Is Biomass Accumulation in Forests an Option to Prevent Climate Change Induced Increases in Nitrate Concentrations in the North German Lowland?

Stefan Fleck,Henning Meesenburg,Johannes Sutmöller,Matthias Albert,Jan Evers,Bernd Ahrends

doi:10.3390/f8060219

Stefan Fleck, Henning Meesenburg + Show 4 more

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https://doi.org/10.3390/f8060219

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Journal: Forests	Publication Date: Jun 21, 2017
Citations: 18	License type: CC BY 4.0

Affiliation: Nordwestdeutsche Forstliche Versuchsanstalt

Abstract

The North German Lowland is a region with locally high nitrate (NO3−) concentrations in seepage water, inducing an increased susceptibility to the effects of climate change. The future risk of rising NO3− concentrations in seepage water from forests was quantified for four regions in the North German Lowland using climate projections and a modelling system comprising submodels for forest stand development (WaldPlaner), water budgets (WaSiM-ETH), and biogeochemical element cycles (VSD+). The simulations for the period from 1990 to 2070 included three different forest management scenarios (reference, biodiversity, and climate protection) and showed a general decrease in groundwater recharge which could hardly be influenced by any of the management options. The simulated soil organic matter stocks adequately represented their past increase as expected from the National Forest Soil Inventory (NFSI), but also showed a future decline under climate change conditions which leads to higher organic matter decomposition and a long-lasting increase of NO3− leaching from forest soils. While the climate protection oriented scenario shows the highest increase in NO3− concentrations during the projection period until 2070, the biodiversity scenario kept NO3− concentrations in seepage water below the legal thresholds in three of four selected model regions.

Highlights

To carbon (C), oxygen, and hydrogen, nitrogen (N) is one of the main building elements of plant biomass, being of central importance for plant metabolism and growth
Results are presented as means aggregated over 20-year periods from 1991 to 2070 in order to enhance the visibility of long-term trends and to eliminate the inter-annual variations of climate projections
In DH, starting from a low level, standing volume accumulates over time; a slight decrease is only projected Forests between and 2070 for the climate protection scenario

Summary

Introduction

To carbon (C), oxygen, and hydrogen, nitrogen (N) is one of the main building elements of plant biomass, being of central importance for plant metabolism and growth. Since nitrogen is mainly taken up by the roots of plants in the form of soluble nitrate (NO3 − ) or ammonium (NH4 + ), the availability of these ions in the soil solution is a precondition for plant growth and has been a growth limiting site condition in many ecosystems including forests [1,2]. Subsequent deposition to terrestrial ecosystems increased N availability to a level exceeding the demand of forest stands’ growth increment [3]. It has been shown that this long-term increase in N deposition significantly increased forest productivity [4], thereby making forest biomass a valuable sink for excess N. Excess N is usually not completely retained within the forest ecosystems: After a period of N accumulation in the ecosystem, forests may become N saturated and NO3 − is increasingly leached with seepage water [5,6], causing

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