植被沙漠化在農(nóng)業(yè)生產(chǎn)量和生產(chǎn)力方面的不利影響受到廣泛的關(guān)注。氣候變化和人類活動(dòng)通常被認(rèn)為是導(dǎo)致植被沙漠化的兩大根本原因。在本研究中,采用基于凈初級(jí)生產(chǎn)力（NPP）的綜合分析方法定量評(píng)估2000-2008年科爾多凡省北部蘇丹地區(qū)氣候變化和人類活動(dòng)對(duì)沙漠化的影響。采用三種形式的凈初級(jí)生產(chǎn)力（NPP）,即實(shí)際NPP,潛在NPP和HNPP（人類占用的NPP）,來描述了沙漠地區(qū)氣候變化和人類活動(dòng)的相對(duì)作用。結(jié)果表明,研究區(qū)63.75%的地區(qū)經(jīng)歷了沙漠?dāng)U張,其中受人類活動(dòng)影響的占76.32%,受氣候變化影響的占32.03%,受兩者共同影響的占0.65%。人類活動(dòng)造成的沙漠化的縮減占2.3%,氣候變化占97.7%。相比之下,氣候變化是沙漠化縮減的主導(dǎo)因素,在縮減地區(qū)并不存在氣候變化和人類活動(dòng)的相互作用。最大擴(kuò)張區(qū)和縮減區(qū)分別分布在研究區(qū)的東北部和西部地區(qū)。通過研究,我們可得到兩個(gè)主要結(jié)論:一是在研究區(qū)的北東部,中部和南部的典型區(qū)域,沙漠?dāng)U張主要是由人類活動(dòng)引起的,沙漠的縮減主要是由氣候變化引起的;二是在研究區(qū)的西北部,沙漠的擴(kuò)張和縮減都是由氣候變化引起的。因此,人類活動(dòng)對(duì)荒漠化擴(kuò)張的影響比氣候變化更... 

【文章來源】：西北師范大學(xué)甘肅省

【文章頁數(shù)】：93 頁

【學(xué)位級(jí)別】：博士

【文章目錄】：
Abstract
摘要
CHAPTER ONE INTRODUCTION
    1.1 Background and Significance
        1.1.1 Research backgrounds
        1.1.2 Research significant
    1.2 General concepts
    1.3 Aim and Objectives
    1.4 Hypothesis
    1.5 Research contents
CHAPTER TWO THEORETICAL BACKGROUND
    2.1 Desertification
    2.2 Arid and semi-arid lands
    2.3 Vegetation indices
        2.3.1 The calculation of vegetation indices
        2.3.2 Normalized difference vegetation index (NDVI)
        2.3.3 Net Primary Productivity (NPP)
        2.3.4 Moderate Resolution Imaging Spectroradiometer (MODIS)
        2.3.5 The MOD17 products
        2.3.6 Application of MODIS for observing vegetation
        2.3.7 MODIS NPP (Actual NPP)
        2.3.8 Potential NPP (P NPP)
        2.3.9 The impact of climate change and human activities on NPP
        2.3.10 Correlations between NPP and climate variables
    2.4 Desertification dynamics
    2.5 Quantitative assessments the contribution of climate and human to desertification
CHAPTER THREE THE DATA AND METHODS
    3.1 Sudan
    3.2 Northern Kordofan province
        3.2.1 Population
        3.2.2 Climate
        3.2.3 Topography
        3.2.4 Soils
        3.2.5 Geology
        3.2.6 Vegetation
        3.2.7 Crops Production
        3.2.8 Crops Production
        3.2.9 Human activities
    3.3 Data
        3.3.1 Data source and processing
    3.4 Methods
        3.4.1 Estimation of actual NPP
        3.4.2 Estimation of potential NPP
        3.4.3 Statistical analysis
        3.4.4 Correlation analysis between NPP and climate factors
        3.4.5 Desertification dynamics analysis
        3.4.6 Scenario design and quantitative assessment method
CHAPTER FOUR RESULTS AND DISCUSSION
    4.1 Results
        4.1.1 Spatial and temporal dynamic based on actual NPP and potentialNPP
        4.1.2 Temporal (mean annual) variation of NPP
        4.1.3 Correlation between annual variation of climate and NPP
        4.1.4 Correlation between NPP and temperature
        4.1.5 Correlation between NPP and rainfall
        4.1.6 Desertification dynamics analysis
        4.1.7 Relative roles of inter-annual climate change and human activities in desertification expansion based on area
        4.1.8 Relative roles of inter-annual climate change and human activities in desertification expansion based on NPP variation
    4.2 Discussion
        4.2.1 Methodology
        4.2.2 The responses of annual NPP to climate variables
        4.2.3 Driving factors of desertification
CHAPTER FIVE CONCLUSION AND LIMITATION
    5.1 Conclusion
    5.2 Limitations
    5.3 Recommendations
REFERENCES
ACKNOWLEDGEMENT



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