Chinese Tallow Invasions into the Endangered Coastal Prairie: Causes and ConsequencesEPA Grant Number: R828903
Title: Chinese Tallow Invasions into the Endangered Coastal Prairie: Causes and Consequences
Investigators: Siemann, Evan , Grace, James , Rogers, William
Institution: Rice University
EPA Project Officer: Hiscock, Michael
Project Period: June 1, 2001 through May 31, 2004 (Extended to May 31, 2005)
Project Amount: $381,687
RFA: Exploratory Research to Anticipate Future Environmental Issues (2000) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Ecosystems
Chinese Tallow Tree (Sapium sebiferum) is a major invader in the southeast United States which aggressively displaces native plants. Our research will focus on the mechanisms that allow Tallow Tree to establish in endangered coastal prairies and transform them into biotically depauperate forests.
The main objective of this work is to understand how abiotic conditions interact with biotic factors to influence the likelihood, severity and impacts of Chinese Tallow Tree invasions into coastal prairie. Specifically, we will address the following questions: 1) How do fire (annual or periodic), soil fertility and herbivores interact to influence Tallow Tree invasion? 2) How do flooding, soil fertility and herbivores interact to influence Tallow Tree invasion? 3) How important is local recruitment limitation vs. local conditions in determining the likelihood and severity of Tallow Tree invasion?
We will use four experiments in East Texas coastal prairie to address these questions. One pair of experiments will involve fire, fertilizations, Tallow Tree seed and seedling additions, manipulations of insect and vertebrate herbivores and measurements of Tallow Tree success and impacts. The other pair of experiments will involve flooding, fertilizations, Tallow Tree seed and seedling additions, manipulations of insect herbivores and measurements of Tallow Tree success and impacts. Because fire and flood mortality are strongly size dependent (with small saplings almost always killed and larger ones rarely affected), herbivores or fertility may interact with fire and flooding by changing Tallow Tree growth rates. Some of the data we will collect includes Tallow Tree seed germination and survival rates, Tallow Tree seedling survival and growth rates, diversity and composition of the prairie plant community, soil carbon and nitrogen and aboveground carbon and nitrogen.
The experiments will provide results that address both basic and applied questions. Understanding the mechanisms of invasion is critically important to both society, with increasing economic and political impacts of alien species, and ecology because invasion plays a key role in community assembly and greatly influences ecosystem function. In addition to advancing basic scientific understanding, our research will inform management of Tallow Tree by providing information on its growth and survival in a number of environmental conditions at different life stages. Because Tallow Tree invasion shares many features with other alien plant invasions, our results should have broad applicability.
Coastal prairie kept free of Sapium by annual mowing (left). An adjacent area is a Sapium forest 25 years after mowing was stopped (right).