Can the inter-rotational productivity in ponderosa pine plantations be sustained in the face of climatic change?

Abstract

Inter-rotational productivity (i.e., productivity of successive rotations) of ponderosa pine plantation was measured on experimentally treated plots with a common design at three diverse sites in northern California. The objectives were to examine the carryover effect of fertilization (F) and understory control by herbicide (H), applied in the first rotation of plantation, on growth in the second rotation and to determine the sustainability of plantation productivity between rotations. Carryover effect varied among the three sites. There was a significant and positive H and F effect (P < 0.03) on height and aboveground biomass at Whitmore, a site of intermediate quality; only an H effect at Elkhorn (P < 0.01), the site of low quality; and an F effect at Feather Falls (P = 0.05), the site of high quality. Genetically improved seeds resulted in slightly taller height than the original seed sources, but the difference was not statistically significant. While annual precipitation was similar, growing season precipitation was 6-42% lesser and air temperature was about 0.9-1.4 ˚C higher during the second rotation than in the first rotation. Due to the warmer air temperature, the sites likely endured drier air, greater evapotranspiration, and lesser soil water availability. These environmental changes appear to have caused the observed growth reduction in these ponderosa pine plantations. This was despite the management techniques we applied for improved pine growth during the second rotation: genetically improved seeds and control of competing vegetation. It is believed that these are the first reported observations of growth decline in managed ponderosa pine plantations associated with warming climate. If these results are representative of a larger region and a future trend, use of ponderosa pine plantation forestry as a method of increasing forest carbon sequestration, may be overestimated in for future rotations.

Citation

Zhang, Jianwei. 2023. Can the inter-rotational productivity in ponderosa pine plantations be sustained in the face of climatic change?. Forest Ecology and Management. 549(4): 121499. https://doi.org/10.1016/j.foreco.2023.121499.