UC Davis Department of Plant Sciences

RIPARIAN ECOSYSTEM RESPONSE TO TIMBER HARVSESTING FOR THE PURPOSE OF RESTORING ASPEN


Stream Chemistry & Turbidity

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The modification of nutrient concentrations in streams through logging activities can alter aquatic ecosystem structure and function. In particular, increases in NO3-N, NH4-N, and PO4-P have been found to cause eutrophication. Additionally, increases in sediment loading into streams due to logging activities have been found to modify streambed surface conditions, decrease light penetration, and alter primary production, which can have detrimental impacts on all forms of stream biota.

There was no increase in the difference (Δ) between upstream and downstream nutrient, TSS, or turbidity levels following the implementation of any of the Pine-Bogard or Bailey Project treatments. The analysis of NO3-N, NH4-N, and PO4-P across all stations and years revealed extremely clean water conditions along both treated and untreated stream reaches at Pine, Bogard, and Bailey Creeks (Table 2). More than 80 % of all samples analyzed for NO3-N, NH4-N, and PO4-P were below the detection limit, with the exception of PO4-P in Bogard Creek, for which only 15 % of samples were below the detection limit.

The nutrient levels measured indicate that Pine and Bailey Creeks are both N and P limited. Bogard Creek has higher levels of P than Pine and Bailey Creeks, due to the large influence of sub-surface flow inputs (phosphorus is derived from geologic weathering) on Bogard Creek’s background chemistry. However, Bogard Creek is N limited, which limits the potential of P to cause eutrophication. Such low levels of nutrients are characteristic of Sierra Nevada forests.

 

 

     

 

 

 

Table 2. The mean results for all samples collected across stations PC17 to PC7 at Pine Creek (2003 – 2010), across stations BO6 to BO1 at Bogard Creek (2003 – 2010), and across stations BR1 to BR6 at Bailey Creek (2003-4004, and 2006-2010).
DL = Detection Limit

 

 

     

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