- Award ID(s):
- 1832221
- NSF-PAR ID:
- 10293995
- Date Published:
- Journal Name:
- Forests
- Volume:
- 12
- Issue:
- 8
- ISSN:
- 1999-4907
- Page Range / eLocation ID:
- 1063
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Drivers of shrub primary production and associated landscape impacts of encroachment are well known in drylands but have not been thoroughly studied in mesic and coastal habitats. The native, nitrogen-fixing shrub,
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Coastal forested wetlands support many endemic species, sequester substantial carbon stocks, and have been reduced in extent due to historic drainage and agricultural expansion. Many of these unique coastal ecosystems have been drained, while those that remain are now threatened by saltwater intrusion and sea level rise in hydrologically modified coastal landscapes. Several recent studies have documented rapid and accelerating losses of coastal forested wetlands in small areas of the Atlantic and Gulf coasts of North America, but the full extent of loss across North America’s Coastal Plain (NACP) has not been quantified. We used classified satellite imagery to document a net loss of 13,682 km2 (8%) of forested coastal wetlands across the NACP between 1996 and 2016. Most forests transitioned to scrub-shrub (53%) and marsh habitats (24%). Even within protected areas, we measured substantial rates of wetland deforestation and significant fragmentation of forested wetland habitats. Variation in the rate of sea level rise, the number of tropical storm landings, and the average elevation of coastal watersheds explained about 78% of the variation in coastal wetland deforestation extent along the south Atlantic and Gulf Coasts. The rate of coastal forest loss within the NACP (684 km2/y) exceeds the recent estimate of global losses of coastal mangroves (210 km2/y). At the current rate of deforestation, in the absence of widespread protection or restoration efforts, coastal forested wetlands may not persist into the next century.more » « less
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Abstract Understanding the complex and unpredictable ways ecosystems are changing and predicting the state of ecosystems and the services they will provide in the future requires coordinated, long‐term research. This paper is a product of a U.S. National Science Foundation funded Long Term Ecological Research (LTER) network synthesis effort that addressed anticipated changes in future populations and communities. Each LTER site described what their site would look like in 50 or 100 yr based on long‐term patterns and responses to global change drivers in each ecosystem. Common themes emerged and predictions were grouped into state change, connectivity, resilience, time lags, and cascading effects. Here, we report on the “state change” theme, which includes examples from the Georgia Coastal (coastal marsh), Konza Prairie (mesic grassland), Luquillo (tropical forest), Sevilleta (arid grassland), and Virginia Coastal (coastal grassland) sites. Ecological thresholds (the point at which small changes in an environmental driver can produce an abrupt and persistent state change in an ecosystem quality, property, or phenomenon) were most commonly predicted. For example, in coastal ecosystems, sea‐level rise and climate change could convert salt marsh to mangroves and coastal barrier dunes to shrub thicket. Reduced fire frequency has converted grassland to shrubland in mesic prairie, whereas overgrazing combined with drought drive shrub encroachment in arid grasslands. Lastly, tropical cloud forests are susceptible to climate‐induced changes in cloud base altitude leading to shifts in species distributions. Overall, these examples reveal that state change is a likely outcome of global environmental change across a diverse range of ecosystems and highlight the need for long‐term studies to sort out the causes and consequences of state change. The diversity of sites within the LTER network facilitates the emergence of overarching concepts about state changes as an important driver of ecosystem structure, function, services, and futures.
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Abstract Questions Vascular epiphytes constitute a large proportion of tropical forest plant biodiversity, but are among the slowest plants to recolonize secondary forests. We asked whether tree planting for ecological restoration accelerates epiphyte community recovery. Does the spatial configuration of tree planting matter? What landscape contexts are most suitable for epiphyte restoration?
Location Restored pastures in premontane Coto Brus County, Puntarenas, Costa Rica.
Methods We surveyed vascular epiphyte species growing on the lower trunks of 1083 trees in 13 experimental restoration sites. Each site contained three 0.25‐ha treatment plots: natural regeneration, trees planted in patches or ‘islands’ and tree plantations. Sites spanned elevational (1100–1430 m) and deforestation (4–94% forest cover within a 100‐m radius around each site) gradients.
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