Study Of Wetland Landscape Pattern Changes In The Yellow River Delta Under Human Disturbance

The Yellow River Delta is located in the interchange of river-sea-land, multiple interfaces of environmental characteristics lead to its fragile ecological environment.In recent years, due to the deepening of human activities, such as land reclamation, irrigation and reclamation, port construction and oil exploration, the sphere of influence has been expanding dramatically. The Yellow River Delta wetland landscape pattern changed significantly, suffering from wetlands shrinking, ecological information loss, functional decline, structure broken, ecological environment deterioration and other difficulties, human interference has become the main driving force and source of wetland landscape pattern differentiation in short temporal and spatial scales. Therefore, to strengthen the dynamic monitoring and research of the Yellow River delta wetland, to discuss wetland landscape evolution characteristics and human disturbance mechanism, to grasp spatial and temporal dynamic changes of wetlands under anthropogenic interference, is of great significance for wetland landscape restoration and reconstruction in the Yellow River delta.This paper, supported by the National Natural Science Foundation of China(41371517), Shandong Province Science and Technology Program(2013GSF11706), taking the Yellow River delta(Dongying City) as the study area, with 1989, 1999, 2009 and 2014 remote sensing images as the main data source. First of all, pretreatment of interpretation were carried on to get wetland landscape classification map of different periods, to extract wetland landscape types, area and other information, then with the help of ArcGIS and FRAGSTATS, carries on the landscape types transfer and landscape pattern change analysis; Based on the interpretation result, select cultivated land, residential and industrial land and roads three factors to construct human activity intensity index, using natural-break method to classify the human activity intensity from strong to weak into 1-10 transects, from the perspective of landscape ecology, we analyse wetland landscape pattern characteristics change with the intensity of human activities presented by gradient differentiation characteristics. Finally analyses specific human activity and its ecological effect, basically we have got the following conclusions:(1) Overall, study area increased slightly from 1989 to 2014. Among them, the natural wetlands showed fluctuated decreasing trend, among which the largest reduction is the area of tidal flats, followed by the meadow; artificial wetland landscape continued to increase; among non-wetland landscape, cultivated land, industrial land and other construction land has also increased, but the substantial reduction of unused land resulting in a smaller reduction of non-wetland landscape as a whole;(2) Landscape type conversion was very dramatic from 1989 to 2014, especially between wetlands and non-wetlands, as well as other landscape types. Due to human disturbance, transferred amount of landscape type was very complicated when it comes to moving large amounts of natural wetland in and small amounts out such as meadows and tidal flats, while construction land, industrial land and other non-wetland landscape remained the opposite trend of small convert-out and large convert-in. In the recent 25 years, the entire landscape suffered from high degree of fragmentation, which has been intensified, and more diverse types of patch, besides each patch type distribution in the landscape become more even;(3) On the patch level, with the decreasing of human activities intensity, reservoir ponds, aquaculture farms, salt land and unused land 4 main landscape types reflected the changes of landscape pattern characteristics in the gradient belt quite well. Among them, PLAND, PD, and LPI fluctuated obviously along the gradient of human activities intensity, which change was very complex and hard to find regularity, while the trends of LSI and FRAC_MN were much more obvious, showing a fluctuated upward trend, that is to say with the reduction of human activities intensity, landscape shape tended to be more complicated;(4) On the landscape level, with the human activity intensity decreasing, richness of wetland landscape increased gradually in intensity transects from 1 to 10, while the PD is also increasing, SHDI and SHEI showed a trend of decreases after first increase change, which was in line with the intermediate disturbance hypothesis. At the same time, aggregation degree of patches in different intensity increased, the distribution tends to concentrate. Overall, landscape connectivity has increased, while the fragmentation degree reduced;(5) Due to the different human activities, such as reclamation, coastal construction projects, oil exploration and the resulting offshore environmental pollution makes the Yellow River Delta wetland suffering from shrinking, biodiversity loss, ecological environmental deterioration and other risks. Although water-sediment regulation of the Yellow River and the wetland ecological restoration projects curbed the degradation trend of Yellow River Delta wetland to a certain extent, but from the point of succession and development of an ecosystem, the restoration and succession of degradation wetland is still a long process.