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Urban grasslands often exist as fragmented patches with varying threat levels. These patches are generally inappropriately managed due to limited data on their responses to disturbance and seed bank regenerative potential. This study compared seed banks between non-naturally disturbed and undisturbed patches of South African subtropical grasslands in an urban environment. Standing vegetation was characterised via year-round quadrat and monthly transect sampling. The seed banks were sampled after the two main dispersal periods and assessed for species composition and density. The seed bank species (24) represented a subset (9%) of the standing vegetation, with forbs being the most speciose lifeformandgrasses themostabundant. Disturbancehada moderate impactonseedbankdensity but significantly affected species composition and ordering. Clustering and ordination analyses separated seed banks based on disturbance history. However, seed banks in disturbed patches maintained the general character of the grassland type. Diagnostic, rare and threatened taxa were absent from seed banks, irrespective of disturbance history. Consequently, restoration will possibly require seed enrichment and species reintroduction rather than exploitation of natural seed banks. Identifying disturbance-sensitive species through seed bank surveys can inform grassland conservation and restoration strategies. Key words: disturbance, grassland, seed banks, urban environment. Les prairies urbaines existent souvent sous forme de parcelles fragmentees, menacees a des degres variables. Ces parcelles sont generalement gerees de facon inappropriee a cause des donnees limitees quant a leurs reponses aux perturbations et au potentiel regenerateur des banques de graines. Cette etude a compare des banques de graines issues de parcelles perturbees de facon non naturelle et de parcelles non perturbees de prairies subtropicales d'un environnement urbain en Afrique du Sud. La vegetation sur pied a ete caracterisee au moyen d'echantillonnage tout au long de l'annee de quadrats et d'un echantillonnage mensuel de transects. Les banques de graines ont ete echantillonnees apres deux periodes principales de dispersion et evaluees quant a la composition et la densite des especes. Les especes des banques (24) representaient une sous-categorie (9 %) de la vegetation sur pied, les herbes non gramineennes constituant la forme de vie la plus diversifiee alors que les graminees etaient les plus abondantes. La perturbation avait un impact modere sur la densite des banques de graines, mais elle affectait significativement la composition et le classement des especes. Les analyses par segmentation et d'ordination separaient les banques de graines sur la base de leur historique de perturbations. Cependant, les banques de graines des parcelles perturbees conservaient le caractere general de la prairie. Les taxons diagnostiques, rares et menaces etaient absents des banques de graines, nonobstant l'historique de perturbations. En consequence, la restauration necessitera possiblement un enrichissement en graines et la reintroduction d'especes plutot que l'exploitation des banques de graines naturelles. L'identification d'especes sensibles aux perturbations par le suivi des banques de graines peut guider les strategies de conservation et de restauration des prairies. [Traduit par la Redaction] Mots-cles : perturbation, prairie, banques de graines, environnement urbain., Introduction Tropical and subtropical grasslands are ancient, with high levels of plant endemism and many specialised plant taxa (Bond 2016). In South Africa, subtropical grasslands occur along the eastern seaboard, [...]

Highlights • Seed recalcitrance occurred in 721 species, 297 genera and 84 families. • The trait was apomorphic in numerous extant lineages. • There is evidence of a radiation of recalcitrant taxa from the Miocene onwards. • Transition rates from orthodox to recalcitrant state were lower than vice versa. • Time spent in the recalcitrant state is shorter than that of the orthodox state. Abstract This analytical review builds on previous descriptions of the recalcitrant seed trait's taxonomic and phylogenetic coverage and provides new insights into the recalcitrant seed trait's apomorphic or plesiomorphic character state, transition rates and residence time in relation to Earth's geological history. A comprehensive global list of recalcitrant-seeded species (RSS) was compiled to assess taxonomic and phylogenetic coverage. Plesiomorphic character state (orthodox or recalcitrant) was established via a comparison of the species stem ages of RSS and orthodox-seeded species (OSS) within specific lineages. Using a previously published tree, frequency by which transitions between OSS and RSS occur and the average time spent in each state was calculated. The recalcitrant seed trait occurred in 721 species, 297 genera and 84 families, with 92% of RSS being tropical phanerophytes. The recalcitrant seed trait was apomorphic in numerous extant lineages, with the earliest representative species appearing in the late Cretaceous. The ratio of RSS to OSS divergence changes from favouring recalcitrance in the late Cretaceous, to the Eocene, when it favoured orthodoxy, reaching the highest difference in the Pleistocene and abating in the Holocene. Transition rates from the orthodox to the recalcitrant state were lower than vice versa. The average time RSS spent in the recalcitrant state is considerably shorter than that spent by OSS in the orthodox state. Recalcitrance is more likely a consequence of gradual adaptation and taxa appear to be more likely to transition from recalcitrant to orthodox than the reverse. By occurring in relatively warm and wet environments, RSS need not invest in desiccation tolerance mechanisms, constituting a metabolic 'saving'. However, some RSS persist in arid and temperate regions, and have arisen during and survived periods associated with major climatic changes. This, together with their representation in numerous ancient lineages, suggests that RSS are 'evolutionary survivors'. [ABSTRACT FROM AUTHOR]

The restoration of degraded forests to enhance biodiversity, ecosystem services, as well as climate change mitigation and adaptation is now a major priority in cities around the world. This study evaluated the success of the Buffelsdraai Landfill Site Community Reforestation Project in Durban, South Africa, by assessing ecological attributes. Measures of plant richness, diversity, vegetation structure, invasive alien plants (IAPs) and ecological processes were contrasted across a chronosequence of habitats under restoration (0-year-old, 3-year-old and 5-year-old) and compared with a reference forest habitat (remnant natural forest). Native tree species recruitment and vegetation structure increased with restoration age. Ecological processes, represented by the composition of pollination and seed dispersal traits in all of the habitats under restoration, were similar to the reference habitat. However, low tree density and an increase in IAP cover with an increase in restoration age were identified as threats to reforestation success. We recommend enrichment planting and an effective IAP management strategy to promote more rapid habitat restoration while reducing site maintenance costs. Enrichment planting should not only focus on increasing tree species density and richness, but also on the inclusion of species with missing pollination and seed dispersal categories. [ABSTRACT FROM AUTHOR]

Plant biowaste of alien species represents a potential resource for compost production. This study investigated the seed and seedling responses of maize and pea to composts generated from the biowaste of four invasive species in eThekwini, South Africa: Acacia podalyriifolia, Hedychium gardnerianum, Litsea glutinosa, and Tithonia diversifolia. Except for a 40% concentration of T. diversifolia, leachates of the biowaste from the four species had no marked effects on germination. In seedling growth studies, Berea Red soil (control) was supplemented with composts produced using combinations of the four species (A. podalyriifolia + T. diversifolia [T1], A. podalyriifolia + H. gardnerianum [T2], L. glutinosa + T. diversifolia [T3], and L. glutinosa + H. gardnerianum [T4]), and a commercial compost (T5). Carbon and nitrogen levels of the biowaste composts were higher than the control, while their associated C/N ratios were low enough to encourage microbial growth, facilitate rapid decomposition, and support plant growth. A comparison of percentage seedling production, growth rate, and biomass production between the commercial compost and alien biowaste treatments revealed all parameters to be statistically comparable among T5, T1, and T3 for maize, and between T5 and T1 for pea. These superior biowaste composts did not enhance growth relative to the commercial compost, but supported growth to the same extent. However, N and P levels in T1 and T3 were lower than the commercial compost and appear to have altered biomass allocation patterns in both species relative to the commercial compost. The results suggest that there is potential to use invasive alien plant biowaste to improve soil for agricultural purposes. [ABSTRACT FROM AUTHOR]

Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H2SO4: HNO3) on germination, seedling growth and oxidative metabolism in a recalcitrant-seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non-acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success. [ABSTRACT FROM AUTHOR]

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species. Thus, when compared to the most recent comprehensive review of insect herbivory (Kozlov et al.), our data set has increased the base of available data for the tropical plants more than 460% (from 33 to 152 species) and the Brazilian sampling was increased 7,300% (from 2 to 146 species). Data on precise levels of herbivory are presented for more than 57,000 leaves worldwide. There are no copyright restrictions. Please cite this paper when using the current data in publications; the authors request to be informed how the data is used in the publications. [ABSTRACT FROM AUTHOR]

• Urban green spaces hosted many alien and invasive aliens. • Shrubs and herbs from Asteraceae, Fabaceae, Verbenaceae are dominant aliens. • Disturbance and informal settlements influence invasive alien species composition. • The Alien Invasive Index developed identified hotspots of invasiveness. • The Alien Invasive Index can be used to prioritise green spaces for alien control. Urban natural green spaces are becoming increasingly impacted by anthropogenic disturbances, promoting alien plant invasions. Using a rapidly developing city in South Africa as a case study, we related distribution, composition, and ordering of alien plant species to environmental and anthropogenic factors to identify drivers of invasiveness. Vegetation surveys were used to identify and quantify (in terms of composition and density) alien species within 30 natural green spaces. Floristic characteristics were then related to levels of non-natural disturbance and selected abiotic parameters. Based on the relationships observed, selected floristic parameters were used to develop an Alien Invasive Index to identify 'invasive alien hotspots'. Collectively, 80 alien plant species (from 30 families) were found, 35 of which are invasive. The most speciose families were Asteraceae > Fabaceae > Verbenaceae. Their representatives, specifically the invasive shrubs Lantana camara (Verbenaceae) and Chromolaena odorata (Asteraceae) and alien herbs Conyza sumatrensis , Bidens pilosa and Tagetes minuata (Asteraceae) were also the most dominant in terms of frequency across sites and density. A Principal Component Analysis showed invasive alien plant species composition to be most strongly related to level of disturbance, followed by distance to informal settlement and soil moisture content. The Alien Invasive Index could discriminate between sites with low and high levels of invasiveness, and its suitability was validated by the fact that sites with very high index values were in close proximity to informal settlements. The study demonstrates the value of combining classical in situ vegetation surveys and overlay analysis using Geographic Information System for prioritising green spaces and alien species for management in cities that are limited in terms of financial resources. [ABSTRACT FROM AUTHOR]

Natural and human-induced disturbances influence the biodiversity and functionality of forest ecosystems. Regular, repeated assessments of canopy intactness are essential to map site-specific forest disturbance and recovery patterns, an essential requirement for forest monitoring and management. However, accessibility to images required for this practice, uncertainty around the levels of accuracy achieved with images of different resolution, and the affordability of the practice challenges its application in many developing regions. This study aimed to compare the accuracy of forest gap detection (in subtropical forests) achieved with lower-resolution (SPOT7 5 m) and higher-resolution (SPOT7 1.5 m) pan-sharpened imagery. Additionally, the Normalised Difference Vegetation Index (NDVI) and Synthetic Aperture Radar (SAR) were compared in terms of their ability to increase the accuracy of this detection when used in conjunction with both high and low resolution imagery. Results indicate that the SPOT7 1.5 m imagery produced an overall accuracy of 77.78% and a ϰ coefficient of 0.66 compared with the 69.44% accuracy and the 0.59 ϰ coefficient achieved with the SPOT7 5 m imagery. Computing image texture analysis within the Random Forest classifier (RF) framework increased classification accuracies to 75.00% for the SPOT 5 m and 86.11% for the SPOT7 1.5 m imagery, validating the usefulness of texture analysis. Variable importance was used to identify wavebands and texture-derived variables that were the most effective in discriminating canopy gaps from intact canopy. In this regard, near infrared, NDVI, SAR, contrast, mean, entropy and second moment were the most important. Collectively the results indicate that the approach adopted in this study, i.e., the use of SPOT7 1.5 m imagery in conjunction with image texture analysis and variable importance, can be used to accurately discriminate between canopy gaps and intact canopy, making it a cost-effective spatial approach for monitoring and managing natural forests. [ABSTRACT FROM AUTHOR]