Forested Wetlands and Eastern North Carolina: Silviculture in Pocosins. James D. Gregory

Transcription

1 Forested Wetlands and Eastern North Carolina: Silviculture in Pocosins James D. Gregory

2 Topics Overview of Section 404 of the Federal Water Pollution Control Act Amendments of 1972 (Public Law ) and U.S. Army Corps of Engineers (Corps) implementing regulations that apply to silviculture on jurisdictional wetlands. Pocosin ecosystems - what and where? Hydrology of pocosin ecosystems, hydrologic impacts of plantation forestry, and the objectives of drainage. Section 404 and intensive forestry normal silviculture and minor drainage; regulatory uncertainties

3 Applicability of Clean Water Act, Section U.S. Code Par Permits for Dredged or Fill Material First sentence of 33 U.S. Code 1344: The Secretary may issue permits, after notice and opportunity for public hearings for the discharge of dredged or fill material into the navigable waters at specified disposal sites. 33 U.S. Code 1362 Definitions (CWA, Section 502); Definition (7): The term "navigable waters" means the waters of the United States, including the territorial seas. Wetlands are a component of Waters of the U.S. Wetlands subject to Corps (EPA) jurisdiction in applying Sec. 404 (jurisdictional wetlands) are determined and delineated in accordance with Corps of Engineers wetlands delineation methodology.

4 Clean Water Act Section 404 Regulatory Issues, EPA and Corps Regulations EPA: 40 CFR Part 230 Section 404(b)(1) Guidelines for Specification of Disposal Sites for Dredged or Fill Material Corps 33 CFR 323 Permits for Discharges of Dredged or Fill Material into Waters of the United States Section defines discharge of dredged or fill material Section Discharges not Requiring Permits Agriculture and Silviculture Exemption 33 CFR 328 Definition of Waters of the United States

5 Key Elements of 33CFR (My Paraphrasing) (a) General.. any discharge of dredged or fill material that may result from any of the following activities is not prohibited by or otherwise subject to regulation under section 404: (1)(i) Normal farming, silviculture and ranching activities such as plowing, seeding, cultivating, minor drainage, and harvesting for the production of food, fiber, and forest products. (ii) To fall under this exemption, the activities specified in paragraph (a)(1)(i) of this section must be part of an established (i.e., on-going) farming, silviculture, or ranching operation

6 Key Elements of 33CFR Continued (1) Minor Drainage means: (ii) installing ditching or other such water control facilities incidental to planting, cultivating, protecting, or harvesting of wetland crop species, where these activities and the discharge occur in waters of the United States which are in established use for such agricultural and silvicultural wetland crop production; (2) Minor drainage does not include drainage associated with the immediate or gradual conversion of a wetland to a nonwetland or conversion from one wetland use to another (for example, silviculture to farming). In addition, minor drainage does not include the construction of any canal, ditch, dike or other waterway or structure which drains or otherwise significantly modifies any water of the United States.

7 The Recapture Provision of Section 404(f)(2) (c) Any discharge of dredged or fill material into waters of the United States. must have a permit if it is part of an activity whose purpose is to convert an area of the waters of the United States into a use to which it was not previously subject, where the flow or circulation of waters of the United States may be impaired or the reach of such waters reduced. a permit will be required for the conversion of a wetland from silvicultural to agricultural. A conversion of a Section 404 wetland to a non-wetland is a change in use of an area of waters of the United States.

8 Mineral Flat and Organic Flat Wetlands Wetland Type Terminology of the Corps Hydrogeomorphic Wetland Classification What: large, interstream flats with poorly/very poorly drained mineral or organic soils. Where: distributed across the Lower Coastal Plain of NC east of the Surry Scarp. Largest pocosins are east of the Suffolk Scarp at elevations less than 100 ft. True pocosins (domed peatlands on large interstream flats) typically have a central area of organic soils surrounded by wet mineral soils. These forested wetland systems contain the largest tracts of intensively managed pine plantations to which Section 404 of the Clean Water Act applies.

9 North Carolina Pocosins

10 Pocosin Confusion: Schafale & Weakley Classification of the Natural Communities of NC, 3 rd Approximation: 3 vegetation types with pocosin in the name Schafale s 4 th Approximation: 11 vegetation types with pocosin in the name.

11 Great Dismal Swamp

12 East Dismal Swamp & Albemarle-Pamlico Peninsula

13 Croatan National Forest, Hofmann Forest, Open Ground Farms

14 Holly Shelter/Angola Game Lands, Green Swamp

15 Soil Mapping Units on Eastern Side of Croatan National Forest

16 Hydrology of Pocosin Ecosystems Water inputs: rainfall, lateral input of groundwater (Great Dismal and East Dismal Swamps), upward flux of groundwater from Castle Hayne aquifer (south of Neuse River)? Water outputs: evapotranspiration (ET) (main output), runoff to streams (small portion of the water balance), downward seepage to deep aquifers (little to none due to dense clay layers near the surface) Seasonal water table hydroperiod water table is at or above the surface when ET is low; water table declines (often to depths of 10 ft or more) when ET is high

17 Hydrologic Impacts of Pine Silviculture With Drainage on Pocosin Ecosystems Hydrologic Stand Phases Rotation age stand - maximum ET, driest soil conditions, i.e. lowest average water table level; ET is likely much higher than for the natural vegetation community that the plantation replaced. Post-harvest site preparation phase minimum ET, wettest soil conditions, i.e. highest average water table level. Growing young stand ET increasing annually from the minimum, soil becoming slowly drier Stand closure and beyond ET increasing to the maximum, soil becoming slowly drier

18 Hydrologic Impact of a Mosaic of Hydrologic Phases Pocosin west of Suffolk Scarp Between Tar-Pamlico and Neuse Rivers

19 Objectives of Silvicultural Drainage Improve soil trafficability for timber harvesting and site preparation, increase the number of days per year that harvesting and site prep can be conducted with minimal soil damage

20 Timber Harvesting on Wetland Site with Drainage

21 Objectives of Silvicultural Drainage Improve soil trafficability for timber harvesting and site preparation, increase the number of days per year that harvesting and site prep can be conducted with minimal soil damage Improve seedling survival and early growth rates of trees: Drainage and bedding often are the difference between achieving a well-stocked stand and achieving no stand Research in the 60s 80s showed that growth rates of individual trees up to about 15 years was much higher on drained sites than on undrained sites. Growth rates of individual trees on undrained sites tended to catch up with that of trees on drained sites. BUT, the undrained stands never caught up with the tremendous volume growth advantage of the drained stands.

22 Drainage and Bedding Essential to Seedling Survival

23 Regulatory Uncertainties of Normal Silviculture on Pocosins What is minor drainage? No specific guidance on design/management of silvicultural drainage systems in the Corps regulations My concept: Temporary drainage prior to and during harvesting, site prep, and early stand establishment - 1 bucket lateral ditches plus sufficient transport and outfall capacity to provide needed hydraulic gradient from the lateral ditches. Implement water management when the stand is 3-5 years old and restore all wetland hydrologic functions to the stand. Water management structures control outflow and water quality. Roadside borrow/transport ditches

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25 New One-Bucket Ditch

26 So What is a Jurisdictional Wetland? Corps wetland delineation methodology has undergone a number of revisions since the 1987 delineation manual was published. Those revisions have had the objective of making drier sites meet the Corps delineation criteria, i.e. expand the total area of jurisdictional wetlands. Those revisions have especially affected mineral flats. Many soil mapping units that were not jurisdictional wetlands in 1987 now are. So, minor drainage of mineral and organic flats is much less likely to result in a wetland being converted to a nonwetland.