Pasture Productivity Changes In Mongolia

Pasture Productivity Changes In Mongolia

Consistent with the diverse vegetation and soil, the pasture distribution is different in ecosystems. Pasture and hay land occupies 76.5 % of the total area and 99 % of the agricultural used land of the country. However, 94896.6 thousand ha of the total pasture is distributed in the steppe, 9367.8 thousand ha is in the mountain forest, 7376.1 thousand ha – in the high mountains, 28340.5 thousand ha – in the desert and 7185.5 thousand ha is in the meadows. We have analyzed the Natural zone map of Mongolia and tried to classify this map using long term NDVI data and the result was highly correlated (Fig. 3) with original map (correlation coefficient is 0.9619).


a	b

Fig. 3. Natural zones of Mongolia

a. National Atlas of Mongolia, b. NOAA/NDVI classification
This result could approve that NDVI data could be illustrate the natural zones more precisely. The mean NDVI values for each natural zone derived from time series analyzed NDVI data of 1982-2001 and in Table 2 showed NDVI values of each decade from June to August.

Table 2.

Mean NDVI of June-August for each natural zone

6_10 6_20 6_30 7_10 7_20 7_30 8_10 8_20 8_30

Forest steppe 0.31 0.37 0.42 0.45 0.46 0.47 0.47 0.48 0.46

Step-pe 0.21 0.22 0.25 0.27 0.30 0.33 0.34 0.36 0.36

Moun-tains 0.21 0.27 0.34 0.38 0.39 0.40 0.41 0.40 0.37

Desert steppe 0.08 0.08 0.09 0.09 0.09 0.10 0.11 0.12 0.13

Desert 0.04 0.04 0.04 0.04 0.03 0.04 0.04 0.04 0.05

By the changes of NDVI value of each zone we could estimate their vegetation condition. Further NDVI analysis based above

NDVI changes
By time series analysis of NDVI data, from 1982 to 2001 and calculated long term mean values for each month and for all year over whole territory of Mongolia within various natural zones. With comparison of above mean NDVI of each zone we could assess in which month and of which year its vegetation condition was lower or better than long term average.

To correlate them with peak standing biomass data we have analyzed NDVI deviation from the mean in July and August. And there are 2 different trends, and from 1982 to 1994-1995 NDVI deviation increased 0.33-1.1 values a year (green color trend) in different zones and then it decreased stronger than its increase and it reached – 0.87 to -2.78 values a year (blue color trend) up to 2001 (Fig. 4). We need to distinguish above statistical results that, these are corresponding to some climate variability or pasture degradation, related with increase of livestock numbers or they could present only natural changes of pasture or human impacts.

Fig. 4. NDVI deviation trends in different zones (July and August, 1982 – 2001)

Page 4 of 6
| Previous | Next |