Methods

Summary

Methods

The biome logs project employs a community-driven, multi-method approach combining field trials, ecological monitoring, and financial analysis. This study assesses mitigation approaches to fuel (flammable materials) in the Home Ignition Zone (HIZ), within 100 ft (approximately 30 m) of a human-made structure, in areas recently impacted by fire. The project consists of two phases: (1) a preliminary study examining microbial inoculation strategies using partially buried logs and (2) a primary field experiment comparing biome logs to common fuel treatments.

Experimental Design

The preliminary study was established at San Vicente Redwoods in the Santa Cruz Mountains in 2023. Experimental treatments included logs inoculated with Pleurotus pulmonarius, reference forest soil, untreated logs, biochar, and untreated controls. Treatments were installed adjacent to existing Continuous Forest Inventory (CFI) plots to facilitate comparison with ongoing forest monitoring efforts. Logs were sourced locally and partially buried along replicated transects.

The primary study was established at two residential properties in Bonny Doon, California, within the wildland–urban interface (WUI). Four treatment types were replicated across study blocks: biome logs (BL), pile burning (PB), lop-and-scatter (LS), and untreated controls (CO). Study sites were selected based on wildfire history, fuel availability, similar environmental conditions, and proximity to a locally produced bio-compost source.

Fuel Treatment Installation

Prior to treatment installation, ladder fuels and small-diameter vegetation were removed using hand tools and chainsaws. Biomass was measured, sorted into standardized fuel size classes, and distributed evenly among treatment plots to ensure comparable inputs.

Biome log installations were constructed using techniques informed by traditional land stewardship practices, including hügelkultur and bioswale design. Shallow trenches were excavated and filled with layered woody material, beginning with large-diameter fuels and progressing to medium and small fuels. Excavated soil was then replaced over the material to create partially buried woody beds designed to retain moisture, support microbial activity, and gradually decompose.

Pile burn treatments consisted of concentrated fuel piles intended for prescribed burning in accordance with CAL FIRE regulations. Lop-and-scatter treatments distributed the same biomass across the soil surface. Untreated control plots received no fuel treatment.

Bio-Compost Production and Microbial Inoculation

A biologically active compost pile was established in October 2024 under the guidance of Keisha and Casey Ernst of Catalyst Bioamendments using principles derived from Dr. Elaine Ingham's BioComplete™ composting methodology (see lab note). Locally sourced wood chips, manure, acorns, leaves, and branches were combined using calculated carbon-to-nitrogen ratios to encourage the growth of diverse, locally adapted microbial communities.

The compost pile was monitored through repeated microscopic assessments and periodic turning to maintain aerobic conditions. In April 2026, compost quality was independently evaluated by experienced compost practitioners, who verified high microbial diversity, fungal abundance, and balanced microbial composition. A compost extract was subsequently produced using unchlorinated water and applied directly to selected biome log installations to introduce beneficial microorganisms and accelerate decomposition processes.

Soil and Microbial Monitoring

The project uses multiple techniques to evaluate ecological responses to treatments. Soil samples are collected using standardized protocols and analyzed for active carbon and microbial community composition.

Total Organic Carbon, C:N ratio, Cation Exchange Capacity and mineral analysis of soil provides an indicator of biologically available soil carbon and soil health. Samples are collected at regular intervals and processed through laboratory analysis.

Microbial community composition is assessed using both microscopy and environmental DNA (eDNA) metabarcoding. Soil samples are collected using sterilized equipment, stored under controlled conditions, and analyzed using 16S, 18S, fungal ITS1, and fungal ITS2 genetic markers. These methods allow characterization of bacterial, fungal, protist, and other microbial communities associated with each treatment.

Pathogen Prevention and Biosecurity

To minimize ecological risks, the project follows established pathogen prevention protocols. Source materials for inoculants are collected locally to promote adaptation to regional environmental conditions while reducing the risk of introducing non-native organisms. Known pathogens and pests are avoided, and all sampling equipment is sterilized between sites. The project benefits from ongoing microbial assessments, pathogen testing and consultation with restoration practitioners, microbial ecologists, and community stakeholders to ensure safe implementation and scientific rigor.

Financial Analysis

In addition to ecological monitoring, the project evaluates the economic feasibility of each treatment. Labor time required for installation of biome logs, pile burns, lop-and-scatter treatments, and controls is recorded in the field. Average implementation times are converted to labor costs using a standardized hourly wage rate. This analysis provides a practical comparison of treatment costs and helps assess the potential for community-scale adoption.

Challenges

Several challenges may affect the success of the Biome Logs project. One of the primary challenges is the significant amount of time and labor required to install treatments, maintain study sites, collect samples, and process data over multiple years. Another major challenge is securing sufficient funding for laboratory analyses, particularly soil microbial community sequencing which is the most expensive component of the project.

Environmental variability also presents a risk. Differences in rainfall, temperature, soil conditions, and future wildfire activity may influence treatment outcomes and make it difficult to isolate treatment effects. Because this project evaluates ecological processes such as decomposition and microbial community development, measurable changes may occur more slowly than anticipated.

To overcome these challenges, the project has been designed with replicated treatments across multiple sites, standardized installation methods, and long-term monitoring protocols. Partnerships with community members, interns, researchers, and restoration practitioners help distribute labor and provide technical expertise. Soil samples are being archived for future analysis if funding becomes available, allowing data collection to continue even during funding constraints. Finally, maintaining strong relationships with participating landowners and project partners will help ensure site access.

Pre Analysis Plan

Primary Study Site Data Collection

Block Establishment

Chosen blocks have been measured with field measuring tape and marked using flags. Treatment plots were established on contour. Slope and aspect were measured to ensure consistency. 4 m x 4 m plots were established on slopes between 6° and 19° with a minimum of a 2 m buffer between plots. Treatment locations within each block were randomized.

Table 3

Primary Study Types of Analyses

Variable	Analysis to be used
Soil Moisture	Soil Moisture Meter
Decomposition rate/decay chronosequence	Bulk density and biomass volume testing estimate
Carbon	Total organic carbon test
Fungal and mycorrhizal abundance, soil microbial community composition	Microscopy and metabarcoding amplicon DNA sequencing
Water Stable Aggregates	Slakes Method
Calcium	Calcium test
Heavy metals	Mobile XRF unit
Financial viability	Financial analysis

 

Soil Moisture

Soil moisture will be measured using a Soil Moisture Meter MO750 or similar instrument, on each future study block during initial site visits, and every 3 months for the duration of the study. The moisture meter will be used uphill, downhill, and underneath each block. An average of these three measurements will be calculated.

Bulk Density and Biomass Volume Testing Estimate

I will conduct a decay chronosequence to measure decomposition rates of woody materials with bulk density analyses and volume testing estimates of the logs and coarse woody debris. For the study site that burned, I will estimate that many of the trees died during the August 2020 CZU Lightning Complex Fire or shortly afterward. For other trees, I will ask neighbors and do my best to estimate the date of tree mortality. I will conduct a chronosequence of dead wood samples by measuring wood density at different stages of decomposition. I would then create an equation where I substitute space for time since mortality.

 To measure decomposition rates, I will take a core sample of one log from each Biome Log bed and each lop and scatter site at the time of installation, and once a year after that. This core will be weighed, dried, and weighed again, and the results will be plugged into an equation to measure bulk density. Changes in biomass size will be calculated using a volume testing estimate. This will involve measuring the total volume of the BL and LP treatment, and subsequently measuring it once a year after that. The results of these measurements will be used to determine a log response ratio. 

Total Organic Carbon

I will measure Total Organic Carbon in the soil at each treatment plot at the time of installation and after a certain period of time. When combined with the decomposition data, I will be able to better understand the changes in carbon dynamics over time.

Soil Microbial Communities

Samples will be collected gently using a soil probe and cleaned with alcohol between each sample. Samples will be placed in sterile Whirlpak bags and kept in a cooler with ice packs during transport. They will be analyzed using metabarcoding amplicon sequencing at the Meyer lab at the University of California Santa Cruz with the following biomarkers: 16S, 18S, Fungal ITS1, and Fungal ITS2.

Calcium

Calcium and calcium carbonate will be measured alongside Total Organic Carbon in the Maltz lab to provide data on carbon storage potential.

Analytic Methods

Broad Question: Can biome logs be used as an effective pre-prescribed burn treatment to reduce fire severity? To answer my broad question, I will summarize the analyzed data and describe what it indicates about this question.

Inferential Methods

Soil Moisture

To evaluate the effect of Biome Logs on soil moisture retention relative to untreated areas, I will conduct a one-way analysis of variance (ANOVA). The dependent variable will be soil moisture content, and the independent variable will be treatment type (Biome Logs, Lop and Scatter, Pile Burn, and Control).

Viable Woody Debris Volume

To estimate the amount of on-site woody debris available for incorporation into Biome Log installations, I will measure and track all materials used during construction. Volume will be calculated at two time points using the Smalian Cubic Volume Model:

where and represent the small- and large-end diameters, respectively, and is the log length. This analysis will address an inductive research question regarding material feasibility.

Bulk Density of Logs

To assess changes in the physical properties of biome logs over time, I will measure bulk density at installation and after 12 months. Bulk density will be calculated using the equation:

This will indicate decomposition and compaction rates within biome log structures.

Soil Microbial Community Composition

To examine changes in soil microbial community composition over a two-year period, I will perform a permutational multivariate analysis of variance (PERMANOVA) using Bray–Curtis dissimilarity indices. Principal component analysis (PCA) plots will visualize community shifts among treatments and time points. These analyses will be conducted as part of the genetic sequencing services at the CALeDNA laboratory