9. An Overview of the Vascular Plants of the Highlands and the Threats to Plant Biodiversity

We examined the worldwide literature on biodiversity in forest plantations for the indicator organism assessed, species composition (native versus exotic), tree species diversity, and appropriateness of the comparisons made. Fifty percent of the studies used invertebrates, 36% birds, 6% mammals, and 6% vascular plants as bioindicators. We found that 76% of the existing literature compares exotic plantation forests to native/natural forests, 9% of studies compare native plantations to native/natural forests, and 3% examine plantations to plantations. Lower biodiversity in plantation forest compared to other forests was reported by 94% of the reviewed studies. However, some studies indicate higher biodiversity in plantation forests compared to other land uses such as agriculture. We argue that much of the literature reporting lower biodiversity in plantation forests is based on inappropriate comparisons. We suggest more appropriate approaches to assessing the effects of plantation forests on biodiversity.

AimsMany studies of vegetation change over multiple decades have focused on vascular plants, but very few on bryophytes, despite the importance of bryophytes for overall plant biodiversity and ecosystem functioning. Using a repeated survey of vascular plants and bryophytes in a forest ecosystem, we tested predictions of the hypotheses that: (1) vegetation change has been driven by N deposition and climate warming, and (2) bryophytes are more responsive to environmental change than vascular plants.LocationLowland temperate forest, northwest France.MethodsIn forest plots initially surveyed in 1976, we re‐surveyed both vascular plants and bryophytes in 2009 and 2012, respectively. We analysed changes in α‐diversity, β‐diversity, and species composition, and we used community‐weighted mean values of species affinities for temperature, light, pH, soil moisture and N to assess the temporal responses potentially caused by warming, N deposition, or possibly a changing light regime.ResultsWe observed significantly increased species richness of bryophytes and decreased richness of vascular plants. Community affinities to N, pH and temperature increased significantly for bryophytes, but not for vascular plants, although the change over time in N affinities for vascular plants was qualitatively in the predicted direction. Bryophytes showed a higher magnitude of temporal community change than vascular plants, both in terms of overall species composition and environmental affinities, indicating a higher responsiveness of bryophytes to environmental change.ConclusionOverall, the result of more marked temporal community change for bryophytes suggests that the many studies of changes in vascular plant communities over time might underestimate the sensitivity of the broader plant community (including cryptogams) to environmental change.

The decline in plant biodiversity is evident at global scale, but little is known about the loss of microbial diversity associated with diverse plant phyla and their influencing factors. This study investigates the microbial diversity associated with mosses and co-occurring vascular plants in the Alpine ecosystem, focusing on 52 plant “twins” growing on contrasting soil types (carbonate and silicate). Despite co-occurring in the same soil, mosses harbored significantly higher microbial richness and diversity than vascular plants. Across all samples, mosses supporting a total of 3,435 bacterial ASVs and 1,174 fungal ASVs. In contrast, vascular plants hosted a total of 1,760 bacterial ASVs and 911 fungal ASVs. Plant phyla strongly influenced microbial community composition, with vascular plants exhibiting a selective microbial assembly strategy, while mosses showed greater environmental influence. Soil type significantly influenced microbial composition in both plant types, with carbonate soils supporting greater bacterial richness, particularly in mosses. Linear discriminant analysis effect size (LEfSe) analysis highlighted consistent enrichments of Proteobacteria, i.e., Sphingomonadales, Rhizobiales, Burkholderiales and, Pseudomonadales, in vascular plants across soil types, whereas mosses displayed distinct microbial enrichment patterns between carbonate and silicate soils, suggesting a higher environmental connectedness. Our findings demonstrated that plant phyla are a major determinant of the phyllosphere microbiota, and that mosses represent a currently untapped source of microbial biodiversity. This study highlights the importance of considering both host traits and environmental factors for protecting microbial biodiversity and implementing them in global strategies for restoring biodiversity.

Recent forests may be an asset for green infrastructure and ecological restoration, but studies are needed of the variation in forest biodiversity among sites, and possible reasons for observed patterns. In boreonemoral Scandinavia, reforestation occurs on abandoned agricultural land, and we studied 27 such recent (40–80 years old) mixed forests with temperate deciduous trees and boreal trees including Norway spruce, and their communities of dead wood fungi and vascular plants. By analysing aerial photos from 1960 and 2017, we explored how species richness and composition within sites vary with historical and present tree cover, and separately spruce cover, at site scale (2 ha) and within the surroundings (12.5 ha). Tree cover, and the percentage spruce cover, had increased considerably from 1960 and 2017, while open areas had decreased accordingly, at both scales. We found no significant relationships between species richness of forest plants, or fungi on coarse woody debris, and tree cover at any scale. On the other hand, species richness of grassland plants, and fungi on fine woody debris, showed significant negative correlations with high tree cover, and thus the recent forests with the highest total species richness seem to occur in surroundings with lower tree cover, currently dominated by agriculture. The reason may be a correlation between richer soils and more agriculture; the area with the richest soil have been extensively cleared and cultivated, and therefore currently have lower tree cover and more fragmented forests. Furthermore, ordination analysis showed that several deciduous tree species were negatively correlated with tree cover, locally and in the surroundings, while the tree species preferring rich soil such as Fraxinus and Ulmus (and several associated fungal species), were positively correlated with spruce cover. A possible explanation is that spruce colonize well on abandoned grasslands and therefore tends to be associated with grassland plants and trees requiring the richer soils of these areas. We suggest that recent forests in boreonemoral areas could be used for instance for restoration of temperate deciduous woodland, especially in areas dominated by agriculture, but that recurrent management may be needed to avoid spruce domination.

Agguttinni Territorial Park is a large, newly established park on the east-central coast of Baffin Island in Nunavut, Canada. Previous knowledge of the plant and lichen biodiversity was limited and based mostly on collections made during the 1950 Baffin Island Expedition. We conducted a floristic inventory of the park in 2021 and re-examined previous collections. We recorded 141 species of vascular plants belonging to 25 families, 69 species of bryophytes in 27 families, and 93 species of lichens in 23 families. Most of the vascular plant and bryophyte species are new records for the park area, and some vascular plants, bryophytes, and lichens are newly reported for Baffin Island, Nunavut, or the Canadian Arctic or represent significant range extensions. Vascular plant species diversity varied greatly among localities, with inland valleys at the heads of fiords showing highest diversity and interior rocky barrens showing the lowest.

Effects of root plates, pits and mounds following windthrow events on the biodiversity of plants and lichens in Central European mountain forests

Enhancing vegetation diversity in glades, rides and roads in plantation forests

The Arabian Peninsula is known to have a comprehensive and rich endowment of unique and genetically diverse plant genetic resources. Analysis and conservation of biological diversity is a crucial issue to the whole Arabian Peninsula. The rapid and accurate delimitation and identification of a species is crucial to genetic diversity analysis and the first critical step in the assessment of distribution, population abundance and threats related to a particular target species. During the last two decades, classical strategies of evaluating genetic variability, such as morphology and physiology, have been greatly complemented by phylogenetic, taxonomic, genetic diversity and breeding research molecular studies. At present, initiatives are taking place around the world to generate DNA barcode libraries for vascular plant flora and to make these data available in order to better understand, conserve and utilize biodiversity. The number of herbarium collection-based plant evolutionary genetics and genomics studies being conducted has been increasing worldwide. The herbaria provide a rich resource of already preserved and identified material, and these as well as freshly collected samples from the wild can be used for creating a reference DNA barcode library for the vascular plant flora of a region. This review discusses the main molecular and genomic techniques used in plant identification and biodiversity analysis. Hence, we highlight studies emphasizing various molecular techniques undertaken during the last 10 years to study the plant biodiversity of the Arabian Peninsula. Special emphasis on the role of DNA barcoding as a powerful tool for plant biodiversity analysis is provided, along with the crucial role of herbaria in creating a DNA barcode library.

This chapter reviews evidence for reticulation in higher plants and discusses its significance as an evolutionary mechanism. Reticulation (hybridization between divergent taxa) contributes to biodiversity in higher plants through the creation of new hybrid lineages and the transfer of genes between species. Even low levels of hybrid formation can have a significant evolutionary outcome. Hybrid speciation is of major importance in the plant kingdom and can occur with or without a change in ploidy. Introgressive hybridization contributes to genetic variability, and probably adaptability, within established species. Hybridization can lead to extinction by assimilation in rare species.

China was dubbed as “the Mother of Gardens” by gardener and botanist Ernest Henry Wilson who collected and shipped about 2000 species of plants from Asia to Europe and North America. Many ornamentals in western countries originated from China. This paper presents the biodiversity of native Chinese ornamental plants at ecosystem, species and genetic levels, focusing on species and genetic resources with aesthetic potentials, based on literature studies and authors’ participatory investigations. The latest statistics reported 31,362 vascular species (taxa) occurring in China, of which about 6000 species are with gardening values. The diversified ornamental plants become important components of different ecosystems. As the dominant species, some ornamental plants established the plant communities in forests and grasslands, which made the landscapes more colourful and beautiful. Famous representatives were introduced including Camellia, Rhododendron, Rosa, Lilium, Chrysanthemum, Cymbidium and others. Lots of species are with multiple uses in addition to aesthetic values, like medicinal, edible, agricultural or daily life uses. The relationship between biodiversity and cultural diversity of ornamental plants is discussed. Biodiversity of Paeonia, mei flower, Chrysanthemum, sweet osmanthus, Chinese roses and many flowers endowed special meanings to traditional Chinese culture, which enriched cultural diversity. On the other hand, the traditional Chinese culture affected the diversity of ornamental plants. Some potential ornamental plants but underutilized or neglected, including Musella lasiocarpa (Musaceae), Lycoris (Amaryllidaceae), and Leucocasia gigantean (Araceae), are presented. The strategies for conservation and development of Chinese ornamental plants are proposed.

This study investigates the impact of three understorey management practices – herbicide application, understorey clearing, and undisturbed understorey – on the biodiversity of plant and arthropods in olive groves in the Gera region on Lesvos, Greece. The study found that herbicide application had a negative effect on plant diversity, but less pronounced effects on arthropods. The rapid recovery of arthropod biodiversity is likely due to the high structural complexity in the Gera region. Abandoned olive groves displayed the lowest arthropod abundance and vegetation, leading to gradual impoverishment of plant biodiversity and negative impacts on arthropod diversity. The proportion of annual species in the plant cover was positively associated with arthropod abundance. The study proposes a new eco-scheme that supports farmers for maintaining understorey plant cover, with periodical clearing through ruminant grazing, to enhance plant and arthropod biodiversity in olive grove systems.

Excessive forest exploitation significantly contributes to land degradation and the creation of human-made deadwood. Stumps are sometimes ignored in studies on the biodiversity of coarse woody debris. We investigated whether the type of stump, i.e. broken stumps (naturally created) and cut stumps (formed during forestry operations) had an impact on the species composition and species diversity as well as due to this fact they can be characterized by plant indicators. The research covered 728 spruce stumps (287 broken and 441 cut stumps) that were inhabited by lichens, liverworts, mosses and vascular plants in mountain forest belt (Karkonosze Mts., Poland). The following types of microhabitats were included in the research: the upper surface and the lateral surface of a stump with both bark and wood. There are statistically significant compositional differences between the two types of stumps, which was demonstrated by ordination analyses and indicator species analysis. According to the generalized linear models, the probability of occurrence increases in cut stumps in case of liverworts and vascular plants and also along the decomposition stages. The generalized linear mixed-effects model showed that there was a higher species richness of liverworts, mosses and vascular plants on the cut stumps and less drier but the reverse situation was in lichens. The generalized additive models for their cover showed similar trends. Almost all of the taxonomic groups were affected by altitude both in terms of species composition and total cover on the stumps. We concluded that cut stumps are an important type of deadwood for biodiversity and provide a convenient habitat, especially for many lichens and bryophytes.

The current interest among resource managers in ecosystem management necessitates a better understanding of the response of plant species diversity to forest management practices. This study attempted to assess the effects of one forest management practice–clear‐cutting–on plant biodiversity in a mid‐Appalachian hardwood forest by comparing species composition and diversity between two young (≈ 20 yr following clear‐cutting) and two mature (> 70 yr following selective cutting) watersheds. Sampling was confined to the herbaceous layer (vascular plants ≤ 1‐m in height) and woody overstory (stems ≥ 2.5 cm diameter at 1.5‐m height). The important tree species occurred on all watersheds, but the relative importance of these species varied greatly with stand age. Less shade‐tolerant species, such as black cherry (Prunus serotina) and tulip poplar (Liriodendron tulipifera), are replaced by more‐tolerant species, such as northern red oak (Quercus rubra) and sugar maple (Acer saccharum), as the stand matures. Analysis of tree species richness per plot suggests that the competitive thinning process decreases species evenness as the stand develops. Important herb‐layer species included stinging nettle (Laportea canadensis), violets (Viola spp.), seedling of striped maple (A. pensylvanicum), and several fern species. In sharp contrast with the trees, these species appeared to vary little with stand age. Species diversity (H') did not vary with stand age for either the overstory or the herbaceous layer. Detrended correspondence analysis showed a significant correlation between species composition of the two strata for the mature watersheds, but not the young, clear‐cut watersheds. Thus, we suggest a temporal shift in processes influencing species composition following disturbance from allogenic factors (e.g., soil characteristics) to autogenic factors (e.g., stand characteristics), which lead to a linkage between forest strata later in succession. The degree to which forest management alters species composition in these central Appalachian forest ecosystems may be tied to the degree of alteration of the link between strata.

Biodiversity net gain is a policy focus worldwide, acknowledging ongoing losses of biodiversity to development, and a commitment to offsetting any residual impacts on biodiversity elsewhere. At least 37 countries have mandatory offsetting policies, and a further 64 countries enable voluntary offsets. Offsets rely on credible and evidence‐based methods to quantify biodiversity losses and gains. Following the introduction of the United Kingdom's Environment Act in November 2021, all new developments requiring planning permission in England must demonstrate a biodiversity net gain of at least 10% biodiversity net gain from 2024, calculated using a statutory biodiversity metric framework. The metric uses habitat as a proxy for biodiversity, scoring habitats' intrinsic distinctiveness and current condition. We carried out a study of the metric's performance across England in terms of outcomes for biodiversity. We used generalized linear mixed models to regress baseline biodiversity units against five long‐established single‐attribute proxies for biodiversity (species richness, individual abundance, number of threatened species, mean species range and mean species range/population change). Data were gathered for species belonging to three commonly used indicator taxa (vascular plants, butterflies and birds) from 24 sites, including all terrestrial broad habitats except urban. In baseline assessments, metric‐derived biodiversity units correlated with most plant biodiversity variables, but not with any of the bird or butterfly biodiversity variables used in this study. Plant species recorded in habitats with higher baseline biodiversity units had slightly more restricted ranges (slope −16.22 ± 1.52, p < 0.001) on average and had shown stronger past declines (slope −0.02 ± 0.00, p < 0.001) than those in habitats with lower baseline biodiversity units. Each additional baseline biodiversity unit was associated with a 1% increase in plant species richness (p < 0.01). Synthesis and applications: Using the statutory biodiversity metric to define 10% biodiversity net gain without additional species‐focused conservation management is likely to translate into small gains for plant biodiversity, and negligible gains for birds and butterflies. We make specific recommendations to improve the metric's efficacy in achieving desirable biodiversity outcomes. Our results provide a valuable case study for other countries interested in developing metrics to support biodiversity net gain policies.

The history of the Red List of Japanese vascular plants is briefly reviewed for editing and research. Especially on the results of recent monitoring, the present status of information and conservation activities on the endangered plants in Japan is discussed and the dynamics of the Japanese flora are taken up, in relation to basic research on plant biodiversity on the Japanese Archipelago. The figures of endangered plants are not very variable during the past quarter of a century, but we can surmise that the conservation of threatened species in Japan has been promoted to some extent. Based on the results of such a study, proposals are made to contribute to the sustainable use of plant biodiversity on the Japanese Archipelago under a global conspectus.