All but one of the treatments would end up failing to improve conifer growth and, no surprise, native plant diversity was lowered. In the case of birch, killing it improved the growth of some of the firs but caused even more to die—the opposite of expectations. When the birch roots had become stressed by the hacking and spraying, they had been unable to resist the Armillaria pathogenic fungus living naturally in the soil. The fungus infected the suffering birch roots and from them spread to the roots of the neighboring conifers. Where white-barked birch was left untouched in the control plots,
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