The effect of water spreading system on the functionality of rangeland ecosystems

Journal ofJournal of Arid LandArid Land2012, 4(3): 292 -299doi: 10.3724/SP.J.1227.2012.00292Science Pressjal.xjegi.com; www.chinasciencejourmal.comThe effect of water spreading system on the functionalityof rangeland ecosystemsMohammad Rahim FOROUZEH, Mohsen SHARAFATMANDRAD*PhD Student of Rangeland Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49138 -15739, IranAbstract: In recent decades, the control of flods is an eficient management practice for the rebiltation ofrangelands in most arid and semiarid areas. To evaluate the benefts, we used the Landscape Function Analysis(LFA) method to assess the function of patches and qualitative capability of a rangeland ecosystem in Gareh By-gone region, Fars province, southwestern Iran. Landscape functionality depends on soil, water and nutrient (col-lectively clled "resources") conservation and use witin a given ecosystem. Many landscapes are naturally het-erogeneous in terms of resource control and possess patches, where resources tend to accumulate, and in-ter-patches. Assessing rangeland health and function of landscape patches in response to environment and man-agement can give rise to correct management decisions for qualitative improvement of the ecosystem. Therefore,our study area was divided into two parts, i.e. water spreading) and control parts, and sampling was done using LFAmethod in each part separately. Structural parameters, including the number, length and width of patches, and themean length of inter-patches, were determined by the method to characterize the functional status of the monitoringsites. For each patch/inter-patch type identifed in the trant organization log, we recorded its soil surface proper-ties clasified according to the Soil Surface Assessment Method. The density, canopy cover and composition ofplants were then assessed. The results showed that the number of ecological patches and their dimensions weresignificanty increased in the water spreading site. Soil stability and the values of nutrient cycling indices were in-creased but the infitrtion values were decreased in the water spreading site. It could be related to the effect ofsuspended materials transported by foods to the soils in the study area. The improvement of ecological patchesand rangeland ecosystem was achieved where water spreading systems were practiced. Therefore it can be con-cluded that water spreading as a management plan plays an important role in arid land ecosystem functionalit.Keywords: ecological patch; landscape funtion analysis; water spreading; arid landsThere is a close relationship between hydrologicalple qualitative monitoring procedure that uses rapidlyprocesses and vegetation, especially in water-limitedacquired field-assessed indicators to assess the bio-environments. In particular, vegetation pattern is ageochemical functioning of arid and semi-arid range-composite of fertile patches with high biomass andlands. In rangeland inventory studies, it is possible tobare open soil in such moisture regimes (Saco et al,judge the effects of management actions by using2006). Therefore, the understanding of processes thatfunctional analysis of ecological indicators.regulate resources in an ecological system and land-Controlling and spreading flood is one of the effi-scape is a fundamental step in ecosystem conserva-cient management practices in recent decades; floodion. Landscape functioning is dependent on the control has come to be considered as one of the mostconservation and use of soil, water and nutrient (col-effective actions for arid and semi-arid rangeland res-lectively called “resources") within the landscapetoration and rehabhilitatin (Fororeh 2007). Being si-system (Tongway and Hindley, 2004; Tongway and中国煤化工Ludwig, 2010). Landscape Function Analysis (LFA)Reccived 211-122Corresponding aY片CN MH G CEm santmintroduced by Tongway and Hindley (2004) is a sim- dnd@yahoo com)No.3 Mohammad Rahim FOROUZEH et al: The efeet of water spreading system on the functionality of rangeland ecosystems 293mple and reasonable in comparison to other endeavors(pastoralists and/or native residents). Monitoring will(Branson, 1956), water spreading plans are multipur-allow decision-making for qualitative improvement ofpose and effective options for restoring arid andthese ecosystems (Pyke et al, 2002). The ecohy-semi-arid rangclands (Forouzeh and Heshmati, 2005).drological viewpoint is dominative in new approachesTherefore, the LFA method was applied in this studyto rangeland management; in these approaches,to assess the effects of water spreading system on thepatches and inter-patches are considered as spaces thatpatch function and qualitative capability of rangelandhave different roles in retaining water and nutrients asecosystems. In rangeland inventory studies, it is possi-well as controlling erosion based on their naturesble to judge the effects of management actions by us-(Ghodsi, 2009). So assessing the functionality ofing functional analysis of ecological indicators.patches in rangeland ecosystems provides informationSoil and vegetation parameters that are consideredfor day-to- day management of rangelands on the scaleas representative ecological indicators of ecosystemsof a gcographical region that can aid administrative(Pyke et al, 2002) are quantitatively measurableprocedures and utilization of land based on their po-characteristics that indicate the dynamic condition of atential capabilities. By assessing patches and in-habitat or natural field (Pellanet et al, 2000). Detec-ter-patches, and monitoring, observing, detecting, andtion of changes occurring in the rangeland by the LFArecording their changes in natural ecosystems overmethod gives an understanding of natural processestime, it is possible to identify occurred ecologicaland provides more capability for converting data to anthresholds (Friedel, 1991) using soil and vegetationapplicable body of informnation for direct use by landindices (Andreasen, 2001) in the ecosysterms. Patchmanagers and supervisors. Rapidly acquired field-and inter-patch structurcs affct soil moisture in aridassessed indicators and simple tools to assess soil andand semi-arid zones, and thus determine soil erosionvegetation parameters are two strengths of the methodrate. A reduction in the size, number, spacing or effec-that duplicate its importance for use; environmentaltiveness of fertile patches may increase runoff andvariables were shown to have a very high degree oferosion in intense rainfall and cause landscape degra-dation (Saco et al, 2006).correspondence with measured indicators (TongwayOne of the important points of patch assessment isand Hindley, 2004). Plant patches or ecologicalthe consolidation of data from smaller units (patchpatches are arrayed in terms of amplitude and eco-scale) to larger units (plant species, communities andlogical nature of resources; plant communities are dis-landscapes) that can aid to make a good interpretationtributed based on the tolerance of various species toof rangeland condition (Tongway and Hindley, 2005).different environmental resources (Heshmati, 2003).For example, by knowing the structural parameters ofAssesing the ecological function of rangelands re-patches, relative distribution of patches in the range-quires the monitoring of both soil and vegetation fac-land can be determined, and also, by determining thetors and the understanding of them is an importantfunctionality in each patch and considering the relativestep in determining the site potential. By examiningdistribution of different patches in the landscape, it israngeland functionalty, current condition and trendpossible to predict the functional characteristics ofcan be investigated in relation to vegetation dynamics.rangelands (Ghodsi, 2009). Application of ecologicalFunctionality of arid and semi-arid rangeland ecosys-models that have long been used in rangeland studiestems around the world is extensively affected by eco-can facilitate the processing of data about patches as .logical and bydrological processes, and feedbacks andan aid to asssment and management planning.responses at different scales Noy-Meir, 1973; Wilcoxet al, 2003; Ludwig et al, 2005; Tongway and1 Materials and methodsLudwig, 2010).It is also important to monitor the health and func-.1 Study areational status of rangeland patches over time in re-The researct中国煤化工h Bygone, 200sponse to environmental change and management re-km southea:YHCNMH Gince (28935'N,gimes imposed by land users of such ecosystems53957'E; 1,140 m aslj. 1he area Is part of the arid294JOURNAL OF ARID LANDVol. 4rangeland ecosystems of Southwest Iran. It is char-LFA method in the water spreading and control sitesacterized by a mean annual precipitation of 259 mm.respectively along five 50-m transects with 150-mThe mean annual temperature is 20.6°C and regionalintervals that ran parallel to the slope gradient of theclimate is arid as potential evaporation exceeds pre-study area. Each transect includes the space coveredcipitation by a large extent.by patches as well as the distance between successiveThe study area is one of the eight watershed man-patches. Five examples of each identified patch/inter-agement stations in Gareh Bygone. For the conven-patch types were determined as replication and thereience of the study, this area was divided into twowere 11 soil surface indicators for each of the threeparts: water spreading site and control site. Thindices (stability, inflration, and nutrient cycling)250-hm2 water spreading site was irigated con-according to the methods of Tongway and Hindleytinuously for 30 years and the 10-hm2 control site(2005). To assess vegetation effects on soil indicators,was located west of the water spreading site (Fig.plant density was measured using Point Centered1)Quarter (PCQ) (Krebs, 1999) with a minimum of 201.2 Data collectionpoints on transects. Plant canopy cover and com- posi-Systematic-random sampling was done using thetion were also measured using line intercept method.IranShirazQare AghajFasaFasceBasinoyinceShur RiverofJahrom sub-basinPersian Gnlf53*50'E54°00'E54°10'ETo FasaBisheh Zard Basin2840N-t 28*40NBisheh Zard RiverRowsar( FWSystemTchah Qootch RiverTchah QootchoahroeroenonGareh Bygone PlainAhmad Abadproject siteGehrab Basin28930N-中国煤化工2830N53950'E5400'EMYHCNMHGFig. 1 The location of the Gareh Bygone water spreading system296JOURNAL OF ARID LANDVol. 4.Maximum area, if all transects were patches) in theThere was no significant difference between stabil-water spreading site and the control site was 0.03 andity and nutrient cycling indices in both sites (P>0.05),0.I, respectively. Landscape Organization Index thatbut the two indices have generally been increased inindicates landscape potential and capability in the wa-the water spreading site where the infiltration indexter spreading site was 2.15 times more than in thehas been decreased (Figs. 3- -5).control site (Tablc 1).2.3 Vegetation indices assessment2..2 Soil surface assessment indicatorsThe results showed that spreading flood water canRegardless of the number and arca of patches, the re-have meaningful effects on species canopy cover, sosults of assessment of 11 soil surfacc factors for thethat the canopy cover in the water spreading site wasthree indices of stability, infiltration and nutrient cy-increased morc than two fold than in the control site.cling in the water spreading site and the control siteTable 2 indicates the percentages of species composi-showed that grass patch had the highest stability indextion and canopy cover for diffrent growth forms.value and significant differences compared to theShrub patches have the highest percentages of canopyother patches, but there was no significant differencescover and species composition in both the waterbetween the other patches in respect to stability indexspreading site and the control site.in both sites (Fig. 3). All patches have no signifcantVegetation assessment showed that the densities ofdifferences in respect to infiltration index (Fig. 4). Theplants for the water spreading site and the control sitevalue of nutrient cycling index was highest for thewere 3,256 and 1,283 plant/hm", respectively; and theshrub-grass patch and the difference among the othermean intervals between plants were 1.3 and2.i m, re-patches was significant in both sites (Fig. 5).spectively. It should be noted that flood spreading hasTable 1 The means of quantiative characteristics and patch indices in the water spreading and control sitesLandscapePatchMean lengh(m)_ Length(%) Mean widh (m) Patch Area Index Landscape Organiztion IndexGrass0.430.750.030.581.960.62Shnub-grass1.229.20.11Water spreading siteForb0.3410.10.06Litter0.5614.0Bare soil0.6121.4Control sile0.154.10.380.100.27Shrub0.6618.40.47Shrub-grass0.2811.90.330.189.0.2112.4.1.8243.48 80p■Water spreading site食80a. Control sitei 70-■Water spreading sie60-男6。 Control siteb后5; 40复30fg 30-g 2020昌10员chrubGrass Shrb-Grass ForbGrass Shrub-Grass Forb Litter Bare soilFig. 3 Siability index of iferent patches without considering theFig. 4 Infiltration index of diferent patches without consideringnumber of patches; Different letters mean significance at P<0.05the number中国煤化工3n significance atlevel.P<0.05 level.1YHCNMH GNo.3Mohammad Rahim FOROUZEH et al: The efect of water spreading system on the functionality of rangeland ecosystems297E 70wind speed, air temperature and evaporation as the70「■Water spreading siteresult of restoration actions in arid rangelands. TheseControl sitechanges initially caused an increase of ephemeral spe-50cies, especially grasses. In general, the increase in thefive patches in the water sprcading site is indicative ofbpositive effects of water spreading plans on the re-20gion's vegetation; since moisture is the most importantlimitation of arid land soils (Rahbar, 2006), the im-provement of soil moisturc condition can account forShrub Grass Shrub-Grass ForbLitter Bare soilthese changes. The positive effects of water spreadingFig. 5 Nutrient cycling index of diferent patches without con-system on vegetation have been rcported by other re-sidering the number of patches; Different letters mean signif-searchers (Suleman, 1995; Forouzeh, 2007; Movahedcance among different patches at P<0.05 level.and Mosavi, 2007).The value of stability index of grass patches wassubstantial effects on shrub density so that there is asignificant increase in the density of shrub patches inhigher than at other patches in both sites probably be-cause of changes in the underground parts of grasses.the water spreading site.Underground parts of plants have an important role in3 Discussion and conclusionshe constitution of aggregation in both physical andchemical forms and lead to soil structure improvementThe value of Landscape Organization Index wasind thereupon surface soil compactness. One of thehigher in the water spreading site than in the controlunique characteristics of the studied grass patches issite, which was caused by the differences betweenhe formation of underground parts including rela-patch structure in the two sites, i.e. there was greatertively solid, thin and complicated rhizomes, scatterednumber, arca and uniformity of patches, especiallystolons and roots that extend to the 30-cm depth of soil.shrub and grass patches, in the water spreading site.Therefore they are able to protect the surface layer ofThe substantial increase in shrub species in the wa-soil. The value of the infiltration index was reduced iner spreading site was the consequence of seed trans-the water spreading site compared to the control site.portation by floods from uplands and good conditionThe reduction of the infiltration index value can befor plant establishment in alluvial sediments. Forouzehrelated to the following points (Rahbar, 2006):and Heshmati (2005) examined the effects of flood(1) Suspended material fills soil pores by forming aspreading plans on some vegetation characteristics andlayer with low permeability on top soil, closing sur-surface soil properties, and reported the substantialface soil pores and blocking the space between soilincrease of shrub species in water spreading sites.particles in depth.There was a positive response of some shrub species(2) Because of the absorption of dissolved cations into water spreading plans (Bayat Movahed and Mosavi,water and the tensile properties of ions, clay is swelled,2007). Researchers have also reported the reduction ofwhich decreases the free space between soil particles;Table 2 The means of canopy cover and species composition in the water spreading and control sitesCanopy cover (%)Species composition (%)Growth formWater sprcading siteWater spreading siteShrub24.8213.3743.752.3Perennial grass like4.402.309.0Perennial grass1.70.0Perennial forb3.60中国煤化工14.2Annual grass14.103.4013.5Annual forb7.402.92MYHCNMHG 11.0298JOURNAL OF ARID LANDVol. 4this swelling usually happens in cases where watertion in the top soil and organic matter increment im-contains organic matter and exchangeable ions such asprove N content of the soil (Rahbar et al, 2001). In-Na* and K*crease of organic carbon in the watcr sprcading site(3) It is possible that some of the dissolved materialcould be the result of processes such as the transportinfiltrates into soil and sediments, and closes the soilof sediments containing plant residuals from uplandspores because of chemical reaction, and thus reducesinto the water spreading system, the increase of vege-the infiltration rate.tation cover and litter in the water spreading site, and(4) Growth of algae and bacteria, especially whenthe increase of soil saturation percentage, which regu-water is rich in nutrients, causes biological clogging,lated soil temperature and increased soil microbial ac-and thus reduces permeability.tivities.The value of infiltration index of shrub and shrub-The vegetation density and canopy cover of differ-grass patches was higher than that of the other patchent growth forms showed a substantial increase in thetypes. It could be the result of extensive root devel-water spreading site compared to the control site. Itopment of shrubs, providing better condition for watercould be another reason for the increases of the twoinfiltration into soil.indices of stability and nutrient cycling as well asThe value of nutrient cycling index in the waterlandscape organization index in the water spreadingspreading site was higher than in the control site. It is .sitc. These results coincide with those of Tongway andthe result of an increase in the organic matter and NHindley (2004). In general, the results showed the im-content in the water spreading system. There is a closeprovement of ecological patches and rangeland eco.relationship between the amount of N and the increase systems where waler spreading systems were prac-of organic matter in arid lands since litter decomposi- ticed.ReferencesHeshmati G A. 2003. Multivariatedevelopment of a trrestrial index of ecological integrity. 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