Classification and Characterization of the Manoor Valley's (Lesser Himalaya) Vegetation from the Subtropical-Temperate Ecotonal Forests to the Alpine Pastures along Ecological Variables

Abstract

Plant species are distributed in different types of habitats, forming different communities driven by different sets of environmental variables. Here, we assessed potential plant communities along an altitudinal gradient and their associations with different environmental drivers in the unexplored Manoor Valley (Lesser Himalaya), Pakistan. We have implemented various ecological techniques and evaluated phytosociological attributes in three randomly selected 50 m-transects within each stand (a total of 133) during different seasons for four years (2015-2018). This phytosociological exploration reported 354 plant species representing 93 different families. The results revealed that the Therophytic life form class dominated the flora, whereas Nanophyll dominated the leaf size spectra. There were a total of twelve plant communities identified, ranging from the lowest elevations to the alpine meadows and cold deserts. The maximum number of species were found in Cedrus-Pinus-Parrotiopsis community (197 species), in the middle altitudinal ranges (2292-3168 m). Our results showed that at high altitudes, species richness was reduced, whereas an increase in soil nutrients was linked to progression in vegetation indicators. We also found different clusters of species with similar habitats. Our study clearly shows how altitudinal variables can cluster different plant communities according to different microclimates. Studies such as ours are paramount to better understanding how environmental factors influence ecological and evolutionary aspects.

Keywords: Himalaya; PC-ORD; environmental variables; plant community assembly; vegetation structure.

Figure 1

GIS map (generated using ArcGIS version 10.1) depicting the altitudinal layers and distribution pattern of communities of the studied area (Manoor Valley). Com 1: Salix–Sorbaria–Impatiens, Com 2: Indigofera–Juglans–Isodon, Com 3: Cedrus–Cynodon–Isodon, Com 4: Indigofera–Parrotiopsis–Bistorta, Com 5: Sambucus–Cedrus–Desmodium, Com 6: Indigofera–Cedrus–Pinus, Com 7: Cedrus–Pinus–Parrotiopsis, Com 8: Pinus–Viburnum–Cedrus, Com 9: Abies–Picea–Juniperus, Com 10: Juniperus–Sibbaldia–Juniperus, Com 11: Sibbaldia–Bergenia–Rheum, Com 12: Poa–Bistorta–Primula.

Figure 2

The relationship between the altitude and the species richness of 12 plant communities.

Figure 3

The NMDS ordination reveals the relationship between communities and edaphic variables. The length of the arrows illustrates the influence range, while the direction shows the correlation of the variables with plant communities. Plant communities that are close together or on the same axis have a positive correlation. The codes represent community types.

Figure 4

NMDS ordination is based on plant species that are in association with sampled stands and grouped into communities Plant communities that are close together or on the same axis and have a positive correlation. Only the three most representative plant species for each community are plotted. Some species are present in different communities and due to that, the total number of species are not 36.