Windrowing Mr. John Clarke Prof. Michael Bruen
Introduction Before a forest is replanted a number of ground preparation operations are carried out. These include windrowing as well as the clearing of debris from drainage channels. Additional drainage channels may also be dug at this time if they are required
Windrowing The stacking of leftover vegetation, brash and other organic matter into long narrow rows Purpose To clear enough space for the replanting of new trees To maintain the site- clear blocked drains, remove brash mats, construct new drainage channels in wet locations What is windrowed Decaying branches, leaves and needles stripped off trees during felling Brash mats and brash bridges left behind after clearfelling Tree stumps and roots (not practiced in sites as part of this study)
Pre Windrowing Some pine needles still attached to branches More pine needles on the ground
During Windrowing Brash Mat Over Stream Removed New Drainage Channels Dug
During Windrowing
After Windrowing
Water Quality Concerns Increased soil disturbance by machinery during windrowing Increased soil disturbance caused by the scraping and gathering of brash from the ground Release and mobilisation of loose sediment and nutrients from underneath the brash Mobilisation of sediment during drain clearing, bank collapses, increased sediment loss if new drainage channels are dug Removal of protective cover that the brash provides
Hypotheses of Study Reforestation practices result in ground disturbance that increases sediment and nutrient losses to streams draining the catchment
Study Site- Annalecka Plantation Size- 10 Ha Catchment Size- 167.5 Ha Felled in Spring 2010- Sitka Spruce (Picea sitchensis). Some needles still attached to branches, more on ground. Windrowing began 3 rd September 2011 and lasted until 1 st October 2011 No new drainage channels dug
Annalecka Brook Aerial Photographs
Suspended Solids Event Loads (Kg) 3500 3000 3,167 2500 SS (Kg) 2000 1500 1,700 2,085 1,326 1000 500 0 5 230 111 21 264 651 10 50 80 100 % Area WR 9 88 1,011 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 A15 805 145 3 6 12 27 27 28 28 28 Months Post WR
SS FWMC (mg/l) and Average Rainfall Rate (mm/hr) SS FWMC (mg/l) 250 200 150 100 50 0 SS FWMC (mg/l) Average Rainfall Rate (mm/hr) P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 A15 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Rainfall Rate (mm/hr) 10 50 80 100 % Area WR 3 6 12 27 27 28 28 28 Months Post WR
SS (mg/l) SS (mg/l) 300.0 250.0 200.0 150.0 100.0 50.0 600.0 500.0 400.0 300.0 200.0 100.0 502.0 0.4 282.5 116.0 0.2 2.1 48.1 56.9 0 00:00 12:00 00:00 12:00 00:00 12:00 00:00 0.0 SS (mg/l) 258.0 22.8 2.3 2.3 0.0 0 00:00 12:00 00:00 12:00 00:00 12:00 00:00 SS (mg/l) D6 D7 68.5 Flow (m3/s) 16.4 3.3 Flow (m3/s) 0.5 0.4 0.3 0.2 0.1 0.8 0.6 Flow (m3s) Flow (m3s)
Total Event Phosphorous Loads (Kg) 4 3.5 3.697 3 2.5 TP (Kg) 2 1.5 1.226 1.421 1.881 1 0.5 0 0.254 0.585 0.541 0.223 10 50 80 100 % Area WR 0.153 0.461 0.598 0.632 0.426 0.760 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 3 6 12 27 27 28 28 Months Post WR
TP Flow Weighted (mg/l) TP FWMC (mg/l) 0.3 0.25 0.2 0.15 0.1 0.05 0 TP FWMC (mg/l) Average Rainfall Rate (mm/hr) 0.178 0.077 0.085 0.067 0.046 0.049 0.041 0.046 0.042 0.034 0.026 0.035 0.035 0.022 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Rainfall Rate (mm/hr) 10 50 80 100 % Area WR 3 6 12 27 27 28 28 Months After WR
SS and TP Relationship 600 500 400 SS (mg/l) 300 200 100 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 TP (mg/l) R2= 0.82
Variation of Soluble Reactive Phosphorous Loads During Sampled Events (Kg) 0.3 0.25 SRP Load (Kg) 0.2 0.15 0.1 PWR DWR AWR 0.05 0 Time
Nitrate FWMC (mg/l) 0.25 0.2 Nitrate FWMC (mg/l) 0.15 0.1 0.05 0 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 10 50 80 100 % Area WR 3 6 12 27 27 28 28 Months Post WR
Total Ammonia Flow Weighted Mean Concentrations (mg/l) 0.3 Ammonia FWMC (mg/l) Average Rainfall Rate (mm/hr) 0 Ammonia FWMC (mg/l) 0.25 0.2 0.15 0.1 0.05 0.5 1 1.5 2 2.5 Rainfall Rate (mm/hr) 0 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 3 10 50 80 100 % Area WR 3 6 12 27 27 28 28 Months Post WR
0.6 Potassium Flow Weighted Mean Concentrations (mg/l) 0.5 Potassium FWMC (mg/l) 0.4 0.3 0.2 0.1 0 P1 P2 P3 D4 D5 D6 D7 A8 A9 A10 A11 A12 A13 A14 10 50 80 100 % Area WR 3 6 12 27 27 28 28 Months Post WR
Annalecka Seasonal Trends FWMC (mg/l) 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 DOC FWMC (mg/l) FWMC (mg/l) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 Aluminium FWMC (mg/l)
Annalecka Conclusions Removing the effect of flow magnitude indicates that increased sediment and nutrient concentrations observed were as a result of windrowing operations. Elevated concentrations, while declining, seem to persist for up to 2 years after operations ceased Management No observed silt trapping structures used during windrowing. Some observable rutting in places. No streams crossed by machinery.
Study Site- Oakwood Site Size- 1.17 Ha Catchment Size- 48 Ha Felled in 2010- Sitka Spruce (Picea sitchensis) Windrowing began 17 th October 2011 and lasted until 24 th October 2011 One new drainage channel dug Between the studied plantation and the study stream there is a 2-3 year old strip (50-100m+ wide in places ) of planted pine trees.
Oakwood Aerial Photographs
Oakwood Map
Event Loads (Kg) SS Loading (Kg) TP Loading (Kg) 70 60 R2= 0.90 0.35 0.3 50 0.25 SS (Kg) 40 30 0.2 0.15 TP (Kg) 20 0.1 10 0.05 0 P1 P2 P3 P4 D5 D6 D7 A8 A9 A10 10 50 100 % Area WR 6 12 24 Months After WR 0
Variation of SRP Loads (Kg) During Sampled Events 0.0160 0.0140 0.0120 SRP Loading (Kg) 0.0100 0.0080 0.0060 PWR DWR AWR 0.0040 0.0020 0.0000 Time
Nitrate Event Loads (Kg) 0.45 0.40 0.35 0.30 Nitrate (Kg) 0.25 0.20 0.15 0.10 0.05 0.00 P1 P2 P3 P4 D5 D6 D7 A8 A9 A10 10 50 100 % Area WR 6 12 24 Months After WR
Total Ammonia Event Loads (Kg) Ammonia (Kg) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 P1 P2 P3 P4 D5 D6 D7 A8 A9 A10 10 50 100 % Area WR 6 12 24 Months After WR
Total Ammonia Flow Weighted Mean 0.12 Concentrations (mg/l) 0.10 Ammonia FWMC (mg/l) 0.08 0.06 0.04 0.02 0.00 P1 P2 P3 P4 D5 D6 D7 A8 A9 A10 10 50 100 % Area WR 6 12 24 Months After WR
Potassium Event Loads (Kg) 3.00 2.50 2.00 Potassium (Kg) 1.50 1.00 0.50 0.00 P1 P2 P3 P4 D5 D6 D7 A8 A9 A10 10 50 100 % Area WR 6 12 24 Months After WR
Seasonal Trends Oakwood FWMC (mg/l) 30.00 20.00 10.00 0.00 DOC 05-Jul 16-Jul 28-Jul 10-Sep 17-Oct 22-Oct 24-Oct 25-Apr 11-Oct 25-Oct FWMC (mg/l) 0.8 0.6 0.4 0.2 0 Aluminium 05-Jul 16-Jul 28-Jul 10-Sep 17-Oct 22-Oct 24-Oct 25-Apr 11-Oct 25-Oct
Oakwood Conclusions Sediment and nutrients showed the same increasing trends during windrowing but on a reduced scale. Concentrations recorded were lower due to the distance of operations from the sampling location and mitigation by the presence of the 2-3 year old plantation and/or due to the size of the plantation windrowed- 1.17 Ha DOC, Aluminium and Calcium showed similar seasonal trends to Annalecka. Management No observed silt trapping structures used during windrowing. Some observable rutting in places. New drainage channel dug No streams crossed by machinery.
Study Sites Kilcoagh Site Size- 29.69 Ha Catchment Size- 118.87 Ha Felled in 2011- Pine/Spruce Windrowing began 25 th September 2012 and lasted until 30 th October 2012 One new drainage channel dug
Kilcoagh
Flow Weighted Mean Concentrations (mg/l) SS FWMC (mg/l) 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 SS FWMC (mg/l) R2= 0.73 TP FWMC (mg/l) 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 TP FWMC (mg/l) 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11 10 50 100 % Area WR 6 12 15 16 16 Months After WR 0.00
0.12 Variation of SRP Loads (Kg) During Sampled Events 0.1 SRP Loading (Kg) 0.08 0.06 0.04 PWR DWR AWR 0.02 0 Time
Nitrate FWMC (mg/l) 0.45 0.40 0.35 Nitrate FWMC (mg/l) 0.30 0.25 0.20 0.15 0.10 0.05 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11 10 50 100 % Area WR 6 12 15 16 16 Months After WR
Total Ammonia FWMC (mg/l) 0.14 0.12 Ammonia FWMC (mg/l) 0.10 0.08 0.06 0.04 0.02 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11 10 50 100 % Area WR 6 12 15 16 16 Months After WR
Potassium Event Loads (Kg) 3.50 3.00 2.50 Potassium (Kg) 2.00 1.50 1.00 0.50 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11 10 50 100 % Area WR 6 12 15 16 16 Months After WR
Kilcoagh Seasonal Trends DOC Aluminium FWMC (mg/l) 40.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11 FWMC (mg/l) 0.80 0.60 0.40 0.20 0.00 P1 P2 P3 D4 D5 D6 A7 A8 A9 A10 A11
Kilcoagh Conclusions Sediment and nutrients showed the same increasing trends during windrowing. Concentrations recorded were lower than those recorded at Annalecka Catchment characteristics- drainage network DOC, Aluminium and Calcium showed similar seasonal trends to Annalecka. Management No observed silt trapping structures used during windrowing. Some observable rutting in places. No streams crossed by machinery.
Kilcoagh
Windrowing Summary and Conclusions Annalecka- large increases in sediment and nutrient concentrations during windrowing. Oakwood- an increasing trend in sediment and nutrients observed. Concentration increases not significant in terms of biological impact due to the presence of the 2-3 year old plantation and the size of the plantation windrowed. Kilcoagh- an increase in sediment and nutrient concentrations recorded during windrowing. Some large peaks observed in sediment and phosphorous.