Model Analysis of the Effects of Historic CO 2 Levels and Nitrogen Inputs on Vegetation Succession

Abstract

Simulation models are useful to analyze and predict the effects of changes in atmospheric CO 2 concentration and N deposition on terrestrial ecosystems. The effects of such abiotic changes on ecosystem variables such as nitrogen mineralization and carbon accumulation can affect plant species composition, which in turn may affect various ecosystem processes. However, these interacting effects of plant species composition on ecosystem processes and vice versa are often not included in simulation models. In this paper, a model is developed that includes both plant competition and the flows of nutrients, carbon, and water through the ecosystem. Direct effects of changing atmospheric CO 2 on biomass, plant nitrogen concentrations, and litter quantity and quality are simulated together with indirect effects through changes in plant species composition. This model is validated against data from a primary succession chronosequence sere of Dutch inland dunes. For this validation, historical N deposition and atmospheric CO 2 concentration records are used. Simulated plant species biomass, organic matter C and N, and total C and N accumulation were found to correspond to measured data. The model simulated plant species replacement well at the different sites of the chronosequence even though the historic conditions differed much between the sites. Additional analyses of the effect of N deposition (preindustrial to present-day) and elevated CO 2 (preindustrial to present-day) in this ecosystem showed that N deposition had a strong effect both on vegetation development and on C and N accumulation. Compared to this, the stimulating effects of elevated CO 2 on vegetation development were relatively small. Elevated CO 2 affected early vegetation development, but the long-term response of vegetation development is dependent on N availability. In old mature forest, N deposition had only small effects while elevated CO 2 delayed forest aging. Indirect effects of CO 2 on C and N accumulation through changing plant competitive relations may ultimately be larger than direct CO 2 effects.

An ecohydrological sketch of climate change impacts on water and natural ecosystems for the Netherlands: bridging the gap between science and society

“…Based on empirical work on competition for resources between species, also a few mechanistic competitionsuccession models have been built that can be used for climate projections (for the Netherlands: Van Oene et al, 1999;Van Oene and Berendse, 2001). A drawback of these models is that the inclusion of more processes requires a higher number of input parameters, which usually comes at the cost of the model accuracy and applicability (Baird, 1999;Douma, 2011;Guisan and Zimmermann, 2000).…”

Long‐term effects of climate change on vegetation and carbon dynamics in peat bogs

“…Most equations were from earlier NUCOM models Van Oene et al 1999). The model follows changes in carbon, nitrogen and water (Fig.…”

“…In addition, growth can be restricted because of unfavourable temperatures or water levels. Most equations are from earlier NUCOM versions van Oene et al 1999van Oene et al , 2000. First, potential growth rate (G pot in g-C.m -2 .month -1…”

“…The model, named NUCOM-BOG, is derived from earlier NUCOM (nutrient cycling and competition) models describing long-term dynamics in ecosystems (heathland, forest), in which a variable number of plant species compete for light, nitrogen and water van Oene et al 1999). Our NUCOM-BOG model contains general equations for plant growth, decomposition and other processes involved in carbon, nitrogen and water cycling, but the parameter values are specific for bog plant species.…”

“…The historical CO 2 concentrations were from van Oene et al (1999), who used measured data from the Siple ice core and from Mauna Loa, Hawaii . The historic N-deposition was also derived from measured data.…”