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 km 2 ) 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.

The study of the extent of variability and the order of importance for the impact of environmental factors on species distribution and weed community structure from one region to the other is an interesting research subject. The present study aimed to discuss the issue to give a comparative view with the author's findings about the impact of the prevailing climate, soil type, crop type, crop sustainability and urbanization on species distribution and weed community structure in the coastal farmland and adjacent territories in northwest delta region (Mahgoub, 2019). A new sample area selected and comprised the reclaimed land of El Ballah region in Isthmus of Suez and adjoining farmland east Nile delta. A total of 245 species were recorded. Agglomerative Hierarchical Clustering (AHC) identified four vegetative sociation groups (VSG). The diversity of the four identified VSG or weed communities was evaluated at different levels. Parincipal Component Analysis (PCA) indicated the influence of the five eco factors on species distribution and variability of weed community structure, summarized the relationships among variables and investigated the proximity among samples and how they related to variables. ANOVA followed by Tukey's test were applied twice for the resulted VSG, one depending on soil variables as explanatory variables and the other on sampling site's indicative scores for the five eco factors. The results of ANOVA (R 2 , F, P), sample variance (S 2 ) and other multivariate analyses indicated a different order of importance for the impact of the five eco factors in comparable to the former study denoted above. The soil type was the most impacting factor on species distribution and weed community structure, followed by crop type, crop sustainability, prevailing climate and urbanization, respectively.

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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 studying of the performance of weeds and weed assemblages associated with different crops through phytosociological researches derives its importance mainly from weeds adverse impact on crop productivity. Hopefully, the current study is beneficial for developing a sustainable long term weed control and soil management strategy. The objective of the present work is to measure three ecological preferences: crop diversification, soil type and crop seasonality. A sample area was selected comprising farmland of Nile Delta and its adjoining east and west territories, Egypt. Sixty-four sites in 12 governorates comprising 30 agroecosystems were monitored. 150 species were designated as most influential weed-species out of 555 species recorded. Ecological preference for species for crop seasonality was evident through the results of Agglomerative hierarchical clustering (AHC). Three weed communities or weed assemblages’ groups (WAG) were identified. Their diversity evaluated and their linear correlation strength was determined. The fidelity measurements showed that 60-species have fidelity to WAG A; 46 to WAG B; 44 to WAG C. Measuring the ecological preference of species for crop diversification and soil type indicated that the growth activity of 36-species was more affected by crop diversification; 63-species preferential for growth in fine grained soil (FGS) and 87-species in coarse grained soil (CGS). By employing Redundancy analysis (RDA) with variation partitioning (VP), the variability in species frequency in WAG that can be explained by ecological preference of species for the three ecological preferences was determined and variation was partialized out to estimate their partial, linear effect. In fact, weed control is a recalcitrant issue and the current study revealed that a portion of the solution is in a successful crop diversification plan. The successful selection for a competitive crop that can be taken seriously as an adequate weed controlling mechanism in a crop rotation technique will cause the strongest population reduction of harmful weeds on infested farmland, especially in relevance for crops grown for organic certification.