In this case, porosity should be taken into account when considering the ��-�� relationship.There quality control are some models of the ��-�� relationship that do not fit with data in a certain range. For equations with one parameter, the model of [21] for mineral soil and the model of [20] indicate curves which tend to slow down the increase in permittivity at near saturation conditions of soil. Furthermore, equations with one parameter are also not able to cover all areas of the data.However, of the models that included a porosity parameter, apparently not all of them could explain the effect of porosity on the ��-�� relationship very well. From this study, only the equation proposed by [23] gives a fairly good conformity of data for different porosity values of soil.

AcknowledgmentThe authors would like to express their appreciation to the financial support provided by the Ministry of Higher Education (MOHE) of Malaysia.
Arnica montana L. (Asteraceae) is a rhizomatous herbaceous perennial herb and a medicinal plant widely used as a herbal remedy occurring throughout the entire range of the species, from South Norway and Latvia southwards to the Apennines and the South Carpathians [1]. This species prefers acid and poor soil conditions. It is mainly found in grasslands and shrublands and alpine mountain environments. A. montana also grows in dry pine forests, meadows on siliceous soils, marginal parts of spruce forests, open forest edges, mowing pastures, and margins of peatlands [2�C7]. The species is a component of the five habitat types of the Habitats Directive [8].

Eutrophication, habitat fragmentation, and agricultural intensification have led to a rapid decline in the mountain arnica in many European countries [9, 10]. A. montana habitats have been fragmented, especially at the edge of its dense geographical range [11]. The negative influence on the arnica population comes from such competitors as Dactylis glomerata [12], Agrostis capillaris [7], Deschampsia flexuosa, and Calamagrostis villosa [10]. Additionally, the main serious damage is caused by slug herbivores and the specialist fly Tephritis arnicae��highly specialized on A. montana, the only parasite found in mountain arnica flower heads being a limiting factor for the geographical and mountain altitude range of this species [13, 14].Arnica montana is a medicinally important plant species widely applied in pharmacy, homeopathy, and cosmetics.

Different plant parts such as inflorescences, rhizomes, roots, and leaves are collected for healing purposes. Arnica is a source of sesquiterpenes, essential oils, terpenoids, sesquiterpene lactones, flavonoids, and phenolic acids, especially chlorogenic acids [15�C17] and exhibits antiseptic, anti-inflammatory, antibacterial, antisclerotic, antifungal, and antioxidant activities [15, 18]. Recently, new derivatives of Anacetrapib chlorogenic acids in A.