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Full-Text Articles in Life Sciences
Increased Weed Diversity, Density And Above-Ground Biomass In Long-Term Organic Crop Rotations, Samuel E. Wortman, John L. Lindquist, Milton J. Haar, Charles A. Francis
Increased Weed Diversity, Density And Above-Ground Biomass In Long-Term Organic Crop Rotations, Samuel E. Wortman, John L. Lindquist, Milton J. Haar, Charles A. Francis
Department of Agronomy and Horticulture: Faculty Publications
While weed management is consistently a top priority among farmers, there is also growing concern for the conservation of biodiversity. Maintaining diverse weed communities below bioeconomic thresholds may provide ecosystem services for the crop and the surrounding ecosystem. This study was conducted to determine if weed diversity, density and biomass differ within and among organic and conventional crop rotations. In 2007 and 2008, we sampled weed communities in four long-term crop rotations near Mead, Nebraska, United States using seedbank analyses (elutriation and greenhouse emergence) and above-ground biomass sampling. Two conventional crop rotations consisted of a corn (Zea mays) …
From Energy Gradient And Natural Selection To Biodiversity And Stability Of Ecosystems, Bo Deng
From Energy Gradient And Natural Selection To Biodiversity And Stability Of Ecosystems, Bo Deng
Department of Mathematics: Faculty Publications
The purpose of this paper is to incorporate well-established ecological principles into a foodweb model consisting of four trophic levels --- abiotic resources, plants, herbivores, and carnivores. The underlining principles include Kimura's neutral theory of genetic evolution, Liebig's Law of the Minimum for plant growth, Holling's functionals for herbivore foraging and carnivore predation, the One-Life Rule for all organisms, and Lotka-Volterra's model for intraand interspecific competitions. Numerical simulations of the model led to the following statistical findings: (a) particular foodwebs can give contradicting observations on biodiversity and productivity, in particular, all known functional forms -- - positive, negative, sigmoidal, and …