Land use effects and stream metabolic rates: a review of ecosystem response

Abstract

Aim To conduct a review of the literature in order to identify the general stream metabolic responses to land use change. Methods I conducted a scientometric review analyzing the distribution of the studies among different environments, the land use scale used, and the general trends in stream metabolism response under each kind of land-use impact. Major Results Most of the analyzed studies were conducted in temperate environments, studying land-use impacts at catchment scale. Ecosystem metabolism responded to land use impacts most of the cases, especially under agricultural pressure. The general responses to land-use alterations were increases in rates of Gross Primary Production (GPP) and ecosystem Respiration (R). Primary production increases were mostly related to light and nutrient concentration increases, while R was usually related to water nutrient concentration, temperature and amount of particulate organic matter, but this general behavior can change under high impact levels where sometimes GPP decreases in response to turbidity increases. Riparian vegetation restoration have a positive effect in driving stream metabolic conditions in the direction of pristine condition, but the effectiveness of this approach is reduced in highly impacted systems. Conclusions To elucidate the mechanistic relations between stream metabolic changes and land use impacts is still one fundamental aspect to study in order to best predict effects of land use changes and establish management and protection programs. Thus, studies should focus on the causative relations between stream processes and land use changes considering different scales and multiple stress scenarios in order to improve our understanding about factors that drive the observed metabolic changes.

Agriculture influences ammonium and soluble reactive phosphorus retention in South American headwater streams

“…In contrast to the global trend, agricultural streams in our study had lower rates of GPP and ER than their low‐intensity agricultural counterparts. Silva‐Junior () performed a systematic review to evaluate land use effects on stream metabolism worldwide and found that most studies reported increases in GPP and ER rates associated with agriculture. Whereas Gücker et al () found lower rates of ER in agricultural Cerrado streams as a result of increased bottom shear stress that decreased benthic microbial biomass in the central streambed, we did not find significant differences in current velocity between agricultural and low‐intensity agricultural streams in the present study.…”

“…The studied agricultural streams also had lower ratios of transient storage areas to stream channel cross-sectional area (A S /A; Table 2) that may be important predictors of ecosystem function in South American streams (Gücker et al, 2009;Gücker & Boëchat, 2004 In contrast to the global trend, agricultural streams in our study had lower rates of GPP and ER than their low-intensity agricultural counterparts. Silva-Junior (2016) performed a systematic review to evaluate land use effects on stream metabolism worldwide and found that most studies reported increases in GPP and ER rates associated with agriculture. Whereas Gücker et al (2009) found lower rates of ER in agricultural Cerrado streams as a result of increased bottom shear stress that decreased benthic microbial biomass in the central streambed, we did not find significant differences in current velocity between agricultural and low-intensity agricultural streams in the T A B L E 4 Best multiple linear regression models (p < .05 and adjusted R 2 ≥ .60) for the ambient SRP uptake metrics Sw amb and V famb as functions of environmental variables for the low-intensity agricultural and agricultural stream sites in Brazil and Argentina Note.…”