Regulation by the Pitcher Plant Sarracenia purpurea of the Structure of its Inquiline Food Web

Phytotelmata, the water-filled habitats in pitcher plants, bromeliad tanks, and tree-holes, host multitrophic food webs that are model experimental systems for studying food-web structure dynamics. However, plant usually is considered simply as an inert container, not interacting part of web. We used a manipulative field experiment with response-surface design to determine effects nutrient enrichment (multiple levels NH4NO3, PO4, captured prey), top predators (removed or present), itself (with without plastic tubes inserted into pitchers isolate web from plant) on macrobial within modified leaves (“pitchers”) carnivorous Sarracenia purpurea. Connection plant, addition removal predator significantly increased web's saturation, defined its trophic depth number interactions. No saturation resulted PO4 supplemental prey. Plants such S. purpurea create phytotelmata more than containers their inhabitants commensal inquilines. Rather, both inquilines partners complex network