Perspectives on Piciformes: impacts on biodiversity from holes to whole landscapes

Abstract

The development of tools that accurately describe relationships between woodpeckers and their environment is important for natural resource management, since woodpecker cavities can be used by a diversity of animals. We can use molecular tools to identify patterns of within-cavity diversity, and remote sensing tools can assist in characterizing the environments associated with woodpeckers and the cavities they create. Our objectives were to: 1) use molecular methods to describe some aspects of the diversity found within cavities, 2) describe lidar-based tools that can be used to measure small structures such as cavities, and 3) explore how lidar technologies can be used to explore woodpecker-associated diversity from the cavity to the landscape. In Washington and Idaho (USA), we used molecular approaches, bird surveys, and a variety of remote sensing tools to examine relationships between woodpeckers and diversity in ponderosa pine (Pinus ponderosa) and aspen (Populus tremuloides) forests. We characterized the fungal communities in recently excavated cavities (n=31) of four different woodpecker species and compared those fungal communities with those from unexcavated trees (n=31). Fungal community composition differed between cavities and unexcavated trees, and finer-scale differences were seen between cavities of different excavators. At the cavity scale, we used a lidar (i.e. laser-based) smartphone device and app called the Spike by ikeGPS to measure known cavity entrance dimensions as small as 3cm by 3.5cm. Such information is important because the size of the cavity entrance influences cavity accessibility for different users. Additionally, cavity entrance sizes might influence microclimate characteristics, which could be particularly important for groups such as fungi. The Spike device was highly accurate in measuring cavity entrance dimensions within 30m of a target cavity and up to 15m above the ground (r=0.91). Using airborne lidar remote sensing, we modeled and mapped both woodpecker species richness and total bird species richness across an aspen-conifer gradient using the program RandomForest. We then examined the spatial congruence between woodpecker richness and overall bird species richness, and we found a high correlation (r=0.71) between woodpecker species richness and total avian species richness. Woodpeckers can be considered surrogates for diversity, and the integration of multiple tools and approaches to further understand the relationships between woodpeckers and their environment will improve conservation in the context of changing forest management practices and changing climates.