查看更多>>摘要：Savanna occurs in specific locations throughout the Indonesian archipelago, including some high rainfall regions. Little is known about its defining characteristics, such as structure, composition or diversity, and what these characteristics reveal about the origin and age of these savannas. At four locations in eastern Java (Baluran National Park & Alas Purwo National Park), Bali (Bali Barat National Park) and Lombok (Rinjani National Park), we used plots to record the abundance and cover of plant species and to measure local environmental parameters. MODIS burned-area product and field observations were used to obtain information on recent fires. We compared each savanna in terms of dominant species, species diversity and species richness. We also used ANOSIM to analyse the variation in community composition and canonical correspondence analysis to explore relationships between floristic and measured environmental factors. Our results showed there were distinct gradients in elevation (along with related climatic factors such as temperature and precipitation) and fire regime linked to floristic composition across the savannas of Java, Bali and Lombok Islands. Each savanna was characterized by a different set of woody and grass species, with invasive alien species, such as Acacia nilotica (syn. Vachellia nilotica), Lantana camara and Chromolaena odorata, being particularly important in differentiating between savannas. Characteristics of the Baluran savanna suggest that this ecosystem may be of considerable age, whereas the other savannas are likely to be maintained by regular fire. This study is the first study to describe more thoroughly the savanna plant community in the wetter parts of Indonesian archipelago and should serve as a valuable foundation for further studies on the Indonesian savannas and those of other parts of Southeast Asia.
查看更多>>摘要：Biological soil crusts (BSC) play a crucial role in arid ecosystem functioning, yet the effect of their properties (e.g. whether they are dominated by mosses and lichens) on the germination has rarely been investigated. Here, we analysed the effects of intact, dead and removed moss or lichen BSC on seed germination of Stipa caucasica, a key species in the Iranian Artemisia steppes. Our results revealed that both dead and intact moss BSC significantly and strongly reduced and delayed germination putatively due to the physical properties of the crust limiting water supply to the large seeds of the focal species. Further, we found out that intact lichen BSC had no significant effect on the germination traits studied whereas lichen BSC removal and heat treatment ('dead' BSC) reduced germination percentage. The reduction is most likely due to the allelopathy effects and surface properties of the lichen crust. The detected patterns suggest that moss and lichen BSC play different roles in S. caucasica seed regeneration in the steppe; however, the effect on the species population dynamics deserve further study including also later stages of seedling establishment.
Aguayo-Villalba, Antonio AngelAlvarez-Gomez, Concepcion MariaAisa-Ahmed, MimuntBarroso-Rodriguez, Laura Maria...
11页
查看更多>>摘要：Fire is a natural phenomenon that is very frequent in ecosystems of the Mediterranean basin. Cistus ladanifer and C. salvifolius (Cistaceae family) are evergreen shrubs and components of plant communities found in this region. The objective of this study was to evaluate the effect of fire on the germination of C. ladanifer and C. salvifolius seeds. For this purpose, seeds of both species were subjected to different heat-shock treatments simulating natural fire conditions (50-175 degrees C for 1 and 5 min). To elucidate the ecological significance of the effects of fire, viability and different traits informative about the dynamics of the germination process, such as final germination percentage (FGP), first day of germination (FDG), last day of germination (LDG), time spread of germination (TSG) and coefficient of velocity of germination (CVG), were determined. Seeds of both species exhibited fire-related behaviour, as they showed seed heat resistance and heat-stimulated germination. Germination in control, untreated seeds was very low, with 10 and 0% FGP for C. ladanifer and C. salvifolius, respectively. Thermal treatments significantly increased germination in both cases, with optimal results achieved at 100-125 degrees C for 1 min and 75-100 degrees C for 5 min. Under these conditions, greater germination percentages were obtained in C. salvifolius (92-95%) than in C. ladanifer (64-68%). Temperature proved to have a greater influence on seed viability and germination than the accumulated heat dose. The pattern of seed germination varied depending on the species and the heat shock treatments. In general, C. ladanifer exhibited earlier and faster germination. These characteristics, along with the high number of seeds produced per plant, make C. ladanifer a more competitive species for colonizing empty spaces after fire.
Pereira, Crisliane J.Silva, Jhonathan OliveiraRodrigues, Priscyla M. S.Cavalcanti, Airton C....
13页
查看更多>>摘要：Palm trees provide several non-timber forest products in the tropics and are commonly found in human-modified habitats. Land use and cover changes have impacted habitat climatic conditions, biodiversity, and the recruitment and survival of palm species. The objective of this study was to evaluate the seed fate and demographic structure of Syagrus coronata (Mart.) Becc. (Arecaceae) in natural (oldgrowth vegetation) and managed habitats (pastures for cattle ranching). This palm is widely found in Brazilian semi-arid regions, and there is no information on the impacts caused by fruit harvest, management practices and land use on the persistence of this species' population. We evaluated seed fate for two years, in which 400 ripe post-dispersal fruits were buried and evaluated after 10, 20, 40, 80, 160 and 240 days. We also established 20 plots (20 x 20 m), 30 m apart, in each habitat to obtain data on population demography. In general, greater seed mortality was found in the managed habitat, mostly as a result of desiccation. We found 2,090 S. coronata individuals in the natural habitat with seedling dominance, while only 45 individuals were found in the managed habitat with reproductive adult dominance. Humanmodified habitats, like pastures, negatively affected seed survival and, consequently, plant recruitment. The future of this species is alarming given their current fruit harvesting levels, land cover change, and that climate changes predict desertification in the semi-arid region, making it even more difficult seed germination. The social and economic importance of this species reinforces the need for increasing biodiversity-friendly farming practices.
查看更多>>摘要：How plant communities in Anatolian steppes recover after disturbances has remained unknown. To study the effects of small-scale disturbances on plant communities of the central Anatolian steppe, we established thirty-two plots 1 x 1 m in size in a natural steppe near Ankara (Turkey). The plots were subjected to mowing or hoeing treatments representing low- and high-intensity disturbance, respectively. Some plots were left untreated to serve as the control. The plots were sampled for three consecutive years to investigate changes in species occurrence, cover and biomass under various disturbance frequencies and intensities over time. The vegetation was able to recover within a few months, particularly in the growing season after mowing treatments, but the recovery level of the vegetation was lower after hoeing, especially when it was applied with high frequency. Species richness and cover of annual herbs increased with moderate disturbance frequencies in both disturbance types whereas perennial herbs were negatively affected by the hoeing disturbance, but not by the mowing disturbance. Both types of disturbance had a significant negative effect on plant aboveground biomass in the plots. The results partly support the intermediate disturbance hypothesis. High-level resilience to small-scale disturbances was observed, possibly due to adaptations of Anatolian steppe plants to natural and anthropogenic disturbances.
查看更多>>摘要：This study examines an assumed hybrid between Gymnocalycium capillense and G. intertextum discovered in a mixed population of the putative parents at Villa Viso in Cordoba Province, Argentina. Eleven quantitative morphological characters (including two ratios) were measured in the natural populations of the presumed parental species and the assumed hybrid. Five of these characters differed between the parental species whereas the assumed hybrid usually showed intermediate values. Eleven qualitative morphological characters were compared for all three taxa, whereby two characters of the assumed hybrid were closer to G. intertextum, one character was closer to G. capillense, six characters were intermediate (but two of them closer to one presumed parent), and three characters were unique. The seed morphology is the most important character separating the subgenera of Gymnocalycium: the assumed hybrid is most similar in this regard to the nominate subgenus, but the seeds are larger than in both assumed parents and have a very broad hilum-micropylar region and conspicuous strophiole at the margin, like in the subgenus Trichomosemineum. Genome sizes estimated by means of flow cytometry shows that G. capillense is tetraploid and G. intertextum diploid, while the assumed hybrid plants are hexaploid (i.e. allopolyploid hybrids). Sequencing and phylogenetic analysis of a low-copy nuclear PHYC gene also revealed that this genomic region of the hybrid combines sequences present in G. capillense and G. intertextum. In combination with the morphological data, these results support the hybrid nature and parentage of the studied plants. The hybrid is formally described here as G. xapplanatum and is the first documented hybrid between the subgenera Gymnocalycium and Trichomosemineum. The results show the potential of allopolyploidy in which different subgenera participate for the evolution of the genus.
NSTL
Springer Nature