Search USGS⌕ Search
Home/Archive/USGS

USGS · 70251303

Demography with drones: Detecting growth and survival of shrubs with unoccupied aerial systems

Peter J. Olsoy·Andrii Zaiats·Donna M. Delparte·Matthew J. Germino·Bryce Richardson·Anna V. Roser·Jennifer S. Forbey·Megan E Cattau·Trevor Caughlin
View original source ↗Export metadata ↓

Abstract

Large-scale disturbances, such as megafires, motivate restoration at equally large extents. Measuring the survival and growth of individual plants plays a key role in current efforts to monitor restoration success. However, the scale of modern restoration (e.g., >10,000 ha) challenges measurements of demographic rates with field data. In this study, we demonstrate how unoccupied aerial system (UAS) flights can provide an efficient solution to the tradeoff of precision and spatial extent in detecting demographic rates from the air. We flew two, sequential UAS flights at two sagebrush ( Artemisia tridentata ) common gardens to measure the survival and growth of individual plants. The accuracy of Bayesian-optimized segmentation of individual shrub canopies was high (73–95%, depending on the year and site), and remotely sensed survival estimates were within 10% of ground-truthed survival censuses. Stand age structure affected remotely sensed estimates of growth; growth was overestimated relative to field-based estimates by 57% in the first garden with older stands, but agreement was high in the second garden with younger stands. Further, younger stands (similar to those just after disturbance) with shorter, smaller plants were sometimes confused with other shrub species and bunchgrasses, demonstrating a need for integrating spectral classification approaches that are increasingly available on affordable UAS platforms. The older stand had several merged canopies, which led to an underestimation of abundance but did not bias remotely sensed survival estimates. Advances in segmentation and UAS structure from motion photogrammetry will enable demographic rate measurements at management-relevant extents.

Explore related subjects

Restoration EcologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Peter J. Olsoy, Andrii Zaiats, Donna M. Delparte, Matthew J. Germino, Bryce Richardson, Anna V. Roser, Jennifer S. Forbey, Megan E Cattau, Trevor Caughlin. 2024-01-25. Demography with drones: Detecting growth and survival of shrubs with unoccupied aerial systems. https://doi.org/10.1111/rec.14106

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Assessing working lands as habitat for disturbance-dependent birds using autonomous recording units

Introduction Working lands can provide habitat for declining disturbance-dependent birds, such as Bachman's Sparrow ( Peucaea aestivalis ) and Northern Bobwhite ( Colinus virginianus ), but it remains unclear whether restoration following intensive land use (e.g. surface mining) yields habitat comparable to less intensive land uses (e.g. timber production). Objectives We evaluated effects of land use both in working lands (recently replanted surface mine reclamation site and recently replanted timber production site) and reference sites explicitly managed for wildlife (recently restored young pine savanna and mature pine savanna) and understory vegetation characteristics on relative abundance of disturbance-dependent birds within upland pine ( Pinus spp.) communities in southeastern Georgia, United States. We hypothesized that the mine reclamation site would support similar bird species but in lower relative abundances than other land uses. Methods We conducted daily acoustic surveys using autonomous recording units (ARUs) and measured vegetation surveys once per point from May to June 2024. We used Royle-Nichols models, an adapted occupancy model, to estimate relative abundance for eight bird species. Results Land use influenced relative abundance for all species and explained more variation in relative abundance than measured understory vegetation characteristics. The mining reclamation site supported most disturbance-dependent species and, in some cases, equal or higher relative abundances, particularly for Northern Bobwhite and Common Nighthawk ( Chordeiles minor ). Responses across timber production and savanna sites varied by species. Vegetation effects were generally weaker and species-specific, suggesting that land use history and associated habitat legacies play an important role in structuring these bird communities. Conclusion Working lands, including reclaimed mines, can provide habitat for disturbance-dependent birds, and ARUs are effective for evaluating these patterns across land uses.

Restoration Ecology↗
USGS2026

Mesophotic octocoral larval settlement preferences and behaviors

Introduction Lab-based coral reproduction is advancing restoration efforts to support coral populations injured by the 2010 Deepwater Horizon oil spill. Objectives This study aimed to answer foundational questions concerning coral spawning and larval settlement that need to be resolved for these mesophotic and deep-sea coral species before restoration efforts can be scaled up. Methods From 2021 to 2023, fragments of the mesophotic octocorals Swiftia exserta and Thesea nivea were collected from the continental shelf offshore from Texas to Florida and transported to a federal facility in Florida. Multiyear spawning allowed for in-depth analysis of spawning periodicity, egg development, larval behavior, settlement rate, and substrate preference. In addition, we determined the likelihood of successful development and survival during early stages of development. Results Fertilization rates remained high throughout spawning periods of both species, with S. exserta spawning during a 1-month period and T. nivea continuing to spawn year-round. Larvae from both corals significantly preferred tiles seeded with crustose coralline algae, and there were species-specific preferences in substrate material. Additionally, larval survival or mortality was typically evident within a few days when in the presence of settlement substrates. In the absence of substrates, we observed larvae surviving for up to 2 months without settling. Conclusions This work answers critical questions to inform the long-term logistical planning for eventual out-planting of these species. Further, it highlights avenues that could accelerate future restoration-based reproduction efforts into unexplored mesophotic and deep species.

Alabama, Louisiana, Mississippi, Texas↗
USGS2026

High and dry: The persistence of diverse coastal marsh communities depends on available upland area and connection to surrounding waters

Sea-level-rise and alterations to natural hydrology have contributed to coastal land loss. To combat coastal land loss and maintain the ecosystem services provided by marshes, marsh creation has been broadly implemented. Marsh creation projects can be performed in conjunction with the construction of elevated terrestrial ridges that seek to mimic historic delta-formed distributary ridges. Ridges and similar elevated structures, such as those surrounding created marshes, offer the opportunity to sample the ecotones between low marsh and upland areas within a small area. We sampled marsh assemblages on elevation gradients at eight sites in the Louisiana coastal zone. We identified nine marsh communities based on co-occurrence of taxa and abiotic conditions (soil salinity, percent time inundated, soil percent moisture, soil bulk density, and soil pH) with a two-step process of hierarchical clustering and random forest classification. Inundation time and salinity were identified as the most important conditions related to community composition. We used future estimates of coastal elevations based on local relative sea-level-rise estimates to make predictions of community change up to 50 years into the future. Our predictions, meant to serve as generalizations for the coastal region, indicate a near total loss of high-elevation salt marsh communities at the sites sampled. Elevation variation supports diverse marsh communities when water is allowed to flow as in a natural marsh. Hydrology regulates inundation, and by extension, salinity. Evaluating hydrologic exchange can be incorporated into decisions regarding future marsh creation to support marsh health and persistence.

Louisiana↗