**Phytosociological Surveys in Weed Science: Old Concept, New Approach**

Germani Concenço, Patrícia Menegaz de Farias, Néstor Fabio Alzate Quintero, Fábio Schreiber, Leandro Galon, Michely Tomazi, Ivana Santos Moisinho, Mariane Camponogara Coradini, William Christofari Ceolin and André Andres

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.69083

#### Abstract

Phytosociological surveys have been applied to studies on agroecosystems, especially in relation to weed populations into arable fields. These surveys can indicate trends of variation of the importance of plant populations within a crop, and whether the variations are associated to agricultural practices adopted, which can be further used to support the development of weed management programs. However, to understand the applicability of phytosociological studies for weeds, it is necessary to understand the ecological basis and determine the most appropriate methods to be used when surveying arable fields. Therefore, the aim of the present chapter is to introduce a new approach of phytosociological survey to be used as a tool for the weed science. Throughout the chapter, this new approach is presented in details covering aspects related to methods for sampling and describing weed communities. The following sequence of steps is proposed as the most suitable for a weed phytosociological and association survey: (1) overall infestation; (2) phytosociological tables/graphs; (3) intra-characterization by diversity; (4) inter-characterization and grouping by multivariate analysis; and (5) weeds association through contingency tables.

Keywords: weed species, survey, data processing, diversity, sustainability, agriculture
