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Restoration practices are still scarce for the dry tropics. In this study, we tested if the removal of climbing plants and soil plowing (assisted natural regeneration) enhanced tree biomass accumulation within tropical dry forest old fields (defined as cattle pastures abandoned for ca.10 years) on the Pacific Coast of Mexico. In each of three old fields, six 25-m2 blocks were randomly positioned. The soil from three blocks was plowed and climbing plants removed from the tree stems and canopy; another three blocks were used as experimental controls. Climber removal was done at the beginning of the experiment and 7, 17, 25, 30 and 37 months later. The soil was plowed twice, once at the beginning of the experiment and again 7 months later. Before and after assisted natural regeneration, all woody stems (i.e. tree species dbh > 1cm) and their canopy cover were recorded to calculate the rate of increase in standing biomass and stem growth and survival. The results showed a strong site effect on the response of trees to assisted natural regeneration. Nevertheless, all sites showed a significantly positive effect of assisted natural regeneration on overall biomass gain despite differences in vegetation structure and tree species composition. Removal of climbing plants and soil plowing concurrently appeared as a useful technique for tropical dry forest recovery. Further studies, however, are needed to evaluate if the initial trends of recovery are maintained over the long term. [ABSTRACT FROM AUTHOR]

Jacquemontia species are often found in disturbed areas, and their flowers are ephemeral and very attractive to insects. We investigated the interaction between the flowers of Jacquemontia evolvuloides and its visitors, with emphasis on potential pollinators, considering morphological, temporal, and behavioral aspects, between September/2009 and August/2010 in an anthropized area in Bahia State, Northeastern Brazil. Jacquemontia evolvuloides flowers are diurnal, ephemeral (approximately five to six hours duration), are present throughout the year, and offer nectar and pollen rewards. Because of the floral morphology of J. evolvuloides insect visitors have easy access to its resources, and its pollination could be considered generalized. While J. evolvuloides flowers are visited by several insects, only small bees (Augochlora spp.) and syrphids (Toxomerus spp.) appear to play a role in pollination of flowers. Although bees have been considered efficient pollinators of that plant, the significant presence of syrphids (considered occasional pollinators but showing high frequency visitation), may indicate their role as potential pollinators, especially when bees are not abundant in the fall/winter. As such, even in pollination systems that are considered generalized (with flowers allowing easy access to various visitor groups), visitor size may be an important factor for efficient pollination, especially when associated with high visitation frequencies.

This study examined three herbaceous plant species, namely Calamagrostis epigejos , Chamaenerion palustre and Tussilago farfara spontaneously colonizing spoil heaps after hard (bituminous) coal mining for their effects on selected physico-chemical and microbial parameters of the spoil material. The parameters were measured for plots of C. epigejos , C. palustre , T. farfara and controls (bare ground) established on heaps belonging to two age categories: 5–10 and 15–20 years from the end of spoil heaping. The spoil material was characterized by varying pH values (from 4.0 to 9.1), high content of total C (10.3 ± 3.8%), deficiency of other nutrients (1.04 ± 0.76 mg N–NO 3 kg −1 , 2.16 ± 1.07 mg Olsen P kg −1 , 572 ± 163 mg exchangeable Ca kg −1 ) and low respiration rate (0.64 ± 0.34 μM CO 2 g dwt −1 24 h −1 ). The spoils under the plants had less N–NO 3 and more exchangeable Ca and K, available (Olsen) P and total C than the spoils from non-vegetated plots. The effect for the latter three variables was species-dependent. Electrical conductivity and N–NO 3 concentrations were lower in the spoils from the older heaps than those from the younger ones, while the opposite effect was found for N–NH 4 and Ca concentrations. The spoils from the vegetated plots supported more active and richer microbial communities than the bare spoils. This effect was strong, especially for the older heaps. Microbial respiration was the highest under C. palustre ; it averaged 0.92 ± 0.31 μM CO 2 g dwt −1 24 h −1 , i.e., 2.6 times more than in the bare spoils. Microbial communities studied with Biolog plates were more active and utilized a higher number of carbon substrates under the plants than in the bare spoils. T. farfara differed considerably from the two other species in the structure of microbial communities (the metabolic fingerprint) it supported. Overall, the results show that the three plant species significantly affected nutrient availability and enhanced microbial performance in the coal mine spoil material. Since these plants effectively colonize industrial waste sites, they can be recommended for use in reclamation programs. [ABSTRACT FROM AUTHOR]

Melilotus albus Medik. is a cosmopolite and invasive species, native to the Old World, which in Brazil had its occurrence hitherto recorded only in the states of São Paulo, Paraná and Rio Grande do Sul. This study extends its distribution to Santa Catarina state, southern Brazil, due to the recent discovery of populations in the municipalities of Florianópolis and Xanxerê. These new records are ca. 250 km distant from the nearest records, in Paraná state, also in southern Brazil. [ABSTRACT FROM AUTHOR]

In this study, we determined the heavy metal content (Cd2+, Cr3+, Cu2+, Fe3+, Ni2+, Pb2+, and Zn2+) in the soil surrounding the roots and different organs of Verbascum bombyciferum Boiss. (Scrophulariaceae), which is endemic to Uludağ Mountain, Bursa, Turkey. Plant samples were collected from roadsides, and heavy metal accumulation capabilities were tested. This is one of the pioneer species of ruderal plant communities on roadsides, building sites, rubbish dumps, etc. Different organs of plant samples (roots, stems, leaves, and flowers) and their soils were analyzed by inductively couple plasma optical emission spectroscopy for their heavy metal contents. Some of the analyzed heavy metals (Cd2+, Cr3+, Pb2+, and Zn2+) were usually increased depending on the traffic in the sample sites, and this variation was also reflected in heavy metal content of plant samples. Our results show that this plant can be used as a bio-indicator species in the monitoring of increased Cd2+, Cr3+, Pb2+, and Zn2+ in the environment. We also concluded that V. bombyciferum have the capability of Cd2+, Cr3+, Cu2+, Ni2+, Pb2+, and Zn2+ accumulation. [ABSTRACT FROM AUTHOR]

The aim of this work was to analyse the phenological variation of a residual invasive semi-evergreen shrub in Sahelian fallows in Niger. This species, Guiera senegalensis (Combretaceae), has benefited from the elimination of other species thanks to its high resistance to the increasing cutting pressure for cultivation. We sought to identify traits of its life cycle that could contribute to its persistence and widespread dominance under such a disturbance regime. Leafing, flowering and fruiting were monitored on seven fallows differing in topographic location, age, shrub density and degradation state, during two rainy seasons and one dry season. Phenological spectra showed similar timing of the three phenophases of the seven populations. Differences were observed mainly in magnitude of the phases. However, there were both a high intra-fallow variability (64.6% of the whole variability) and a statistically significant inter-fallow variability, despite only 35.4% of the total variability being due to differences between fallows. A statistical classification of the fallows was proposed based on shrub phenological course over the two cycles monitored. This classification corresponds to a gradient of life-cycle achievement primarily linked to the topographic situation of the stations, and then to a combination of other factors. The flexibility of the phenology at the individual, population and metapopulation scales, inherent to its specific semi-evergreenness property, appeared as an essential phenological attribute contributing to successful widespread persistence of G. senegalensis in the study area. [ABSTRACT FROM PUBLISHER]