Vegetation and pollen along a 200-km transect in Khyber Pakhtunkhwa Province, northwestern Pakistan

Abstract

This paper presents the first study on the relationship between vegetation and modern pollen rain along a 200-km elevational gradient (275À2600 m above sea level), in the Khyber Pakhtunkhwa Province of northwestern Pakistan. A vegetation survey of 24 plots (six plots of 10 £ 10 m from four elevational zones) was carried out following the Braun-Blanquet method. The percentage cover of all taxa was documented and species were assigned to their respective families. Twenty-four surface samples (taken from the same plots from which the vegetation data were recorded), were processed according to standard methods for retrieving pollen grains. Based on a count of 300 pollen grains per sample, the percentage abundance of taxa in the pollen assemblages was compared to the corresponding percentage of cover abundance in the vegetation, at the family level. Results of the constrained incremental sum of squares (CONISS) derived from the pollen data reveal that the natural vegetation zonation is well reflected in pollen assemblages despite alteration of the vegetation by human activities. The identification of key taxa for the different vegetation zones improves our confidence to draw vegetation boundaries and distinguish the elevational zones along the gradient. The Spearman's rank correlation coefficient at P < 0.05 indicates a significant correlation between vegetation cover and pollen rain in Acanthaceae, Asteraceae, Cyperaceae, Euphorbiaceae, Poaceae, and Verbenaceae, whereas weak correlations were observed in Apiaceae, Balsaminaceae, Boraginaceae, Rubiaceae, and Saxifragaceae. Results based on the comparison of vegetation and the pollen spectra at the family level, and their transfer factors (TF), reveal that large-sized Asteraceae, Brassicaceae, Cannabaceae, Chenopodiaceae/Amaranthaceae, Myrtaceae, Poaceae/cereal pollen grains > 45 mm, and Polygonaceae reflect the proximity of cultivated land and human habitation in the lower three vegetation zones of Peshawar valley, lower montane Malakand hills and Swat valley. Contrarily, the abundance of the Dryopteridaceae, Pinaceae, Pteridaceae and certain spores reflects natural vegetation in the upper montane Malam Jabba zone.

Vegetation and climate dynamics in Khyber Pakhtunkhwa (NW Pakistan), inferred from the pollen record of the Kabal Valley in Swat District during the last 3300 years

“…3) shows the pollen taxa assigned to the different vegetation groups. Our published study of a pollen rain transect of this area (Jan et al 2015) indicated that the source of the pollen is local (originating from vegetation on a 5 km 2 mountain area around the coring site) and represented predominantly by Pinus, Picea, Cedrus, Abies, Cyperaceae and Poaceae species.…”

“…At present, the conifers on the surrounding mid-altitude mountains (1500-3000 m a.s.l) include Pinus and Picea species, while the high-altitude mountains (3000-5000 m a.s.l.) have Cedrus species (Jan et al 2015, Siddiqui et al 1999). An important task is to trace the history and temporal dynamics of these conifers on the surrounding Hindu Kush mountains of the Swat Valley.…”

Palynological studies and Holocene ecosystem dynamics in north western Khyber Pakhtunkhwa Province of Pakistan in the Hindu Kush Himalayan region

“…3) shows pollen taxa assigned to the different vegetation groups such as conifers, Trees/Shrubs and herbs. Our published paper on the pollen rain transect study of this area reveals that the source of the pollen is local, originating in the surrounding mountain vegetation with Pinus, Picea, Cedrus, Abies, Cyperaceae and Poaceae species (Jan et al, 2015). 115…”

“…Natural coniferous forests of Pinus, Abies, Cedrus and Picea are also under the heavy social and economic pressure of logging . Our paper dealing with vegetation and modern pollen rain in Kabal Swat (Jan et al, 2015)…”