As cities worldwide adopt data-driven approaches to optimize urban forests, computational tools like agent-based models (ABMs) are increasingly popular to simulate forest growth and inform planting decisions. However, ABMs often focus on individual metrics, neglecting forests as interdependent ecosystems. Rooted in anthropocentric ideals, these models risk reducing forests to infrastructures for human benefit, undermining their long-term resilience. This pictorial challenges these limitations by exploring how interface design can transcend reductive, agent-centric representations to foster relational understandings of forest ecosystems as more-than-human bodies. Drawing on feminist theorist Karen Barad's concepts of "diffraction"and "agential cuts,"we craft a repertoire of diffractive interfaces that engage with forest simulation data, revealing how more-than-human bodies can be encountered across diverse temporal, spatial, and agential scales. Through this design exploration, we operationalize more-than- human perspectives in data practices, deepening our understanding of the performative dimensions of interfaces and advancing nuanced, practical approaches to more-than-human design.

While decentering the human has been a key approach in posthumanist HCI, there are still questions and tensions around it. To address them, we outline emergent notions of decentering, tracing it back from HCI to critical posthumanism and connecting epistemological developments in the humanities to design scholarship. Then, reviewing how decentering is understood and practiced in HCI, we distill five emerging dimensions for articulating more-than-human practices. We conclude by unpacking “decentering through design” as an ongoing material practice through which more-than-human designers not only materialize (apply) posthuman theory but also “make” posthuman knowledge in their own unique ways.