Abstracto
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ABSTRACT
Trees are intentionally integrated in agroforestry for numerous ecosystem services including carbon sequestration, environmental, production, and economics. Open tree growth is different from that in forests and data is limited, thus restricting integration of trees in agroforestry for optimum benefits. Growth of pin oak (Quercus palustris Muenchh.), swamp white oak (Q. bicolor Willd.), and bur oak (Q. macrocarpa Michx.) were evaluated for 24 years in an alley cropping agroforestry watershed in Northern Missouri, USA. Containerized oak seedlings were planted at 3-m spacing in the center of 4.5-m wide contour grass-legume strips established at 22.8–36.5 m intervals on a 4.44-ha watershed with a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation. Tree height and diameter (dbh and 10-cm) were recorded. Among the three species pin oak had the greatest height, diameter at 10-cm, and dbh growth during the 24-year study. Pin oak trees showed 1.2-, 1.4-, and 1.2-times greater height, 10-cm diameter, and dbh than swamp white oak trees, the second-best species at the watershed. Biomass and carbon values of pin oak were 1.7 and 3.7 times in 2021 than swamp white oak and bur oak. Bur oak trees had the lowest height, 10-cm diameter, dbh, biomass, and carbon values among the three species. With the 3-species composition, tree biomass and carbon accumulation in a 24-year period were 22,613 and 10,854 kg ha−1. Trees had > 20% tapering in the main stem. Among the three species swamp white oak had 21% tapering while pin and bur oak both had 25% tapering. All three species appear to be suitable for watershed protection while pin oak showed promising growth and greater accumulation of biomass and carbon. The study emphasizes development of agroforestry-specific tree growth models as open-grown trees differ from those in conventional forestry. This can help the selection of suitable species for enhanced ecosystem services.
AUTHORS
Sidath S. Mendis
Miguel Salceda
Lalith M. Rankoth
Chamara Weerasekera