Biochar as a Soil Amendment for Willow and Cottonwood Plantings in a Riparian Restoration

Sechler, Brian Clyde

Graduate Thesis Or Dissertation

Biochar as a Soil Amendment for Willow and Cottonwood Plantings in a Riparian Restoration Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/12579s43r

Abstract

Riparian areas provide some of the most valuable ecosystem services of any habitat type, both for native flora and wildlife, as well as human society. The global degradation of these critical systems makes their restoration imperative for the preservation of overall ecological integrity since depleted riparian corridors will have cascading effects that pervade upland and downstream regions alike. In western river systems there are two key limiting factors that can lead to failures during re-vegetation efforts along riparian stream banks: one is a lack of available soil nutrients, and the other is a lack of soil moisture. Biochar has been promoted as an effective soil amendment that increases both nutrient availability and soil moisture but to my knowledge has not been used in the context of riparian restoration. My experiment tested biochar as an effective addition to the slurry backfill of planted poles and container plants of two essential riparian tree species along Colorado’s Front Range: Populus deltoides and Salix exigua. Convention dictates that poles planted for restoration purposes should be selected from dormant cuttings and planted in the early spring to ensure that environmental cues for growth do not yield premature budding until spring runoff has achieved an adequate supply of ground water to sustain long term survival. In practice however, early spring plantings can be logistically challenging and the ability to plant non-dormant cuttings later in the summer could make restoration efforts easier for land management agencies to complete. I used non-dormant poles to test whether biochar’s effect on soil characteristics could offset the disadvantages associated with harvesting and planting cuttings in the late summer. My results showed no effects of biochar on the survivorship of either poles or container plants. Container stock of both P. deltoides and S. exigua survived better than poles of either species with or without a biochar treatment. Anecdotally, there was superior early growth in biochar treated plants, but this growth may have been phenologically maladaptive. Due to logistical constraints early in the planting process this growth could not be quantified.

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