Grasses in Semi-Arid Lowlands—Community Composition and Spatial Dynamics with Special Regard to the Influence of Edaphic Factors

Abstract

Edaphic properties have been widely shown to influence community composition and distribution. However, the degree to which edaphic factors can affect grasses in semi-arid lowlands is still little researched. We assessed the significance of nine edaphic factors to explain the distributions of 65 grass species with various ecological traits (i.e., the ecological indicator values for their preferred habitat) in the semi-arid lowlands of Pakistan. To record information on species composition and related ecological conditions, we selected 10 random sampling locations between 2020 and 2021. For each species, we determined the important value index (IVI) and looked at the primary indicator species that were identified using the indicator species analysis approach. The major genera were Setaria, Brachiaria, and Cenchrus with 6.15% species in each followed by Aristida, Panicum, and Eragrostis with 4.61% wild grass species, Bothriochloa, Bromus, Phragmites, Polypogon, Saccharum, Poa, Echinochloa, and Dactyloctenium with 3.07% species, whereas other genera had a single species each. In total, 80% of the species were native, while only 20% were introduced species. Microphylls accounted for 49.23% of the leaf size spectra of the grass flora in the study area. The other frequent traits included macrophylls (21.53%), nanophylls (20%), and leptophylls (9.23%). The major life forms were therophytes (56.92%) followed by hemicryptophytes (38.46%) and geophytes (4.61%). The results of an ordination analysis indicated that the distribution of grasses was significantly (p ≤ 0.002) influenced by several edaphic parameters, with pH having the greatest impact on species distribution. The analyses of indicator species showed that pH and EC were the most powerful and important edaphic factors for determining the composition of plant communities and indicator species. The significant indicator species in various ecosystems were Cynodon dactylon (L.) Pers. rainer.bussmann@smnk.de and Leptochloa chinensis (L.) Nees (agroecosystem), Brachiaria reptans (L.) C.A. Gardner and C.E. Hubb, Dichanthium annulatum (Forssk.) Stapf, and Saccharum spontaneum L. (forest ecosystem), Cenchrus biflorus Roxb., Cenchrus ciliaris L., and Desmostachya bipinnata (L.) Stapf (urban ecosystem), Arundo donax L., Echinochloa crus-galli, and Phragmites australis (wetland ecosystem), and Saccharum spontaneum and Echinochloa crus-galli (L.) P. Beauv. (riparian ecosystem). We discovered that different species groupings had different habitat preferences and that soil pH had a significant beneficial effect on plant variety. These results provide a scientific roadmap for soil and plant restoration in semi-arid lowland habitats.