The Tehsil Katlang lies from 32⁰ 06^' to 32⁰ 21^' North latitudes and 61⁰ 46^' to 62⁰ 25^' East longitudes. It is bounded on the north by swat district, on the east by district of Buner, on the South by mardan city of district Mardan and on the west by Tehsil Takht Bhai. The total area is 1098573km. The research area is very fertile. It is a great sate of Gandhara remains. It may broadly be divided into two parts, the North-East hills and the South-West plains (Figure 1). The entire northern side of the research area is bounded by the hills. The summer season is extremely hot. A steep rise of temperature is observed from May to June. During May and June, dust storms are frequent at night. Due to usual cultivation and irrigation, the environment is humid. The relative humidity is quite high throughout the year while maximum humidity has been recorded in August. Maximum temperature (41.50⁰C) and rainfall (125.85mm) are recorded in June and August Respectively (Khan et al., 2011d). Taxonomists are naturally interested to record flora of diverse geographical areas. Since very long time many attempts have been through by different workers in searching away Flora of our dear native soil, Pakistan. The effort of both Pakistani and Foreign Taxonomists is basic approach. Different workers have worked in different parts of Pakistan still when it was part of United India. The area under discussion is typically unfamiliar and very a small number of reports are originated (Khan, 2004; Khan, 2007; Parveen et al., 2008; Qureshi, 2008; Hussain et al., 2009; Muhammad et al., 2009; Qureshi and Bhatti, 2010; Khan et al., 2011a; 2011b; Khan et al., 2011c; Khan, 2013). Biological spectrum of vegetation is the index of the phytoclimate of the site, deduction of which is based on diverse life-forms composing the flora of the site. The life-form  in  its  turn  is  the  ultimate  manifestation  of  the sum  of  all  the  adap- tations  undergone  by  a  plant  to  the climate in which it resides. Raunkiaer (1934) proposed the term “Biological Spectrum” to express both the life-form distribution in a flora and the phytoclimate. Oosting (1956) stated that the leaf size knowledge may help out in the accepting of physiological processes of plants. Khan (2013) stated that in testing area the climatic, physiognomic and plant life disturbance was designated with ecological characteristics. The life form spectra are supposed to be the signal of micro and macroclimate (Shimwell, 1971; Agrawal, 1989). Literature dealing with the life form and leaf size spectra shows that very little work has been made in Pakistan i.e. Abbas et al. (2010), Qureshi and Ahmad (2010) and Khan et al. (2011a; 2011b; 2012; 2013). The biological spectrum is thus useful as an index of the health status of flora. When worked out at periodic intervals, biological spectrum may set the guidelines for eco-restoration and optimization of a community. In view of this, the present work was under taken in the areas of Tehsil Katlang, Mardan.

Figure 1 Research site of the study area

Table 1 Floristic list of Katlang, District Mardan

Table 2 Total number of plant species and percentage of life-form and leaf size classes of research area

Discussion
The research area is very interesting consist of both hill and plain, changeable much in floristic composition. The present work was design to explore the flora for taxonomist and other researcher trying in this field. Due to be present irrigation services the flora; particularly cultivated flora has much difference from hilly area. The chief agriculture crops are wheat, fodder crops and barely. On hills different grasses, Acacia modesta, Achyranthus aspera, Calotropis procera, Xanthium strumarium, Opuntia littoralis and Sorghum halepense etc are commonly found. With the passage of time, increase in population and rising in need of facilities in the culture declining the natural habitats. Our result is similar with that of Khan et al. (2012). Mostly the Xerophytes such as Broussonitia papyrifera, Ficus carica, Ficus palmata, Morus alba, Eucalyptus camaldulensis, Eucalyptus lanceolatus etc are found on road sides. Such type of study was also taken by Khan et al. (2011a; 2011b; 2012; 2013). In the research area, commonly people depend on agricultural and domestic animals. They also collect medicinal plants, fodder, fuel wood and timber. The natural assets are being over-used, indistinct and spoil.

Comparisons of the percentage of the life form classes of the research area with Raunkiaer standard biological spectrum (RSBS), therophyte form the largest life form class and their percentage is more than thrice (47.73%) that of the RSBS (13%). The phanerophytes forms, the second highest class with (24.24%). Their percentage was 46.0 in the RSBS. Thus, the biological spectrum of the research area marker “Therophytic” Phytoclimate at the same time as this class proves the greatest deviation from the standard spectrum. Hemicry- ptophyte is equal (8.49 %) with that of the RSBS (9.00 %). Cryptophytes was less 2.42% than in the RSBS (6.00 %) (Figure 2). According to the Raunkiaer (1934) that climate of a region is characterized by life form. Plant species were identified and classified into major life forms to build biospectrum. The biological spectra is helpful to comparing geographically far and wide separated plant life and used as an indicator of prevailing environment. Biological spectrum may be significantly changed due to preface of therophytes like annual weeds, biotic pressure like agricultural practices and grazing, deforestation and trampling etc. The dominance of therophytic life form showed that the area was under heavy biotic pressure. Khan et al. (2011a; 2011b) and Khan et al. (2012) also agree with the same statement.

Figure 2 Comparison of biological spectrum of the area with Raunkiaer’s Standard Biological Spectrum (SBS)

In this region’s the plant face drought during winter especially in dry soil. The present study shows that leptophylls were high at the hilly area while microphylls and nanophylls were present in plain area. Species with large leaves take place in warmer wet climates while smaller leaves are characteristic of cold and arid climates and degraded habitats. A high percentage of microphylls might be due to dry climate in hilly area. Leaf size spectrum of the plant revealed that microphyllous species followed by nanophylls species were dominant in the investigated area. Microphylls are usually characteristic of steppes while nanophylls and leptophylls are characteristic of hot area (Khan et al., 2013; Tareen and Qadir, 1993). The soil was poorly developed with thin sheet that banned root penetration. Furthermore, roots absorb low moisture and nutrients under dry conditions. The species with microphyllous leaves were abundant due to ecological adaptation for these arid conditions. The present findings agree with those of Khan (2013) who reported high percentage of microphylls in the dry climate of Tehsil Takht-e-Nasratti. These data indicated that the percentage of various leaf form classes varied with increasing altitude. Khan (2013) and Khan et al. (2013) also observed that the percentage of microphylls was positively linked with the increasing altitude and this also hold up our findings. According Dolph and Dilcher (1980a; 1980b) large leaved species were dominant in tropical wet forest. This difference is mainly due to climatic variation such as temperature and wet tropical condition. The situation in our case is far more xeric than in the wet tropics. The size of leaves alone could not be used to identify specific leaf zone or climates. Other features of plants such as habit and root system might also play important role in biodiversity. An ecologically operating problem of the area is grazing, browsing, and trampling by domestic animals (Figure 3). These elements cause species not to reach its climax stage. Grazing is one of the depressing aspects, which has caused the reduction in vegetation (Khan and Hussain, 2012). In these processes the palatable species are selected and these make the non-palatable species to increase in hilly area. This can be noticeably seen in many places, which results in stunting growth and not reaching to flowering stage: so these are a danger of their extinction. The most important factors disturbing the flora of area are humidity, light, temperature, soil conditions, topography, elevation from sea level, rain fall and other forms of precipitation. On soil having high Nitrogen content are found Malva neglecta, Chenopodium album etc, as occurring near human duellings, on compost heaps and in back yards. The finding is similar with that of Khan et al. (2012; 2013), Khan and Hussain (2013) and Khan (2013).

Figure 3 Stunting growth of Accia modesta due to grazing

Collection and preservation
It presents a prospect to compose plant compilation and field interpretation throughout the flowering and fruiting of maximum quantity of species. Plant specimens collected from the area were dried and preserved. These preserved plant specimens were submitted to the Herbarium, Department of Biology, Federal Government College Mardan, Pakistan (Figure 4).

Figure 4 Collection of plant species during study in research site

Classification
The plant species were classified into different classes on the basis of different aspect like growth habit, life span, light frequency and moister.

Ecological characteristics
The plants were classified into different life form and leaf size classes as follows after Raunkiaer (1934), Muller and Ellenberg (1974) and Hussain (1989).

Aknowledgement
Authors are grateful to the local people and student of Federal Government College Mardan who have exposed valuable information of plant species and facilitate all way throughout the study. Special thanks to Mr. Ali Gul lecturer in statistics, FGC Mardan for providing company during research work.

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