Ethiotime1
1. Introduction
Crucial information may be achieved from the biological richness of a vegetation pattern for the planning and management of protected areas, which are prerequisite for sustainable use of biodiversity, particularly due to global variations which are especially caused by anthropogenic factors [1,2]. However, in the field of ecology, identifying and understanding the mechanisms underlying these patterns remains a difficult task. In biological diversity, species richness which is an important aspect of vegetation has been formerly used widely in environmental studies [3,4]. Several theories have been tested and planned, particularly the hypothesis concerning the environment and niche conservation to understand the mechanism effecting species richness and vegetation pattern [5,6].The vegetation, its compositional distinctions and the co-existence of species is effectively represented by the prime environment and ecological variables [7] governing the occurrence of species in any geographical landscape. Vegetation is the aggregation of plant species along with its structure, composition, distribution, and classification in relation to edaphic, climatic, and other several anthropogenic influences [8]. Vegetation is repented by the total plant species in a certain region under its environmental influences [9], with relation to the physiognomic, synthetic, analytical and quantifiable characteristics and is influenced by abiotic and biotic features. The present study was conducted with the aims to explore the ecological features, e.g., habit, life form, leaf size spectra, life cycle, and flowering phenology of wild woody flora. Studying and exploring the biological spectra (life form, leaf size) are helpful measures to comprehend eco-physiological establishment of communities which elaborates the underlying climatic conditions [10].Woody vegetation [2], especially trees, plays a central role in the effectiveness and sustainability of ecosystems, particularly forest habitats. Because phytodiversity influences the structure, composition, and richness of allied biota, having a high degree of tree species diversity is beneficial for conserving forest ecosystems from catastrophic losses caused by illnesses and pests, as well as ensuring the enhanced functioning of ecosystem services. Although several explorations have been carried out to assess the hypotheses, researchers in the field of ecology remain unsuccessful in finding an agreement about the comparative relation of these hypotheses of species richness patterns [11,12].Previous studies have shown that plants with varied development patterns (herbs, shrubs, and trees) have a variety of features, ecological adaption, evolutionary degrees, and evolutionary niche conservation. [13]. Furthermore, species with a diversity in size tend to have a different ability for dispersal to adapt to ecological conditions, and they may exhibit distinct responses to their environment. [14]. It can be suggested from the present findings that the results of various measures on the wide range configurations of plant types with varied range size and development patterns could be disparate for distinct life forms. The distinction in the relative impacts of several hypotheses suggested for species abundance patterns through species range in size and growth forms probably one of the most important causes for the hurdle to gain achievement in the prior investigations and it is still in pending evaluation in ecological studies [15]. Despite widespread awareness for the vitality of forest diversity, knowledge on the distribution pattern of tree diversity is still lacking. The district Kasur has a lush, wild, woody, floristic diversity due to varied topography and climate. Previously, only few preliminary research has been undertaken in this semi-arid lowlands of Punjab, Pakistan [16,17]. Therefore, widespread classification along with ordination are valuable tools to understand the local dynamics of species association along with uses, planning and conservation. As conserving trees is so critical, this study was planned to highlight the following objectives: (i) to compile the taxonomic diversity of the wild woody flora of the area; (ii) to comprehend the developing tendencies within applied taxonomic diversity to document taxa, and lastly (iii) to realize whether ecological factors impact the structure, diversity, and associations of species in this region. Due to the economic value of tree species in this region, the findings from the present study will provide sustainable management policies and habitat restoration measures particularly for the local landscape in relation to the rest of the biosphere.
3. Results
3.1. Woody Vegetation of Study Area
A total of 86 woody species belonging to 61 genera and 26 families were recorded from different habitats of semi-arid lowland of Punjab, Pakistan. The most leading families were Leguminosae with 21 species (24%), followed by Moraceae and Bignoniaceae with nine species each (10%), Apocynaceae, Combretaceae, Myrtaceae, and Salicaceae, including four species each. The remaining families have either one or two species in each (Figure 3). The number of species recorded from forest habitat was much higher than in the other habitats with 42 species (48.27%) followed by home gardens with 32 species (36.78%), arable land with 29 species (33.33%), roadside with 20 species (22.98%), riparian zones with 19 species (21.83%), canal banks with 15 species (17.24%), graveyards with 13 species (14.94%), scrubland with 12 species (13.79%), and sandy places with 10 species (11.49%) (Table 1). The distribution of woody species in different habitats is depicted in the chord diagram with different colors (Figure 4).
3.2. Classification of Woody Vegetation
Using Ward’s agglomerative clustering method, the 86 woody species recorded from 120 sampling sites from semi-arid lowland were classified into 5 major community types (Table 1). The five woody plant communities were renamed using the highest indictor-valued plant species, such as those listed below; 1. EDM: Eucalyptus-Dalbergia-Morus community; 2. PBM: Populus-Bombax-Morus community; 3. ZTZ: Ziziphus-Tamarix- Ziziphus community; 4. PAP: Prosopis-Acacia-Prosopis community, and 5. BCR: Broussonetia-Conocarpus-Ricinus community. The grouping pattern and sample size of each plant community is shown in an agglomerative hierarchical clustering tree of the 120 examined woody vegetation samples (Figure 5). The dendrogram tree shows that the closely related vegetation samples (those with the least difference in species composition) clustered together and were represented by the same color coding. Overall, this graph shows that the district Kasur possessed five woody plant communities comprised of different plant species. The results of this study also indicate that the majority of the examined sampling sites (53) belong to community 1, whereas community 3 contains the lowest number of sampling sites (11).
Color Coding: Red = 1. EDM: Eucalyptus-Dalbergia-Morus community;
Yellow = 2.PBM: Populus-Bombax-Morus community;
Purple = 3. ZTZ: Ziziphus-Tamarix- Ziziphus community;
Green = 4. PAP: Prosopis-Acacia-Prosopis community;
Blue = 5. BCR: Broussonetia-Conocarpus-Ricinus community.
3.3. Community 01 (EDM: Eucalyptus-Dalbergia-Morus Community)
This plant community was found in forest, arable land, canal banks, home gardens, and roadside plantations sampling sites. The community comprised of 53 sampling sites and 66 (76.7%) woody species from the study area. The indicator species in this community have significant p-value include Eucalyptus camaldulensis, Dalbergia sisso, and Morus nigra. The other leading species in this community include Terminalia arjuna, Tecoma stans, Psidium guajava, Populus alba, Polyalthia longifolia, Albizia lebbek, Alstonia scholaris, Cascabela thevetia, and Conocarpus erectus. Higher Shannon’s diversity (3.7 ± 0.36), Simpson diversity (0.96 ± 0.29), Margalef’s richness (9.19 ± 1.32), and Pielou’s evenness (0.88 ± 0.03) were recorded in this community.
3.4. Community 02 (PBM: Populus-Bombax-Morus Community)
This plant community was also recorded from arable land, plantations, canal banks, and roadside sampling sites. The community comprised of 18 sampling sites and 31 (36%) woody species from the semi-arid lowland district Kasur Punjab, Pakistan. The indicator species in this community with significant p-value include Populus nigra, Bombax ceiba, and Morus alba. The other leading species in this community include Acacia nilotica, Broussonetia papyrifera, Dalbergia sisso, Ehretia laevis, Populus alba, Prosopis juliflora, Terminalia. arjuna, Sapium sebiferum, Prosopis juliflora, Pongamia pinnata, and Acacia farnesiana. Higher Shannon’s diversity (3.04 ± 0.33), Simpson diversity (0.94 ± 0.23), Margalef’s richness (4.43 ± 1.13), and Pielou’s evenness (0.77 ± 0.02) were recorded in this community.
3.5. Community 03 (ZTZ: Ziziphus-Tamarix- Ziziphus Community)
This woody community was recorded from riparian zones and sandy places sampling sites. The community comprised of 11 sampling sites and 34 (40.69%) woody species from the semi-arid lowland district Kasur Punjab, Pakistan. The indicator species in this community with significant p-value include Ziziphus jujuba, Tamarix aphylla, and Ziziphus nummularia. The other leading species in this community include Tamarix dioica, Prosopis juliflora, Parkinsonia aculeata, Ficus palmata, Dalbergia sisso, Broussonetia papyrifera, Acacia modesta, Acacia nilotica, Grewia tenax, Prosopis glandulosa, and Prosopis cineraria. Higher Shannon’s diversity (3.08 ± 0.24), Simpson diversity (0.94 ± 0.24), Margalef’s richness (5.14 ± 1.21), and Pielou’s evenness (0.84 ± 0.03) were recorded in this community.
3.6. Community 04 (PAP: Prosopis-Acacia-Prosopis Community)
The sampling sites of this community mainly comprised of scrubland, dry places, and along the roadsides. The community comprised of 17 sampling sites and 44 (51.16%) woody species from the semi-arid lowland district Kasur Punjab, Pakistan. The indicator species in this community with significant p-value include Prosopis juliflora, Acacia nilotica, and Prosopis cineraria. The other notable species in this community include Acacia farnesiana, Broussonetia papyrifera, Celtis australis, Ehretia laevis, Eucalyptus camaldulensis, Ficus palmata, Leucaena leucocephala, Sapium sebiferum, Tamarix aphylla, Ziziphus nummularia, and Ricinus communis. Higher Shannon’s diversity (3.36 ± 0.15), Simpson diversity (0.95 ± 0.31), Margalef’s richness (6.09 ± 1.31), and Pielou’s evenness (0.886 ± 0.02) were recorded in this community.
3.7. Community 05 (BCR: Broussonetia-Conocarpus-Ricinus Community)
The sampling sites of this community mainly comprised of scrubland, home gardens, arable land, and along the roadsides. The community comprised of 21 sampling sites and 26 (30.23%) woody species from the semi-arid lowland district Kasur Punjab, Pakistan. The indicator species in this community with significant p-value include Broussonetia papyrifera, Conocarpus erectus, and Ricinus communis. The other notable species in this community include Alstonia scholaris, Erythrina suberosa, Eucalyptus camaldulensis, Parkinsonia aculeata, Salvadora oleoides, Prosopis juliflora, Pongamia pinnata, Acacia farnesiana, Cascabela thevetia, and Acacia modesta. Higher Shannon’s diversity (2.83 ± 0.13), Simpson diversity (0.92 ± 0.18), Margalef’s richness (3.98 ± 1.12), and Pielou’s evenness (0.72 ± 0.01) were recorded in this community.
3.8. Community 05 (BCR: Broussonetia-Conocarpus-Ricinus Community)
The importance value of all recorded woody species is depicted in Figure 6. The species Acacia nilotica, Dalbergia sisso, Broussonetia papyrifera, Bombax ceiba, Eucalyptus camaldulensis, and Ziziphus nummularia were the most frequent species in semi-arid lowland recorded from all five community types with different IV values (Figure 6).
3.9. Role of Soil Properties on Distribution of Woody Vegetation
The CCA ordination makes it evident that applicable edaphic factors, such as pH, moisture, organic matter, N, P, K, soil texture (silt, sand, and clay), and cation exchange capacity (CEC), have a significant impact on how woody species are distributed. Each triangle represented a distinct species of woody vegetation, with the distance between them showing how similar they are to one another. The species in the first quadrat were under the influence of silt, potassium (K), and electrical conductance (EC), while the species in second quadrat were influenced by soil organic carbon (SOC), cation exchange capacity (CEC), and nitrogen (N). The distribution of woody species in third quadrat was impacted by sand, clay, and moisture. The distribution of woody species found in fourth quadrat of CCA diagram was controlled by soil pH and phosphorus concentration in soil (Figure 7). The first axis identified 6.3 variations, the second, 9.7, and the third and fourth, 12.4–14.8 of the total variation, indicating that soil pH, soil moisture, sand, clay, and phosphorus have a strong relationship with the third and fourth axes and have a significant impact on the diversity patterns of wild grass species (Table 2).The woody species that are sensitive to pH and phosphorus (P) include Albizia procera, Alstonia scholaris, Bischofia javanica, Cascabela thevetia, Albizia lebbek, Gleditsia triacanthos, Plumeria obtusa, Plumeria rubra, Phyllanthus emblica, Lagerstroemia indica, Gmelina arborea, Conocarpus erectus, Tecoma stans, Saraca asoca, Tectona grandis, and Polyalthia longifolia. Soil moisture and soil texture (sand and clay) also have an impact of distribution of grasses. However, the woody species that are positively associated with their values comprise Acacia farnesiana, Bombax ceiba, Prosopis cineraria, Butea monosperma, Erythrina suberosa, Ehretia laevis, Acacia nilotica, Prosopis cineraria, Sapium sebiferum, Cedrela toona, Eucalyptus citriodora, Leucaena leucocephala, Parkinsonia aculeate, Broussonetia papyrifera, Grevillea robusta, Prosopis glandulosa, Chukrasia tabularis, Ehretia obtusifolia, Trewia nudiflora, and Salix alba. The species impacted by nitrogen (N), soil organic carbon (SOC), and cation exchange capacity (CEC) include Dalbergia sisso, Ziziphus jujuba, Ziziphus nummularia, Acacia modesta, Celtis australis, Salix tetrasperma, Tamarix aphylla, Tamarix dioica, Cordia dichotoma, Capparis decidua, and Grewia tenax. The species that were sensitive to electrical conductance (EC), potassium (K), and silt include Bauhinia purpurea, Heterophragma, Ficus elastica, Ficus infectoria, Ficus religiosaMangifera indica, Putranjiva roxburghii, Cordia myxa, Ficus macrophylla, Salvadora oleoides, Syzygium cumini, Kigelia africana, Cassia surattensis, Morus alba, Morus nigra, Cassia fistula, Pongamia pinnata, and Terminalia chebula (Figure 7). Silt, sand, and clay were significantly associated with woody community distribution and the relationship between EDM, PBM, ZTZ, PAP, and BCR woody communities was shown in a ternary with the aforementioned three edaphic factors (Figure 8). According to the soil composition based on these three variables, it was also possible to clearly see a clustering in the woody communities. EDM-community was hosted by soil having sandy texture and PAP-community hosted by soil having silty texture. The other three communities (PBM, BCR, and ZTZ) were hosted by soil having equal percentages of silt, sand, and clay (Figure 8).
3.10. Correlation of Soil Factors
The interrelationship between several soil factors was calculated using Pearson correlation. Silt is positively correlated with potassium (K), soil organic carbon (SOC) and clay are positively correlated with nitrogen (N), and clay is also positively correlated with the cation exchange capacity (CEC) of soil. Sand and silts are negatively correlated with cation exchange capacity (CEC) (Figure 9).
4. Discussion
Our findings emphasize the significance of the semi-arid lowlands of Punjab, Pakistan for the conservation of native flora in diverse landscapes. Our findings are critical for the development and application of management techniques in rural environments to enhance biodiversity protection without halting livestock production. The field survey results showed that study region has a high species diversity. The current study identified 86 woody species belonging to 61 genera and 26 families from diverse habitats of semi-arid lowland of Kasur, Punjab, Pakistan. The most leading families were Leguminosae with 21 species. Healso reported Leguminosae as dominant family in Margalla Foothills Pakistan [30]. The other leading families were Moraceae and Bignoniaceae which are well-known in the tropics for their diversity, variety, and abundance [16]. Home gardens host a higher number of species as compared to scrublands, canal banks, roadside, graveyard, arable land, and riparian zones. Several woody species that were either rare or non-existent in the other habitats were found in the home gardens. Tolera et al. also reported higher diversity of woody species from south-central highlands of Ethopia [31]. Some of these species included exotic trees, e.g., Eucalyptus spp. and Broussonetia papyrifera, and fruit trees, e.g., Syzygium cumini and Mangifera indica, all of which are economically or nutritionally important to farmers. The majority of the species found in the home gardens, on the other hand, were indigenous tree species brought from either other areas or other countries.Various types of analysis have been utilized in the current ecological inquiry to quantify the recorded data of all species and stands in relation to geographic and environmental gradients. Plant community structure and distribution patterns in Himalayan forests are poorly understood. The results presented in this study clearly explain the distribution pattern of woody species composition in these microhabitats using the quantitative classification method (Ward’s method) and the ordination approach (CCA). Five woody plant communities were found in the semi-arid lowlands of Pakistan based on the results of the hierarchical cluster analysis. The three community types (EDM, PBM, and BCR) were distributed in forest, roadside, arable land, home garden, and canal banks microhabitat. The floristic composition of the recognized five woody communities distinguishes them. This could be due to changes in environmental conditions. According to [14,32,33], the variation in species composition within plant communities is most likely caused by environmental conditions. Nonetheless, species diversity and richness varied between plant habitats. For example, the EDM-community has the highest species richness and diversity. The BCR-community, on the other hand, has the lowest species richness and diversity among the other community types. The great species variety and richness of EDM-community may be attributed to the community’s largest microhabitat ranges. Furthermore, the BCR-community is the most troubled community due to settlement, agricultural growth, animal overgrazing, and land degradation.In different aspects, as mentioned in this study, consistent to our hypothesis, shrubby vegetation had higher specialization than tree vegetation [34]. In other words, shrubs had high precise preferences as that of trees in various aspects. Broadly tree species distribution was chiefly affected by climatic conditions like temperature and rainfall. As shrubs are shallow feeders as that of tress, so are vulnerable to native ecological factors such as soil and precipitation. In spite of topography and soil features (physical and chemical), canopy cover also affects shrubs. Hence, shrubs largely displayed more specific distribution preferences than trees in different aspects of the forest ecosystem [35,36].Understanding the communities of woody species in a particular environment depends on the interaction between plant communities, soil characteristics, and topography [20,37]. Our findings indicate that the distribution of woody plant species within the identified communities is significantly influenced by the spatial diversity in soil properties and topography across the semi-arid lowlands Punjab Pakistan. The main indicator species were Dalbergia sisso, Eucalyptus camaldulensis, Populus alba, Prosopis cineraria, Prosopis juliflora, Ricinus communis, Tamarix dioica, and Ziziphus nummularia. A similar pattern of woody species was recorded from another arid region of Pakistan [14,20,27,38]. In the studied region, the distribution of woody communities reflects the impact of soil characteristics. Although certain community types overlap, soil texture was shown to be the main environmental variable that explained variations in plant species distribution and patterns of plant community development. Other researchers in Pakistan have also found that soil texture is the most important soil variable in determining vegetation composition [26,27,39]. Furthermore, potassium (K) is significant in identifying the ecological groupings and species richness in the current study since it regulates photosynthesis, carbohydrate transport, protein synthesis, and other physiological functions [40]. The indicator species positively associated with potassium (K) include M. alba, M. nigra, and P. alba. Ahmad et al. also reported P. alba and M. alba as indicator species in marble polluted ecosystem of Pakistan [41].In the arid tropical regions, ecological studies, in particular vegetation analysis, are crucial to understanding the actual picture of species compositional variations and their underlying environmental drivers throughout both time and geographic scales [42,43]. Documenting changes in species abundance over various environmental gradients can aid in determining the value of the various predictors [27,44]. In many biological processes, nitrogen is a crucial nutrient, and it is also the primary driver of plant development. It also has a significant impact on the fauna and flora of the soil, which can either increase the availability of nutrients to plants or bind them in biological processes and growth, leading to temporary deficits in plants. The leaching of nitrogen occurs as well, especially in well-drained soils [45,46]. The key soil components that have an impact on the distribution of the ZTZ-community were nitrogen and soil organic carbon (SOC). The indicator species positively associated with nitrogen and soil organic carbon include Z. jujube, Z. nummularia, D. sisso, and T. aphylla.Anthropogenic impacts [47,48] upon the spreading of the invading species in distinct surroundings can be described by the physical shape of the landscape. For example, those landscapes that are moderate in advance nations have been revealed to have better plant diversity due to a more heterogeneous landscape [49,50]. There are several zones that have scarce habitat niches for supporting the diversity and abundance to other regions. Our findings are consistent with these observations with richness of targeted species and overall abundance significantly less in the urban sector. The physical features of the landscape elucidate part of the observed patterns. Other potentially key factors are dispersal mechanism, introduction histories, and current along with past human uses and preferences. The rest of this section discusses plausible descriptions for the spatial pattern of occurrence and abundance of the species found in this study.
5. Conclusions
This study found that the district of Kasur in semi-arid lowland Pakistan supports a total of five woody vegetative communities that are notably different from one another. This exhaustive first-ever survey reports 86 woody plants, illustrating a highly diversified, semi-arid tropical region. The five woody plant communities were identified using the indicator species analysis, such as; 1. EDM: Eucalyptus-Dalbergia-Morus community; 2. PBM: Populus-Bombax-Morus community; 3. ZTZ: Ziziphus-Tamarix- Ziziphus community; 4. PAP: Prosopis-Acacia-Prosopis community, and 5. BCR: Broussonetia-Conocarpus-Ricinus community. Numerous environmental factors play a key role in regulating the species distribution in the studied area. The most important factors are the soil pH, soil moisture, sand, clay, and phosphorus. The mapping of species diversity was performed, and the data can be utilized to identify conservation hotspots. Overall, this study found that a range of variables are impairing the ecosystem’s ability to function normally in this Pakistani part of the semi-arid tropics. Based on the findings of this study, soil and vegetation assessment analysis may be helpful in determining the most appropriate habitat manipulation techniques, such as planting, top-soiling, and irrigation techniques for the rehabilitation of degraded lands in the semi-arid region. To preserve this priceless local biodiversity and avert the potential extinction of the rare plant species, sustainable resource management and the implementation of conservation programs are necessary.
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