perú; así como las orquídeas que se han registrado en cada tipo de vegetación.

Evolutionary Trends in Magdalenian Societies in southwestern France (18-14 Ky calBP) : Survey of a Complex Process

During the mid-to-late Pliocene (ca. 4–3 Ma), several hominin species were present in central Sahel, eastern and southern Africa. The potential for the discovery of hominin remains from this interval is limited by the availability of exposed Pliocene deposits and the ability to investigate them. As a result, most discoveries have been made in the Afar region of Ethiopia and in the Lake Turkana basin, thus unveiling only a portion of Pliocene hominins' probable geographical presence. In this study we provide a continental view of geographic areas potentially accessible to these hominins. To do so, we estimate the climatic envelope suitable for mid-to-late Pliocene hominin presence, using the earth system model IPSL-CM5A and the Maxent habitat suitability algorithm. Our analysis reveals high habitat suitability for these hominin species in semi-arid regions where annual thermal amplitude and mean annual precipitation are moderate, mostly corresponding to tropical xerophytic shrublands. Our habitat model estimates geographically continuous, suitable climatic conditions for hominins between central Sahel and northeastern Africa, but not between eastern and southern Africa. This discontinuity suggests that southern African and eastern African hominins were separated by an environmental barrier that could only be crossed during particularly favourable periods or by undertaking long-range dispersal over climatically hostile habitats. Under climate conditions of northern hemisphere summer at perihelion this climatic barrier is not present. In contrast, the Turkana basin, the Laetoli region, and a large part of southern Africa remain suitable for all precession angles, suggesting that these areas may have functioned as refugia. The constant presence of these stable areas combined with the periodic establishment of corridors for dispersion can potentially explain hominin diversity in eastern Africa.

Seed rain after a fire in a xerophytic shrubland

Fire causes a reduction of plant cover due to the death of several structures, especially of those that are not isolated from high temperatures; such as seeds and fruits. After a disturbance the availability of diaspores is crucial for the recovery of the community. This work studied the composition and abundance of the seed rain in the xerophytic shrubland of the Pedregal de San Angel Ecological Reserve, located at the Universidad Nacional Autonoma de Mexico campus in Mexico City, which was affected by a surface fire. In order to understand the role of diaspores in the natural regeneration of a burned site, seed traps were placed on 2 sites, one affected by the fire and the other in an unburned location. During 1 year the dispersed seeds and fruits were collected and identified. Results showed that species richness, life forms, and dispersal syndromes were different between sites. The highest abundance and richness values were observed in the burned site. This work offers basic data on the availability of species as diaspores, information which is useful for potential restoration strategies especially in those areas under constant anthropogenic disturbances.

Simulating Biome Distribution on the Tibetan Plateau Using a Modified Global Vegetation Model

We used a regionally modified global vegetation model (BIOME4-Tibet) to simulate biome distribution on the Tibetan Plateau under current climate conditions derived from regional meteorological observations. The bioclimatic limits (mean temperatures of the coldest and warmest months, minimum temperature, growing degree-days on 5 °C and 0 °C bases) for some key alpine plant functional types (temperate deciduous and conifer trees, boreal deciduous and conifer trees, desert woody plants, tundra shrubs, cold herbaceous plants, and lichens/forbs) were redefined based on regional vegetation-climate relationships. Modern vegetation maps confirmed that the BIOME4-Tibet model does a better job of simulating biome patterns on the plateau (gridcell agreement 52%) than the original BIOME4 model (35%). This improved model enhanced our ability to simulate temperate conifer forest, cool conifer and mixed forest, evergreen taiga, temperate xerophytic shrubland, temperate grassland and desert, and steppe and shrub tundra biomes, but made a negligible or reduced difference to the prediction of temperate deciduous forest, warm-temperate mixed forest, and three tundra biomes (erect dwarf-shrub tundra, prostrate dwarf-shrub tundra, and cushion forb, lichen, and moss tundra). Future modification of the vegetation model, by increasing the number of shrub and herb plant functional types, re-parameterization of more precise bioclimatic constraints, and improved representation of soil, permafrost, and snow processes, will be needed to better characterize the distribution of alpine vegetation on the Tibetan Plateau.

Banco de semillas después de un incendio en un matorral xerófilo

A través de la emergencia de plántulas estudiamos los efectos del fuego en el banco de semillas del suelo de un matorral xerófilo en dos años consecutivos. Comparamos su composición y abundancia en dos sitios, uno quemado y uno no quemado. Una proporción importante de semillas murió debido a las altas temperaturas alcanzadas por el fuego. La riqueza y diversidad de especies fueron negativamente afectadas. Estas variables mostraron diferencias significativas entre sitios y años. Después de un año, la abundancia y diversidad del banco de semillas alcanzaron mayores valores. En términos de riqueza dominaron las hierbas perennes y en términos de abundancia, dominó una especie arbórea. El fuego no fue un factor determinante en la composición de especies. Estos resultados son importantes para explicar los cambios en la vegetación después del fuego, especialmente si consideramos que este sitio es una reserva natural inmersa en un área urbana.

Palaeovegetation in China during the late Quaternary: Biome reconstructions based on a global scheme of plant functional types

Two previous reconstructions of palaeovegetation across the whole of China were performed using a simple classification of plant functional types (PFTs). Now a more explicit, global PFT classification scheme has been developed, and a substantial number of additional pollen records have become available. Here we apply the global scheme of PFTs to a comprehensive set of pollen records available from China to test the applicability of the global scheme of PFTs in China, and to obtain a well-founded reconstruction of changing palaeovegetation patterns. A total of 806 pollen surface samples, 188 mid-Holocene (MH, 6000 14C yr BP) and 50 last glacial maximum (LGM, 18,000 14C yr BP) pollen records were used to reconstruct vegetation patterns in China, based on a new global classification system of PFTs and a standard numerical technique for biome assignment (biomization). The biome reconstruction based on pollen surface samples showed convincing agreement with present potential natural vegetation. Coherent patterns of change in biome distribution between MH, LGM and present are observed. In the MH, cold and cool-temperate evergreen needleleaf forests and mixed forests, temperate deciduous broadleaf forest, and warm-temperate evergreen broadleaf and mixed forest in eastern China were shifted northward by 200–500 km. Cold-deciduous forest in northeastern China was replaced by cold evergreen needleleaf forest while in central northern China, cold-deciduous forest was present at some sites now occupied by temperate grassland and desert. The forest–grassland boundary was 200–300 km west of its present position. Temperate xerophytic shrubland, temperate grassland and desert covered a large area on the Tibetan Plateau, but the area of tundra was reduced. Treeline was 300–500 m higher than present in Tibet. These changes imply generally warmer winters, longer growing seasons and more precipitation during the MH. Westward shifts of the forest–shrubland–grassland and grassland–desert boundaries imply greater moisture availability in the MH, consistent with a stronger summer monsoon. During the LGM, in contrast, cold-deciduous forest, cool-temperate evergreen needleleaf forest, cool mixed forests, warm-temperate evergreen broadleaf and mixed forest in eastern China were displaced to the south by 300–1000 km, while temperate deciduous broadleaf forest, pure warm-temperate evergreen forest, tropical semi-evergreen and evergreen broadleaf forests were restricted or absent from the mainland of southern China, implying colder winters than present. Strong shifts of temperate xerophytic shrubland, temperate grassland and desert to the south and east in northern and western China and on the Tibetan Plateau imply drier conditions than present.

La heterogeneidad ambiental en un matorral xerófilo

Se caracterizó la heterogeneidad biótica y abiótica tanto espacial como temporal en dos zonas del matorral xerófilo de la Reserva Ecológica del Pedregal de San Ángel(REPSA). Se identificaron nueve grupos florísticos, los cuales presentaron una distribución diferencial de las especies vegetales presentes en la zona. Cada uno de los grupos fue nombrado respecto a las especies indicadoras, las cuáles fueron consideradas como determinantes de la fisonomía de la comunidad. Utilizando los análisis multivariados(TWINSPAN y CANOCO) se observó que la composición de especies de los grupos se modifica espacial y temporalmente. Este estudio sugiere que la variación de algunos factores abióticos como la profundidad del suelo y la pendiente influye de diferente manera en la heterogeneidad del sistema. La heterogeneidad temporal fue evidente al existir una diferente composición florística en la zona a lo largo de la temporada de lluvias y la temporada de secas.

Propagule banks: Potential contribution to restoration of an impounded and dewatered riparian ecosystem

The Agua Fria River in Arizona’s Sonoran Desert was impounded and diverted more than 70 years ago. Immediately below New Waddell dam there are semi-permanent pools, but water has been released into the channel only during rare wet years. To determine whether a propagule bank exists below the dam, and whether it could contribute to the revegetation of the Agua Fria riparian ecosystem should flow be restored to the dewatered reach, we collected 45 soil cores from four plant associations. We examined species in the samples in a growth chamber using the seedling emergence method. A total of 74 species (mostly herbaceous) and an abundance of individuals were present in propagule banks. The propagule banks were similar to those of a free-flowing reference river despite considerable differences in extant vegetation. Riparian species were present in propagule banks of all four associations and were the dominant type in three (Tamarix forests, Tamarix-Salix forests, and Baccharis-Bebbia shrublands). Propagule distribution varied with soil depth in three of the associations (Tamarix forests and the two xerophytic shrublands) with riparian species more prevalent in deep sediment and upland species more prevalent in surface soil and litter. Collectively these patterns suggest that a riparian legacy is present in Agua Fria propagule banks. However, riparian propagule density was low in the Hymenoclea-Bebbia shrublands, reflecting xerification of the riparian corridor. Given the physical barrier of the dam, continued diversion of stream flow, and rare flood releases, local inputs from xerophytes will dominate propagule bank dynamics in the future. Although propagule banks could contribute to redevelopment of the herbaceous component of the vegetation should stream flows be restored to this river reach, the riparian legacy likely will decline over time as riparian propagules reach the end of their lifespan while propagules of xerophytes continue to be replenished.

Interacciones Planta‐Nodriza en Lophophora diffusa (Cactaceae) en un Desierto Subtropical de México1

ABSTRACTOne of the two species from the genus Lophophora is the false peyote Lophophora diffusa, an endemic cactus species of the xerophytic shrubland at Querétaro, México, considered threatened from illegal extraction due to its hallucinogenic and medicinal properties. We analyzed the spatial distribution of L. diffusa and its association with the locally dominant shrub species with the system SADIE (Spatial Analysis by Distance IndicEs). We also studied the principal microclimatic factors (light, temperature, and humidity) beneath the canopy of the possible nurse plant species. The use of SADIE is a new approach to study the mechanisms of spatial distribution. Lophophora diffusa and the shrub species presented an aggregated distribution with patches and gaps, as indicated by the values of Ia= 4.179 for L. diffusa and Ia= 1.660 for the vegetation. Lophophora diffusa was positively associated with the arboreal vegetation, particularly with Larrea tridentata and Acacia sororia, but was negatively associated with Celtis pallida and Myrtillocactus geometrizans. Microclimate evaluation indicated that C. pallida canopy significantly reduced radiation and temperature compared to the other species (L. tridentata, A.sororia y P. laevigata). We had expected L. diffusa to exhibit a positive spatial association with C. pallida; however, the reduction in light availability apparently limited seedling establishment of L. diffusa.

Global middle Pliocene biome reconstruction: A data/model synthesis

The middle Pliocene warm interval (ca. 3 Ma BP) has been extensively studied. However, our knowledge concerning the global distribution of middle Pliocene biomes remains far from complete. This paper presents the results from a “first attempt” at simulating the distribution of different mid‐Pliocene biomes using an advanced numerical general circulation climate model (Hadley Centre Atmospheric Model Version 3) and the BIOME 4 vegetation model. The modeling indicates that during the middle Pliocene the geographical coverage of tundra type biomes may have been significantly reduced compared with the present day in the Northern Hemisphere. High‐latitude forests expand in the place of tundra forms of vegetation. Total area covered by forest increases for the Pliocene case compared with the present day. Arid deserts become less prevalent in the Pliocene scenario and are replaced by tropical xerophytic shrublands and savanna‐type vegetation. These results compare favorably with geological data in general and with the U.S. Geological Survey's PRISM2 middle Pliocene vegetation reconstruction, although data/model inconsistencies are apparent. Although some of these inconsistencies relate to the weaknesses of the climate and biome model employed, others identify deficiencies in the extant geological data set or the interpretation of this data. This modeled biome reconstruction will serve as a useful vehicle for aiding in future comparisons between geological data on middle Pliocene biomes and model predictions.

Fragmentation and genetic differentiation among subpopulations of the endangered Hawaiian mintHaplostachys haplostachya(Lamiaceae)

Haplostachys haplostachyawas at one time a prevalent species in the mid‐elevation (1650–1800 m) xerophytic shrubland between Mauna Loa and Mauna Kea on Hawaii. Grazing pressure by feral ungulates, destruction of habitat from military activity, and conversion of forest to pastures have fragmented its range to small subpopulations restricted to several cinder cones and portions of the remaining shrubland. Some subpopulations are still extensive, while others are reduced to 20 or fewer individuals. Genetic analyses using random amplified polymorphic DNA (RAPD) markers demonstrate that plants in subpopulations with a large number of individuals maintain levels of genetic variation similar to the entire population, whereas plants in a small subpopulation at Pu‘u Leilani (14 individuals remaining) have reduced levels of variation. Of the 122 loci identified, 54 (44%) were polymorphic. Two large populations showed variation at 45 and 49 loci, but the Pu‘u Leilani plants showed variation at only 37 loci. The mean expected heterozygosity (H) in this subpopulation was also lower (0.137 vs. 0.163 and 0.154) and genetic differentiation (GST) was higher (0.167 vs. 0.018 and 0.052) than in other subpopulations. An examination of variation indicates that although plants of the three subpopulations are genetically similar, there is evidence of genetic restructuring among the subpopulations. The impact of these results towards conservation efforts of this and other endangered species is discussed.

Territoriality and determinants of group size in the Karoo Korhaan Eupodotis vigorisii ( Otididae)

Karoo Korhaans Eupodotis vigorsii are endemic to the dwarf xerophytic shrublands of southern Africa. They normally occur in territorial pairs, but up to five individuals may defend a group territory. Group size increases, and proportionally larger territories are defended, in low rainfall areas. Groups of three and four birds invariably contain the breeding pair plus one or two sub-adult males. These patterns are interpreted in terms of advantages to the parents in receiving assistance with territory defence, in which males play the lead role. Advantages accrue to male offspring, which have deferred maturity, through gaining experience in territory defence and obtaining the benefits of a territorial existence before reaching sexual maturity. The fate of early dispersing females is unknown.