Folia Geobotanica最新文献

Hemiparasitic plants can reduce photosynthesis and alter the host plant’s foliar traits. This relationship may be more intense in ecosystems with nutritionally poor soil, such as the campo rupestre, known for its high endemism. This work evaluated the impact of a generalist hemiparasitic species (Struthanthus flexicaulis) on the physiology as well as physical and chemical traits of a native species (Baccharis dracunculifolia) frequently found in the campo rupestre. We planted twenty 60-day-old B. dracunculifolia individuals in a campo rupestre area. Two year after planting, during the 2019 dry season, we evaluated the water potential (Ψw), photosynthetic efficiency (PE), specific leaf area (SLA) and succulence (SU) of parasitized and non-parasitized host plants. These parameters were measured again in the dry season of 2020, when we also measured chlorophyll, nitrogen balance index (NBI) and phenolic content of leaves of the same individuals. Parasitized individuals had a higher Ψw and PE compared to non-parasitized individuals during the most critical period of the day (12:00 pm to 3:00 pm). However, towards the end of the day, parasitized individuals had lower Ψw and PE than non-parasitized ones. There was no effect of parasitism on SLA and SU. Parasitized plants had higher NBI and lower phenolic content than non-parasitized plants. We concluded that S. flexicaulis parasitism interfered in the physiology and chemical leaf traits of B. dracunculifolia. Parasitism, while momentarily increasing the PE and Ψw of parasitized individuals, can cause physiological imbalances, which could negatively affect the development and lead to the death of the host plant over time.

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 (old-growth 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 × 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. Human-modified 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.

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 × 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.

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.