A stand level application of efficiency analysis to understand efficacy of fertilization and thinning with drought in a loblolly pine plantation
2021
Shephard, Noah T. | Joshi, Omkar | Susaeta, Andres | Will, Rodney E.
Loblolly pine (Pinus taeda L.) is the most important and productive commercial timber species in the southern USA. Common plantation management practices such as fertilization and thinning could become inefficient and economically disadvantageous given anticipated climate change effects, such as increased drought severity, especially in the drier Upper Gulf region of the south-central USA. To calculate technical and economic efficiency, we used data envelopment analysis (DEA) to assess the ability of fertilized, thinned, and drought-induced loblolly pine plots in southeastern Oklahoma (n = 32) to turn volume growth and stand density (inputs) into timber products- pulpwood, chip-n-saw, sawtimber- and stored carbon (outputs) across 21, 26, and 31-year rotations. The highest efficiencies were for the fertilized-thinned treatments. We found that thinned stands remain technically, economically, and overall efficient as rotation age increased. Non-thinned stands had lower efficiencies than thinned stands and exhibited a 28% decrease in overall efficiency between ages 21 and 31. Drought decreased overall efficiency by at least 11% when rotation age was 26 years or longer. Fertilization with drought decreased overall efficiency on average by 24%. The results reiterate the importance of thinning to efficiently mediate drought conditions and should remain a staple of plantation silviculture. Results also indicate that fertilization is not likely to help ameliorate drought impacts, from an efficiency standpoint. Study results will benefit practitioners in gauging active forest management decisions and their likely outcomes from a resource efficiency perspective.
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