The relationship between Invasive Alien Solanum elaeagnifolium Cav. characters and impacts in different habitats

Invasive alien plants are one of the most serious threats to agriculture. The growth traits of Solanum elaeagnifolium Cav. in crops and their demographics in invaded vs non-invaded communities were examined. The majority of S. elaeagnifolium germination was observed in the spring compared to the summer. Five stages were distinguished, which started with a short time of seedling and juvenile stages, extended flowering, and fruiting stages, and seed dispersion in the winter season. An increase in shoots/roots ratio, leaf area ratio and leaf mass fraction during growth with the varied rate was proved. The accumulation coefficient of dry mass exceeded 0.93 and was significant (P > 0.001) with great variability within plant parts, and stage intervals. While the high growth rate is influenced by the stages and habitats. The recipient communities are affected negatively by S. elaeagnifolium invasion which is associated with lower diversity, richness, and evenness vs non-invaded communities. High similarities were found in the invaded area and communities. Finally, high and varied growth and plasticity of S. elaeagnifolium characterized their invasion behavior via different habitats. There were suitable determinants indices of diversity that can be used in the comparison between invaded and non-invaded communities. This knowledge may be useful for use in agro-environment protection and to improve the management methods of invasive alien species.

Ecological importance and sociological characters of fourteen widespread weeds and their contribution to the observed (dis)similarity between weed communities

Widespread weeds are a serious nuisance to farmers in any country whether they are growing agricultural or horticultural crops for the great damage they cause to the economy, human health and environment loss. Thus, it is important to measure their ecological importance, sociological characters, their contribution to the observed (dis)similarity between weed communities associated with agronomic and horticulture crops, as well as performing time series analysis and forecasting for their cumulative records. Hopefully with the aforementioned information available, it will be possible to determine the most detrimental which deserve resistance priority within a successful weed control plan, which is the aim of the current study. Depending on species records 2018-2020, fourteen weeds assigned widespread out of the 537-species recorded. Their values in the Importance Value Index (IVI) suggested that Sonchus oleraceus had the highest ecological importance among winter weeds (IVI = 50.5), whereas Bassia indica had the highest IVI among summer weeds (IVI = 42.7) and Cynodon dactylon showed the highest value in the observed competition throughout the year (IVI = 46.2). Analysis of Similarities (ANOSIM) indicates that the weed community structure is significantly affected by widespread weeds and the mean of ranked dissimilarities in floristic composition between groups (weed communities associated with crop categories) is greater than within groups. Similarity Percentage analysis (SIMPER) based on Bray-Curtis as a distance dissimilarity measure, revealed that Cyperus rotundus, Melilotus indicus and Beta vulgaris were the most discriminant species in creating the observed pattern of (dis)similarity between the weed community structure associated with agronomic and horticultural crops during the winter half of the year, while Aster squamatus and Echinochloa colona were the most discriminant during the summer half. It is prominent from the results of the current study and the implemented time-series analysis and forecasting that no-decline is expected in the cumulative records of the 14-widespread weeds when the same current weed management strategy is applied.

Measuring the ecological preference for growth of 150 of the most influential weeds in weed community structure associated with agronomic and horticultural crops

The phytosociological researches which intent for studying the performance of weeds and the structure of weed assemblages associated with different crops derives their importance mainly from the adverse effect of weeds on crop productivity. Consequently, it is worth questioning about the ecological preferences of the weed growth in response to three main drivers for weed community structure associated with agronomic, and horticultural crops: crop diversification, crop seasonality, and soil type. A study area was selected comprising farmland of Nile Delta and its adjoining east and west territories, Egypt. A total of 555 species were recorded in 30 agroecosystems monitored and depending on species frequency/abundance values, 150 species were designated as the most influential weeds in weed community structure associated with agronomic and horticultural crops. The ecological preference of species for crop seasonality was evident through the results of Agglomerative hierarchical clustering. Three weed assemblage groups (WAG) identified: WAG A associated with winter agronomic crops, WAG B associated with summer agronomic crops, and WAG C associated with perennial agronomic crops and horticultural crops (orchards). Their diversity evaluated at different levels. The growth preference of the 150 species which were assigned as most influential weeds was gauged in response to the three environmental variables. 61 species were faithful to WAG A, 45 to WAG B, and 44 to WAG C. Concerning crop diversification, 34-species were significantly affected and scored coefficient of variation ≥ 100%. As for soil type, indicator species analysis revealed that 66-species show growth preference in fine grained soil while 84-species prefer coarse grained soil. In the three vegetation units (WAG A - C), 12 within-group associations (alliances) were specified of less-common (differential) species. The record of these alliances match to a specific environmental condition (ecological niche) and in them 29 strong indicators are identified. Redundancy analysis was used to extract and summarize the variation in species records in the response matrix (species vs. sites) that can be explained by the three different types of growth preference (explanatory variables), and the partial linear effect of them was evaluated by variation partitioning.

The impact of five environmental factors on species distribution and weed community structure in the coastal farmland and adjacent territories in the northwest delta region, Egypt

The importance of the soil type and its properties cannot be denied as one of the major environmental factors affecting the weed community structure in an area, but what is the effect of the other environmental factors as the prevailing climate, crop type, urbanization and crop sustainability? What is the order of importance for their impact? The present study aims to measure these concepts. A sample area (3500 km²) was selected in the Northwest Delta, Egypt. 473 species recorded and four VSG or vegetative sociation groups (weed communities) identified using Agglomerative Hierarchical Clustering (AHC). The diversity of the 4 VSG was calculated. PCA used to get a view for the influence of these five variables (environmental factors) on species distribution and variability of weed community structure, summarize the relationships among variables and investigate the proximity among samples and how they relate to variables. The measurement of the degree of seasonal bias of species added more clarification for the impact of crop type. ANOVA followed by Tukey's test showed the significance of 9 soil variables and determined which of the pairs were statistically significant. The results of the study revealed that the prevailing climate was the most impacting factor on species distribution and weed community structure followed by urbanization, crop type, soil type and crop sustainability, respectively.

Beta diversity at different spatial scales: plant communities in organic and conventional agriculture

Biodiversity studies that guide agricultural subsidy policy have generally compared farming systems at a single spatial scale: the field. However, diversity patterns vary across spatial scales. Here, we examined the effects of farming system (organic vs. conventional) and position in the field (edge vs. center) on plant species richness in wheat fields at three spatial scales. We quantified alpha-, beta-, and gamma-diversity at the microscale in 800 plots, at the mesoscale in 40 fields, and at the macroscale in three regions using the additive partitioning approach, and evaluated the relative contribution of beta-diversity at each spatial scale to total observed species richness. We found that alpha-, beta-, and gamma-diversity were higher in organic than conventional fields and higher at the field edge than in the field center at all spatial scales. In both farming systems, beta-diversity at the meso- and macroscale explained most of the overall species richness (up to 37% and 25%, respectively), indicating considerable differences in community composition among fields and regions due to environmental heterogeneity. The spatial scale at which beta-diversity contributed the most to overall species richness differed between rare and common species. Total richness of rare species (present in < or = 5% of total samples) was mainly explained by differences in community composition at the meso- and macroscale (up to 27% and 48%, respectively), but only in organic fields. Total richness of common species (present in > or = 25% of total samples) was explained by differences in community composition at the micro- and mesoscale (up to 29% and 47%, respectively), i.e., among plots and fields, independent of farming system. Our results show that organic farming made the greatest contribution to total species richness at the meso (among fields) and macro (among regions) scale due to environmental heterogeneity. Hence, agri-environment schemes should exploit this large-scale contribution of beta-diversity by tailoring schemes at regional scales to maximize dissimilarity between conservation areas using geographic information systems rather than focusing entirely at the classical local-field scale, which is the current practice.