Past and present climate change impacts on rangeland production

1. Past and present climate change impacts on rangeland production Bolortsetseg B., Erdenetuya M., Sanjid S., Manibazar N., Gantsetseg B., Bat-Oyun Ts.

2. Impact of climate change • Introduction to rangeland • Rangeland productivity • Pasture carrying capacity • Plant phenology • Plant population • Land cover change • Modeling of rangeland ecosystem

3. Introduction to rangeland • The total agricultural used land - 130541.3 thousand ha in Mongolia • Pasture – 97.5 % (127307.0 thousand ha) • Hay – 1.5 % (1986.6 thousand ha) • Agricultural land per person - 53.8 ha (20 times the world average) • Livestock –23.6 million • Scientific research of vegetation has started since 1950 by Russian scientists and national specialists. • Geobotanical field surveys were done in 1950-1955, water resource exploration expedition in 1959-1961, rangeland mapping and expedition in 1991-1992.

4. Rangeland ecosystems • The high mountain belt • The mountain taiga belt • The forest steppe • The steppe • The desert steppe • The desert

5. 0.01 -0.01 0.01 -0.05 -0.03 -0.03 -0.06 -0.05 -0.07 -0.06 the forest steppe Ecosystem N of stations time series 4. Jun 14. Jun 24. Jun 4. Jul 14. Jul 24. Jul 4. Aug 14. Aug 24. Aug peak -0.04 -0.07 -0.06 -0.07 -0.07 -0.07 -0.05 -0.05 the steppe the forest steppe 18 16-31 1.3 1.9 2.5 3.0 3.6 4.3 4.9 5.3 5.3 5.9 the steppe 13 19-34 1.2 1.5 1.8 1.8 2.0 2.3 2.7 2.8 2.8 3.0 0.00 -0.01 -0.02 -0.02 -0.01 -0.02 -0.01 -0.01 -0.02 the Altai mountains the Altai mountains 5 17-24 0.7 0.7 0.9 1.0 1.1 1.3 1.3 1.4 1.3 1.7 -0.01 -0.02 -0.04 -0.01 -0.01 -0.01 0.00 -0.02 -0.01 -0.03 the desert steppe the desert steppe 18 17-29 0.7 0.8 1.0 1.0 1.2 1.4 1.5 1.6 1.7 2.2 -0.01 -0.03 -0.04 -0.05 -0.06 -0.05 -0.07 the desert the desert 2 18-21 0.6 0.7 0.8 0.9 1.2 1.2 1.4 1.5 1.4 1.7 Rangeland biomass Biomass, 100kg/ha • Data: Rangeland monitoring biomass data of 64 sites for 1966-2001 Changes in biomass, g/m2/1year

6. Rangeland biomass (continued) • Peak biomass trend at Arvaiheer (steppe), Erdenemandal (forest steppe), Mandalgobi (desert steppe), Ulgii (Altai mountains)

7. Ecosystems based on average biomass taking account of biomass decrease the forest steppe 15090140 12223013 the steppe 11065023 7413566 the Altai mountains 957624 737370 the Gobi desert 17417462 12192224 total 44530249 32566173 Pasture carrying capacity • The total pasture carrying capacity - 44.5 million sheep unit based on average observed peak biomass. • Based on the decreasing trend of peak biomass by 20-30 %, the total pasture capacity was calculated as 32.6 million sheep unit. • Past 40 years the total pasture carrying capacity was drop down by 27 % because of biomass decrease.

8. Ecosystems based on average biomass taking account of biomass decrease the forest steppe 15090140 12223013 the steppe 11065023 7413566 the Altai mountains 957624 737370 the Gobi desert 17417462 12192224 total 44530249 32566173 Pasture carrying capacity • The total pasture carrying capacity - 44.5 million sheep unit based on average observed peak biomass. • Based on the decreasing trend of peak biomass by 20-30 %, the total pasture capacity was calculated as 32.6 million sheep unit. • Past 40 years the total pasture carrying capacity was drop down by 27 % because of biomass decrease.

9. Plant Ecosystem N of stations time series, years emergen-cy heading Flowe-ring seeding Senes-cence Trend-emrg Trend-Sensc. Cleistogenes the steppe 5 18-25 5/13 7/29 8/17 9/6 9/18 -0.14 -0.34 Cleistogenes the Altai mountains 1 27 5/16 6/26 7/30 8/25 9/13 0.65 -0.31 Cleistogenes the desert steppe 11 16-30 5/24 7/14 8/17 9/8 9/16 -0.01 0.14 Stipa the forest steppe 17 15-32 5/9 7/4 7/28 8/21 9/11 -0.49 -0.12 Stipa the steppe 14 14-34 5/8 7/7 8/3 8/26 9/15 -0.46 -0.04 Stipa the Altai mountains 5 18-29 5/15 6/18 7/12 8/10 8/31 0.00 -0.75 Stipa the desert steppe 14 19-32 5/11 6/19 7/13 8/5 9/6 0.07 -0.11 Stipa the desert 2 22-24 5/3 6/11 6/21 7/17 9/9 -0.03 0.30 Plant phenology • Phenological date of 8 dominant plants such as Agropyron sp., Cleistogenes sp., Festuca sp., Leymus chinensis, Stipa sp., Carex sp., Allium polyrrhizum and Artemisia frigida was analysed and defined their trends. Time series longer than 15 years were selected for the analysis. • Plants emergency is tend to start earlier in the forest steppe and the steppe. In the Altai mountains, the desert steppe and the desert some of plants (Artemisia frigida, Stipa sp.) have had delayed onset trend. • Plant senescence occurred earlier in the forest steppe, the steppe and the Altai mountains, later in the desert steppe and the desert.

10. flowering season in 1970 years in 2000 years No of species % No of species % spring 9 16,6 15 27,0 the whole summer 15 27,8 18 31,6 summer 23 42,6 2 3,5 autumn 7 13,0 14 24,5 not stable 8 14,0 Source: Sanjid, 2002 Plant phenology (continued) • Because of extended drought, some plants such as Allium polirrhizum, Rheum nanum, Limonium tenellum, Ferula bungeana and etc. have not flowered and develop just after rain. • As a result, summer flowering plants have been become to flower early spring or late autumn and flowering occurred indefinite time. • Some plants such as Pulsatilla, Caragana sp. have flowered in autumn which is considered as plant special responces to environmental negative effects. • Flowering rhythm changes in the desert steppe

11. Plant population Source: Manibazar N Plant composition and species number changes of communities with Leymus - Potentilla bifurca, Leymus chinensis – Stipa krylovii, Agrostis mongolica – Carex orthostachys, Carex orthostacys – Potentilla anserine in Orkhon meadow. Due to field survey of communities with Leymus - Potentilla bifurca, Leymus chinensis – Stipa krylovii, Agrostis mongolica – Carex orthostachys, Carex orthostacys – Potentilla anserine,plant composition and species numbers in autumn of 2002 are more than in the beginning of 1980 years that those years were very dry, but less than in the middle of 1980 years. In some sources, biomass of low nutrient plants increased and production of high quality plants decreased because of intensified grazing.

12. Land cover change 1992 1997 2002

13. Modeling of rangeland ecosystem • Century 4.0 is used for the study. • 37 sites in different ecosystems were selected. • 0.5x0.5 0 grids were prepared. • Monthly climate data were input. • Soil data () for sites and grids were defined in the model. • Plant composition C3:C4 was defined • The average annual nitrogen (N) fixation rate was defined as 0.2 to 0.8 g/m-2 year-1.

14. Modeling of soil organic matter • Soil organic C • Soil organic N Comparison of simulated and actual steady state soil carbon and nitrogen

15. Soil organic matter changes for past 40 years • Soil organic C According to soil organic matter changes distribution, soil organic matter raised in the north part of the forest steppe and the eastern steppe. Generally in the southern part of the country had decreased trend of soil organic matter. • Soil organic N

16. Simulation of rangeland biomass • Simulated aboveground live peak biomass, g/m2 • Comparison of simulated and actual biomass

17. N Ecosystem NPP, g/m2 simulated biomass, g/m2 measured biomass, g/m2 change in simulated biomass, %/40 years change in rain, %/40 years 1 The forest steppe 584.5 179.5 71.7 -11.84 -1.58 2 The steppe 418.4 119.7 47.1 -12.31 -3.07 3 The Altai mountains 198.8 36.8 16.3 19.76 16.26 4 The Gobi desert 142.1 24.0 21.3 21.30 12.38 Rangeland peak biomass changes Annual NPP, biomass and biomass and rainfall changes for 1961-2000 years

18. ecosystem April May biomass, g/m2 biomass change, g/m2/1 year precipitation change, cm/1 year biomass, g/m2 biomass change, g/m2/1 year precipitation change, cm/1 year the forest steppe 26.75 -0.20 -0.01 50.27 -0.34 -0.12 the steppe 14.97 -0.04 -0.01 32.60 -0.18 -0.01 the Altai mountains 4.53 0.04 0.00 13.13 0.05 0.01 the desert steppe 2.54 0.01 0.00 5.74 0.01 0.00 Rangeland spring biomass and its changes Spring biomass and biomass and precipitation changes

19. Thank you for your attention