# Assessing the Functional Response to Streamside Fencing of Pastoral Waikato Streams, New Zealand
## 1 Introduction
For example, [PERSON], [PERSON], [PERSON] and [PERSON] [39] showed that cotton strip decomposition rates increased with higher dissolved phosphorus concentrations which were linked to intensely developed catchments, and [PERSON], [PERSON], [PERSON] and [PERSON] [38] linked increased decomposition rates to higher water temperatures due to a lack of canopy shading. In addition to organic matter retention, organic matter processing and ecosystem metabolism, nutrient processing and nutrient assimilation into stream food-webs have been explored as functional metrics of stream health [40; 41; 42]. The \(\delta^{15}\)N values of aquatic plants and animals reflect both the source of N and processes that can influence N cycling and have been shown to increase in response to land use intensification [31; 43]. While technically a structural aspect of stream communities, several studies have suggested that the \(\delta^{15}\)N values of aquatic biota represent an integrated signature of N cycling [44; 45]. Ideally, indicators of stream ecosystem health are sensitive to change in human actions over time, such as restoration. While the primary focus of the above studies has been to quantify the response of functional indicators to land use effects, there is little if any, scientific evidence on the suitability of functional measures as indicators of restoration success [46; 47]. Functional indicators are responsive to a range of reach-scale and catchment-scale drivers [48], and as such may be useful for discerning the optimum design of restoration methods to improve stream health. Further, functional indicators are predicted to respond to streamside fencing variably over time (Figure 1) following the restoration of physical metrics and other drivers discussed above. Multiple functional indicators may therefore be required to assess the restorative effect of fencing on stream functioning, considering the multidimensional character of stream function as well as its temporal character. The overall objective of this study was to assess the effectiveness of streamwise fencing at a reach scale to restore stream function. We measured a range of functional metrics to indicate potential restoration recovery trajectories in the retention, transformation and absorption of nutrients and carbon into stream food-webs. Functional metrics, including GPP, ER, wood mass loss, cotton strip decomposition, organic matter retention, and \(\delta^{15}\)N values of primary consumers, were measured alongside metrics describing physical stream habitat and water quality. Potential recovery trajectories were measured in the range of functional metrics to indicate potential restoration recovery trajectories in the retention, transformation and absorption of nutrients and carbon into stream food-webs. Functional metrics, including GPP, ER, wood mass loss, cotton strip decomposition, organic matter retention, and \(\delta^{15}\)N values of primary consumers, were measured alongside metrics describing physical stream habitat and water quality. Potential  
were explored by surveying 11 pairs of sites, with and without riparian buffers fenced between five to 34 years previously in the central North Island, New Zealand. Overall, we expected to see a shift in stream function from impacted states for unfenced sites (i.e., \"poor\" ecosystem health) to less-impacted states for fenced sites (i.e., \"healthy\" ecosystem health). We hypothesised that  
(1) fencing would improve the state of ecosystem health as described by physical and functional indicators due to riparian re-establishment, leading to a higher proportion of shade, lower average water temperature, greater hydraulic retention, decreased rates of GPP and ER, decreased organic matter processing rates, and decreased \(\delta^{15}\)N values indicative of more efficient biogeochemical cycling and  
(2) time since fencing would lead to a greater difference between fenced and unfenced sites as described by physical and functional indicators of ecosystem health, hence illustrating a 'rubber-band' model of recovery.