Impacts of Nicotiana glauca Graham Invasion on the Vegetation Composition and Soil: A Case Study of Taif, Western Saudi Arabia.

Abdulaziz M Assaeed,Ahmed M Abd-Elgawad,Abdullah S Alharthi

doi:10.3390/plants10122587

Abdulaziz M Assaeed, Ahmed M Abd-Elgawad + Show 1 more

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https://doi.org/10.3390/plants10122587

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Abstract

Invasive species are considered a serious problem in different ecosystems worldwide. They can compete and interfere with native plants, leading to a shift in community assembly and ecosystem function. The present study aimed to evaluate the effects of Nicotiana glauca Graham invasion on native vegetation composition and soil of the most invaded locations in the Taif region, Western Saudi Arabia, including Alwaht (WHT), Ar-Ruddaf (RDF), and Ash-shafa (SHFA). Plant species list, life span, life form, and chorotypes were assessed. Six locations highly infested with N. glauca shrubs were selected, and the morphological parameters of the shrubs were measured. Within each location, richness, evenness, relative density of species, and soil were measured either under the canopy of N. glauca shrubs or outside the canopy. Floristic analysis revealed the existence of 144 plant species, mainly perennial. The shrubs at the SHFA1 location showed the highest values of all measured morphological parameters. The WHT 1 location showed high richness and evenness, while the WHAT 2 location showed less richness and evenness. The invaded locations showed substantial variation in the community composition. Additionally, the effect of N. glauca on the understory species varied from competition to facilitation, where most of the understory species were inhibited. As an average of all locations, 65.86% of the plant species were recorded only outside the canopy of N. glauca. The vegetation analysis revealed that the SHFA location is more vulnerable to invasion that could be ascribed to its wide range of habitats and high disturbance. The soil–vegetation relationships showed significant variations among the studied locations regarding soil composition, and thereby showed a wide ecological range of the invasive shrubs N. glauca. Therefore, the invasion of N. glauca in the Taif region altered the species interactions, nutrients, and soil properties.

Highlights

Introduction published maps and institutional affilInvasive species are a serious threat to ecosystems worldwide [1], and they are major drivers of global change
The floristic analysis of the habitats invaded by N. glauca revealed the presence of 144 plant species, which are categorized into 79 perennial, 62 annual, and 3 biennial species (Table S1)
The present results showed that N. glauca shrubs growing in SHFA 1 showed the highest number of all measured parameters

Summary

Introduction

Invasive species are a serious threat to ecosystems worldwide [1], and they are major drivers of global change. Invasive species threaten habitats and harm the function and structure of ecosystems, either terrestrial or aquatic [2,3]. Invasive species are known to be the main cause of reduction in native species richness and are involved in biodiversity loss, as well as in damage to ecosystem services [4,5]. Invasive species lead to a shift in the community structure, thereby increasing the challenge of the conservation of biodiversity and ecosystem functioning worldwide [6]. Direct impacts of invaders on ecosystem functioning may occur through changes in nutrient levels [4], and they can change the soil water dynamics and energy budgets, thereby influencing native flora, fauna, and ecosystem services [8,9].

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