Journal of Rangeland Science, 2014, Vol. 4, No. 3 Kavandi Habib et al. /234 Contents available at ISC and SID Journal homepage: www.rangeland.ir Full Length Article: Comparison of Ecological Patches' Potentials and Functions in Rangeland Ecosystems (Case Study: Qahavand Rangelands, Hamedan Province, Iran) Reza Kavandi HabibA, Gholamali HeshmatiB, Hamid SiroosiC APh.D. Student of Rangeland Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Golestan, Iran (Corresponding Author), Email: [email protected] BFaculty Member of Rangeland Sciences, Gorgan University of Agriculture and Natural Resources, Golestan, Iran CPh.D. Student of Rangeland Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Golestan, Iran Received on: 13/04/2014 Accepted on: 11/08/2014 Abstract. Interrupting the processes which control ecosystem resources has dramatic impacts on the rangeland conditions. To protect ecosystems and landscape, it needs to understand the ecosystem processes which regulate the ecosystem resources. As main components of ecosystems, patches and inter-patches play important roles in energy and materials cascade. Ecologically, functional parameters such as stability, infiltration and nutrient cycling serve as key factors determining the movement of sediments, nutrients and organic matter as well. The present research aims to evaluate and compare the ecological patches of grasses, shrubs and mixed grasses- shrub using indices of stability, infiltration and nutrient cycling. Therefore, sampling was carried out in Qahavand rangelands located in the south east of Hamadan province, Iran on three patches of grass (Cynodon dactylon), shrub (Camphorosma monspeliaca L. and Astragalus microcephalus) and mixed grasses- shrub (Camphorosma monspeliaca + Cynodon dactylon) to evaluate the aforementioned parameters. Samples were taken along three 50 m transects using LFA (Landscape Function Analysis) method. Three indices of stability, infiltration and nutrient cycling and their individual contributions on the whole ecosystems' functions were determined. Results showed that all three patches vary significantly in function so that the mixed patch (Camphorosma monspeliaca + Cynodon dactylon) may be accounted for the highest values among the others. The study area had a good level of stability and nutrient cycling while infiltration rate was moderate mainly due to much proportion of clay in soil texture. Somehow, results of soil profile study in the area imply good stability and moderate infiltration. Key words: Ecological patches, Stability, Infiltration, Nutrient cycling J. of Range. Sci., 2014, Vol. 4, No. 3 Comparison of …/ 235 Introduction Wise protection of ecosystems needs to some soil surface properties are closely understand the ecosystem pathways tied to soil stability. In respect to controlling resources. Patches and inter- empirical data and theoretical predictions patches are integral parts of ecosystems within most landscapes, some resources affecting the transportation and storage including water, organic matter and materials (Tongway and Ludwig, 2002). nutrient cycle are characterized by Patches may be found as single plant, patched distribution (Noy-Meir, 1973; stone or any other object conserving the Tongway, 1995). This pattern in turn resources (Whitford, 2002). Pattern and improves productivity (Montana et al., dynamics of patches represent the main 2001; Noy- Meir, 1973) emerging as characteristics of vegetation. Most spatially heterogeneous vegetation along researchers have emphasized on the with perennial species surrounded by importance of patch structure as a fertile soil matrix. Vegetation and soil determinant of ecosystem functions parameters as the main ecological indices (Fahrig and Paloheimo, 1988; Pickett and (Pyke et al., 2002) are known as White, 1985). quantifiable measures showing dynamical Patched structure in vegetation state of a given habitat or landscape communities frequently leads to some (Pellanet et al., 2000). differences in survival, reproduction and To shed lights on the changes migration of single species, life forms, occurred in rangeland by LFA method etc. (Fowler, 1984; Gibson, 1988 a, b). facilitates understanding the natural Such heterogeneity not only is resulted processes, providing data transformation from changes occurred in the abiotic potential in the form of useful components of environment, but also information to be used directly by users, may be due to biotic components (passive managers and practitioners of rangelands. and active). Getting aware of surface soil Vegetation or ecological patches are conditions seems to be essential. This distributed in terms of magnitude and helps us to conceive rangeland potentials ecological nature of resources. However, and soil properties among many others. vegetation associations are arranged Nearly, all erosion types occur as a result according to the tolerance of different of low soil infiltration and its instability species to varying environmental (Rezaei et al., 2006). resources (Heshmati, 2003). Patchiness in Wide varieties of vegetation are vegetation and soil varies in spatial scales affected by environmental factors from rangeland to basin scales (Li et al., including climate, soil and topography. 2008) as well as individual plant species Establishment of different vegetation (Fahrig and Paloheimo, 1988; Fowler, types due to vegetation ecological nature 1984). Distribution of resources and distribution is based on the controlled by vegetation and soil in turn adaptation of various species to soil results in accurate regulating landscape conditions and environmental agents functions and subsequently production (Heshmati et al., 2007). The relationship and diversity (Rahbar, 2006; Tongway, between vegetation and environmental 1995). It is worthy to note that discrete vegetation is found to be an important nature of vegetation is resulted from point promising the sustainable various erosion and deposition processes utilization, conservation and evaluation as well as complicated interactions of rangelands. As an indispensable part, between individual plants and soil has a considerable importance for surrounding soil matrix (Fowler, 1984; vegetation and others components. Tongway and Ludwig, 2002). Large According to soil science literatures, vegetation patches play enormous Journal of Rangeland Science, 2014, Vol. 4, No. 3 Kavandi Habib et al. /236 ecological roles while providing many underground parts like complex and advantages for rangeland landscapes strong rhizomes, branched stolon and (Forman and Colling, 1995). As a result, roots penetrating to soils deeper than 30 a given landscape will lose major parts of cm (Rahbar et al., 2001). it without big patches. At the same time, Given above discussion, evaluating those landscapes characterized by large the contribution of grass and shrub patches would not have some benefits patches to the rangelands' landscape has and advantages. On the other hand, those been done frequently. To understand this small vegetation patches act as a corridor subject seems to be crucial to predict how or springboard to vegetation colonization, arid and semiarid systems respond to the harbor rare species and small habitats anthropogenic and environmental sharp while improving diversity and changes (Tausch et al., 1993). heterogeneity in the habitat for those Hence, to satisfy this end, the varying species restricted to small patches. functions and structures related to Hence, small patches are of more rangeland patches as well as their advantages than the bigger ones. They implications in the whole ecosystem may serve as the supplement of large components should be evaluated. The patches instead of their substitution. present research aims to shed lights on Increased shrubs within a landscape exert functional and structural changes of some spatial changes in soils (Schlesinger ecological patches and its contribution in et al., 1996), change resource flow the whole ecosystem stability using three among shrub batches and inter-patches indices of infiltration, stability and (Li et al., 2008) and finally, strengthen nutrient cycling. shrubs consistency and durability Materials and Methods (D‘Odorico et al., 2007). Air and windburn nutrients, litters, Study area decomposed materials and seeds are The study was conducted in Qahavand accumulated under shrubs' canopy cover rangeland (Shara district) located in south while increasing the infiltration capability eastern Hamadan province at 33°58´ to (Bhark and Small, 2003). Nonetheless, 35°44´ N and 48°49´ to 33°28´ E. those bare inter-patches are exposed to It is nestled in 1574 m above sea level. high temperature and evapotranspiration. Study area is characterized by shallow Subsequently, their organic nitrogen saline gravels and some calcareous decomposition, denitrification and materials' accumulation. According to ammonium volatilization are lessened soil taxonomy, this is fall into American with the erosion emergence and low classes, Fine loamy, Sodic, Thermic Type landscape function (Schlesinger et al., and Haplo Calcides and pH ranged from 1990). The combined effects (outcomes) 7.3 to 8.8 poor in organic matter that is of such processes strengthen fertile less than 1% (Ahmadian et al., 2010). islands around shrubs by which shrubs As it can be seen from high EC value, get more tolerant against environmental these soils are mostly saline. Soils have adverse impacts (Schlesinger et al., 1996; poor drainage consisting