E environment. In forest ecosystems, tree seedlings allow their roots to proliferate to acquire nutrients and water; seedlings typically contend with heterogeneous resources and competing neighbors, which both exert important effects on root foraging behavior [10,11]. Previous forestry studies on root competition have invested much effort toward investigating the effects of interspecific competition [3,12?4]; the importance of intraspecies interaction has received much less attention. Due to similarity in ecological characters, plants in intraspecies competition cannot avoid or alleviate adverse competition effect via niche complementarity. Accordingly, the thing missing from many studies of root competition is a detailed understanding of intraspecies interactions.Assessing Root Foraging Feature by ArchitectureFigure 1. Schematic of the experimental treatments. The four treatments consisted of fertilization in the vegetated half (FV), the nonvegetated half (FNV), and both compartments (F), as well as no fertilization (NF). doi:10.1371/journal.pone.Title Loaded From File 0065650.gRoot architecture is defined as the spatial configuration of the root system, which has a key role in belowground resource acquisition [15,16]. Fitter et al. [17,18], as well as Farley and Fitter [19], demonstrated that a herringbone topology may be best for locating nutrient-rich patches in the soil, but a less herringbone topology is more suitable for exploiting these resources. Grime and Mackey reported that phenotypic plasticity for specific root architectural traits was significant in resource capture, as a result of nutrient heterogeneity in space and time [20]. In addition, root architecture was shown to be a primary factor affecting the degree of competition among roots of the same plant and/or neighboring plants [21?3]. More recently, Nord et al. found that the presence of a neighbor could lead to alterations in the root architecture, thereby keeping the root biomass stable [24]. To date, accumulating evidence indicated that root architecture was more sensitive to environmental stimuli than root biomass [24,25]. However, most studies addressing plant foraging Title Loaded From File ability have focused on root biomass but overlooked root architecture, which can contribute to a better understanding of the interactions between plant root systems and their environment. Plant root foraging ability is closely related to root architecture, but none of the previous studies thus far have linked these aforementioned aspects of plant root systems. This oversight was probably because root functions, such as resource uptake and transport, were difficult to directly measure [26]. Previous studies mainly utilized lateral root attributes to assess the response of the root architecture to environmental stimuli; these attributes included descriptions of the morphological characteristics [27,28], spatial deployment pattern [29,30], and root-growth patterns [31?3]. However, all these measurements are unsuitable for precisely measuring the root foraging ability. In addition, the entire root system was traditionally divided into different parts based on size classes (e.g., 0? mm roots vs. 0? mm 23977191 roots, based on their diameter), which did not provide information on the root system structure, function, and response to altered environmental conditions. This limitation is particularly true in woody plants because fine roots are complex branching structures composed of numerous individual root segments, which differ in their.E environment. In forest ecosystems, tree seedlings allow their roots to proliferate to acquire nutrients and water; seedlings typically contend with heterogeneous resources and competing neighbors, which both exert important effects on root foraging behavior [10,11]. Previous forestry studies on root competition have invested much effort toward investigating the effects of interspecific competition [3,12?4]; the importance of intraspecies interaction has received much less attention. Due to similarity in ecological characters, plants in intraspecies competition cannot avoid or alleviate adverse competition effect via niche complementarity. Accordingly, the thing missing from many studies of root competition is a detailed understanding of intraspecies interactions.Assessing Root Foraging Feature by ArchitectureFigure 1. Schematic of the experimental treatments. The four treatments consisted of fertilization in the vegetated half (FV), the nonvegetated half (FNV), and both compartments (F), as well as no fertilization (NF). doi:10.1371/journal.pone.0065650.gRoot architecture is defined as the spatial configuration of the root system, which has a key role in belowground resource acquisition [15,16]. Fitter et al. [17,18], as well as Farley and Fitter [19], demonstrated that a herringbone topology may be best for locating nutrient-rich patches in the soil, but a less herringbone topology is more suitable for exploiting these resources. Grime and Mackey reported that phenotypic plasticity for specific root architectural traits was significant in resource capture, as a result of nutrient heterogeneity in space and time [20]. In addition, root architecture was shown to be a primary factor affecting the degree of competition among roots of the same plant and/or neighboring plants [21?3]. More recently, Nord et al. found that the presence of a neighbor could lead to alterations in the root architecture, thereby keeping the root biomass stable [24]. To date, accumulating evidence indicated that root architecture was more sensitive to environmental stimuli than root biomass [24,25]. However, most studies addressing plant foraging ability have focused on root biomass but overlooked root architecture, which can contribute to a better understanding of the interactions between plant root systems and their environment. Plant root foraging ability is closely related to root architecture, but none of the previous studies thus far have linked these aforementioned aspects of plant root systems. This oversight was probably because root functions, such as resource uptake and transport, were difficult to directly measure [26]. Previous studies mainly utilized lateral root attributes to assess the response of the root architecture to environmental stimuli; these attributes included descriptions of the morphological characteristics [27,28], spatial deployment pattern [29,30], and root-growth patterns [31?3]. However, all these measurements are unsuitable for precisely measuring the root foraging ability. In addition, the entire root system was traditionally divided into different parts based on size classes (e.g., 0? mm roots vs. 0? mm 23977191 roots, based on their diameter), which did not provide information on the root system structure, function, and response to altered environmental conditions. This limitation is particularly true in woody plants because fine roots are complex branching structures composed of numerous individual root segments, which differ in their.
