Social–ecological landscape patterns predict woody encroachment from native tree plantings in a temperate grassland. Issue 19 (5th September 2018)

• Record Type: Journal Article
• Authors: Donovan, Victoria M.; Burnett, Jessica L.; Bielski, Christine H.; Birgé, Hannah E.; Bevans, Rebecca; Twidwell, Dirac; Allen, Craig R.
• Is Part Of: Ecology and evolution. Volume 8:Issue 19(2018)
• Page Start: 9624
• Page End: 9632
• Publication Date: 2018-09-05
• Subjects: afforestation -- agroforestry -- Juniperus virginiana -- tree planting -- windbreak -- woody encroachment; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.4340
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Afforestation is often viewed as the purposeful planting of trees in historically nonforested grasslands, but an unintended consequence is woody encroachment, which should be considered part of the afforestation process. In North America's temperate grassland biome, Eastern redcedar ( Juniperus virginiana L.) is a native species used in tree plantings that aggressively invades in the absence of controlling processes. Cedar is a well‐studied woody encroacher, but little is known about the degree to which cedar windbreaks, which are advocated for in agroforestry programs, are contributing to woody encroachment, what factors are associated with cedar spread from windbreaks, nor where encroachment from windbreaks is occurring in contemporary social–ecological landscapes. We used remotely sensed imagery to identify the presence and pattern of woody encroachment from windbreaks in the Nebraska Sandhills. We used multimodel inference to compare three classes of models representing three hypotheses about factors that could influence cedar spread: (a) windbreak models based on windbreak structure and design elements; (b) abiotic models focused on local environmental conditions; and (c) landscape models characterizing coupled human‐natural features within the broader matrix. Woody encroachment was evident for 23% of sampled windbreaks in the Nebraska Sandhills. Of our candidate models, our inclusive landscape model carried 92% of the model weight. This model indicated that encroachment from windbreaks was more likely near roadways and less likely near farmsteads, other cedar plantings, and waterbodies, highlighting strong social ties to the distribution of woody encroachment from tree plantings across contemporary landscapes. Our model findings indicate where additional investments into cedar control can be prioritized to prevent cedar spread from windbreaks. This approach can serve as a model in other temperate regions to identify where woody encroachment resulting from temperate agroforestry programs is emerging. Abstract : An unintended consequence of native tree plantings is woody encroachment, which should be considered part of afforestation. Eastern redcedar is a native species that aggressively invades North American grasslands in the absence of controlling processes, yet little is known about the contribution of encroachment from cedar windbreak plantings to afforestation nor what factors can influence patterns of cedar spread from windbreaks. We identified encroachment from 23% of sampled eastern redcedar tree plantings in one of the largest contiguous grasslands in North America, the Nebraska Sand Hills, and identified patterns in encroachment linked to social–ecological landscape features.