Impact of Depression Areas and Land-Use Change in the Soil Organic Carbon and Total Nitrogen contents in a Semi-Arid Karst Ecosystem

Dindaroglu, Turgay; Babur, Emre; Battaglia, Martin; Seleiman, Mahmoud; Uslu, Omer Suha; Roy, Rana

doi:10.1590/01047760202127012980

ABSTRACT

Background:

Depression areas are essential structural components of Karst ecosystems. Their influence in the carbon and nitrogen dynamics under different land uses, which could be effectively used to define management strategies aiming to combat global warming, however, is not clear. This study investigated the changes in selected soil attributes across four land use types (forest, degraded forest, rangeland and cropland) both in depressed and non-depressed areas in a karst ecosystem in Kahramanmaras, Turkey. Soil attributes investigated in this study included soil pH, soil moisture (SM), soil organic carbon (SOC), total nitrogen content (TN), available water (AW), hydraulic conductivity (HC), root rate (RR) and C/N ratio.

Results:

Discriminant analyses showed that N, AW, SOC, pH and landuse were the most effective variables affecting the distinction between depression and none-depression areas in karstic ecosystems. According to the structural matrix, the most important single factor affecting the distinction between depression and none-depression areas was SOC, with a correlation coefficient of 0.62. Highest values for SOC, TN and other attributes were found in forest and rangeland land use types, while minimum values were found in cropland land use in most comparisons. Depression areas reduced the negative effects of land use in terms of C, TN, C/N, SM, and RR.

Conclusion:

As a result, while constructing restoration plans, the study area should be evaluated from a geo-ecological perspective. Ecological capabilities of depression areas should be considered especially in karst environments.

Keywords:
Depression area; Soil management; Karst environment; Discriminant analysis; Carbon; Nitrogen

HIGHLIGHTS

Different land uses in karst ecosystems can affect the dynamics of carbon and nitrogen dramatically in the soil.

Soil remediation strategies should focus on carbon nitrogen balance in depressed areas

First reclamation strategy is reducing the pressure on agricultural areas in the karst ecosystem.

Depressed area can provide resistance in the fight against global warming.

[TFN1] H: Soil Reaction, SOC: Soil Organic Carbon, TN: Total Nitrogen, C/N: Carbon/Nitrogen, RR: Root Rate, SM: Soil Moisture, AW: Available Water, HC: Hydraulic Conductivity; SD= Standard Deviation

Land use type	Depression Area			None-Depression Area
	Area	Area	25o46’N
	Ha	%	Ha	%
Forest	175.3	41.3	412.4	56.3
Degarded Forest	85.4	20.1	189.1	25.8
Cropland	146.6	34.6	102	13.9
Rangeland	16.7	3.9	28.8	3.9
Total/Mean	424.2	100	732.3	100

Soil parameters	Depressed area in rangeland			Non-depressed area in rangeland			Depressed area in cropland		Non-depressed area in cropland
Soil parameters	Mean	SD	Mean	SD	Mean	SD	Mean	SD
pH	7.37	0.22	7.74	0.50	7.24	0.36	7.85	0.39
SOC (g.kg^-1)	3.79	0.49	1.42	1.6	2.11	0.36	0.72	0.35
TN (g.kg^-1)	0.16	0.02	0.08	0.03	0.10	0.01	0.04	0.01
C/N	23.51	3.85	18.06	2.06	21.01	1.40	16.64	3.12
RR (%)	48	8.30	35.45	8.20	35.7	7.87	33.3	6.05
SM (%)	6.2	1.45	5.61	2.56	6.5	1.73	5.6	2.67
AW (cm cm^-1)	0.10	0	0.10	0.02	0.10	0.01	0.10	0.03
HC (mm/h)	2.42	1.07	20.84	28.62	1.91	0.46	13.11	15.17

Soil parameters	Depressed area in forest			Non-depressed area in forest			Depressed area in degradedforest		Non-depressed area in degraded forest
Soil parameters	Mean	SD	Mean	SD	Mean	SD	Mean	SD
pH	7.28	0.47	7.43	0.34	7.56	0.47	7.40	0.24
SOC (g.kg^-1)	6.37	1.04	3.73	1.47	3.33	0.84	1.56	0.64
TN (g.kg^-1)	0.27	0.04	0.21	0.10	0.16	0.00	0.09	0.02
C/N	23.39	3.26	18.79	5.54	21.36	5.59	16.95	5.92
RR (%)	37.6	11.94	24.63	11.33	33.75	7.5	21.2	8.37
SM (%)	7.7	2.68	6.8	2.02	8.9	5.77	4.7	1.24
AW (cm cm^-1)	0.11	0.02	0.11	0.02	0.09	0.04	0.08	0.02
HC (mm/h)	17.72	25.30	8.17	15.35	16.55	13.81	8.03	7.84

Soil parameters	p values
pH	0.02
SOC (g.kg^-1)	0.00
TN (g.kg^-1)	0.02
C/N	0.00
RR (%)	0.00

	LU	DA	pH	SOC	TN	C/N	RR	SM	AW	HC
LU	1.000	0.019	0.215*	-0.081	-0.103	-0.093	0.154	-0.291**	-0.259*	0.022
DA		1.000	-0.203*	0.322**	0.244*	0.316**	0.266*	0.057	0.179	0.070
pH			1.000	-0.294**	-0.294**	-0.281**	-0.281**	-0.302**	-0.134	0.088
SOC				1.000	0.902**	0.869**	0.189	0.056	0.221*	0.015
TN					1.000	0.675**	0.173	0.089	0.192	0.013
C/N						1.000	0.153	0.023	0.188	0.016
RR							1.000	0.137	0.187	0.118
SM								1.000	0.154	-0.158
AW									1.000	0.104
HC										1.000

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