The Spatial Sampling Design

The Spatial Sampling Design

How do plants and animals respond to environmental disturbances and changes in climate? Rising average annual temperatures or changes in rainfall patterns may influence the timing of flowering for plant species in a region. These changes can have a ripple effect on interacting species in the ecosystem, like pollinators that depend on the flowers and fruit.

A change in a species trait can be a bellwether for changes in the biodiversity of the ecosystem as a whole. From monitoring population and community dynamics of organisms, to measuring fluxes of carbon, water, and energy between terrestrial ecosystems and the atmosphere, to mapping changes in land surface characteristics.

Terrestrial field site characteristics and size vary considerably, from one of the smallest field sites at Lajas Experimental Research Station at only 3.95 square kilometers, to the much larger Santa Rita Experimental Range field site, that spans an impressive 215 square kilometers.

Observational field sampling, automated instruments, and airborne remote sensing. All three systems are standardized across field sites, while automated instruments and remote sensing are routinely calibrated and tested. This all contributes to a more accurate and detailed picture of ecosystem function and change on a local, regional, and continental scale.

To get a better idea of this let’s walk through the integrated spatial sampling design of a terrestrial field site. In the dominant vegetation, a meteorological tower rises above the plant canopy. This tower collects measurements of weather and climate including fluxes of carbon, water, and energy between terrestrial ecosystems and the atmosphere.

At each tower an upland area captured by the atmospheric measurements is defined as the tower air shed. Where there is more than one prevailing wind direction there can be a secondary air shed too. Phenocams mounted on the top and bottom of the tower and typically facing north, collect time-lapse photos of the nearby environment throughout the year.

Over time this imagery data will reveal trends related to the greening of vegetation at each site. An array of five soil plots is installed within the tower air shed. Sensors in the soil array collect above-ground meteorological data and below ground soil measurements to allow for research on biogeochemical processes.

Soil data are collected at multiple depths and include temperature, soil moisture, and CO2 concentration. Using standardized protocols NEON scientists collect observations of soil microbes, ground beetles, mosquitoes, ticks, plants, birds, and small mammals at these plots.

These data include individual traits, population dynamics, and the composition of organismal communities. A subset of organisms are sampled for pathogens and DNA sequences. NEON field scientists also collect biogeochemical data of plants and soils. In addition to observational sampling, NEON archives thousands of specimens and samples from each site every year.

This includes biological, genomic, and geological samples that are stored in the NEON Biorepository, and are available for scientists upon request. NEON also takes to the skies conducting airborne remote sensing surveys. Using discrete and waveform lidar, spectrometry data, and high-resolution digital camera images, NEON scientists map the land surface of each field site providing information about vegetation composition, chemistry, and structure.

NEON’s standardized methods and collection systems allow for users to compare data within a single field site and across multiple field sites to answer more complex ecosystem questions. For example, using NEON data we can study the changing characteristics and composition of mosquito populations at a field site in relation to meteorological data and remote sensing derived vegetation biomass maps.

We can then apply these data to how mosquito populations are moving between sites. This will result in improving our ability to detect and predict the movement of mosquito species into new ecosystems. So from the sky down into the soil, NEON is collecting a wide variety of ecological data at different spatial and temporal scales.

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