Land use type and indicators affecting land degradation and desertification. C. Kosmas Agricultural University of Athens

Transcription

1 Land use type and indicators affecting land degradation and desertification C. Kosmas Agricultural University of Athens

2 Desertification The consequence of a series of important degradation processes in the Mediterranean environments where water is the main limiting factor of land use performance on ecosystems Important processes Soil erosion (hilly areas) Soil salinization (lowlands)

3 Desertification a serious threat to soil quality and land productivity 2000 Oil production (Kg/ha) N P F1 F2 F3 C1 C2 Mean olive oil production in various types of environmentally sensitive areas (ESA) to desertification (C1,C2 = Critical, F1, F2, F3 = Fragile, P = Potential, N = Non-threatened areas-n) ESA

4 Desertification a serious threat to soil quality and land productivity 7000 Seed production (kg/ha) P F1 F2 F3 C1 C2 C3 ESA Mean yield of wheat in various types of environmentally sensitive areas (ESA) cultivated with cereals

5 Desertification affects population density and migration rate mythimna mytilini plomari P eo p le p e r h a 1,40 1,20 1,00 0,80 0,60 0,40 0,20 0, Year

6 Indicators and Environmentally sensitive areas to desertification Characteristics for identification and evaluation of indicators (Riley, 2001; Stein et al., 2001) (a) objectively and scientifically measurable (b) preferentially quantitative (c) easy and cost-effective to be measured (d) sensitive to environmental changes (e) simple in concepts (f) able to support policy decisions

7 Rating of indicators with respect to the importance to desertification by various people Rainfall Slope gradient Number of animal grazing per area Soil depth Type of vegetation Available w ater Policy enforcement Plant cover Present type of land use Rate of land abandonment Land ow nership Drainage Crop water demand Level of education Water quality Fire risk Area burned per year Farmer age Frequency of floods Cultivation practices Subsidies Rock fragment Forest forest frequency Xerothermic Indices Application of fertilizers Information / Perception Loss in farmer income Organic matter Population changes Migration Existence of appropriate policy Texture Previous type of land use Deforestation rate Farmer income Evapotranspiration Irrigated/rainfed crops Slope exposure Loss in forest productivity Loss in land productivity Parent material Rate of chage in salt affected soils Change in w ater consuption Farm size Changes in tourist arrivals Land productivity (production per Forest productivity Application of pesticides Family size Rate of change in acidified soils Number of farm parcels Parallel employment Bioclimatic Indices Change in water stored in dams Produced/ imported animal feed Rate of dam sedimentation

8 Desertification risk can be better assessed on the basis of land use type Indicators related to land management practices such as: Tillage operations Tillage depth Controlled grazing Period of existing land use type Erosion control measures Policy enforcement are very important for agricultural land use types. Indicators related to physical environment such as: Annual rainfall Aridity index Soil depth Slope gradient Slope aspect Rock fragment content are very important for natural areas.

9 An example in using indicators for defining land desertification risk Methodological approach The analysis have been conducted using a series of 48 indicators related to the soil, topography, vegetation, climate, social, economic, and management characteristics. The study was conducted (a) In hilly areas with the main process of land degradation soil erosion (b) in plain areas with the main process of land degradation soil salinization Data were collected from 428 field sites under various types of land use Olive groves Vineyards Cereals Pastures Pine and oak forests Natural vegetation

10 Methodological approach Definition of desertification risk was based on the type of environmentally sensitive area (ESA) and the degree of soil erosion. Type of ESA Degree of soil erosion Desertification risk Critical Very severe, severe, moderate High Fragile Potential Slight, no erosion Very severe Severe, moderate Slight, no erosion Very severe, severe Moderate, slight, no erosion Moderate High Moderate Low Moderate Low Non-threatened Any degree of erosion No risk

11 Methodological approach Table used in collecting field data

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18 Methodological approach Principal component and stepwise statistical analysis was conducted for all indicators separately for each land use type and the sensitivity of each indicator to land degradation and desertification was identified. Algorithms were defined for each land use type for identifying land degradation and desertification risk at farm level.

19 Using indicators in assessing desertification risk adequate moderate low no 100 Frequency (%) N P F1 F2 F3 C1 C2 C3 ESA Degree of policy enforcement in the various types of environmentally sensitive areas (ESA)

20 Frequency of appearance of fertilizer application in various types of ESAs Frequency (%) yes no N P F1 F2 F3 C1 C2 C3 ESA

21 Frequency of appearance of measures applied for reducing surface water runoff in the various types of ESAs No Adequate Moderate Low 100 Frequency (%) N P F1 F2 F3 C1 C2 C3 ESA

22 Important indicators related to desertification risk in areas cultivated with olives

23 DRI = TIL 0.56*DEP *POL FLD *PAR -0.78*RAIN *SLO *EXP *NPAR *PER *SUS R² = 0.49, n = 93 Where: DRI = desertification risk for olives TIL = tillage operations DEP = soil depth POL = policy enforcement FLD = frequency of flooding PAR = parent material RAIN = annual rainfall SLO = slope gradient EXP = slope exposure NPAR = number of parcels PER = period of existing land use SUS = sustainable farming

24 Important indicators related to desertification risk in areas cultivated with cereals

25 Important indicators related to desertification risk in areas cultivated with vines

26 Important indicators related to desertification risk in areas with oak forests

27 Important indicators related to desertification risk in areas with pastures

28 Important indicators related to desertification risk in areas with pine forests

29 Important indicators related to desertification risk due to salinization

30 Examples of application Land use: Pasture DRI = 8.39 Desertification risk: high

31 Land use: Deciduous forest DRI = 1.7 Desertification risk: low

32 Land use: Pine forest DRI = 2.99 Desertification risk: moderate

33 Land use: vineyard DRI = 4.7 Desertification risk: moderate

34 Land use: cereals DRI = 6.88 Desertification risk: high

35 Salt affected area DRI = 6.12 Desertification risk: high

36 Assessment of desertification risk for a certain piece of land Annual rainfall = 450 mm Aridity index (BG) =165 Soil depth = 55 cm Slope gradient = 18% Slope aspect = NW Soil texture = fine Rock fragments on the surface = 40% Parent material = Shale

37 Estimated desertification risk for a certain piece of land under various land use types DRI Pasture Vines Land use Pines Cereals Olives Oaks S1

38 Desertification Indicator System for the Mediterranean Europe DIS4ME

39 CONCLUSIONS Desertification risk can be defined by using simple indicators related to the physical environment, management, social and economic characteristics. Indicators related to social and economic characteristics can not be easily generalized. The analysis of indicators becomes more effective if land is classified according to the land use type. The used indicators must be easily measured, preferentially quantitative, simple in concepts and sensitive to environmental changes. The main source of indicators must be existing regular soil, vegetation, climate, etc. reports.

40 THANK YOU FOR YOUR ATTENTION

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