Responses of Picea, Pinus and Pseudotsuga roots to heterogeneous nutrient distribution in soil

Abstract

The spatial distribution of plant-available mineral nutrients in forest soils is often highly heterogeneous. To test the hypothesis that local nutrient enrichment of soil leads to increased root proliferation in the nutrient-rich soil zone, we studied the effects of nutrient enrichment on the growth and nutrient concentrations of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) roots. Three-year-old seedlings were grown for 9 months in split-root containers filled with nutrient-poor forest mineral soil, with one side supplemented with additional mineral nutrients. Root dry weight and root length in Scots pine and Norway spruce were increased in the nutrient-supplemented soil compared with the nonsupplemented side, whereas root growth in Douglas-fir was unaffected by nutrient enrichment. Of the three species examined, Norway spruce exhibited the highest root and shoot growth and the highest nutrient demand. Specific root length (m g(-1)) and the number of root tips per unit root length were not affected by local nutrient addition in any of the species. Despite increased root growth in Norway spruce and Scots pine in nutrient-supplemented soil, their root systems contained similar nutrient concentrations on both sides of the split-root container. Thus, coniferous trees may respond to local nutrient supply by increased root proliferation, but the response varies depending on the species, and may only occur when trees are nutrient deficient. As a response to local nutrient enrichment, increases in root dry matter or root length may be better indicators of pre-existing nutrient deficiencies in conifers than increases in root nutrient concentrations.

Fine-root trait plasticity of beech (Fagus sylvatica) and spruce (Picea abies) forests on two contrasting soils

“…Similar to our results, several studies did not find plasticity in tree root morphological traits (George et al 1997;Espeleta and Donovan 2002;Leuschner et al 2004;Meier and Leuschner 2008;Hertel et al 2013), whereas others did. For example, Fahey and Hughes (1994) and Ostonen et al (2007a) found lower SRL on resource-poor compared to resource-rich soils, whereas Ostonen et al (2007b) observed the opposite response.…”

The effects of water, nutrient availability and their interaction on the growth, morphology and physiology of two poplar species

“…fertilization when compared to conditions without fertilization despite the same watering regimes. These results indicated that supply fertilization treatments could reduce the growth of roots as well as promote the growth of shoots, especially the growth of leaves, as also previously observed (George et al, 1997;Berger and Glatzel, 2001;Ewers et al, 2001;Trapeznikov et al, 2003;Coleman et al, 2004;Kaakinen et al, 2004). Moreover, nitrogen deficiency suppresses growth rate and leaf photosynthesis (Zhao et al, 2003), and N pulse increases photosynthetic rates and thus growth (Warren et al, 2004).…”

Growth, morphological traits and mycorrhizal colonization of fine roots respond differently to nitrogen addition in a slash pine plantation in subtropical China

“…Kong et al (2014) has shown that root diameter and RTD have greater Blomberg's K values (an index assessing the phylogenetical conservativeness of different biological traits) (Blomberg et al 2003) among 14 root functional traits, implying that they are phylogenetically conservative within species and poorly plastic in response to changing soil environment. SRL is considered to be indicative of interspecific differences in environmental change response (Ostonen et al 2007), but it may be less responsive to N addition within species (George et al 1997;Mei et al 2010). Our results showed that SRL did not change with N addition (data not shown).…”