No abstract

With the aim to identify future challenges and opportunities in vegetation science, we brought together a group of 22 early career vegetation scientists from diverse backgrounds to perform a horizon scan. In this contribution, we present a selection of 15 topics that were ranked by participants as the most emergent and impactful for vegetation science in the face of global change. We highlight methodological tools that we expect will play a critical role in resolving emerging issues by providing ways to unveil new aspects of plant community dynamics and structure. These tools include next generation sequencing, plant spectral imaging, process‐based species distribution models, resurveying studies and permanent plots. Further, we stress the need to integrate long‐term monitoring, the study of novel ecosystems, below‐ground traits, pollination interactions and global networks of near‐surface microclimate data at fine spatio‐temporal resolutions to fully understand and predict the impacts of climate change on vegetation dynamics. We also emphasize the need to integrate traditional forms of knowledge and a diversity of stakeholders into research, teaching, management and policy‐making to advance the field of vegetation science. The conclusions reached by this horizon scan naturally reflect the background, expertise and interests of a representative pool of early career vegetation scientists, which should serve as basis for future developments in the field.

Biological invasions remain one of the greatest threats to biodiversity and livelihoods, and this is predicted to increase due to climate change and globalization. In this study, we produced a comprehensive checklist of alien plants in Nigeria from online flora databases, herbarium records, published field surveys, and questionnaires administered to botanical gardens. The resulting alien flora was classified into naturalized, invasive, and cultivated plants. We then fitted a random forest model to identify the attributes which facilitate the naturalization of alien plants in Nigeria. We also used separate chi-squared tests to investigate if the frequency of these attributes is statistically significant between the naturalized and invasive plants. The results include 1,381 alien plant taxa, comprising 238 naturalized, 190 invasive, and 953 cultivated species. The naturalized and invasive plants (428 species) spread across 91 families, with Fabaceae and Poaceae having the highest representations. The random forest model showed that life forms and local economic uses were the most important drivers of alien plant naturalization in Nigeria. Chi-squared tests revealed a non-random distribution of life forms (P < 0.001), higher frequencies of naturalized plants from the Indomalaya (P = 0.006) and the Neotropics (P = 0.04), greater introductions during the British colonial rule, and are used mostly for medicinal, ornamental, food, and fodder. Naturalized and invasive plants were recorded in all regions of Nigeria and are mostly found in urban ruderal and agricultural landscapes. This baseline information can support further ecological studies and conservation actions in Nigeria.

Invasive alien species (IAS) and land-use represent major threats to native plant communities around the globe. However, studies on IAS and potential ecological impacts in the context of land-use are limited in sub-Saharan Africa. Using a set of 45 plots in Jos metropolis in central Nigeria, we assessed the abundance of invasive Tithonia diversifolia (Hemls.) A. Gray, and its relationship with abundance and diversity of native plant species among land-use types. Abundance of T. diversifolia was the highest in farmland when compared to riparian and roadside land-use types. Also, the abundance and diversity of native species were lowest in farmland when compared to the roadside and riparian plant communities with increased T. diversifolia abundance. We showed that while T. diversifolia has low impact on native species, land-use type is an important predictor of native abundance and diversity. Although T. diversifolia has benefitted from the disturbances across land-use types, we found a very weak negative estimate of T. diversifolia effects on native species. These results consolidate existing evidence that land-use transformation in sub-Saharan Africa provides opportunities for alien plant invasion and native species decline. More important is the preservation of land-use types, which will result in a synergy of conservation effort - both reducing T. diversifolia abundance and preserving native plant abundance and diversity in central Nigeria.

Biological invasions are one of the major challenges to the restoration of post-mining sites. Most post-mining sites are under technical reclamation with only a few left to spontaneous vegetation processes. Therefore, we know little about alien plant species on spontaneously-vegetated post-coal mine heaps and how native community characteristics predict their establishment. To fill the knowledge gap, we aimed to determine the drivers of alien species colonisation on post-coal mine heaps. Specifically, we asked: (i) Which alien species are the most successful on post-coal mine heaps and why? (ii) What are the drivers of alien species richness and cover, and how are they affected by the native community? (iii) What does it mean for predicting threats from alien species and management? We recorded vascular plant species and their abundance across 400 plots on post-coal mine heaps in Upper Silesia, Poland. We calculated plant community taxonomic and functional characteristics and, using mixed-effects models, we estimated predictors of alien species richness and cover. We found 65 alien species on post-coal mine heaps, comprising 20.4% of all recorded species, including 36 neophytes and 29 archaeophytes. Amongst them – Erigeron canadensis, Solidago gigantea, Solidago canadensis, Erigeron annuus and Impatiens parviflora – were the most frequent on the studied heaps. We showed that native functional richness significantly predicts alien species richness and cover. Similarly, native community-weighted mean (CWM) seed mass and plant height predict alien species cover. However, CWM of specific leaf area for native species marginally predicts alien species richness. We showed that alien species cover decreases with native species cover. Our findings revealed the ecological significance of niche-filling and the biotic acceptance hypotheses on post-coal mine heaps. We demonstrated how exploring native community characteristics can help in understanding the invasibility and management of post-industrial vegetation.

The African continent has the most extensive grassland cover in the world, providing valuable ecosystem services. African grasslands, like other continental grasslands, are prone to various anthropogenic disturbances and climate, and require data-driven monitoring for efficient functioning and service delivery. Yet, knowledge of how the African grassland cover has changed in the past years is lacking, especially at the subcontinents level, due to a lack of relevant long-term, Africa-wide observations and experiments. Here, we used Moderate Resolution Imaging Spectroradiometer (MODIS) Land Cover Type (MCD12Q1) data spanning 2001 to 2017 to conduct Land Use Land Cover (LULC) change analyses and map grassland distribution in Africa. Specifically, we assessed the changes in grassland cover across and within African subcontinents over three periods (2001–2013, 2013–2017, and 2001–2017). We found that the African grassland cover was 16777765.5 km2, 16999468.25 km2, and 16968304.25 km2 in 2001, 2013, and 2017, respectively. There were net gain (1.32%) and net loss (0.19%) during 2001–2013 and 2013–2017 periods, respectively. Generally, the African grassland cover increased (1.14%) over the whole study period (2001–2017) at the expense of forestland, cropland, and built-up areas. The East and West African grassland covers reduced by 0.07% and 1.35%, respectively, in 2013–2017, and increased in other periods; those of North and Central Africa increased throughout the three periods; but Southern Africa grassland cover decreased over the three periods. Overall, the net gains in the grassland cover of other African subcontinents offset the loss in Southern Africa and promoted the overall gain across Africa. This study underscores the need for continuous monitoring of African grasslands and the causes of their changes for efficient delivery of ecosystem services.

The African continent has the most extensive grassland cover in the world, providing valuable ecosystem services. African grasslands, like other continental grasslands, are prone to various anthropogenic disturbances and climate, and require data-driven monitoring for e cient functioning and service delivery. Yet, knowledge of how the African grassland cover has changed in the past years is lacking, especially at the subcontinents level, due to a lack of relevant long-term, Africa-wide observations and experiments.Here, we used Moderate Resolution Imaging Spectroradiometer (MODIS) Land Cover Type (MCD12Q1) data spanning 2001 to 2017 to conduct Land Use Land Cover (LULC) change analyses and map grassland distribution in Africa. Speci cally, we assessed the changes in grassland cover across and within African subcontinents over three periods