Life Sciences Commons^™

Effects Of Experimental Nitrogen Additions On Plant Diversity In Tropical Forests Of Contrasting Disturbance Regimes In Southern China, Xiankai Lu, Jiangming Mo, Frank S. Gilliam, Guirui Yu, Wei Zhang, Yunting Fang, Juan Huang

Biological Sciences Faculty Research

Responses of understory plant diversity to nitrogen (N) additions were investigated in reforested forests of contrasting disturbance regimes in southern China from 2003 to 2008: disturbed forest (withharvesting of understory vegetation and litter) and rehabilitated forest (without harvesting). Experimental additions of N were administered as the following treatments: Control, 50 kg N ha1yr1, and 100kg N ha1yr1. Nitrogen additions did not significantly affect understory plant richness, density,and cover in the disturbed forest. Similarly, no significant response was found for canopy closure in thisforest. In the rehabilitated forest, species richness and density showed no significant response to Nadditions; however, understory cover …

Eastern Temperate Forests, Frank S. Gilliam, Christine L. Goodale, Linda H. Pardo, Linda H. Geiser, Erik A. Lilleskov

Biological Sciences Faculty Research

Human activity in the last century has led to a substantial increase in nitrogen (N) emissions and deposition. This N deposition has reached a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. One approach for quantifying the level of pollution that would be harmful to ecosystems is the critical loads approach. The critical load is dei ned as the level of a pollutant below which no detrimental ecological effect occurs over the long term according to present knowledge.

The objective of this project was to synthesize …

Effects Of Nitrogen On Temporal And Spatial Patterns Of Nitrate In Streams And Soil Solution Of A Central Hardwood Forest, Frank S. Gilliam, Mary Beth Adams

Biological Sciences Faculty Research

This study examined changes in stream and soil water NO3−and their relationship to temporal and spatial patterns of NO3−in soil solution of watersheds at the Fernow Experimental Forest, West Virginia. Following tenfold increases in stream NO3−concentrations over a 13-year period (1969–1981) on untreated WS4, concentrations have declined through 2006. Followingfourfold increases in stream NO3−on treatment WS3 from pretreatment levels to a 1998 maximum, concentrations have declinedthrough 2006, despite additions of N. Concentrations of soil water NO3−were consistently lower for WS4 compared to WS3.Data for soil water NO3−on WS3 versus WS4 followed patterns of net mineralization and nitrification for these watersheds.Nitrogen …

Nitrogen Addition Shapes Soil Phosphorus Availability In Two Reforested Tropical Forests In Southern China, Xiankai Lu, Jiangming Mo, Frank S. Gilliam, Hua Fang, Feifei Zhu, Yunting Fang, Wei Zhang, Juan Huang

Biological Sciences Faculty Research

Scant information is available on how soil phosphorus (P) availability responds to atmospheric nitrogen (N) deposition, especially in the tropical zones. This study examined the effect of N addition on soil P availability, and compared this effect between forest sites of contrasting land-use history. Effects of N addition on soil properties, litterfall production, P release from decomposing litter, and soil P availability were studied in a disturbed (reforested pine forest with previous understory vegetation and litter harvesting) and a rehabilitated (reforested mixed pine/broadleaf forest with no understory vegetation and litter harvesting) tropical forest in southern China. Experimental N-treatments (above ambient) …