Results
Rate of CO2 emissions were directly detected on the
mounds of 5 dominant termite species (n = 5) during the dry and wet
seasons in the DEF at SERS. The characteristic of the selected termite
mounds was described as the size, feeding group, and physical and
environmental factors (Table 1). The mound CO2 emissions
were widely variable ranging from 0.17 to 55.15 µmol CO2m-2 s-1, while the range of
CO2 emissions from their surrounding soil was
considerably narrower from 0.68 to 14.86 µmol CO2m-2 s-1. The results showed that the
mean of the CO2 emission rate was significantly
different between the termite species (F= 49.174 P< 0.001) (Table 2).
The highest average of the mound CO2 emission was fromG. sulphureus that reached up to 37.7 ± 14.7 µmol
m-2 s-1 mean± SD, followed byM. crassus , T. comis , T. propinquus and D.
makhamensis which were 15.50 ± 7.84, 6.45 ± 2.35, 1.98 ± 1.78, and 1.79
± 0.99 µmol m-2 s-1 mean ± SD,
respectively. In both locations, CO2 emission rate was
significantly different between the mound and surrounding soil
(F =35.2.10, P < 0.001) (Table 2) (Fig 4). While
CO2 emission from the surrounding soil alone was not
different between species (P = 0.657) (Fig 4).
The mean of the total CO2 emission from the mounds
(12.68 ± 15.41 µmol m-2 s-1 mean±
SD) was 2.5 times higher than surrounding soils (5.06 ± 3.29 µmol
m-2 s-1 mean± SD). The overall mean
of CO2 emissions from the mounds was 3.9 and 2.1 times
higher than surrounding soils in the dry and wet seasons, respectively
(Fig 5). There was a significant difference for both mounds and
surrounding soils between the dry season and wet season (F =
14.957 P < 0.001) (Table 2). In each season, mound
CO2 emissions were significantly different among the
species and surrounding soils in the dry season and wet season
(P < 0.001). The mound CO2 emissions
from G. sulphureus and M. crassus mounds were
significantly higher than surrounding soils in both dry and wet seasons.
In contrast, T. propinquus and D. makhamensis emitted
significantly CO2 less than the surrounding soils (Fig
6).
The average rate of CO2 emission from surrounding soils
was 3.4 times higher in the wet season (7.83 ± 2.33 µmol
CO2 m-2 s-1 mean ±
SD) than the dry season (2.29 ± 0.89 µmol CO2m-2 s-1 mean ± SD). The relationship
between the soil CO2 emissions, soil temperature, and
soil moisture content aids in distinguishing seasonal variations. The
CO2 emission rates from surrounding soils were
positively correlated with soil moisture contents. (Pearson correlation,r = 0.804, P < 0.001) (Fig 7). The highest
CO2 emission rates (more than 10 µmol
CO2 m-2 s-1) were
found at around 10 to 19% of the soil moisture content. While the
relationship between soil temperature and surrounding soil
CO2 emission was not significant (Pearson
correlation, r = -0.024, P = 0.768). The soil temperature
had limited variation from 21.8 to 27.5 °C.