| dc.description.abstract | Wood debris is an important C pool in forest ecosystems. Understanding the controls on wood decomposition is necessary for predicting the response of forest ecosystem carbon cycling to management and climate. The productivity of managed pine plantations, primarily loblolly pine (Pinus taeda L.), in the southeastern United States has been improved through nutrient management. Although uncertainty exists, climate change may drive a reduction of precipitation of 10%-30% by 2080 for the region and an increase in temperature. In managed forests that undergo periodic harvesting, the forest can become a source of C when decomposer activity increases C loss from residual wood. Two questions motivated this research. How does reduced precipitation, interacting with fertilization, affect wood decomposition in managed pine forests? How does wood decomposition vary for decomposer community, across climatic regions and within forest ecosystems?
To address these questions, the mass loss of southern pine wood substrates were analyzed under a factorial combination of two treatments: soil moisture (30% throughfall removal) and nutrient addition (224 kg/ha N, 64 kg/ha P and 67 kg/ha K). The experimental sites were located in loblolly pine plantation forests in Oklahoma (OK), Florida (FL), Georgia (GA), and Virginia (VA). The results showed that throughfall reduction inhibited wood decomposition, while fertilization stimulated wood decomposition overall in OK, despite a significant inhibition of wood decomposition of fertilization when soil microbes were the only decomposer affecting the substrate. However in the following years in OK, fertilization increased wood decomposition regardless of decomposer type. Across sites, temperature was the predominant predictor for wood decomposition, but macro-invertebrates were an important modifier of cross site sensitivity to temperature.
The results suggest that the response of macro-invertebrates to climate and fertilization needs to be included in ecosystem carbon models to better predict how the cycling of woody debris will respond to climate change and forest management. Temperature, as well as macro-invertebrate effects, were both important predictors for wood decomposition in loblolly pine forests in the southeastern US. | en |
