Carbon Storage and Nutrient Stocks Distribution of Three Adjacent Land Use Patterns in Lake Danao National Park, Ormoc, Leyte, Philippines
Carbon Storage and Nutrient Stocks Distribution of Three Adjacent Land Use Patterns in Lake Danao National Park, Ormoc, Leyte, Philippines
Carbon Storage and Nutrient Stocks Distribution of Three Adjacent Land Use Patterns in Lake Danao National Park, Ormoc, Leyte, Philippines
Abstract
The country experienced drastic decrease of forest cover due to land use conversion, cutting
of trees and doing agriculture to support food security. Secondary forests are an important
component of land cover in the tropics, and when transformed or converted into another
land-use, it is believed to have negative effects on some soil properties and forest ecosystem
in general. A paired-area/space-for-time substitution approach was conducted to determine
the changes in carbon storage: soil organic carbon (SOC) and total above ground biomass
(TAGB), soil nutrient stocks and fertility status due to land use change. The study was
conducted in Lake Danao National Park (LDNP), Ormoc City, Leyte, Philippines. Adjacent
to the secondary forest (<1 km away), grassland and forest plantation land uses were
chosen and sampled for possible changes on SOC, TAGB and nutrient stocks due to land
use change. Results showed that conversion of forest to grassland and forest plantation
decreased the organic carbon, exchangeable aluminum, exchangeable acidity, effective
cation exchange capacity, TAGB while pH in H2 O; exchangeable magnesium and potential
cation exchange capacity increased when the forest was converted to grassland and forest
plantation. Additionally, available P, base saturation, Ca, K, and Na increased while total N,
and SOC stocks decreased when the forest was converted to grassland and forest plantation.
This study indicates that conversion of forest to grassland and forest plantation greatly affected
the SOC stocks, TAGB, soils nutrient stocks and fertility status. It also revealed that changes
in soil properties largely depended upon the land use.
Keywords: Andisol; forest plantation; grassland; organic carbon; secondary forest; total aboveground
biomass
2
Carnıce and Lina JSET Vol.5, 2017
Figure 1. (A) Map of Leyte (Redrawn from Department of Environment and Natural Resources); (B)
Sketch of the sampling sites in LDNP, Ormoc City, Leyte, Philippines
air-dried, pulverized and passed through a Total SOC (Mg C ha−1 ) = (%SOC)/(100)
2mm sieve. The following soil physical and x soil depth (m) x bulk density (Mg m−3 )
chemical properties were determined: bulk x 10000 m2 ha−1
density using paraffin clod method (Blake
and Hartge, 1986); porosity by calculation In the F and FP, representative sampling
of particle density and bulk density; particle plots (10 m x 10 m) were laid-out. All trees
size distribution (soil texture) using pipette inside the plots with a diameter at breast height
method (ISRIC, 1986); soil pH was analysed (dbh) of at least 10cm were identified and
potentiometrically using soil and water ratio recorded.
of 1:2.5 (ISRIC, 1986); delta pH using The aboveground tree biomass with
KCl (pH KCl–pH H2 O) (Mekaru & Uehara, dbh <10cm (Lasco and Sales, 2003) was
1972); soil organic matter (%) using modified calculated using allometric equation (Brown
Walkley-Black method (Nelson and Sommers, and Lugo, 1990). Total aboveground biomass
1982); Total N (%) using the micro-Kjeldahl (trees):
method; extractable P (mg kg−1 ) was
determined according to Bray #2 method (Bray %Y = exp [-2.134 + 2.530*ln (dbh)]
and Kurtz, 1945; Murphy and Riley, 1945);
cation exchange capacity (CEC) using 1N Where:
NH4 OAc adjusted to pH 7.0 method (ISRIC,
• Y = biomass per tree in kg;
1986) with some modifications; exchangeable
acidity (Acidity (Al3+ and H+ ) (cmolc kg−1 ) • dbh = diameter at breast height in
(Thomas, 1982) and exchangeable K, Ca, centimeters
Mg (mg kg−1 ) was quantified using Atomic
Absorption Spectrophotometer (AAS) (Varian C storage (t ha−1 ) = Total biomass/ha x 0.45
Spectra 220 FS) reading. SOC contents were
analyzed for the specified three depths from Aboveground and root biomass from 1
each land use. SOC stock was calculated m x 1 m plot at each grassland site were
using the equation. determined. All grasses found within the plot
were collected. The harvested grasses were
washed thoroughly with tap water and then
3
Carnıce and Lina JSET Vol.5, 2017
distilled water. After which, fresh weight was as Typic Hapludand under the soil order
determined. Representative samples were Andisols (USDA, 2003) and some evidences
oven-dried at 65◦ C. The carbon stock of the are presented in Table 1 along with other
grass biomass was calculated with following characteristics of the site. Soil profile (cambic
formula: soil horizon) development in F is poor and the
area has common rock outcrops. Dipterocarp
tree species are dominant in the secondary
WC = WO x 0.5 forest. Based on the interview of the caretaker
of LDNP, the conversion of forest occurred in
Where: 1970s. G is located in the same volcanic
hill which is less than 700 m away from
• WC = Weight of carbon in grass biomass the secondary forest (F). FP, with less than
(g); 300 m distance from F, was planted with
• WO = Oven-dry weight of aboveground Gymnostoma phumphianum in 1971 and was
biomass; not disturbed since then. Ormoc highlands
climate is Type II in the Coronas climate
• 0.5 = Estimated C percentage in classification (Asio, 1996). The presence
plant biomass (Sarmiento et al., 2005; of the Central Cordillera of Leyte delineates
Redondo, 2007) eastern side of the range having slightly
different climate from that of the western side.
Calculation and Data Analysis The eastern side of Leyte is exposed to
trade winds from the Pacific Ocean resulting
Using paired-site approach, the effects of in the absence of a dry season with a
FP and G on SOC stocks and soil nutrient very pronounced maximum rain period from
stocks were evaluated. Data generated from December to March. Average temperature is
F was used as the baseline values (reference) 24.50 C and average annual rainfall is 3391
against changes in SOC stocks and nutrient mm.
stocks in different land uses. The effects
of land use on SOC stocks and nutrient
Nutrient stocks
stocks within each depth and each site were
subjected to one-way ANOVA and multivariate Figure 2 shows strongly acidic to moderately
analysis. Multiple regression analyses were acidic pH (H2 O) sites which ranged from
used to evaluate the relationships between 5.2-5.7. Values of pH (H2 O) in the surface
SOC concentration and nutrient stocks in did not vary much as the depth increases.
different land uses. Respective correlation However, pH (H2 O) between land uses
coefficients for each land use were calculated differed in the surface horizon (0 – 20 cm)
including all soil depths from all sites. in which the forest plantation showed the
highest value while grassland had the lowest.
Results and Discussion Nonetheless, the significant interaction effects
between these differences could be due to the
Environmental Setting type of vegetation.
Similarly, significant difference was noted
The LDNP in Ormoc City, Leyte is one of on soil pH (KCl) between land uses (P-value:
the forest reserves in the Philippines and 0.0012) which values ranges from 4.2 - 4.7
a suitable site for land use study because (Figure 2). Among the three sites, FP had
the secondary forest is still preserved and higher value of pH (KCl) while F soils had the
adjacent to grassland and forest plantation lowest pH which means H+ ions were held
areas of <1 km apart. The soil was classified tightly in the soil particles of the F soils. In
4
Carnıce and Lina JSET Vol.5, 2017
comparison, pH (H2 O) showed higher values decreased when forest was converted into
than pH (KCl) as expected since addition of grassland but seemed to have recovered
salt solution releases cations. It replaces in the forest plantation. Forest conversion
some of the protons from the soil particles and to grassland significantly decreased the
these process forces hydrogen ions to pass organic matter content of the soil which
into the solution and make their concentration may be attributed to the clearing of forest
in the bulk solution closer to the value in the vegetation that has interrupted the input of
field. It can also be observed that pH (KCl) organic materials from plants (Asio et al.,
slightly increased with depth across land use 1998). Additionally, there were significant
types. differences in SOC contents among soil depth
Furthermore, differences in 4pH values horizons (P-value: 0.0079). Also, the SOC
were observed between land uses and was higher in the surface and decreased
between soil depths. All land uses showed as the depth increased (Figure 2). This
negative charge indicating that the soil could be due to the higher accumulation of
colloids possess cation exchange capacity organic matter and higher root allocation on
and the occurrence of net negative charge the soil surface since it is the main habitat of
could be attributed to the negative charge microorganisms. Generally, total N contents
of the clay minerals. On the other hand, of soil were considerably affected by land use
the 4pH values were similar across all land change because of marked influence on the
uses. The negative values obtained indicate changes in detrital inputs, perturbations of
that soil colloids possess cation exchange the ecosystem, and on N stocks and fluxes
capacity. The occurrence of net negative (Bolin and Sukumar, 2000). Figure 3 shows
charge could be attributed to the negative the total N contents among land uses where
charge of the clay minerals. Forest soils a significant difference was observed. Forest
had the highest SOC concentration (8.31%), soils rendered the highest N (0.3-0.9%) which
followed by forest plantation (5.99%) while can be interpreted as medium to high total
the lowest was grassland (2.87%). Significant N while grassland soils showed the lowest
differences (P-value: 3.67308x10−7 ) in the (0.08–0.11%) N content. The grassland site
SOC concentrations were observed between was subjected to long years of cultivation (≈15
land uses. SOC concentration significantly years) before it was converted into the present
5
Carnıce and Lina JSET Vol.5, 2017
Figure 2. Depth function of Db (bulk density), porosity, OC and pH (H2 O, KCl, and 4 pH)of soils as
influenced by forest transformations in LDNP, Ormoc City, Leyte. Horizontal bars represent
standard errors
6
Carnıce and Lina JSET Vol.5, 2017
Figure 3. Depth function of total N, available phosphorus, exchangeable Ca, exchangeable Mg,
exchangeable K, and exchangeable Na of soils as influenced by forest transformations in
LDNP, Ormoc City, Leyte. Horizontal bars represent standard errors
amorphous clay minerals that creates a strong its high P-fixation capacity.
sorption of P in the soil which is relatively Generally, grassland soils contained
unavailable for plant absorption (Asio, 1996). significantly higher amount of exchangeable
The same site tends to have high aluminum bases than the forest and forest plantation.
(Figure 3) which can bind P via an anion Only magnesium (Mg) was significantly
exchange. Its fine-textured soil also adds to different between land use (P-value: 0.0131)
7
Carnıce and Lina JSET Vol.5, 2017
and depths (P-value: 0.0033). However, all means that the soil has low resistance to
levels of exchangeable bases (Ca, Mg and changes in soil chemistry caused by land use
Na) are low to very low among land uses change. Significant differences in CECef f
except on grassland which had moderate (P-value: 0.0069) were observed between
level of K. Base saturation of F, G, and FP land uses while no significant differences were
was significantly different among land uses. observed in CECpot among land uses.
G had the highest base saturation (24.5%)
followed by F (15.15%) and FP (11.17%). The
same trend was reported in previous studies Carbon Stocks Assessment
(Asio et al., 1998) wherein conversion of
forest to grassland and other land uses could SOC Stocks
be beneficial as it improved the availability
of such nutrients. This was attributed to The F soil contained 489 t C ha−1 total
the contribution of ash produced during the SOC stock which is the highest among land
slash-and-burn activity. Also, base saturation uses followed by FP (308 t C ha−1 ) and
differed significantly with soil depths. The G (172.5 t C ha−1 ). Significant differences
base saturation across all land uses was in SOC stocks were observed between land
higher at the surface (Figure 4). A similar uses which indicate that forest conversion
trend was also observed with OC content to other land uses significantly decreased
which could be due to high accumulation of SOC stocks. The forest has far greater
organic matter in the surface as the possible canopies which provide a larger quantity of
source of bases. plant litter leading to higher accumulation of
Exchangeable acidity was taken as the carbon. Previous studies (Batjes, 1996; Tian
amount of H+ and Al3+ in the exchange et al., 2002) reported a similar trend that
complex of the soil. Significant differences land use and soil management practices can
were observed on exchangeable H+ (P-value: significantly influence the soil organic carbon
0.0091), exchangeable Al3+ (P-value: 0.0037) dynamics and carbon flux of the soil. It was
and exchangeable acidity (P-value: 0.0056) also reported (Gou & Gifford, 2002) that soil
among F, G, and FP. The F had higher carbon stocks decline after land use change
exchangeable Al3+ and higher exchangeable from native forest to plantation (-13%) and/or
acidity than G and FP (Figure 4). However, native forest to crop land (-42%). Aside from
exchangeable H+ was the major component of nutrient availability, soil organic carbon stocks
exchangeable acidity in all soils across all land may change depending on factors such as
uses and not exchangeable Al3+ which can climate, vegetation type, nutrient availability,
be observed with its pH values and its SOC disturbance, and land use and management
content (Figure 3). practice (Six & Jastrow, 2002; Baker, 2007).
Cation exchange capacity is the capacity of The inconsistent change of SOC stocks can
the soil to absorb or hold cations and be able be partly explained by the complexity of
to exchange cations. It is one of the important SOC, which consists of several pools that
soil chemical properties affecting soil fertility. have a wide range of chemical properties
Forest soils had 18.6 – 20.4 cmolc kg−1 and turnover times and consequently respond
while grassland and forest plantation had differently to land use changes (Paul et al.
approximately 2.8 – 4.3 cmolc kg−1 (Figure 2008). Soil organic carbon could be sensitive
4). These data indicated that F soils possess to the impact of anthropogenic activities and
higher CECeff than those in G and FP. High conversion of natural vegetation to various
CEC provides a buffering effect to the changes land uses (G and FP) which can result into
in pH, available nutrients, calcium levels and a rapid decline in soil organic matter (Post &
soil structural changes. A low CEC value Kwon, 2000).
8
Carnıce and Lina JSET Vol.5, 2017
Figure 4. Depth function of base saturation, exchangeable acidity, exchangeable Al, exchangeable H,
CECef f and CECpot of soils as influenced by forest transformations in LDNP, Ormoc City,
Leyte. Horizontal bars represent standard errors
9
Carnıce and Lina JSET Vol.5, 2017
Figure 5. Depth function of SOC stocks and total aboveground biomass of soils as influenced by forest
transformations in LDNP, Ormoc City, Leyte. Horizontal bars represent standard errors
Figure 6. Biomass carbon stocks (A), relationship between SOC stocks (t C ha−1 ) and Biomass carbon
stocks (Mg C ha−1 ) of forest (B), grassland (C), forest plantation (D) in LDNP, Ormoc City,
Leyte
10
Carnıce and Lina JSET Vol.5, 2017
atmosphere. Results showed that F rendered of the major carbon sinks. It would also
the highest biomass carbon stocks of 311 give knowledge to people that conversion
Mg C ha−1 but significantly decreased when of forest to grassland and forest plantation
converted to G with 0.89 Mg C ha−1 but slightly would have positive and negative effects on
recovered when converted to FP (73.46 Mg C SOC stocks, TAGB, biomass carbon and on
ha−1 ). Such results are comparable with the soil nutrient stocks. However, to estimate
tree carbon density (237 Mg C ha−1 ) of MFR; SOC stocks more accurately, the number per
however, its herbaceous biomass carbon land use type should be increased and the
density is quite lower (0.06 Mg C ha−1 ) (Lasco deeper soil depths should be considered to
et al. 2004). Gymnostoma rumphianum FP include C storage potential of the subsoil.
high biomass carbon stocks could possibly be Further studies should be conducted to
due to its age (47); most forest plantations reveal changes in SOC, TAGB, biomass
in Leyte Island are dominated by Acacia carbon and nutrient stocks at different times
mangium (25.61 Mg C ha−1 ), Gmelina arborea such as a chronosequence study method
(31.59 Mg C ha−1 ) and A. auriculiformis (28.58 which is used to represent and study the
Mg C ha−1 ) at the age of 4 years (Lasco & time-dependent development of a forest. This
Pulhin, 2009). will provide dynamic characteristics of SOC,
Relating SOC stocks and biomass carbon TAGB, biomass carbon and nutrients after land
stocks is important to know if change in SOC use change, and could therefore provide basis
stocks can affect the biomass carbon stocks. for theorizing to predict future changes.
However, no clear relationship was observed
across all land uses (Figure 6) indicating Acknowledgment
that in such soil types SOC stocks does
not significantly affect the biomass carbon The researchers acknowledge Dr. Victor B.
stocks across all land uses. This could be Asio and Dr. Ian A. Navarrete for their key
attributed to the effect of long accumulation inputs during the conduct of this research and
and decomposition of biomass that fast and the Department of Science and Technology
labile carbon may have been already lost, (DOST) – Accelerated Science and
leaving only the recalcitrant carbon in soil Technology Human Resource Development
(Montagnini, 2000; Veldkamp et al., 2003; Program (ASTHRDP), Philippines for giving
Redondo & Montagnini, 2006). the first author an MS graduate scholarship
and for funding the study.
Conclusion
References Cited
The study showed distribution of SOC, TAGB,
biomass carbon, and nutrient stocks across Asio,V.B.(1996). Characteristics, weathering,
three adjacent land use patterns. Results formation, and degradation of soils from
from this study demonstrate that substantial volcanic rocks in Leyte, Philippines.
loss of SOC stocks could be observed upon Hohenheimer Bodenkundliche Hefte,
conversion of secondary forest to grassland Stuttgart, Germany. Retrieved from
and subsequently recovered when converted https://scholar.google.com.ph/scholar?q=
into forest plantations. However, TAGB %5B9%5D.%09ASIO%2C+V.B.+1996.+C
significantly decreased as F was converted haracteristics%2C+weathering%2C+forma
to G and then to FP. The results of the tion%2C+and+degradation+of+soils+from
study would be useful in determining the SOC +volcanic+rocks+in+Leyte%2C+Philippine
sequestration potential of the Andisol soils. s%2C+vol.+33.+Hohenheimer+Bodenkun
These are also important for greenhouse gas dliche+Hefte%2C+Stuttgart%2C+German
inventories since soil is considered as one y++209+pp&btnG=&hl=en&as sdt=0%2C5
11
Carnıce and Lina JSET Vol.5, 2017
Bolın, B. & Sukumar R. (2000). Global Lal, R. (2005). Forest Soil and
perspective. In: Watson, R.T., Noble, I.R., carbon sequestration. Forest
Bolin, B., Ravindranath, N.H., Verardo, Ecology and Management, 220,
D.J. and Dokken, D.J. (eds.). Land 242 – 258. Retrieved from
12
Carnıce and Lina JSET Vol.5, 2017
13
Carnıce and Lina JSET Vol.5, 2017
1365-2486.2000.00308.x/full nover/links/546c4f230cf2397f7831d555/Or
ganic-Matter-Turnover.pdf
Redondo, A. & Montagnını, F. (2006).
Growth, productivity, biomass, and carbon Thomas, G.W. (1982). Exchangeable
sequestration of pure and mixed native cations. In: Methods of soil analysis.
tree plantations in the Atlantic lowlands of Part 2. Chemical and microbiological
Costa Rica. Forest Ecology Management, properties (2nd ed.). Retrieved from
232, 168–178. Retrieved from https://scholar.google.com.ph/scholar?q=
https://scholar.google.com.ph/scholar?q= %5B18%5D.%09THOMAS%2C+G.W.+19
%5B34%5D.%09REDONDO%2C+A.%2C 82.+Exchangeable+cations.+In%3A+A.L+
+MONTAGNINI%2C+F.+2006.+Growth%2 PAGE%2C+Editor.+Methods+of+soil+anal
C+productivity%2C+biomass%2C+and+ca ysis.+Part+2.+Chemical+and+microbiologi
rbon+sequestration+of+pure+and+mixed+ cal+properties+%282nd+ed.%29.+Agrono
native+tree+plantations+in+the+Atlantic+lo my+Society+American+Inc.+and+Soil+Sci
wlands+of+Costa+Rica.+Forest+Ecology+ ence+American+Inc.%2C+Madison%2C+
Management+232%3A168%E2%80%931 Wisconsin.+159%E2%80%93165+pp.+&bt
78&btnG=&hl=en&as sdt=0%2C5 nG=&hl=en&as sdt=0%2C5
Redondo, A. (2007). Growth, carbon Tıan, H., Melıllo, J.M. & Kıcklıghter, D.W.
sequestration, and management (2002). Regional carbon dynamics in
of native tree plantations in humid monsoon Asia and implications for the
regions of Costa Rica. New Forests, global carbon cycle. Global and Planetary
34, 253–268. Retrieved from Change, 37, 201-217. Retrieved from
http://www.sidalc.net/repdoc/A11 http://www.sciencedirect.com/science/artic
508i/A11508i.pdf le/pii/S0921818102002059
Sanchez, P.A. & Logan, T.J. (1992). United States Department of Agriculture
Myths and science about the (USDA) Soil Survey Staff. (2003).
chemistry and fertility of soils in the Keys to soil taxonomy (9th ed).
tropics. In: Myths and science of Natural Resources Conservation
soils of the tropics. Retrieved from Service, USDA. Retrieved from
http://pdf.usaid.gov/pdf docs/pnabp506.pdf https://www.nrcs.usda.gov/wps/PA NRCS
Consumption/download?cid...ext=pdf
Sarmıento G., Pınıllos M., & Garay,
I. (2005). Biomass variability in Veldkamp, E., Becker, A., Schwendenmann,
tropical American lowland rainforests. L., Clark, D.A., & Schulte-Bıspıng,
Ecotropicos, 18(1), 1–20. Retrieved from H. (2003). Substantial labile carbon
http://citeseerx.ist.psu.edu/viewdoc/downl stocks and microbial activity in deeply
oad?doi=10.1.1.379.2262&rep=rep1&type weathered soils below a below a
=pdf tropical wet forest. Global Change
Biology, 9, 1171-1184. Retrieved from
Sıx, J. & Jastrow, J.D. (2002). Organic http://onlinelibrary.wiley.com/doi/10.1046/j.
matter turnover. Encyclopedia 1365-2486.2003.00656.x/full
Soil Science. Retrieved from
https://www.researchgate.net/profile/J Six/
publication/268395114 Organic Matter Tur
14