V. SPACE TECHNOLOGY AND ENVIRONMENT

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1 V. SPACE TECHNOLOGY AND ENVIRONMENT FOREST VEGETATION STATE AND DYNAMICS IN THE HASKOVO REGION (BULGARIA) A RESEARCH BASED ON VEGETATION INDICES, CLIMATE AND SOLAR ACTIVITY DATA Daniela Avetisyan, Roumen Nedkov, Deyan Gotchev Abstract.The climate changes and the anthropogenization have been a prerequisite for development of negative trend processes during the last decades, which has resulted in degradation of vegetation and deforestation in particular. This leads to alternation of landscape structure and statement of landscape components. Simultaneously, these processes are accompanied by changing of heat moisture ratio in landscapes, and continuously running drought processes. Aim of the present study is to trace the climatic condition in the region for the period from 1987 to 2013 and to study their impact on the state and dynamics of the forest vegetation. Variations in the activity of specific geoeffective components of solar activity can be considered as one of the possible factors causing vegetation cover degradation, drought, and desertification. In order to achieve this goal Remote Sensing and GIS methods are applied and widely recognized indices as NDVI (Normalized Difference Vegetation Index), NDWI (Normalized Difference Water index) and VCI (Vegetation Condition Index) were calculated. Possible correlations with solar activity are studied. Keywords: Vegetation indices; remote sensing and GIS; climate data 1. INTRODUCTION The vegetation cover is among the most vulnerable to climate changes and human activities natural components. The deterioration of the vegetation cover state and particularly of the forests one influences important environmental processes and results into development of negative phenomena as drought, soil erosion, environmental degradation, and desertification. Aim of the present study is to trace the climatic condition and its variability in Haskovo region for the period from 1985 to 2013 and to examine their impact on the forest vegetation. It is under particular threat in the arid and semiarid areas, where Haskovo region is located. The impact of variations in the activity of specific geoeffective components of solar activity on climatic and vegetation condition is also taken into account. [7] As a general rule, the deterioration of vegetation state is due to prolonged stress, gained over a longer period of time. Therefore, an assessment of the moment state of this natural component is not sufficient for the determination of its development / dynamics trends. For that reason, we investigated a twenty-eight years period. Vegetation condition was assessed by applying of widely recognized indices: NDVI, NDWI, and VCI. NDVI is strongly related to photosynthetic activity, so it can be used to estimate the state and dynamics of forest vegetation. The formula can be expressed as: [5, 9, 10, 11] (1) where ρ NIR and ρ RED indicate the reflectance of the near infrared and red bands, respectively. Essential for forest vegetation condition assessment in semi-arid areas is determination of drought impact. VCI makes available drought studying not only in areas with well-defined, prolonged, widespread, and very strong droughts, but also in such areas, characterized by very localized, short-term, and ill-defined droughts. VCI can be expressed as: [6]. (2) where NDVI is the current value and NDVImin and NDVImax are the maximal and minimal values of NDVI for the investigated period. Water is one of the most common limitations causing drought. NDWI is proposed for remote sensing of vegetation liquid water and it can be expressed as: [3] (3) where NIR and SWIR are the spectral reflectance measurement in the Near Infra-Red and Short Wave Infra-Red regions of the electromagnetic spectrum. 41

2 The combined application of these vegetation indices together with climatic data enable assessment of climate changes impact on the forest vegetation state and dynamics. We also took into account variations in the activity of specific geoeffective components of solar activity which can be considered as one of the possible factors causing vegetation cover degradation, drought, and desertification. The solar terrestrial connections could be traced in some changes of the biosphere. [2] Although some effects are obvious, the mechanisms complexity is checked by differential studies, based on well-known physical processes. 2. STUDY AREA Haskovo region is located in the Southeastern part of Bulgaria, adjacent to Greece and Turkey. (Fig.1) The region occupies 5% of the Bulgarian territory with an area of km 2. The average annual air temperature ranges between 12 C and 13 C. The average air temperature in the warmest month - July ranges between 22.8 C and 23.7 C. The average air temperature in the coldest month - January ranges between 0.5 C and 1.5 C. The average precipitation sum for the period with mean diurnal temperature above 5 C is between 430 mm and 530 mm. The average evapotranspiration sum for the period with mean diurnal temperature above 5 C is around 900 mm. Climate in Haskovo region is distinguished by pronounced draught. The average lack of humidity for the period with mean diurnal temperature above 5 C ranges between 370 mm and 470 mm as in some years it increases to 700 mm. [12] The forest vegetation in the region is represented by broad leafed species. The edificator species are mainly various type of oak - Quercus cerris L., Q. frainetto, Quercus dalechampii, Quercus pubescens, Quercus virgiliane. [1] 3. METHODOLOGY For the purposes of the present study, two types of input data were used: satellite and aero-photo data, and terrestrial data. The satellite data includes raster images from Landsat TM (Thematic Mapper), ETM+(Enhanced Thematic Mapper Plus), OLI (Operational Land Imager), acquired in the growth vegetation season of 1987, 2000, 2007, and 2013, and Modis images from 2011 to 2014 vegetation seasons, when solar activity is increasing. For more precise interpretation and verification of the satellite images, an aerophoto image from June 2011 was used. For the tracing of the spatial relationships in the region, vector and analogue data, generated by terrestrial and terrestrial - remote sensing techniques, was applied as well. It includes a Corine Land Cover (CLC 2006) vector layer and an analogue map of vegetation cover of Bulgaria [1]. Fig. 1. Location of Haskovo Region and the five test forest areas The applied climatic data refers to the period from 1985 to 2013[12]. The researched bursts in solar activity include X-class solar flares and energy plus particle pumping in the atmosphere from coronal jets and coronal mass-ejection originating from filament eruptions. In the last decades correlation between the QBO (quasi bi-annual oscillation) and solar cycle activity is observed. Elements of the latter like high-altitude energy input (solar irradiance) and solar particles ionization of aerosols cause variations in wind distribution (QBO) and cloud formation. In order to fulfill the aim of the present study, we developed an appropriate methodology. It includes several steps, which are presented on Fig.2. Firstly, the satellite images were composed in the visible red, near infrared and short wave infrared range of the electromagnetic spectrum. The composed images were applied in order to achieve two different tasks. On the one hand, test forest areas for a more precise investigation was selected (Fig.1). This selection was on the basis of training samples. This method was validated by using CLC and orthophoto data. [8] On the other hand, vegetation indices were calculated. 42

3 Fig. 2. Methodology Scheme Next step is a selection of climate elements. The region is distinguished by a pronounced drought. Hence, the forest vegetation is especially vulnerable in growth vegetation season. For that reason, the assessment of climatic conditions and their impact on forest vegetation during this season is crucial. Since the growth vegetation season varies over the years, we took into account the average air temperature, the precipitation sum, and the evapotranspiration sum for the period with mean diurnal temperature above 5 C. In estimation of the relations between the indices values and the climatic elements impact, the period between the first decade with mean diurnal temperature above 5 C and the decade when the relevant satellite image was acquired, was took into consideration. Final step is tracing the manifestation of the investigated climatic elements for the period from 1985 to 2013 and marking their fluctuations during this period. Four years were selected for a more detailed survey. These are: 1987, 2000, 2007, and 2013 and they serve as benchmarks depicting the moment state of the forest vegetation. When studying a prolonged period, we seek to capture not only the climatic conditions impact in the relevant year but also those of the previous years and to bring out a more general trend for the whole period. After detecting the climatic elements fluctuation in the above mentioned period, an interrelation with solar activity was sought. Data (Fig.9, 10, 12, 13) about QBO, X-class solar flares and energy, coronal jets and coronal mass-ejection were examined. [13, 14, 15, 16, 17] 43

4 4. RESULTS The estimation of the relation between the climatic elements and the indices values shows large fluctuations in the values of NDVI and VCI, and more stable appearance of NDWI. For 1987 and 2000, the values of NDVI are under 0.4 or very close to it. This value is a kind of threshold, dividing well-functioning forest vegetation of sparse vegetation, grasslands, and bare soil is distinguished by relative better climatic condition. For all of the tested areas the values of this index are above 0.4. For 2013, deterioration in the forest vegetation state is noted. Two of the areas are characterized with NDVI values under 0.4. Despite the similar values, these forests are located at a large distance from one another in quite different geographic areas. The NDVI values for the remaining forests range between 0.4 and 0.5. For the determination of the vegetation condition according to VCI values, a classification of Dillon et al. [3] was applied. All test forest areas are characterized with fair vegetation condition in Similar is situation in 2000 and The most diverse year is 2007 when the lowest and the highest VCI values were calculated (forest 3 close to zero, and forest ). NDWI values are critically low for all of the forests during the years. For 2000, the values of NDWI are negative for all test forest areas, except forest 3 where NDWI is This value however, is under the typical one for a deciduous forest. For 2007 and 2013, the NDWI values are positive but still lower than the typical ones for deciduous forests. (Tab.1; Fig. 3, 4, 5). Table 1. Vegetation indices and climatic elements values for the test forest areas (1987) Fig. 3. Vegetation indices and climatic elements values for the test forest areas (2000) 44

5 Fig. 4. Vegetation indices and climatic elements values for the test forest areas (2007) Fig. 5. Vegetation indices and climatic elements values for the test forest areas (2013) The analysis of the character of the climatic elements for the period from 1985 to 2013 shows that there are clear trends in increase of their values. For a 28 years period, the increase of the average air temperature for the period with mean diurnal temperature above 5 C ranges between 1.55 C for forest 2 and 1.25 C for forest 5. (Fig.6) The increase of the precipitation sum for the different forests ranges between 50 mm and 110 mm, and that of the evapotranspiration sum is around mm and it is almost equal for the whole territory. (Fig.7, 8) 45

6 Fig. 6 Average values of the air temperature for the period with mean diurnal temperature above 5 C Fig. 7 Average values of the precipitation sum for the period with mean diurnal temperature above 5 C 46

7 Fig. 8. Average values of the evapotranspiration sum for the period with mean diurnal temperature above 5 C The analysis of the results obtained after the investigation of the interrelations between the climatic fluctuations and the forest vegetation state in Haskovo region for the twenty-eight years period (1985 to 2013) can be summarized in several statements: 1. The whole study area is characterized with an increase of the values of the climatic elements (average air temperature, precipitation and evapotranspiration sums for the periods with mean diurnal temperature above 5 C) taken into account in this survey. 2. There is a large fluctuation in the NDVI and VCI values. The upper limits of NDVI range around 0.4 and 0.6, as these values are typical for forest vegetation, distinguished by not very good running of photosynthesis and the lower limits remain around 0.3 for all of the investigated years. This value is representative for sparse vegetation and grasslands but not for a well-functioning forest. The variations of VCI are probably a result of the changes of heat - moisture ratio. In different years, the lack of humidity varies between 350 mm and 725 mm. Hence, the differences in local microclimatic conditions are the most probable factor, reflecting on the vegetation condition and dynamics. 3. In the twenty-eight years period, shorter terms, characterized with deterioration of the optimal conditions for forest vegetation, have been observed. Such terms are these distinguished by drought. The most prolonged among them lasted four years from 1997 to In terms like that, the drought severity notably increases. Most negatively affecting climatic conditions are observed in That is the peak year for the period of drought, continued between 1997 and 2000.The average air temperature in this period increased with 2.0 C, the precipitation sum decreased with 225 mm, and the evapotranspiration sum increased with 100 mm. The difference between the evapotranspiration and precipitation sum was around 700 mm. All this reflect on the indices values which are the lowest namely for that year. Furthermore, in the whole period throughout the study territory, the NDWI values are critically low close to zero, and for 2000 the values are negative for 4 of the 5 test forest areas. 4. Most probable reason for the deterioration of the forest vegetation state in Haskovo region is the increase of drought severity in periods of time lasting to four years. This periodicity described above directed our attention to solar activity and the character of its manifestation. These periods of drought could be ruled by the QBO, which influences the General Atmospheric Circulation, i.e. the activity of the cyclo-genesis. In the last decades correlation between the QBO and solar cycle activity is observed. Elements of the latter like high-altitude energy input (solar irradiance) and solar particles 47

8 ionization of aerosols cause variations in wind distribution (QBO) and cloud formation. These climatic changes influence the flora vegetation activity.(fig.9,10a, 10b) [13,14]. Fig. 9 QBO: Zonal wind for the period from 1993 to 2011 Fig. 10(a). Zonal mean wind as a function of time and latitude at 10mb. Note the alternating easterlies and westerlies along the equator. Fig. 10(b). Zonal mean wind as a function of time and latitude at 100mb. Fig. 11. Abrupt decreases of NDVI and VCI values, observed in June 2011 and May 2013 Another trigger effect concerning the biosphere is due to extreme short-term (a couple of days) bursts in solar activity, consisting of X-class solar flares and energy, plus particle pumping in the atmosphere from coronal jets and coronal mass-ejection originating from filament eruptions. The vegetation is sensitive to 48

9 such influences. Usually the retarding effect is reversible. This phenomenon is demonstrated by Fig 11. On the Earth, this phenomenon occurs by abrupt decreased in indices values. (Fig.11) First example period is 2011/06/23-24 when for two days before the index abrupt decreased, 23 6-hrs.-lasting filament eruptions happened, resulting in a coronal jet for 6- hrs. plus a couple of several hours lasting filament eruptions during the period of decrease. A similar phenomenon was observed 2013/05/ (Fig.12, 13) [15, 16, 17] Fig.12. Solar activity data Fig 13. Active regions and geoeffective phenomena on the Sun (2013/05/11-12; 2011/06/23-24) Due to cloud cover, there is a lack of reliable data for other periods of strong solar activity. However, solar activity is in period of growth. That provoked the recent study to be continued in order more detailed connection between solar energy input and biological processes to be determined. 5. CONCLUSION It can be summarized, that the forest landscapes in Haskovo region have been under stress during the last twenty-eight years period (from 1985 to 2013). The relative stable values of NDWI and the fluctuations of NDVI and VCI can be explained with striving of the geosystems towards equilibrium. That could lead to landscapes structure changes in near future. Acknowledgements. This work was supported by the Operational Program Human Resources Development of the Bulgarian Ministry of Education, Youth and Science funded by the European Social Fund (ESF), CONTRACT BG051PO REFERENCES 1. Bondev I. The Vegetation of Bulgaria. St. Kliment Ohridski University Press. (in Bulgarian), Del Guidice et all. Structures, Correlations and Electromagnetic Interactions in Living Matter: Theory and Applications. Biological Coherence and Response to External Stimuli. Springer, Berlin,

10 3. Dillon M, McNellie M, Oliver I. Assessing the Extent and Condition of Native Vegetation in NSW. Monitoring, evaluation and reporting program, Technical report series, Office of Environment and Heritage, Sydney, Gao Bo-cai, NDWI A Normalized Difference Water Index for Remote Sensing of Vegetation Liquid Water from Space. Remote Sensing of Environment; Volume 58, Issue 3, December, , Gausman, H. W. Leaf Reflectance of Near- Infrared. Photogrammetric Engineering, 10, , Kogan F. Droughts of the Late 1980s in the United States as Derived from NOAA Polar Orbiting Sattelite Data. Bulletin of the American Meteorological Society, König H et all. Biologic Effects of Environmental Electromagnetism. Springer, New York, p.135, Milanova Y., Mateeva Z. A Multidisciplinary Approach to Study Climate- Determined Productivity of Agricultural Crops. In CD Proceedings, XXIV International Symposium on Modern technologies, education and professional practice in geodesy and related fields, Sofia, November 6-7, ISSN , Sellers, P. J. Canopy Reflectance, Photosynthesis and Transpiration. International Journal of Remote Sensing, 6, , Sellers, P. J. Canopy Reflectance, Photosynthesis and Transpiration. II. The Role of Biophysics in the Linearity of their Interdependence. International Journal of Remote Sensing, 21, , Sellers, P. J., Berry, J. A., Collatz, G. J., Field, C. B., Hall, F. G. Canopy Reflectance, Photosynthesis and Transpiration. III. A Reanalysis Using Improved Leaf Models and a New Canopy Integration Scheme. International Journal of Remote Sensing, 42, , sunspots_files/bigw04-sunspots-and-cosmicradiation.gif.gif unspots_files/bigw02-sunspots-and-solarirradiance.gif.gif СЪСТОЯНИЕ И ДИНАМИКА НА ГОРСКАТА РАСТИТЕЛНОСТ В ОБЛАСТ ХАСКОВО ИЗСЛЕДВАНЕ, БАЗИРАНО НА ВЕГЕТАЦИОННИ ИНДЕКСИ, КЛИМАТИЧНИ ДАННИ И ДАННИ ЗА СЛЪНЧЕВАТА АКТИВНОСТ Даниела Аветисян, Румен Недков, Деян Гочев Резюме. През последните десетилетия климатичните промени в съчетание с антропогенизацията са предпоставка за развитието на негативни процеси, водещи до деградация на растителността и обезлесяване. Те от своя страна водят до изменения в ландшафтната структура и състоянието на ландшафтните компоненти. Междувременно, тези процеси са свързани с изменения в съотношението топлина-влага в ландшафтите и продължително протичащия процес на засушаване. Цел на настоящето изследване е да проследи климатичните условия в област Хасково за периода от 1987 г. до 2013 г. и да изследва тяхното въздействие върху състоянието и динамиката на горската растителност.флуктуациите в активността на специфични геоефективни компоненти на слънчевата активност могат да бъдат разглеждани като един от възможните фактори водещи до деградация на растителната покривка, засушаване и опустиняване. За постигането на тази цел са използвани методите на дистанционните изследвания и ГИС като са приложени широко приетите вегетационни индекси: NDVI (Normalized Difference Vegetation Index), NDWI (Normalized Difference Water index) и VCI (Vegetation Condition Index). Изследвани са възможни взаимоотношения със слънчевата активност. Ключови думи: вегетационни индекси, дистанционни изследвания и ГИС, климатични данни 50

11 Daniela Avetisyan SRTI BAS Acad. G. Bonchev Str., bl.1, Sofia Prof. Dr. Roumen Nedkov Dipl. Eng. SRTI BAS Acad. G. Bonchev Str., bl.1, Sofia Deyan Gotchev SRTI BAS Acad. G. Bonchev Str., bl.1, Sofia Даниела Аветисян ИКИТ - БАН Ул. Акад. Г. Бончевр бл.1, София davetisyan@space.bas.bg проф. д-р инж.румен Недков ИКИТ - БАН Ул. Акад. Г. Бончевр бл.1, София rnedkov@space.bas.bg гл.ас. Деян Гочев ИКИТ - БАН Ул. Акад. Г. Бончевр бл.1, София dejan@mail.space.bas.bg 51