Enhanced Forest Inventories for Habitat Mapping: A Case Study in the Sierra Nevada Mountains of California

TL;DR

Traditional forest inventories lack fine-grained spatial detail for habitat mapping in multi-resource management. The study develops an Enhanced Forest Inventory (EFI) by integrating 118 FIA plots with LiDAR, NAIP, and Sentinel-2 across 270,000 acres, using a two-tier segmentation and Elastic-Net models to map forest attributes at ~0.5-acre units. It translates these attributes into habitat metrics for the California Spotted Owl and Pacific Fisher, with mapped nesting/foraging and likely habitats totaling roughly 25,600 acres per category, demonstrating precise, plan-ready habitat delineations. This EFI framework provides a practical bridge between forestry data and conservation planning, enabling spatially explicit monitoring and collaboration among managers and ecologists; datasets and code are openly available to support replication and adoption.

Abstract

Traditional forest inventory systems, originally designed to quantify merchantable timber volume, often lack the spatial resolution and structural detail required for modern multi-resource ecosystem management. In this manuscript, we present an Enhanced Forest Inventory (EFI) and demonstrate its utility for high-resolution wildlife habitat mapping. The project area covers 270,000 acres of the Eldorado National Forest in California's Sierra Nevada. By integrating 118 ground-truth Forest Inventory and Analysis (FIA) plots with multi-modal remote sensing data (LiDAR, aerial photography, and Sentinel-2 satellite imagery), we developed predictive models for key forest attributes. Our methodology employed a two-tier segmentation approach, partitioning the landscape into approximately 575,000 reporting units with an average size of 0.5 acre to capture forest heterogeneity. We utilized an Elastic-Net Regression framework and automated feature selection to relate remote sensing metrics to ground-measured variables such as basal area, stems per acre, and canopy cover. These physical metrics were translated into functional habitat attributes to evaluate suitability for two focal species: the California Spotted Owl (Strix occidentalis occidentalis) and the Pacific Fisher (Pekania pennanti). Our analysis identified 25,630 acres of nesting and 26,622 acres of foraging habitat for the owl, and 25,636 acres of likely habitat for the fisher based on structural requirements like large-diameter trees and high canopy closure. The results demonstrate that EFIs provide a critical bridge between forestry and conservation ecology, offering forest managers a spatially explicit tool to monitor ecosystem health and manage vulnerable species in complex environments.

Figures (6)

• Figure 1: Visual representation of the EFI generation process.
• Figure 2: Segmentation of the project area into 0.5-acre polygons.
• Figure 3: Canopy Cover (%) over the project area.
• Figure 4: Basal area covered by snags (square feet/acre) over the project area.
• Figure 5: Habitat suitability for the California Spotted Owl over the project area.