Maine transitioning-and-above late-successional forest: 10 m probability surface, bootstrap uncertainty and extrapolation flag (2024 AlphaEarth embeddings)

A 10 m wall-to-wall probability surface for transitioning-and-above late-successional condition across Maine forestland, with a matching block-bootstrap standard deviation layer and a training-envelope extrapolation flag. Predictions come from a random forest over the 64 Google AlphaEarth Foundations 2024 satellite embedding bands, fitted on 3,015 FIA plots scored with the v5.1 six-axis late-successional and old-growth instrument at a total score of 4 or above. The mosaicked forestland share is 15.18 percent, which falls inside the independent design-based FIA estimate of 14.66 percent (95 percent interval 13.40 to 15.91, EVALID 232301). The surface passed an eleven-gate acceptance suite spanning location, value range, total magnitude and cross-layer consistency, and a separate post-acceptance stress test. Full gate readings, the plot-level spatial agreement test and its permutation null are included. Intended use. This is a continuous probability surface, not a classified map. Ensemble block calibration is attenuated (out-of-fold block slope 0.723 raw, 0.885 disattenuated), which compresses block means toward the middle of the range. Attenuation leaves a state total close to correct but biases a threshold, so a fixed probability cut does not partition the state the way its nominal value implies. Users thresholding this surface should calibrate the cut against design-based estimates for their own domain rather than adopting a nominal value. The fitted random forest and its 20-model block-bootstrap ensemble are included so the surface can be regenerated and audited. Before depositing them, the forest was measured for memorisation of individual training plots: it was fitted with a minimum of 3 samples per leaf, it contains no singleton leaf across any of its 500 trees, and the median leaf holds 7 training plots, so no leaf's split constraints isolate one plot. That measurement is deposited. No FIA true plot coordinates, per-plot embeddings or per-parcel outputs are included in this deposit.