4.5 Net Primary Production NPP
NPP is the rate at which all the plants in an ecosystem produce net useful chemical energy. It is equal to the difference between the rate at which the plants
in an ecosystem produce useful chemical energy GPP and the rate at which they use some of that energy during respiration. Some net primary production goes
toward growth and reproduction of primary producers, while some is consumed by herbivores. It is the fundamental process in biosphere functioning and is
needed for assessing the carbon balance at regional and global scales. Changes in NPP could arise due to anthropogenic effects and climate change, and directly
affect human and animal food supplies.
4.5.1 Monthly mean of NPP
NPP
20 40
60 80
100
Jan-0 1
Ja n-
02 Jan-0
3 Ja
n- 04
Jan-0 5
Ja n-
06 Jan-
07 Jan-0
8 Jan-
09 Jan-1
Time gC
m
-2
m ont
h
-1
NPP
Figure 10 Trends of monthly distribution of NPP in Kalimantan
Figure 10 gives information about the monthly mean NPP in Kalimantan for 10 years 2001-2010. Looking at the figure, it is clearly showed that the
monthly mean of NPP varied between 34 gC m
-2
month
-1
and 86 gC m
-2
month
-1
, and the amount of NPP peaked around April and May of every year. In contrast,
the variation of NPP dropped sharply from June 2006 and it reached a very low proportion, at about 34 gC m
-2
month
-1
in October 2006. Throughout the period, the value of NPP was mostly more than 50 gC m
-2
month
-1
, except in February 2002, September 2002, December 2003, August 2004, February 2008, and
January 2009 where the NPP value was under 50 gC m
-2
month
-1
with a value of
around 48 gC m
-2
month
-1
, 43 gC m
-2
month
-1
, 46 gC m
-2
month
-1
, 46 gC m
-2
month
-1
, 34 gC m
-2
month
-1
, 46 gC m
-2
month
-1
, and 46 gC m
-2
month
-1
respectively. The variation shows a lot of changes: falls and rises. Similarly, the each-
year data provides different values for the NPP. To illustrate, in the beginning of 2001, the amount of NPP was about 61 gC m
-2
month
-1
and reached its peak with 80 gC m
-2
month
-1
in April, then fell dramatically at about 58 gC m
-2
month
-1
in August 2001. The value was almost constant around 60 gC m
-2
month
-1
until September 2001, then increased to 70 gC m
-2
month
-1
in October and decreased to 57 gC m
-2
month
-1
in November 2001. A slight rise was noticed in December 2001 where the value was 61 gC m
-2
month
-1
.
4.5.2 Yearly mean of NPP
NPP
100 200
300 400
500 600
700 800
900 1000
2001 2002
2003 2004
2005 2006
2007 2008
2009 2010
Time gC
m
-2
yr
-1
NPP
Figure 11 Trends of annual distribution of NPP in Kalimantan
Figure 11 illustrates the yearly mean variation of NPP in Kalimantan from 2001 to 2010. As can be seen in the figure, the amount of NPP varied between
703 gC m
-2
year
-1
and 797 gC m
-2
year
-1
, but it rose rapidly from 2009 to 2010 at around 867 gC m
-2
year
-1
. In general, the variation follows the same trends: from 2001 with a yearly mean NPP value of about 762 gC m
-2
year
-1
, a fall was noticed until the next year 2002 to 703 gC m
-2
year
-1
; and it is followed by a slight rise
until the following year 2003 to 778 gC m
-2
year
-1
then fell again to 745 gC m
-2
year
-1
in 2004. It increased to 797 gC m
-2
year
-1
in 2005 and decreased to 713 gC m
-2
year
-1
in 2006. From 2006, there was a rise to 790 gC m
-2
year
-1
in 2007 then a slow fall to 768 gC m
-2
year
-1
in 2008 and to 752 gC m
-2
year
-1
in 2009. The decrease was minimal from 2007 and it continued until 2009. The yearly mean
NPP climbed sharply by 2009, and reached its highest value at about 867 gC m
-2
year
-1
in 2010.
4.5.3 Climatology Process and Anomalies of NPP
Kategori