Folia Geobotanica最新文献

To effectively restore species and habitat diversity in poorly managed degraded grasslands, it is important to understand the relationship between the soil seed bank and aboveground vegetation. Our study aimed to describe changes in soil seed bank composition compared to aboveground vegetation under two ploughing regimes (annual and single ploughing) of narrow strips on the edges of artificially grassed old fields in Podyjí National Park, the Czech Republic. We used the seed germination method, multivariate analyses and Kruskal–Wallis tests to compare differences in the proportion of species and individual numbers in the soil seed bank based on the origin of species (native species, archaeophytes, neophytes) and their habitat preferences (segetal, ruderal, grassland, endangered species) in two types of grasslands with varying soil moisture content. The highest numbers of individuals were present in annually ploughed dry grasslands whereas single ploughing in mesic grasslands resulted in greater species diversity. Ploughing increased the numbers of seedlings of all groups and promoted archaeophytes, grassland specialists, native species and ruderals in dry grasslands whereas mesic grasslands hosted segetal specialists and neophytes. Threatened plants and invasive species rarely emerged from the soil seed bank. The study also revealed the highest similarity between the soil seed bank and aboveground vegetation in annually ploughed plots. It gradually decreased during vegetation succession in the single ploughed variants. Whereas annual ploughing supported segetal specialists, single ploughing promoted grassland species in dry habitats. Neither type of ploughing can be recommended in mesic grasslands because of the risk of inducing the spread of expansive ruderals or invasive neophytes.

Previous studies have demonstrated that the tree community of small and isolated forest fragments show persisting structural and functional attributes characteristic of early-successional systems. Yet, the impacts of forest small size and isolation on several tree community attributes have not been comprehensively quantified in long-term studies. Here we analysed permanent plots over 17 years to investigate the recovery of community attributes in a small tropical forest remnant surrounded by human-modified landscapes in the endangered Brazilian Atlantic Forest. We conducted analyses on community species richness, functional diversity and composition, and aboveground biomass for the overall, adult and juvenile communities. The analysis of the demographic rates indicates a self-thinning phase (reduction in stem density and increase in basal area) characteristic of late-succession stages. In general, we found a reduction in the proportion of simple leaves along with a gradual increase in wood density mostly for the adult tree community and a significant increase in aboveground biomass throughout the years. Despite its reduced size, the fragment studied does not show clear trends of altered forest structure and functional composition dynamics through time. Yet, it holds aboveground biomass values comparable to large undisturbed rainforests, thus indicating that the ecological value of small forest fragments should not be neglected.

The Cerrado is a Neotropical savanna with the highest plant species richness among tropical savannas. Most of these species are herbs and subshrubs, although woody species have been studied much more extensively. We built a database of species constituting the herbaceous–subshrub flora of the Cerrado to provide an in-depth view of its conservation status and reduce knowledge gaps. Our objectives were to (1) gather information on the herbaceous–subshrub flora of the Cerrado, (2) determine the importance of the most common families, genera and species making up this flora, (3) map areas with great species richness in the Cerrado, and (4) assess the status of protected areas in relation to this flora and the conservation status of its species. We have created the ‘CerrHerb’ database with information about herbaceous–subshrub species. We identified 6,492 species distributed across 769 genera belonging to 97 families. We compiled 65,535 occurrences of 4,354 species and mapped two main hotspot clusters of species richness: the Central Cerrado and the Espinhaço Range, with a third, less pronounced hotspot cluster further west in the Eastern Mato Grosso. The richest families were the Asteraceae (742 species), Poaceae (681 species) and Fabaceae (584 species). Of the species, 2,398 (55%) occur in protected areas, while 1,956 species (45%) do not. Additionally, 2,235 species are endemic, with no information available on their conservation status. There is a significant knowledge gap regarding the herbaceous–subshrub flora, which can lead to conservation and ecological problems caused by poor management of Cerrado reserves. There is a need to reassess conservation policies for the Cerrado and adapt the management of conservation units to reflect the actual importance of the herbaceous–subshrub flora.

Information on the extent of the geographic distribution and on the factors affecting the species geographic range is a valuable tool to identify conservation priorities and to protect biodiversity. We focused on Cremnophila nutans (Crassulaceae), a habitat specialist, micro-endemic and ornamental species distributed only in northern areas of the state of Morelos (municipality of Tepoztlan) in central Mexico. Following the criterions established by the International Union for Conservation of Nature, we estimated the range extent (34.9 km²) and area of occupancy (36 km²) of C. nutans. Based on our estimations C. nutans can be considered as a critically endangered species. From an extensive area of accessibility determined by combinations of climate and physiographic layers, the ecological niche modeling (22 occurrence records and three bioclimatic variables) predicted a restricted and stretch band of high habitat suitability coinciding majorly with northern areas of the state of Morelos. Habitat suitability was explained by annual mean temperature (72.5 %) and annual precipitation (25.3%). Potential areas with climatically suitable habitats could be in fact smaller because rocky outcrops usually colonized by C. nutans are not present along the entire potential area. Besides its restricted geographic distribution, C. nutans face threats derived from frequent forest fires, climate change, and extraction from its natural habitat. Management strategies strongly based on ex situ propagation and social working with local people are proposed to assure persistence of this unique rare plant species.

Forest ground vegetation may serve as an early warning system for monitoring anthropogenic global-change impacts on temperate forests. Climate warming may induce a decline of cool-adapted species to the benefit of more thermophilous plants. Nitrogen deposition has been documented to potentially result in soil eutrophication or acidification, which can increase the proportion of species with higher nutrient requirements and species impoverishment caused by competitive exclusion. Abiotic forest disturbances are changing the light conditions in the forest understorey environment. In this resurvey study, we tested the magnitude and direction of change in alpha (species richness) and beta (within-site dissimilarity) diversity and composition of forest ground vegetation in forests of different types in Slovenia over fifteen years. Using plant-derived characteristics (Ellenberg-type indicator values) and by testing a priori predictions concerning expected effects of environmental drivers, we show that the magnitude and direction of forest ground vegetation diversity and floristic changes varies greatly between forest sites. Divergent responses at different sites resulted in low net change of alpha and beta diversity and a weak overall environmental signal. The largest decrease in species number was observed in lowland oak-hornbeam forests, which were also among the sites with the greatest compositional shifts. Changes in beta diversity did not show any consistent trend, and anticipated floristic convergence was not confirmed when all sites were considered. Thermophilization was mainly detected in montane beech sites and alpine spruce forests whereas eutrophication signal was most significant on nutrient-poor sites. Vegetation responses were strongly dependent on initial site conditions. Shrinkage of ecological gradients (process of ecological homogenization) suggests that sites positioned at the ends of the gradients are losing their original ecological character and are becoming more similar to mid-gradient sites that generally exhibit smaller changes. Our results point to the importance of local stand dynamics and overstorey disturbances in explaining the temporal trends in forest ground vegetation. Ground vegetation in Slovenian forests is changing in directions also dictated by multiple regional and global change drivers.

The increasing intrusion of weed species into alpine regions is an alarming threat to native floras because their strong and deep root systems cause a scarcity of nutrients to native alpine plant species. Considering the sensitive nature of alpine ecosystems, integrated weed management may be a means of preventing invasive species from going out of control. The present study investigated the allelopathic effect of Elsholtzia strobilifera on the germination and growth characteristics of Himalayan knotweed (Koenigia polystachya, syn. Polygonum polystachyum) under both field and laboratory conditions. The germination of seeds under laboratory conditions was studied by using different dilutions of hydrosol and aqueous extracts derived from E. strobilifera. In our field study, seedlings of K. polystachya were planted together with E. strobilifera in their natural habitat at a nursery. The study indicates that the seed germination and morphological parameters of seedlings were significantly inhibited by different dilutions of hydrosol and extract (reduction by 83–96% and 62–73%, respectively). In field conditions, significant inhibition in the morphological characteristics of K. polystachya was observed when grown in association with E. strobilifera. The results reveal that E. strobilifera has a significant allelopathic effect on K. polystachya. Based on the results of the present study, it can be concluded that growing plants of E. strobilifera around K. polystachya may be a novel approach to curbing the spread of the latter and suppressing the population of this species in ecologically sensitive alpine or other endangered areas.

Abstract

Recent investigations have revealed the coordination and trade-offs between above- and belowground traits in structuring functional strategies of plant communities, but none of these have addressed ferns, a diverse plant lineage in tropical forests. We investigated terrestrial ferns from the perspective of how below- and aboveground traits are coordinated with functional responses to forest edges, which represent a significant part of the world’s forest cover. Specifically, we examined differences in functional strategies between forest edges and forest interior as well as traits associated with species dominance. Fern richness and abundance were sampled in 24 edge plots and 44 interior plots within the Brazilian Atlantic Forest. We obtained data for five leaf traits and three rhizome traits. Ferns did not express any functional coordination between above- and belowground traits. At the edge, ferns did not display functional homogenization. In both the interior and at the edge, ferns exhibited multiple trait covariations across a broad spectrum of plant sizes and leaf numbers, associated with rhizome type and the presence of leaf trichomes and stolons. There were no cohesive functional groups of generalists or of exclusive species of forest edges and the forest interior. Fern species dominance was related to the species-specific number of leaves and the presence of stolons. We conclude that below- and aboveground traits did neither respond in conjunction nor as a functional response to edge effects. However, both kinds of traits affected the functional structure and species dominance of fern communities at the edge and in the interior of the forest.

Abstract

Effective protection of endangered species is often limited by taxonomic discrepancies across state borders. This is also the case of the Dactylorhiza maculata agg. in Central Europe, where one to three species and several infraspecific taxa are recognized in various countries. Based on an extensive analysis of morphological variation, ploidy levels, environmental traits and habitats of 64 populations in Central Europe and adjacent regions, we aimed to propose a unified taxonomic concept applicable throughout the study area. Multivariate analysis of morphological traits revealed continuous variation at the individual level and only minor differences between particular clusters of populations. Four DNA-ploidy levels were detected using flow cytometry. Diploids (2n = 40) and tetraploids (2n = 80) were the most abundant and usually formed single-cytotype populations whereas DNA-triploids and DNA-hexaploids occurred only sporadically as minority cytotypes. The inferred patterns of morphological and ploidy variation were not congruent with traditional taxonomic treatment regarding diploid D. fuchsii and tetraploid D. maculata as two species with several infraspecific taxa. Instead, all taxa analysed in the current study are best treated at the subspecies level within D. maculata s. lat. due to somewhat continuous morphological variation between morphotypes. A total of eight D. maculata subspecies may be recognized in Central Europe, of which one is newly described here as D. maculata subsp. arcana, subsp. nov. Some nomenclatural riddles have been resolved, and the threat status of the recognized taxa is discussed.