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1

Evaluation of Normalized Difference Vegetation Index by Remote Sensing with Landsat Satellites in the Tayacaja Valley in the Central Andes of Peru

Carbajal-Morán Hipólito, Márquez-Camarena Javier F., Galván-Maldonado Carlos A., Zárate-Quiñones Rosa H., Galván-Maldonado Alberto C., Muñoz-De la Torre Rossibel J.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 7

208--215

EN

The research sought to evaluate the normalized difference vegetation index (NDVI) of the study area located in the province of Tayacaja, which includes the districts of Acraquia, Ahuaycha, Pampas and Daniel Hernández, which is part of the central Andes of Peru. The data were collected in low water seasons with a longitudinal cut of 30 years with one sample per year, starting in 1993 until 2022; these samples corresponded to the month of August of each year. The images were extracted from maps from Landsat satellite databases, which were filtered for low cloud cover to avoid interference with the images. Maps from 1993 to 2012 were obtained from Landsat 5 satellite, while from 2013 to 2022 data were obtained from Landsat 8 satellite. The normalized difference vegetation index was determined using Quantum GIS based on the red and near infrared maps; being the minimum NDVI value obtained -0.18, which corresponds to the aquatic body of the Upamayu River that crosses from west to east the study area; while the highest NDVI obtained was 0.79 indicating a greater vegetation cover constituted by mainly eucalyptus plants. The mean NDVI of the 30 years is close to 0.21; this is an indicator that the vegetation is scarce and that it is decreasing mainly due to population growth.

2

Assessment and mapping of desertification sensitivity with MEDALUS model and GIS – Case study: basin of Hodna, Algeria

Boudjemline F., Semar A.

Journal of Water and Land Development

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2018

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no. 36

17--26

EN

In Algeria, desertification risk is one of the main environmental and also social and economic problems. As much as 20 million hectares of northern Algeria are highly exposed and vulnerable to desertification with large areas falling into his ‘severe’ risk category, because the present massive destruction of vegetation and soils. This study aimed to use geographic information system (GIS) for mapping environmentally sensitive areas to desertification based on Mediterranean Desertification and Land Use (MEDALUS) approach in basin of Hodna, Algeria. Sensitivity is estimated with a modification of the MEDALUS environmentally sensitive area index (ESAI) which identifies such areas on the basis of an index (ESAI) that incorporates data on environmental quality (climate, vegetation, soil) as well as anthropogenic factors. This methodology allows the classification of land in critical, fragile and potentially sensitive areas. The results obtained show that 61% of the area is classified potentially sensitive to low sensitivity. These areas are particularly located in mountain areas. Spatially, the areas sensitive to degradation are as well in the lower region of the Hodna in Highlands consisting mostly of steppe route. The factors that could explain these variations of sensitivity are related mainly to changes in precipitation between the North and the South altitude and pressure of the population and livestock.

PL

Ryzyko pustynnienia jest jednym z głównych problemów środowiskowych, ale także problemem społecznym i ekonomicznym. Aż 20 mln ha w północnej Algierii zagrożonych jest pustynnieniem, a na znacznych obszarach zagrożenie występuje w stopniu poważnym z powodu niszczenia roślinności i gleb na masową skalę. W badaniach wykorzystano system informacji geograficznej GIS i model MEDALUS (ang. – MEditerranian Desertification And Land USe) i zastosowano je w odniesieniu do basenu Hodna w Algierii. Wrażliwość oceniano z zastosowaniem zmodyfikowanego indeksu środowiskowej wrażliwości obszaru (ESAI), który uwzględnia dane o jakości środowiska (klimat, roślinność, gleba) oraz czynniki antropogeniczne. Ta metoda umożliwia klasyfikację obszarów na: krytycznie zagrożone, słabo i potencjalnie wrażliwe. Uzyskane wyniki dowodzą, że 61% badanego obszaru to ziemie potencjalnie wrażliwe lub o niskiej wrażliwości. Są to głównie tereny górzyste. Obszary wrażliwe na degradację znajdują się także w niżej położonych regionach Hodna o cechach stepu. Czynnikami, które objaśniają zmienność wrażliwości na pustynnienie, są różnice w opadach pomiędzy północą a południem oraz presja ludności i zwierząt inwentarskich.

3

A New Model for Desertification Assessment Using Geographic Information System (GIS) — A Case Study, Runiz Basin, Iran

Masoudi M., Jokar P.

Polish Journal of Ecology

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2017

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Vol. 65, nr 2

236--246

EN

The present paper attempts to evolve a new model by considering various indicators of different types of land degradation or desertification, namely, water erosion, soil salinity, vegetation degradation, and lowering of ground water table for finding areas with higher rate of degradation. The Runiz basin, located in the southern Iran, has been selected as a study area to assess the hazard of desertification. The thresholds for the severity classes of indicators were established and then the hazard map for each indicator of types of desertification has been prepared in a GIS. The risk classes of different risk maps were calculated on the basis of classification of risk scores derived by cumulative effect of all the attributes of indicators after overlying them in the GIS. It was possible to distinguish the areas under ‘actual risk’ from areas under ‘potential risk’ of desertification types. Also areas under potential risk were classified to subclasses with different probability level to show a statistical picture of risk in future. The final map of risk of desertification was produced by overlaying all four maps of degradation types. Results show that potential risk areas and areas under actual risk are almost equal, indicating further threat of desertification in future in the half of the region. Also severe condition in the half of region shows environmentally bad situation in the study area. It is hoped that this attempt using GIS will be found applicable for other regions of the world.

4

Characterization of Soil Particle Size Distribution with a Fractal Model in the Desertified Regions of Northern China

Gao G.-L., Ding G.-D., Zhao Y.-Y., Wu B., Zhang Y.-Q., Guo J.-B., Qin S.-G., Bao Y.-F., Yu M.-H., Liu Y.-D.

Acta Geophysica

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2016

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Vol. 64, no. 1

1--14

EN

We constructed an aeolian soil database across arid, semi-arid, and dry sub-humid regions, China. Soil particle size distribution was measured with a laser diffraction technique, and fractal dimensions were calculated. The results showed that: (i) the predominant soil particle size distributed in fine and medium sand classifications, and fractal dimensions covered a wide range from 2.0810 to 2.6351; (ii) through logarithmic transformations, fractal dimensions were significantly positive correlated with clay and silt contents (R2 = 0.81 and 0.59, P < 0.01), and significantly negative correlated with sand content (R2 = 0.50, P < 0.01); (3) hierarchical cluster analysis divided the plots into three types which were similar to sand dune types indicating desertification degree. In a large spatial scale, fractal dimensions are still sensitive to wind-induced desertification. Therefore, we highly recommend that fractal dimension be used as a reliable and quantitative parameter to monitor soil environment changes in desertified regions. This improved information provides a firm basis for better understanding of desertification processes.

5

Carbon accumulation in the bulk soil and different soil fractions during the rehabilitation of desertified grassland in Horqin Sandy Land (Northern China)

Li Y., Zhao X., Wang S., Zhang F., Lian J., Huang W., Mao W.

Polish Journal of Ecology

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2015

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Vol. 63, nr 1

88--101

EN

Desertification, which affects more than two-thirds of the world’s arid and semi-arid regions, is a significant global ecological and environmental problem. There is a strong link between desertification of the drylands and emission of CO2 from soil and vegetation to the atmosphere. The Horqin Sandy Land is a severely desertified area in China’s agro-pastoral ecotone due to its fragile ecology, combined with unsustainable land management. We estimated changes of organic carbon content in the bulk soil (0–5 cm), in the light-fraction of soil organic matter (based on density fractionation), and in the various particle-size fractions in areas with mobile sand dunes after implementing grazing exclusion (12 and 27 years) and tree and shrub planting (22 and 24 years). Carbon stocks in the bulk soil and all soil density and particle-size fractions increased significantly in the exclosure and plantation plots. The average rates of carbon accumulation in the bulk soil in the exclosure and plantation plots were 16.0 and 17.8 g m-2 y-1, respectively, versus corresponding values of 2.3 and 7.1 g m-2 y-1 for the light fraction, 4.3 and 8.0 g m-2 y-1 for the coarse fraction, 5.0 and 3.4 g m-2 y-1 for the fine sand, 4.5 and 4.2 g m-2 y-1 for the very fine sand, and 1.8 and 1.8 g m-2 y-1 for the silt+clay fraction. The older the exclosure and plantation, the more carbon accumulated in the bulk soil and in each fraction. The carbon pool exceeded the level in non-desertified grasslands after 27 years of grazing exclosure and 24 years of the shrub plantation. Our results suggest that both grazing exclusion and planting trees and shrubs can restore desertified grassland, creating a high potential for sequestering soil carbon, but that the plantations appeared to accumulate soil carbon faster than the exclosures.

6

The effect of the halophytic shrub Lycium ruthenicum (Mutt) on selected soil properties of a desert ecosystem in central Iran

Jalali G. A., Akbarian H., Rhoades C., Yousefzadeh H.

Polish Journal of Ecology

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2012

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Vol. 60, nr 4

845--850

EN

We compared soil properties beneath naturally-occurring patches of Lycium ruthenicum Murray (fam. Solanaceae) to evaluate the shrub’s potential to improve the fertility of saline soils. Soil pH, total nitrogen and carbon and extractable potassium, magnesium and phosphorus were respectively significantly higher in the A and B horizons of Lycium shrub patches compared to adjacent unvegetated soils. The influence of Lycium on these soil properties increased with shrub density. Total soil N and extractable Mg and K concentrations were 1.8, 2.6- and 6.6-fold higher under dense Lycium shrub patches compared to unvegetated, bare areas and soil pH was 0.5 units higher. In contrast, the presence of shrubs and shrub density had no clear affect on the EC, Na or CEC of the A horizon soils. The shrub effect extended to the gypsum-rich By horizon (20–50 cm depth) and underlying B horizon (30–80 cm depth) for several soil properties. Total soil C and N were 1.8- and 1.6-fold higher beneath dense Lycium patches than bare soil areas. Soil pH remained 0.4 units higher under dense Lycium than bare soil patches. In the B horizon total soil C was twice as high beneath dense Lycium patches compared to the other patch types. Lycium ruthenicum not only tolerates the saline and drought conditions, it also produces sufficient biomass to increase the nutrient and organic matter content of surface mineral soils in this arid ecosystem and may have potential to improve soil conditions, facilitate ecosystem development and slow desertification.

7

Wpływ mieszanek motylkowato-trawiastych i nawożenia mineralnego na dynamikę przemian przyswajalnych form azotu w glebie w warunkach jej pustynnienia

Babajewa K. M.

Woda-Środowisko-Obszary Wiejskie

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2010

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T. 10, z. 4

7-14

PL

Istotnym problemem współczesnego azerbejdżańskiego rolnictwa w warunkach gospodarki rynkowej jest przygotowanie bazy paszowej odpowiedniej do rozwoju chowu zwierząt, z wykorzystaniem całorocznego wypasu pastwiskowego, który zapewnia odpowiednią ilość pasz objętościowych. Postępujące globalne ocieplenie uznawane jest za jedną z przyczyn postępujących procesów erozji i pustynnienia rozległych terenów wypasowych. Wyniki doświadczeń zaprezentowanych w pracy sugerują sposób polepszania walorów wypasowych zimowych pastwisk, a także tworzenia warunków, zapobiegających erozji i poprawiających żyzność gleb. Dzięki zastosowaniu zabiegów uprawowych, polegających na wysiewie motylkowato-trawiastych mieszanek i nawożeniu mineralnym N30P30K30, polepszono warunki wilgotnościowe gleb i ich zasobność w składniki pokarmowe, a szczególnie w azot. Doświadczenia umożliwiły również rozpoznanie dynamiki powstawania w glebie amonowych i azotanowych form azotu w okresie wiosenno-letnio-jesiennym.

EN

An important issue of current Azerbaijan agriculture under market economy is to prepare food base for animal breeding using year-long pasture grazing which provides sufficient amount of bulk fodder. Proceeding global warming is considered one of the reasons for erosion and desertification of vast pasturelands. Results of experiments presented in this paper suggest a way of improving the grazing value of winter pastures, preventing erosion and increasing soil fertility. Soil moisture and nutrient abundance (particularly nitrogen) were improved after sowing legume-grass mixtures and mineral fertilisation with N30P30K30. The experiments allowed also for understanding the dynamics of ammonium ions and nitrates in soil from spring to autumn.

8

Relationship between groundwater depth and pattern of net primary production in oasis-desert ecotone

Wu F., Deng J., Li T., Wang G., Wei X., Zhao C.

Polish Journal of Ecology

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2010

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Vol. 58, nr 4

681-692

EN

Pattern of plant biomass and net primary production was investigated in two localities (Minqin and Linze) of oasis-desert ecotone (ODE) in Northwest China, in order to recognize the spatial and temporal variability of vegetation under same regional climate with different groundwater depth. The average depth to groundwater was over 14.02 m at Minqin - marked further as DG (deep groundwater) and about 4.96 m at Linze - marked further as SG (shallow groundwater). We have measured plant biomass and net primary productivity (NPP) across species, three times per year for three consecutive years, in six plots along Minqin and Linze oasis-desert ecotone (further marked as DG and SG ODE), respectively. Our results showed that DG and SG ODEs had different growth responses to different groundwater depths. DG ODE exhibited higher inter-annual variation in annual NPP (ranged from 0.18 to 9.30 g m[^-2]) than did SG ODE (ranged from 0.42 to 17.99 g m[^-2]). Decrease of groundwater depth had apparently altered the seasonality of productivity in DG ODE systems, where precipitation in summer maintained plant growth, while ODE with high groundwater depth tended to have higher spring NPP in SG ODE. Spatial and temporal heterogeneity of NPP at the scale of our measurements was significantly greater in DG ODE than in SG ODE. SG ODE tended to support higher NPP than did DG ODE. In addition, the groundwater depth strongly influenced spatial and temporal heterogeneity of NPP in the desert ecosystems. Clearly, the desert ecosystem with higher groundwater depth is more stable and more resistant to long-term drought or climate shifts in arid regions. These investigations and quantitatively analysis are very significant for the execution of conservation and restoration in arid ecosystems.