بررسی اثرهای برخی از شاخص های اکولوژیکی لکه های جنگلی بر روی عرضه خدمات اکوسیستمی منتخب (منطقه مورد مطالعه: بخش شرقی استان گیلان) (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
در سال های اخیر خدمات اکوسیستمی و افزایش آن با رویدادهایی همچون تغییرات اقلیمی و حوادث طبیعی غیرمترقبه به موضوعی مهم تبدیل شده است؛ با این حال اطلاعات محدودی درباره خدمات اکوسیستمی درزمینه برنامه ریزی وجود دارد. در پژوهش حاضر سعی شده است تا این شکاف با ارزیابی میزان تأثیر ساختار لکه ها بر روی عملکرد اکوسیستم بررسی شود. به همین دلیل، بخشی از استان گیلان به عنوان استانی که طی سال های اخیر به دلیل وجود جنگل های هیرکانی، دریای خزر و آب و هوای مطبوع دستخوش تغییرات زیادی شده است، به عنوان منطقه مطالعه شده انتخاب و سپس مدل سازی خدمات اکوسیستمی ترسیب کربن، نگهداشت خاک و جلوگیری از سیلاب با استفاده از نرم افزار InVEST انجام و درادامه، شاخص های اکولوژیکی مقدار زیست توده، از هم گسیختگی، مساحت هسته ها و نسبت محیط به مساحت هسته های جنگلی به عنوان چهار شاخص اکولوژیک مهم با استفاده از نرم افزارهای MSPA و Fragstate استخراج شده است. درنهایت، ارتباط بین شاخص های اکولوژیکی با خدمات اکوسیستمی منتخب بررسی شد. نتایج نشان داد که بین وجود منطقه ها جنگلی و سبزتر و هسته های بزرگ تر و یکپارچه تر در این منطقه ها با ارائه خدمات مد نظر ارتباط مثبت و قوی وجود دارد. همچنین، میزان ارائه خدمات اکوسیستمی لکه ها با افزایش نسبت محیط به مساحت هسته در لکه های جنگلی و نیز با افزایش ازهم گسیختگی به صورت محسوسی کاهش می یابد؛ درنتیجه برنامه ریزی برای استان های شمالی کشور در راستای افزایش بهره وری اکولوژیکی این مناطق نه تنها مستلزم حفظ بقایای جنگل های هیرکانی و افزایش مساحت آنهاست، نیازمند توجه به یکپارچگی و کاهش لکه های ایزوله است.Investigating the Effects of Some Ecological Indicators of Forest Patches on the Supply of Selected Ecosystem Services (Study Area: Eastern Part of Gilan Province)
In recent years, augmentation of ecosystem services has emerged as a critical concern. However, there is a dearth of information regarding ecosystem services within the realm of planning. This study sought to address this gap by assessing the influence of landscape structure on ecosystem functionality. To achieve this, we utilized InVEST software to model ecosystem services, such as carbon sequestration, soil maintenance, and flood prevention. Additionally, we employed MSPA and Fragstate software to derive 4 key ecological indicators: biomass quantity, fragmentation, core area, and ratio of environmental area to forest core area. Subsequently, we examined the relationship between these ecological indicators and the selected ecosystem services. Our findings indicated a robust and positive correlation between the presence of forested and verdant areas, as well as larger and more interconnected cores within these areas, and the provision of desired services. Notably, in forest patches, a decrease in ecosystem service provision was observed with increased fragmentation and instability, underscoring the importance of preserving and expanding the Hyrcanian forests while also prioritizing integrity and reducing isolated patches for enhancing ecological productivity in the northern provinces of the country.Keywords: Ecosystem, Ecosystem Services, Ecological Indicators, PlanningIntroductionThe decline of ecosystem services is a matter of grave concern as it has the potential to undermine the long-term resilience of ecosystems and precipitate abrupt changes that jeopardize a safe habitat for humanity. The type and intensity of land use, along with the spatial arrangement of land cover types within a region, can significantly alter its capacity to furnish ecosystem services. This is because transitioning from one land use type to another impacts crucial ecological processes, such as energy exchange, water cycle, and biogeochemical cycles, consequently influencing the provision of ecosystem services. Configuration of land use is a pivotal structural factor that influences ecosystem functionality and delivery of services. Notably, human activities, land cover, and associated changes have been identified from among the most influential factors shaping the structure, composition, and function of ecosystems that underpin their services.Effective land use management and planning necessitate an initial phase of assessing and mapping ecosystem services. This stage yields crucial information, including identification of areas that yield high levels of service and require protection or management to sustain the services provided, as well as recognition of areas with specific ecosystem services and changes in the provision of ecosystem services over time.Despite previous research efforts, no study has comprehensively explored the significant ecological indicators in relation to overall ecosystem services. Furthermore, optimization of ecological network elements to enhance ecosystem services has been predominantly limited to the establishment of corridors between ecological network cores (Xiao et al., 2020; Guo et al., 2018; Shi and Qin, 2018). Therefore, this study endeavored to identify and evaluate the relationships between key ecological indicators and ecosystem services. Materials & MethodsThe research area encompassed two watersheds, Lahijan Chaboksar and Astana-Kuchesfahan, situated in the eastern and central regions of Gilan Province, respectively.The initial step of this study involved the classification of satellite images of the study area in 2020. To achieve this, Landsat 8 images captured between 01/01/2020 and 12/31/2020 with cloud cover below 10% were utilized. Subsequently, classification of land cover was conducted, employing normalized vegetation difference index products and guidelines for the four seasons, urban areas, and tree cover to identify forested areas with trees exceeding 30 meters in height. Additionally, ground-based data input by the user was utilized to classify land cover into 8 categories: forested areas, open spaces, pastures, agricultural lands, tea cultivation lands, gardens, water bodies, and man-made lands encompassing roads and urban areas.In the subsequent phase, 3 pivotal ecosystem services—carbon storage, flood mitigation, and sediment preservation—were selected for assessment. These services represented crucial contributions of the watershed, reflecting its equilibrium. The latest iteration of the Integrated Valuation of Ecosystem Services (InVEST) model was employed to quantify these services. Following the modeling and unweighting of the targeted services, the aggregate ecosystem service value was computed from the set of unweighted services. Furthermore, 4 ecological indicators—fragmentation, Normalized Difference Vegetation Index (NDVI), forest core area, and ratio of environmental area to core area—were evaluated. Subsequently, 1600 samples were selected using the "Fishnet" tool to calculate the correlation coefficient of total ecosystem services with the designated indicators. The data pertaining to ecological indicators and total ecosystem services were extracted from these samples. Pearson's correlation was then utilized to ascertain the magnitude, nature, and direction of the relationship between the two variables.Research FindingsThe index of Total Ecosystem Services (TES) for the three services under scrutiny ranged from 2.67 to 0.0, representing the highest and lowest values, respectively. Notably, the lowest value of service provision within the watershed was modeled in urban and built-up areas, registering a value of 0, while the highest value was observed in areas with a slope of less than 10% within the Hyrcanian forests, reaching a peak value of 2.67. Furthermore, in the northern region where agricultural lands had expanded, they accounted for the highest level of service provision following the forests.Calculation of NDVI revealed a range of 0.03 to 0.99 across the region. The highest NDVI values were recorded in densely populated areas in the south where the Hyrcanian forests were prevalent, while the lowest values were observed in man-made areas. Additionally, the disintegration index computed using GTB software fluctuated between 0 and 101 within the studied watershed. The lowest forest fragmentation rates were concentrated in the inner and central areas of the Hyrcanian forests in the southern half of the region, whereas the highest rates were found in isolated patches in the northern half part. Despite being fragmented, the forest edges exhibited an intermediate state owing to the high density of patches.An examination of the correlation between the aforementioned indices and TES revealed a significant positive correlation between TES and NDVI, as well as core area, with the correlation coefficients of 0.77 and 0.70, respectively. This suggested that an increase in either of these factors could lead to an enhancement in the quantity of the ecosystem services in question. Conversely, there existed a notable negative correlation between the TES index and the ratio of environmental area to core area, as well as the fragmentation index, with the correlation coefficients of -0.63 and -0.71, respectively. This implied that an increase in forest fragmentation or a shift towards edge-like configurations would diminish the provision of the desired services. Discussion of Results & ConclusionThe findings indicated that areas with more forest cover and greenery, as well as larger cores within these areas, were capable of providing more substantial ecosystem services. These results aligned with the findings of Situmorang et al. in 2016 and Shen et al. in 2019. Conversely, as the perimeter-to-core area ratio of forest patches increased, leading to a greater tendency for patches to become smaller and unstable, and as fragmentation within these patches intensified, the capacity of these patches to provide ecosystem services diminished significantly. These outcomes were consistent with the findings of Saeed et al. in 2019. Overall, this research underscored the influential role of secondary factors, in addition to land use, in the provision of ecosystem services. This insight can inform planning efforts aimed at enhancing the efficiency of programs and optimizing the delivery of desired ecosystem services. It is imperative to take proactive measures in this regard.
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