Matthew W McBroom

Water Quality Effects of Clearcut Harvesting and Forest Fertilization with Best Management Practices

Nine small (2.5 ha) and four large (70-135 ha) watersheds were instrumented in 1999 to evaluate the effects of silvicultural practices with application of best management practices (BMPs) on stream water quality in East Texas, USA. Two management regimes were implemented in 2002: (i) conventional, with clearcutting, herbicide site preparation, and BMPs and (ii) intensive, which added subsoiling, aerial broadcast fertilization, and an additional herbicide application. Watershed effects were compared with results from a study on the same small watersheds in 1981, in which two combinations of harvesting and mechanical site preparation without BMPs or fertilization were evaluated. Clearcutting with conventional site preparation resulted in increased nitrogen losses on the small watersheds by about 1 additional kg ha(-1) each of total Kjeldahl nitrogen (TKN) and nitrate-nitrogen (NO(3)-N) in 2003. First-year losses were not significantly increased on the large watershed with a conventional site preparation with BMPs. Fertilization resulted in increased runoff losses in 2003 on the intensive small watersheds by an additional 0.77, 2.33, and 0.36 kg ha(-1) for NO(3)-N, TKN, and total phosphorus, respectively. Total loss rates of ammonia nitrogen (NH(4)-N) and NO(3)-N were low overall and accounted for only approximately 7% of the applied N. Mean loss rates from treated watersheds were much lower than rainfall inputs of about 5 kg ha(-1) TKN and NO(3)-N in 2003. Aerial fertilization of the 5-yr-old stand on another large watershed did not increase nutrient losses. Intensive silvicultural practices with BMPs did not significantly impair surface water quality with N and P.

Instream Woody Debris and Riparian Forest Characteristics in the Sabine River, Texas

Abstract We examined instream large woody debris (LWD) dynamics on the Sabine River, TX. All wood >10 cm in diameter and >2 m long was measured on four river meanders (meander wavelengths) below the dam on Toledo Bend Reservoir. We determined LWD species, degree of decay, bank orientation, jam association, and stage contact. We also measured riparian vegetation characteristics on each meander. LWD volumes were significantly greater at the site immediately below Toledo Bend Dam, due to the relatively steeper channel gradient and higher rates of channel erosion. Based on mass balance estimates, between 11 and 21% of total annual recruitment came from upstream fluvial transport, and the remainder resulted from bank erosion and tree mortality. We estimated average LWD residence time to be 12–14 years. The lower Sabine River is transport-limited for sediment, and the same is true for LWD. Based on these measurements, it is unlikely that Toledo Bend Reservoir is having a significant impact on LWD dynamics at the measurement reaches due to lacustrine wood storage. Of greater concern in the study system are riparian forest degradation and invasive species spread, which may dramatically affect future LWD loadings and residence times, and thus, riverine biota.

Sediment Losses associated with degree of watershed disturbance resulting from clearcut harvesting with Best Management Practices

Forestry best management practices (BMPs) are effective in reducing water quality and quantity impacts from silvicultural activities and have been shown to be a cost effective means for controlling nonpoint source pollution in complex and variable forested watershed conditions. Nine small (~2.5 ha) watersheds in East Texas were previously instrumented in 1980 to evaluate clearcut harvesting and intensive site preparation on sediment losses, at the time that BMPs had not been adopted in Texas. These same nine watersheds were reinstrumented in 1999 to examine the silvicultural effects on water quality of contemporary silviculture with applications of BMPs. Four large (70-135 ha) watersheds were also instrumented in 1999, with small watersheds nested in them to contrast water quality and site disturbance impacts on stand-sized watersheds. Site disturbance parameters such as degree of surface soil disturbance (% bare soil, % dominant vegetation type, % litter, and % logging slash) and degree of soil compaction (bulk density) were measured on all watersheds in both study periods to determine their relationship to watershed sediment losses. In addition, soil infiltration rates were measured on the nine small watersheds pre- and post-treatment during the 1980 pre-BMP study. First-year post-treatment sediment losses generally decreased with decreasing intensity of site disturbance, from 2,937 kg/ha with the most intensive treatment without BMPs to 225 kg/ha in the most intensive treatment with BMPs. Soils were not compacted sufficiently by harvest to decrease infiltration rates or reduce site productivity. BMPs are designed to reduce site disturbance particularly along sensitive riparian areas. In the current study, streamside management zones (SMZs) were shown to be effective in mitigating harvest disturbance in riparian areas and thus reducing sediment losses. Sediment losses from silvicultural activities were associated with extent of BMP implementation and degree of watershed disturbance.

Expansion of the MANAGE Database with Forest and Drainage Studies

The “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was published in 2006 to expand an early 1980s compilation of nutrient export (load) data from cultivated and pasture/range land at the field or farm scale. Then in 2008, MANAGE was updated with 15 additional studies, and nitrogen (N) and phosphorus (P) concentrations in runoff were added. Since then, MANAGE has undergone significant expansion adding N and P water quality along with relevant management and site characteristic data from: (1) 30 runoff studies from forested land uses, (2) 91 drainage water quality studies from drained land, and (3) 12 additional runoff studies from cultivated and pasture/range land uses. In this expansion, an application timing category was added to the existing fertilizer data categories (rate, placement, formulation) to facilitate analysis of 4R Nutrient Stewardship, which emphasizes right fertilizer source, rate, time, and place. In addition, crop yield and N and P uptake data were added, although this information was only available for 21 and 7% of studies, respectively. Inclusion of these additional data from cultivated, pasture/range, and forest land uses as well as artificially drained agricultural land should facilitate expanded spatial analyses and improved understanding of regional differences, management practice effectiveness, and impacts of land use conversions and management techniques. The current version is available at www.ars.usda.gov/spa/manage-nutrient. (KEY TERMS: nitrogen; phosphorus; water quality; nonpoint source pollution; drainage; forest hydrology.) Harmel, R. Daren, Laura E. Christianson, Matthew W. McBroom, Douglas R. Smith, and Kori D. Higgs, 2016. Expansion of the MANAGE Database with Forest and Drainage Studies. Journal of the American Water Resources Association (JAWRA) 52(5):1275-1279. DOI: 10.1111/1752-1688.12438

A spatial analysis of the forestry industries in East Texas

The 48,400 km2 (12.0 million acres) of timberland in East Texas provides a multi-billion dollar industry that produces a wide variety of goods and services, and supports tens of thousands of jobs. Forest fragmentation, biomass harvesting, land use change such as urbanization and oil and gas exploration, and market challenges are resulting in greater economic volatility for the forestry industry in East Texas. This study investigates the spatial, economic and social factors that may impact the location of forestry industries with GIS spatial analysis tools. Basic information about all the forestry industries in East Texas were collected, compiled, and categorized. Standard Poisson regression analysis was processed between the number of forestry industries per county and potential influencing factors such as forest coverage, developed area, population, road density, average house value, average timberland value, median household income, and tax rate. Significant spatial impact factors on forestry industries were successfully identified, and the output of the research can be useful for policy makers, investors, and resource managers to implement strategies that will ensure the future viability of the forestry industries in East Texas.