Soil Chemical Change during Three Decades in an Old‐Field Loblolly Pine (Pinus Taeda L.) Ecosystem

Abstract

The ability of soil to sustain its supply of nutrients to a growing forest is controlled by a complex of biogeochemical processes. Forest soil data are notably absent, however, that describe sustained nutrient supply of nutrient depletion. The objective of this study was to evaluate how exchangeable nutrient cations of a previously cultivated Ultisol responded to the first three decades of pine forest development. On six occasions during the three decades, the upper 0.6 m of soil was sampled from eight permanent plots and chemically analyzed with the same procedures. During this period, KCl—exchangeable acidity (as positive charges of adsorbed H and Al ions) increased by 37.3 kmolc/ha in the upper 0.6 m of soil and positive charges of exchangeable Ca and Mg were depleted by 34.8 and 8.9 kmolc/ha (by 696 and 108 kg/ha), whereas, exchangeable K was reduced by only 0.5 kmolc/ha (19 kg/ha). Depletion of soil exchangeable Ca was on the same order of magnitude as Ca removals (i.e., Ca accumulation in biomass and forest floor plus that lost in soil leaching). Removals of soil Mg also appeared to outpace resupply from recycling, atmospheric deposition, and mineral weathering, but not the same degree as Ca. Over the three decades, soil leaching loss of these divalent cations (from 0.6 m depth) appeared equal to cation accumulation in biomass plus forest floor, with sulfate balancing about half these cations in leachates. In contrast to Ca and Mg, total K removals from the soil exceeded reductions in soil exchangeable K by nearly 20—fold. Exchangeable K was well buffered in surface mineral soils apparently due to a combination of biological recycling via leaching of canopies and forest floor plus mineral weathering release. These nutrient dynamics may be common to many nutrient—demanding forest ecosystems supported by soils with low activity kandic or oxic horizons. Such soils (Ultisols and Oxisols) occur on many hundreds of millions of hectares in temperate and tropical zones.

Ecological feedbacks following deforestation create the potential for a catastrophic ecosystem shift in tropical dry forest

“…Placement of lysimeters below the root zone is expected to capture soil solution samples that represent a loss to the system, although the presence of deep roots may pose a challenge to this assumption (52). The lysimeters used in this study were modeled after Richter et al (53): 3-in diameter polyvinyl chloride (PVC) pipe was sliced to create an opening with semiaxes of 10.16 and 5.08 cm. The pipe was lined with mesh, capped, and connected by tubing to a 1-liter high-density polyethylene (HDPE) collection bottle.…”

Organic carbon efflux from a deciduous forest catchment in Korea

“…Within the forest soil profile, concentrations of DOC are highest typically in the interstitial waters of the organic-rich upper soil horizons (McDowell and Likens, 1988;Richter et al, 1994;Dosskey and Bertsch, 1997). A significant portion of DOC is transported by the preferential flow, given that the state of adsorption equilibrium cannot be reached owing to the reduced contact time between DOC and the soil surface (e.g., Jardine et al, 1989;Hagedorn et al, 1999).…”

Impact of tree species on nutrient and light availability: evidence from a permanent plot study of old-field succession

“…Vegetation structure can exert large influences on the light transmittance (Binkley and Giardina 1998;Richter et al 1994;Knops et al 2002), as well as on water and nutrients in ecosystems (Leuschner 2002). Several authors showed that dominating tree species in forests can greatly impact soil properties (Binkley and Giardina 1998;Knops et al 2002;Zhong and Makeschin 2004) or that different dominating plant species may have significant effects on environmental conditions, e.g.…”