Exploring the Effects of Landscape Structure at Multiple Scales on River Water Characteristics in the Khorramabad and Chalus River basins

Background It is acknowledged that the landscape composition and configuration of land cover within a watershed could influence a watershed environmental and ecological quality. Therefore, rivers receive pollution from their surrounding landscape and the amount and intensity of this pollution are affected by the landscape structure around the river or within a watershed. Methods In this research, we estimated the relationship between landscape characteristics and water quality in two different basins. We used multiple stepwise regression analysis and redundancy analysis to explore the quantitative association between landscape metrics, at both the watershed and riparian buffer scales. Results The riparian buffer scales metrics were more effective in predicting water quality in comparison with the indices at the watershed scale. The landscape composition and configuration explained 80% of the variation in water quality at 100 m buffer, and the value decreased to 79% at 1000 m. At the 100 m buffer scale, ED of the forest, PLADJ, and MESH of urban areas in Khorramabad basin and AI of the forest, ED of urban, and SPLIT of agricultural lands were recognized as significant variables affecting the water quality in the Chalus basin. In other scales only metrics related to agriculture and urban were seen as dominant variables, indicating that these land-use classes are final determinatives in water quality changes in our study areas. Conclusion All dominant variables at each scale indicated a decreasing trend of the landscape impact on the water quality. Although in the Chalus basin human activities were insignificant, they had considerable effects on Chalus river quality, and urban and agriculture were recognized as dominant usages at all scales, implying that a large amount of forest cover cannot impede the effects of human activities in a basin.

Estimating landscape structure effects on pollination for management of agricultural landscapes

The present study aims to examine the effects of habitat fragmentation to find a pattern of forest patches in agricultural landscapes that provide the highest pollination level. For this purpose, using simulated agricultural landscapes, including different forest proportions and degrees of fragmentation, pollination in different scenarios was estimated. We used landscape metrics to measure the landscape composition and configuration of each simulated landscape and estimated their statistical relationship with pollination. Our results showed that the effects of fragmentation on pollination were affected by two significant factors; 1- habitat amount and 2- small patches' capacity to supply pollination. Our results showed that when small patches' capacity in supplying pollination was low, fragmentation decreased pollination. When this capacity was very high, landscapes with a high degree of fragmentation showed higher levels of pollination. There was an exception for habitat amounts less than 0.1 of the entire landscape that increasing edge density, aggregation, and the number of patches, resulted in increasing pollination in all scenarios.