A method to estimate the impact of clear-cutting on nutrient concentrations in boreal headwater streams

Abstract

Large-scale forestry operations, like clearcutting, may impair surface water quality if not done with environmental considerations in mind. Catchment and country level estimates of nutrient loads from forestry are generally based on specific export values, i.e., changes in annual exports due to the implemented forestry operations expressed in kg ha -1 . We introduce here a specific concentration approach as a method to estimate the impact of clear-cutting on nutrient concentrations and export in headwater streams. This new method is potentially a more dynamic and flexible tool to estimate nutrient loads caused by forestry, because variation in annual runoff can be taken into account in load assessments. We combined water quality data from eight boreal headwater catchment pairs located in Finland and Sweden, where the effect of clear-cutting on stream water quality has been studied experimentally. Statistically significant specific concentration values could be produced for total nitrogen, nitrate, ammonium, and phosphate. The significant increases in the concentrations of these nutrients occurred between 2 and 6 years after clearcutting. Significant specific concentration values could not be produced for total phosphorus and total organic carbon with the whole dataset, although in some single studies significant increases in their concentrations after clear-cutting were observed. The presented method enables taking into account variation in runoff, temporal dynamics of effects, and the proportional size of the treated area in load calculations. The number of existing studies considering large site-specific variation in responses to clear-cutting is small, and therefore further empirical studies are needed to improve predictive capabilities of the specific concentration values.

Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting

“…Second, the proportion of clear-cuts in our catchments (18-44%) was just around the threshold level (~30%) above which significant effects on hydrology and water chemistry can be expected in our 15 study region (Schelker et al 2013;Ide et al 2013;Palviainen et al 2014;Schelker et al 2014). These threshold values can vary and are highly site-specific (Kreutzweiser et al 2008;Palviainen et al 2015). For example, the relatively high baseline DOC concentrations in our streams and lakes (20 and 29 mg L -1 , respectively) are potentially less likely to be further enhanced by forest clear-cuts.…”

Reduction of stream nitrate concentrations by land management in contrasted landscapes

“…Different studies have confirmed that young forests are usually not able to limit nitrogen losses in the years following a clear cut (e.g. Palviainen et al 2015;Vitousek and Melillo 1979) and we checked with TNT2 that it simulated higher leaching on woodlots than on extensive grasslands when implanted on previous croplands (data not presented).…”

Assessment of the Water and Sediment Quality of Tropical Forest Streams in Upper Reaches of the Baleh River, Sarawak, Malaysia, Subjected to Logging Activities

“…Deforestation often results in the degradation of water quality which includes an increase in temperature, sedimentation, and nutrient enrichment [5][6][7][8][9]. In Malaysia, soil loss from logging activities had been predicted to highlight the potential risk posed by logging within water catchment areas [10].…”