Date of Award

2020

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Forest Science (PhD)

Administrative Home Department

College of Forest Resources and Environmental Science

Advisor 1

Rodney A. Chimner

Advisor 2

Sigrid C. Resh

Committee Member 1

Andrew J. Burton

Committee Member 2

David R. Shonnard

Abstract

Many sources of woody biofuels provide alternative options to fossil fuels that can help mitigate greenhouse gases. One key component of feedstock sustainability from an ecosystem service perspective is soil sustainability. We examined eucalyptus (Eucalyptus grandis) plantations in the warm-temperate entic and mollic soils of Northeastern Argentina, oil palm plantations (Elaeis guineensis Jacq.) in the tropical alfic soils of Southeastern Mexico, and aspen (Populus tremuloides) in the cool-temperate spodic soils of Northeastern United States. The following elements were measured in soil increments of 15 cm, down to a total of 60 cm: carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and aluminum (Al). In each country, we used a chronosequence design, measuring forest-stands of different age treatments (postharvest or years since planted) to substitute for time. Each age treatment was comprised of at least three replicates. In Argentina, the total soil C trended downward over the 50 years of Eucalyptus land-use (p = 0.12), however, these trends were driven by reductions in mineral-associated C fractions (heavy fractions) that normally represent persistent C and soil quality. The heavy fraction declines (p = 0.06) suggest long-term land degradation. In Mexico, young oil palm stands, adult oil palm stands, pastures, and secondary forests were all similar in soil C, and most nutrients (0-60 cm). Adult oil palm stands had lower levels of N, while secondary forests had higher levels of iron (Fe) than other land-use treatment groups. Young oil palm stands had higher levels of C, N, and P in their weeded circles than adult oil palm stands, however the total weighted area of the weeded circles is not enough to make significant differences at the scale of 1-hectare. Last, in the United States, Wisconsin coarse-textured aspen stands increased 42% in soil C from a chronosequence of stands aged from 10 to 56 years post-clear-cut in depths down to 45 cm (p = 0.02). Nutrients were relatively stable with increasing age of stands except for P, which increased exponentially with age and depth. While current management is sustainable, caution is warranted for sandy soils to be used as sources of biomass for biofuels, because they are more vulnerable to C and nutrient losses, especially in cases of intensive residue removal. Each country’s potential feedstock poses unique circumstances in which between countries, soils were impacted differently by climates, soil orders, and management. Biofuel management can offer promising sequestration of C in the short-term, and in the long-term, impacts will likely be influenced by proper residue management, preventing soil compaction, and not shortening rotation lengths in order to facilitate soil C and nutrient recuperation.

Download

Share

COinS