Population ecology and management of the invasive plant, Lespedeza cuneata. D. Jason Emry

ISBN: 9780549569329


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135 pages


Population ecology and management of the invasive plant, Lespedeza cuneata.  by  D. Jason Emry

Population ecology and management of the invasive plant, Lespedeza cuneata. by D. Jason Emry
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, talking book, mp3, RTF | 135 pages | ISBN: 9780549569329 | 7.70 Mb

Despite reports that sericea lespedeza (Lespedeza cuneata (Dumont) G. Don., Fabaceae) is one of the worst invasive plants across much of the North American Great Plains, most of the detailed work documenting its biology and ecology was performed in the context of its uses in soil stabilization and reclamation or as a forage crop. In this dissertation, I used a field experiment and spatially explicit computer simulations to investigate the persistence and spread of an invasion of L.

cuneata in a native prairie site.-Chapter 1 describes an experiment in which I tested how the timing of mowing and the local application of herbicide influence the abundance and occupancy of L. cuneata. By collecting data on adult individuals and stems I found that herbicide limited increases in the abundance, average size, and spread of adult plants- but the timing of mowing had little impact on adults.

Large increases in juvenile occupancy and abundance in plots with high seed production (late-mown and unsprayed) suggested that, without soil disturbance, recruitment is affected more by new seed input than a soil seed bank. The effectiveness of treatments varied among years for both adults and juveniles. This result, particularly in light of the large increases in plots where L. cuneata was not sprayed, indicates that continual management efforts over multiple years are necessary to control established infestations.-Collecting data on stem density or the spatial position of plants requires more effort than collecting presence/absence data without any reference to space.

In Chapter 2, I used the spatially explicit data set from the field experiment and statistical models to address how different levels of sampling effort by land managers can influence predictions of spread under managed and unmanaged conditions. I found that density-based models that included simple spatial information provided more reliable estimates of colonization, persistence, and changes in abundance within local infestations. Under managed conditions, the effect of herbicide was so strong that it essentially negated the predictive value of model variables.-Models which simulate the spread of weeds in fields and their response to control treatments frequently assume that all plants in the population are found and treated.

In Chapter 3, I developed a simulation model to address the importance of three factors that could influence the spread of L. cuneata: (1) the spatial distribution of the population, (2) treatment intensity, and (3) the detectability of local infestations. The model indicated that imperfect detectability can reduce the overall effectiveness of control when treatment intensity is low.

The negative impact of imperfect detectability can be outstripped however, when intensive treatment leads to large declines in weed spread and abundance.-By integrating the results of a field experiment, statistical models, and simulation models, this research provides a comprehensive examination of the population ecology of invasion of L. cuneata in native tall grass prairies. It also suggests approaches for monitoring and management.

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