Vineyard landscapes impact bird community and interactions in Mediterranean-climate agroecosystems

Agriculture is a primary driver of global change and biodiversity loss. Several approaches have been proposed to enhance biodiversity conservation in agriculture in order to protect ecosystems while maintaining agricultural production, a critical strategy to stave off a sixth mass extinction./nGlobally, I reviewed 205 studies to evaluate different conservation strategies within agroecosystems that may impact bird conservation. The results reveal that agroecological practices such as increasing structural heterogeneity in agricultural fields, eliminating reliance on agrochemical inputs, and providing supplementary habitat within farms can enhance bird wildlife within agroecosystems. Interestingly, there is a paucity of studies quantifying the influence of vineyards on bird communities in Mediterranean-climate ecosystems./nHuman settlement preference for mediterranean type ecosystems globally has resulted in constant agricultural pressure on these areas. These ecosystems have high rates of endemic biota and include some of the 35 global conservation priority sites. This dissertation addresses the influence of the vineyards on wildlands and vice versa in two new world mediterranean-climate regions, Chile and California. I evaluated the impact of vineyards on bird communities using two natural experiments across gradients of increasing vineyard proportion in the landscape. The first study, conducted in oak woodland fragments surrounded by a vineyard matrix in California, revealed that a subset of birds were significantly associated with increasing vineyard proportion. These birds, designated as agricultural adapters, negatively interacted with the rest of the bird community, revealing a secondary mechanism of the influence of agricultural land use change, in addition to the well-characterized primary mechanism involving loss of habitat. Secondly, in Chile, I assessed the influence of surrounding native Matorral vegetation and habitat fragments within vineyards on birds. Findings showed that proportion of fragments within the vineyard and the proportion of native vegetation surrounding vineyards increase abundance of endemics, insectivores, granivores, and omnivores, indicating that the proportion of fragments can be managed to enhance conservation efforts within vineyard landscapes. Lastly, I compared the influence of vineyards on bird communities in Chile and California. Results from this comparative study reveal that vineyards significantly influence bird communities in both study regions, increasing the abundance of agriculturally adapted species. Co-occurrence analysis showed that these agricultural adapter species are often found together and, importantly, negatively interact with other species in surrounding natural areas./nThese results provide new insight for conservation efforts in agroecosystems as well as information to guide conservation strategies in mediterranean-climate agroecosystems. Specifically, the results suggest that conservation efforts should emphasize the importance of large patches of native vegetation and maintaining fragments of native vegetation within vineyards. These results can help conservation practitioners and farmers promote biodiversity conservation in agricultural landscapes.

Advisor: Merenlender, Adina