Bird community dynamics and vegetation relationships among stand establishment practices in intensively managed pine stands.

摘要

Intensively managed pine occupies 22% of the forest land base in the southeastern United States. More fully understanding effects of standard silvicultural practices on biodiversity could improve wildlife management recommendations on intensively managed landscapes. Although multiple stand-establishment techniques (i.e., site preparation and chemical herbaceous control of competition) are used for forest regeneration, we lack an understanding of causal mechanisms for bird community responses during stand establishment through canopy closure. Therefore, we investigated bird community responses to five stand-establishment treatments in intensively managed pine (Pinus spp.) stands in the Lower Coastal Plain of Mississippi, USA as a function of changes in vegetation structure and coverage. We used a randomized complete block design of four pine stands (blocks) divided into five experimental units and with treatments randomly assigned to each unit. Our treatments represented available establishment practices and increased in intensity from mechanical or chemical site preparation with subsequent banded herbaceous control to mechanical and chemical site preparation with 2 years of subsequent broadcast herbaceous weed control applications. We sampled bird communities with point counts and measured visual obstruction, pine tree height, woody stem density, and vegetation structure and coverage by growth form (e.g., forb, fern, grass, legume, pine, sedge and rush, woody non-pine, vine). Bird communities had an overall negative response to increasing intensity of stand-establishment treatments, and temporal trends from site preparation to canopy closure were absent. Common species appeared relatively unaffected by treatments. However, presence of species with high conservation value and availability of early successional habitat conditions emphasized conservation potential of intensively managed pine forests for birds and justify further experimental investigation of bird community responses to stand-establishment treatments. We recommend forest managers continue to incorporate a variety of stand establishment practices to ensure habitat availability for a variety of bird species, and that researchers further investigate mechanistic factors of avian community responses to silvicultural practices.