At each of the seven AMEX research sites spanning the Sierra Nevada, thousands of seedlings were planted in Spring 2021 to identify the species (and seed sources) best suited for reforestation under current and future conditions. The AMEX Team is testing five of the most widely planted conifer species in Sierra Nevada mixed-conifer reforestation in order to capture species-level successes and failures. The species tested include: Calocedrus decurrens (incense cedar), Pinus jeffreyi (Jefffrey pine), Pinus lambertiana (sugar pine), Pinus ponderosa (ponderosa pine), and Sequoiadendron giganteum (giant sequoia).

​In addition to testing species successes, we are also quantifying seed lot (or provenance) success in order to capture successes and failures within a species, as driven by local adaptation to its home, or source, location. We selected 12 seed provenances for each of the five species (60 total provenances planted at each site!). The planting of these unique species/provenance combinations is what is known as a common garden. Common gardens are used to quantify the species and provenances that can be successful in that local garden.
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The planting of multiple common gardens across our sites is known as a provenance trial. These provenance trials can provide insights into which species and provenance combinations grow best under particular environmental conditions by comparing growth and survival among common gardens. This knowledge will be critical to reforestation efforts as climate and local planting conditions continue to change.

Distribution of selected seed lots from across the Sierra Nevada mixed-conifer landscape. PILA = Pinus lambertiana (Sugar Pine), PIPO = Pinus ponderosa (Ponderosa Pine), PIJE = Pinus jeffreyi (Jeffrey Pine), SEGI = Sequoiadendron giganteum (Giant Sequoia), CADE = Calocedrus decurrens (Incense Cedar)

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Representatives of the 12 seed lots being planted for each of the five chosen species.

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Research technician Matt Campbell plants a giant sequoia seedling at Mountain Home Demonstration State Forest, CA.

Tree seedlings are our future forests and will need to endure not only current stressors but the challenges associated with ongoing climate change, altered disturbance regimes, and other anthropogenically-driven impacts to our forested landscapes. Our team will visit sites each spring and each fall to track growth and survival across sites, species, and provenances.