Fertilization Effects on Interactions between above- and Belowground Competition in an Old Field

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Recent theoretical and experimental studies have addressed whether the relative importance of aboveground and belowground competition changes along gradients of biomass productivity. Results have been contradictory, with some researchers finding a decrease in the importance of belowground competition and an increase in aboveground competition with increased productivity, and others finding either no relationship, or a positive correlation between the various factors. Belowground competitive intensity (BCI), resulting from root interactions, and total competitive intensity (TCI), resulting from both root and shoot interactions, have usually been measured as the proportional growth reduction due to competition (relative to growth without competition). Instead of direct measurement, aboveground competitive intensity (ACI) has been estimated by assuming that aboveground competition and belowground competition do not interact to affect plant growth, and therefore ACI + BCI = TCI. In this study, Abutilon theophrasti was used as a focal species to determine whether an interaction between the two competitive forms could exist. Target plants were grown with varying degrees of interaction with the roots of neighboring plants, through the use of modified root exclusion tubes, and by tying back the aboveground neighboring vegetation. In total, 16 combinations of varying intensities of aboveground and belowground interactions with neighbors were created at each of two fertilization levels. The strength of belowground competition decreased with fertilization, while neither aboveground competition nor total competition (occurring both above-and belowground simultaneously) varied among fertilization treatments. Not only was there evidence for an interaction between aboveand belowground competition, the form of interaction varied with productivity, switching from no interaction in the unfertilized block to a positive interaction in the fertilized block. With fertilization, belowground competition decreased a plant's ability to compete in asymmetric competition for light. These results contrast with existing models of the role of competition in plant communities, and a new model is presented. In order to understand the role of aboveground and belowground competition in plant communities, the potential for interactions between the two competitive forms must be considered in future studies. should instead shift from occurring primarily belowground to primarily aboveground (Tilman 1988, Wilson and Tilman 1991, 1993, 1995). Resolution of this issue requires the experimental separation...

Eco-hydrological impacts of Eucalyptus in the semi humid Ethiopian Highlands: the Lake Tana Plain

“…6) in accordance with findings of Agele et al (2007) and Kotowski et al (2000). The competition of Eucalyptus for nutrients can be overcome somewhat by adding fertilizers (Ayoola and Makinde, 2008;Cahill, 1999).…”

Determination of Effective Spatial Arrangement for Intercropping of Maize (Zea mays L.) and Potato (Solanum tuberosum L.) Using Competition Indices Ethiopia

“…Other results for Cahill et al [10] showed that root competition in the first stages of plant's life cycle leads into weak growth and decreases plant light interception. Another study conducted Ebwongu et al [11] results showed that productivity of the potato crop decreased when intercropped with maize compared to the plantation of sole potato, while; it increased by increasing plant density during intercropping treatments.…”

Interactions of plant species mediated plant competition for inorganic nitrogen with soil microorganisms in an alpine meadow

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