Ganzorig Sumiya

HOSHINO Buho

Purevsuren Tsedendamba

Ts. Tserendulam

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1. Introduction Nomadic livestock husbandry is a traditional sector of Mongolia and plays an important role in Mongolian economy. Livestock husbandry is very sensitive and vulnerable to weather and climate and therefore greatly depends on pasture condition.Intensity and frequency of natural disasters,including droughts and dzuds are increasing sig-nificantly during the last few years because of climate change. These phenomena cause signifi-cant economic damages and losses. Recent studies are show that changes in climate of Mongolia manifest significantly in winter sea-son.??According to climate change studies conducted in Mongolia,during the period between 1940 and 2005,the annual average temperature in Mongolia has increased by about 1.9℃ and winter tempera-ture changes were even greater in the mountain-ous areas (2.0-3.7℃).The annual precipitation has been observed to decrease from the 1940’s to about the mid-1980’s,but has since shown signs of increasing in all areas except the Gobi desert area. Annual mean precipitation has been decreasing in central Mon-golia,but has been increasing in both the eastern and western regions of country. Seasonally,both winter and spring precipitation has decreased,while summer and autumn have registered no changes.??There is a significant change not only in precip-itation amount, but also in its type (synoptic-cyclone related or convective rain),frequency and coverage area.Between 1960 and 1998, precipitation varied greatly, both increasing and decreasing in Mon-golia. The frequency of relatively heavy rainfall events increased in the eastern Gobi desert and Altay Mountains in Mongolia.??Meteorological data of the Hustai National Park shows that seasonal dynamics of the precipi-tation follows the general trend that character-izes the forest-steppe belt of Mongolia. About 85 percent of the annual precipitation falls as rain during the summer,of which about 188.8 mm falls in May and August. Seasonal maximum precipi-tation (60.6 mm) is recorded in July. Seasonal minimum precipitation (2.8 mm) is recorded in January(Fig.1).Mongolian pasture’s growth dynamic and its correlation with weather and climate conditions were studied using meteorological and agro-meteorological regular observation data??, vari-ous maps and digital data of satellite NOAA/AVHRR data??.However, spatial and temporal patterns of NDVI in response to precipitation in Mongolian Steppe still aren’t well interpreted. Therefore itプレブスレン・ツェデンダンバ??，星 野 仏 方??，ガンゾリグ・スミヤ??，Ts.Tserendulam??(Accepted 14 January 2011)時空間NDVIデータを用いたモンゴル草原植生の降水応答Tsedendamba Purevsuren??,Buho HOSHINO??,Sumiya Ganzorig??,Ts.Tserendulam??Spatial and temporal patterns of NDVI response to precipitation in Mongolian Steppe??酪農学園大学大学院酪農学専攻酪農学研究科環境リモートセンシング研究室Graduate school of Dairy Science,Rakuno Gakuen University,582 Bunkyodai-Midorimachi,Ebetsu,Hokkaido 069-8501,Japan??酪農学園大学環境システム学部生命環境学科Department of Biosphere and Environmental Sciences,Faculty of Environment Systems,Rakuno Gakuen University,582 Bunkyodai-Midorimachi,Ebetsu,Hokkaido 069-8501,Japan??Hustai National Park,Mongolia J.Rakuno Gakuen Univ.,35(2):55～62(2011)is necessary to study the relation between vegeta-tion cover and precipitation. Remote sensing technology and methods have proved to be very useful for monitoring of vegetation cover.2.Materials and methods 2.1 Site description and materials Study sites are (Hustai National Park (HNP),47°35′N-47°52′N, 105°23′E-106°00′E elevation 1100-1840 m)situated in the steppe zone in the southwest part of Mongolia,characterized by the pale and dark brown soil,Stipa klemenzii,Convol-vulus ammanii,Caragana sp.,Poa sp.steppe com-munity(Fig.2).The annual (mean) air temperature at the Hustai National Park is 3.5℃ to 0.3℃. The annual monthly average temperature of the col-dest month,January,is－20.2℃ to－27.4℃ in the steppe zone. July is the warmest month. The average air temperature in July is 17.1℃ to 20.9℃.About 80% of annual precipitation occurs in June,July and August (126.7-279 mm). The driest 56  Tsedendamba Purevsuren et al Fig.1 Mean monthly precipitation amount during 2003-2009 at Hustai National Park.Fig.2 Location of the study area.months are from November to March (1.2-31.5 mm). In general,the amount of precipitation in Mongolia is low and varies from 131.1mm to 291.2 mm in this region.??2.2 Data and methods 2.2a.Meteorological variables or ten-day precipi-tation data sets for June 2003 to August 2009,were obtained from HNP meteorological station.2.2b. Pasture plant biomass has been measured with standard methods at the test plots located in the HNP from June 2003 to August 2009.2.3.1 Satellite data NDVI data includes a 10-day composite SPOT VEGETATION (VGT)data set(with 1 km resolu-tion)from June of 2003 to August of 2009 (http://free.vgt.vito.be/home.php).NOAA NDVI data (with 8 km resolution and 15 day)used in this study were processed by in the GIMMS group at NASA.Many experiments have shown that several math-ematical combinations of the 0.55-0.68 μm and 0.725-1.10μm wavelength data on pasture vegeta-tion provide important information on pasture vegetation condition. The parameter is called“Normalized Difference Vegetation Index”(NDVI), which is derived from the visible red(RED) and near-infrared (NIR) spectral bands:NDVI＝(NIR-RED)/(NIR＋RED)??The NDVI was calculated from SPOT VGT data by using the combinations of bands 2 (0.61-0.68 μm) and 3 (0.78-0.89 μm) NDVI＝(Band3-Band2)/(Band3＋Band2).Then, a yearly NDVI anomaly during the warming season (June to August)was calculated as follows:NDVIσ＝｛((NDVIα)/(NDVIμ)-1)100｝where NDVI??are the respective(June to August)percent anomalies, NDVIα are individual sea-sonal (June to August)means,and NDVIμis the long term (June to August)mean.3.Results 3.1 Spatial distribution of NDVI in Hustai National Park.We have analyzed the distribution and long terms vegetation dynamics. The mean NDVI values in HNP’s were highest during 2003,2006,2009,and lowest in 2005,2007(Fig.3). The first Spatial and temporal patterns of response to precipitation Mongolian Steppe Fig.3 Spatial distribution of the mean NDVI changes in HNP during August (1?10 day)of 2003-2009 57 decrease in mean NDVI registered in 2004 and lowest was in 2005. However, in 2006, again NDVI values were very high and comparable with those of 2003. So far, generally (from 2003 to 2005,and from 2007 to 2009)spatial distribution of NDVI has changed in accordance to values of precipitation. As it mentioned above, despite very low precipitation uncharacteristically high NDVI values registered in 2006.In general,the precipitation has been continuos-ly decreasing from 2003 until 2007,however that trend was not followed with means of NDVI(Fig.4). Especially in 2006, despite low amount of precipitation uncharacteristically high mean NDVI was registered.Considering average precipitation level, 2003,2004 and 2009 were recognized as wet years (172 mm,158.8 mm and 243.8 mm,respectively),while the dry year period continued from 2005 to 2008(138.2 mm 2005,125.6 mm in 2006,90.1 mm in 2007)(Fig.4b)3.2 Relationship between NDVI and precipita tion-Fig.5 shows that due to the rain the NDVI values slowly increased with 10 and 20 days time lag.(Fig.5b, 5c). However, cortelation values were low.In the wet year of 2003, positive correlation between amount of precipitation and NDVI was observed at 10 days time lag base (Fig.6b).However, during 2007 period the correlation co-efficient was higher at the 20 days time lag (Fig.7c).3.3 Monthly and10 day time series patterns Fig.8 Shows mean NDVI changes of average 10 days NDVI during 2003-2009. Maximum NDVI value(175.4)was recorded in August and minimal NDVI (66.9)recorded in June.Fig.9 and Fig.10 shows seasonnal in the aver-age of monthly NDVI for HNP’s during 2003-2009. NDVI value in July showed a increase trend.3.4 Trends in spatial variations of NDVI.Fig.11a,11b shows the Hovmo?ller diagram of NDVI patterns during 2005-2006 year. We also have analyzed the NDVI change. The HNP’s NDVI maximum value was 0.8, and minimum Fig.4 Changes in mean NDVI (Fig.4a)and precipitation (Fig.4b)in Hustai National Park during 2003-2009 Fig.5 Relations between NDVI and precipitation during 7 year period.58  Tsedendamba Purevsuren et al value was 0.08. NDVI higher values ranging 0.4-0.8 were distributed over the north-west of the NHP. Lower values of 0.08-0.1 dominate in middle part and south.3.5 NDVI anomaly index.While the period from 2003 to 2009 was dominat-ed by above normal conditions with 71% of the Fig.6 Relations between NDVI and precipitation in 2003 year(a-2003,no time lag,b-2003,10 days lag,c-2003,20 days lag).Fig.7 Relations between NDVI and precipitation in 2007 year(a-2007,no time lag,b-2007,10 days lag,c-2007,20 days lag).Fig.8 NDVI changes between June-August,2003-2009 (10 days)Fig.9 NDVI value between June-August,2003-2009 59 Spatial and temporal patterns of response to precipitation Mongolian Steppe years showing above normal NDVI conditions,the severest departures in NDVI occurred in 2003-2004,2006 and 2008-2009.Fig.12, (Table.1)NDVI anomaly stores (－/＋)showing persistence patterns of below normal or above normal vegetation conditions 4.Summary and Conclusion Understanding of recent trends of vegetetion cover changes and its relationship with climate change will help acquire a more accurate predic-tion of vegetation cover changes. The accurate prediction of vegetation cover is essential in reducing loss and damages to the economy of the country. Vegetation cover activity appears to control rainfall.Both precipitation and mean NDVI were very variable between 2003-2008 in the HNP. The highest amount of precipatation observed in 2003,lowest in 2005 and 2007. And highest value of NDVI observed in 2006 and 2008, lowest in 2005 and 2007.(Fig.4a,4b).The correlation observed between NDVI and precipitation in 10 to 20 days,highest was lag in 10 to 20 days observation in 2007. And 20 days lag happened to be the best predictor in this case.The correlation observed between NDVI and precipitation in 2003 and 2009 was insignificant.Fig.10 Time-Longitude section of monthly NDVI from Jan-Dec,2003-2006 Fig.11a Spatial distributions of NDVI in dry year (Aug,2005)60  Tsedendamba Purevsuren et al Iwasaki??observed strong relationship between precipitation and NDVI. He has found that dur-ing 1993-2000, 10-30 days lag correlations was between precipitation and NDVI in the steppe vegetation zone of Mongolia.NDVI data alone with means of precipitation could not describe productivity of the pastures in condition of Mongolian steppes. For an accurate analysis we need more data on air and soil tem-perature and soil moisture. Also for the precise analysis,data on the pasture use by different kind of herbivores and in closures without grazing impact is required.In this study the temporal and spatial response of 10 days of SPOT vegetation and precipitation was analyzed using data from June 2003 to August 2009 and the main results were as follows:1.The maximum response of mean NDVI to precipitation had a lag of about 20 days.2.In 2007(dry)year,the response of mean NDVI to precipitation had lag of about 20 days.3.In 2003(wet)year,the response of mean NDVI to precipitation had lag of about 10 days.4.Annual mean NDVI and precipitation in-creased on 0.65%,0.8%,respectively.5.Calculated NDVI anomaly indices were sever-est in 2005 and 2007.6.Acknowledgements The study was sponsored by the Rakuno Ga-kuen Unvirsity Joint Resesearch Project and Grand-in-Aid for Scientific Research Project and Grand-in-Aid for Scientific Research, (Project leader Prof. Yoshihito Shimada)of Japan Soci-ety for the Promotion of Science.The study was also supported by the NAM-HEM and HNP’s admiistration. We would like to thank Oyun (University of Agriculture), N.Bandi(HNP)Ts.Tserendulam(HNP),Kh.Oyun-bileg (HNP), N. Bayaraa (Altanbulag soum),Fig.11b Spatial distributions of the trends in NDVI from Aug,2006 Fig.12 Mean NDVI changes in Hustai National Park during 2003-2009 Table.1 Mean NDVI changes in Hustai National Park Year  2003  2004  2005  2006  2007  2008  2009 Anomaly ＋ － － ＋ － ＋ ＋61 Spatial and temporal patterns of response to precipitation Mongolian Steppe Marie Samamukai and the staff of the Labora-tory of Environmental Remote Sensing, Rakuno Gakuen University.Reference 1)Natsagdorj et al.,2001,Some aspect of assess-ment of the dzud phenomena,3-18, Papers in Institute of Meteorology and Hydrology Ulaan-baatar.2)Batima P., Natsagdorj L., Gombluudev P.,Erdenetseteg B.,2005.Observed climate change in Mongolia. AIACC Working Paper, vol.12,pp.12-16 3)Endo., 2006. Climatology and Trends in Sum-mer Precipitation Characteristics in Mongolia for the Period 1960-98.Journal of the Meteoro-logical Society of Japan 84.543-551,4)Dagvadorj, 1996 Climate change issues in Mongolia,79-88,Papers in Hydrometeorology Ulaanbaatar.5)M.Erdenetuya, 2004. “Pasture productivity changes in Mongolia”Geospatial Application Papers.6)Adiya Ts., 2000. The climate condition of Hustai National park. Research report of Hustai.7)Tucker,C.J.(1979)Red and photographic infra-red linear combinations for monitoring vegeta-tion. Remote Sensing of Environment 8:127-150 8)Anyamba A, Turker C J, 2005. Analysis of Sahelian vegetation dynamics using NOAA-AVHRR NDVI data from 1981-2003., Journal of Arid Environments Vol.63(2005)596-614 9)Iwasaki H,2006.Impact of Interannual Varia-bility of Meteorological Parameters on Vegeta-tion Activity over Mongolia. Journal of the Meteorological Society of Japan Vol.84(2006),No.4 pp.745-762要 約降水量はモンゴル国の社会経済発展を制限する主な要因の一つである。従って，近年，モンゴルの気候変動，降水量の変化に対する植生生産力の応答の研究はほとんどない。本研究では，人間の影響が少ないモンゴル国のホスタイ国立公園を研究対象地にして，降水量とNDVIの時系列変化のパターンを解析した。時・空間的な変化は SPOT VEGETATION衛星のNDVIデータに基づいて分析した。その結果，全体的に，モンゴル国ホスタイ国立公園の北部の自然植生の降水量の変化に対する応答は，降水イベントが起きた後，時間的遅れ（delay）があり，10日間と20日間後，最も相関があることが確認された。Abstract Rainfall is one of limiting factors of socio-economic development of Mongolia. Therefore, detailed studies of climate change and variability of precipitation and vegetation cover in Mongolia,using recent data is of fundamental importance. In this study,temporal patterns of normalized difference vegetation index (NDVI)in relation to precipitation in Hustai National Park of Mongolia are analyzed. The spatial and temporal changes have been analyzed based on the SPOT vegetation NDVI data.NDVI from the SPOT vegetation data,at a spatial resolution of 1 km and 10 day intervals,are used to investigate the vegetation variations in Mongolia during the period from 2003 to 2009. Then,RS is used to examine the relationship and NDVI in Mongolia, and the value of NDVI is taken as a tool for drought monitoring. The results showed that in the study period,Mongolia vegetation cover tended to increase,with the annual mean NDVI having increased by 0.65%.The results indicated the response of vegetation NDVI value to the variation of precipitation in northern part HNP. Vegetation NDVI value maximally responds to the variation of precipitation with a lag of about 10 days 20 days in vegetation period.Examination of NDVI time serials reveals that during the period of 2003-2009 marked by low values below average NDVI,there was a persistence of drought with a signature drought during 2005 and 2007. The same period was marked by a wetter trend with HNP-wide high values above average NDVI and a maximum level occurring in 2006 and 2008.If NDVI value and precipitation event were taken into account,then high correlation was observed in wet years and low or no correlation in dry years.ndamba Purevsu 62  Tsede  n et re  l a➡ここます★から送りつめて

時空間NDVIデータを用いたモンゴル草原植生の降水応答

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時空間NDVIデータを用いたモンゴル草原植生の降水応答

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