Correlation of NPP with Climate Variability

4.5.4 Correlation of NPP with Climate Variability

Historical of climate data show that Kalimantan terrestrial has experienced substantial with inter-annual variations and spatial variations in temperature and rainfall during the study period and tightly associated with ENSO. However, ENSO has correlated with temperature and precipitation. Correlation between NPP and climate variability in this study are used as estimation data during normal year in 2005 and during ENSO year 2006 El Nino Event and 2007 La Nina event. 10 20 30 40 50 60 70 80 90 100 J an- 1 Ju l- 1 J an- 2 Ju l- 2 J an- 3 Ju l- 3 J an- 4 Ju l- 4 J an- 5 Ju l- 5 J an- 6 Ju l- 6 J an- 7 Ju l- 7 J an- 8 Ju l- 8 J an- 9 Ju l- 9 J an- 1 Ju l- 1 Time gC m -2 m ont h -1 24 24.5 25 25.5 26 26.5 27 o C NPP Mean TEMP Mean Figure 14 Time series data of NPP and Temperature in Kalimantan Figure 14 illustrates changes in the amount of monthly mean of NPP and average temperature in Kalimantan between 2001 and 2010. During the 10-year period, the amount of both monthly mean of NPP and average precipitation varied a lot and the two graphs showed many upward and downward trends. The figure of temperature peaked in May 2010 and that of NPP in April 2010. During normal year, average maximum temperature reached on April, May, and June and decreased in other monthly period. In addition, average maximum of precipitation reached in November, December, and January and for the other monthly period until July the precipitation decreased. Distribution of the monthly mean of NPP show an increase in April and May and in other monthly period until August the NPP distribution was stable. Increased of NPP occurs in the month of May. During El Nino year, average maximum of temperature reached in May and other monthly period temperature was decreased. However, average maximum of precipitation reached in December and decreased in other monthly period, meanwhile in October to November the precipitation increased. The distribution NPP value showed an increase until May and in other monthly period until October the NPP distribution was decreased. Increase of NPP occurs in April followed with increasing in precipitation. During La Nina year, average maximum of temperature reached in April and decreased in other monthly period. However, maximum average of precipitation was reached in December and decreased during other monthly period, meanwhile in July to December the precipitation increased. The monthly mean distribution of NPP value showed an increase in April and in other monthly period until June, the NPP distribution was pretty stable. However, an increase of monthly mean of NPP distribution occurs in August followed with an increase of precipitation during this period. Chart Title y = 0.0196x + 24.477 R 2 = 0.3202 24.8 25 25.2 25.4 25.6 25.8 26 26.2 26.4 26.6 26.8 27 20 40 60 80 100 TEMP Mean Linear TEMP Mean Figure 15 Correlation between NPP and Temperature data in Kalimantan Fig the ave ure 15 shows that the average of NPP was moderately correlated with rage temperature during the 10-year period in Kalimantan with a value of R 2 0.3202. 10 20 30 40 50 60 70 80 90 100 Ja n-0 1 Ju l-0 1 Ja n- 02 Ju l-02 Ja n-0 3 Ju l-0 3 Ja n-0 4 Ju l-0 4 Ja n- 05 Ju l-05 Ja n-0 6 Ju l-0 6 Ja n- 07 Ju l-0 7 Ja n- 08 Ju l-08 Ja n-0 9 Ju l-0 9 Ja n- 10 Ju l-1 Time gC m -2 mo nt h -1 50 100 150 200 250 300 350 400 mm mo nt h NPP Mean PPT Mean Figure 16 Time series data of NPP and Precipitation in Kalimantan Figure 16 shows the relation between the amount of the mean of NPP and precipitation mean in Kalimantan from 2001 to 2010. In the beginning of 2001, the average precipitation value was by far higher that that of NPP. However, the amount of average precipitation fell dramatically after January 2001, whereas the proportion of NPP increased rapidly after a minimal drop. During the 10-year period, the value of NPP climbed in the beginning of every year, and a lot of changes happened during the rest of the year. The Figure 14 showed that the average precipitation peaked in January 2009 and the lowest proportion in August 2004. On the other hand, the mean of NPP graph shows many variations throughout the period. The amount varies from 34 gC m -2 month -1 to 86 gC m -2 month -1 . 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 Month R R Figure 17 Correlation between NPP and Precipitation data in Kalimantan Figure 17 shows that the correlation between the average of NPP and precipitation could be considered as low to moderate correlation with a time lag of four months. The precipitation was four months in advance before the NPP. Changes of NPP are closely correlated with increase temperature and changing precipitation. Precipitation increases in most Kalimantan areas during La Nina event. Since increase in precipitation is accompanied by increasing clouds cover and decreasing sunlight and radiation, the increased NPP is small. The decreased NPP also correlated with the rapidly increasing of temperature and the decreasing of precipitation.

4.5.5 Spatial distribution of NPP in Kalimantan