R. Scott Beasley

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.

Phenolic compounds and rare polyhydroxylated triterpenoid saponins from Eryngium yuccifolium.

Phytochemical investigation on the whole plant of Eryngium yuccifolium resulted in the isolation and identification of three phenolic compounds (1-3) and 12 polyhydroxylated triterpenoid saponins, named eryngiosides A-L (4-15), together with four known compounds kaempferol-3-O-(2,6-di-O-trans-p-coumaroyl)-beta-D-glucopyranoside (16), caffeic acid (17), 21beta-angeloyloxy-3beta-[beta-D-glucopyranosyl-(1-->2)]-[beta-d-xylopyranosyl-(1-->3)]-beta-D-glucuronopyranosyloxyolean-12-ene-15alpha,16alpha,22alpha,28-tetrol (18), and saniculasaponin III (19). This study reports the isolation of these compounds and their structural elucidation by extensive spectroscopic analyses and chemical degradation.

Ecdysteroids and a Sucrose Phenylpropanoid Ester from Froelichia floridana

Phytoecdysteroid glycosides (1-5) and a phenylpropanoid ester of sucrose (6) were isolated from the whole plant of Froelichia floridana, along with eight known compounds including three ecdysteroids (7-9), four flavonoids (10-13), and one phenolic compound (14). Structures were determined using a combination of spectroscopic techniques. Compounds 1, 2 and 6-14 were tested in vitro for their activity against human DNA topoisomerase I. Compound 13 (diosmetin) showed marginal inhibition against topoisomerase I with IC(50) of 130 microM in conjunction with low intercalation ability.

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.