Affiliation(s)
1. National Council for Scientific Research, Centre for Remote Sensing, Beirut 8281/11, Lebanon
2. Head of Educational Department/MsC, Ministry of Agriculture, Beirut 8281/11, Lebanon
3. Lebanese Agricultural Research Institute, Tal Amara, Bekaa, Zahle 287, Lebanon
4. National Council for Scientific Research, Beirut 8281/11, Lebanon
ABSTRACT
Accurately quantifying SOC (soil organic carbon) store in soils is considered
fundamental to global climate change modeling, notably in soil forest ecosystems
in relation to land cover/use change, forest fires and sustainable land management
practices. Lebanese soils were described as relatively poor in organic matter content.
This work used Landsat and IRS (Indian Remote Sensing) to classify land cover and land use, field survey to map the soil cover
and assess carbon stock in the Lebanese soil and forest ecosystems and link the
frequency of forest fires with the soil nature and land cover land use to assess
the resulting risk of SOC loss from the soil pool.
SOC density and stock was assessed using information from 450 soil profiles and
the average OC content in a given soil type
was calculated involving organic matter content in the soil, bulk density, soil
thickness and the content of coarse fragments to produce the national SOC stock
map. A total of 11 soil types (major classes) represented the mapping units describing
the higher soil component or major classes were identified in Lebanon. The higher
standard deviation observed in Luvisols reflects soil diversity, history and different
management. Comparing the results of surface soil layer with the overall SOC density
and stock in Lebanese soils showed a good correlation (0.98) between the OC stock
within the upper soil layer and in the 100 cm depth, indicating the absolute role
of the upper, biologically most active soil layer in the organic matter accumulation
and carbon sequestration. Observation over a pilot area in the High Meten showed
the calcareous soil group consists of Luvisols with associated Cambisols. Soil units
representing the transition between the two soil groups are markedly affected by
erosion-deposition processes. Pine occupies the largest area of forest (3,600 ha) followed by oak (1,800 ha) and mixed forest
(1,200 ha), representing 24.9%,
12.5 % and 8.2% of forest cover respectively. The analysis of SOC density in the
soil of the pilot area showed relatively higher average organic matter accumulation
rate in the soil under forest stands compared to shrubs and agricultural lands both
at the soil surface (33.5 ton/ha) versus (30 ton/ha) and in the entire soil profile
(99 ton/ha) versus (91 ton/ha) respectively. The burned area on these soil types
reached 700 and 1,500 ha in 2003 while in the
first soil group it did not exceed 50 ha.
KEYWORDS
Land cover, mountain pedogenesis, soil organic matter, east mediterranean, fires, drought.
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