Breeding, Early-Successional Bird Response to Forest Harvests for Bioenergy
Breeding, Early-Successional Bird Response to Forest Harvests for Bioenergy
复制标题
繁殖、早期演替鸟类对森林采伐生物能源的反应
作者：
S. Grodsky;C. Moorman;S. Fritts;S. Castleberry;T. Wigley
木材采伐后的森林再生是早期演替鸟类栖息地的主要来源，其特征是早期演替植被和残留的倒下的木质材料的流入。早期演替的鸟类可能会利用收获残留物进行通信，覆盖，觅食和筑巢。然而，木质生物质作为生物能源原料的市场可行性的提高可能会加强收获残留物的清除。我们的目标是：1）评估不同强度的木质生物量收获对早期演替鸟类群落的影响;（2）记录早期演替鸟类在再生林中利用收获残留物的情况。我们从2012年4月15日至2014年7月15日，在六个木本生物量去除处理再生站在北卡罗来纳州（n = 4）和格鲁吉亚（n = 4），美国的鸟类点映射。处理包括皆伐收获，随后是：（1）没有特定保留目标的传统木质生物质收获;（2）15%保留，收获残余物分散;（3）15%保留，收获残余物聚集;（4）30%保留，收获残余物分散;（5）30%保留，收获残余物聚集;和（6）没有木质生物质收获（即，参考站点）。我们测试了处理水平对繁殖鸟类物种多样性和丰富度的影响，早期演替焦点物种领土密度（组合和个体物种），在收获堆/料堆附近，中或树枝上检测到的繁殖鸟类计数，繁殖鸟类行为计数，以及植被组成和结构。在三个繁殖季节合并，我们划定了536和654领土，并检测到2,489和4,204只鸟在北卡罗来纳州和格鲁吉亚治疗，分别。木质生物量收获有限或短暂的影响，早期演替，繁殖鸟类群落。植被结构的演替轨迹，而不是收获残留物的可用性，主要是驱动鸟类使用再生的立场。然而，许多繁殖鸟类使用倒下的木材，除了植被，表明收获残留物最初可能提供食物和覆盖资源的早期演替鸟类在植被再生之前的再生站。
Forest regeneration following timber harvest is a principal source of habitat for early-successional birds and characterized by influxes of early-successional vegetation and residual downed woody material. Early-successional birds may use harvest residues for communication, cover, foraging, and nesting. Yet, increased market viability of woody biomass as bioenergy feedstock may intensify harvest residue removal. Our objectives were to: 1) evaluate effects of varying intensities of woody biomass harvest on the early-successional bird community; and (2) document early-successional bird use of harvest residues in regenerating stands. We spot-mapped birds from 15 April– 15 July, 2012–2014, in six woody biomass removal treatments within regenerating stands in North Carolina (n = 4) and Georgia (n = 4), USA. Treatments included clearcut harvest followed by: (1) traditional woody biomass harvest with no specific retention target; (2) 15% retention with harvest residues dispersed; (3) 15% retention with harvest residues clustered; (4) 30% retention with harvest residues dispersed; (5) 30% retention with harvest residues clustered; and (6) no woody biomass harvest (i.e., reference site). We tested for treatment-level effects on breeding bird species diversity and richness, early-successional focal species territory density (combined and individual species), counts of breeding birds detected near, in, or on branches of harvest piles/windrows, counts of breeding bird behaviors, and vegetation composition and structure. Pooled across three breeding seasons, we delineated 536 and 654 territories and detected 2,489 and 4,204 birds in the North Carolina and Georgia treatments, respectively. Woody biomass harvest had limited or short-lived effects on the early-successional, breeding bird community. The successional trajectory of vegetation structure, rather than availability of harvest residues, primarily drove avian use of regenerating stands. However, many breeding bird species used downed wood in addition to vegetation, indicating that harvest residues initially may provide food and cover resources for early-successional birds in regenerating stands prior to vegetation regrowth.