Roots, nutrients and their relationship to spatial patterns

Abstract

Ecosystem sustainability and resilience after a disturbance may be regulated by processes occurring at smaller spatial scales. The matrix of different spatial environments are created by (1) individual plants that accumulate higher concentrations of specific nutrients, trace elements or defensive plant secondary chemicals and thereby modify the chemistry of their ecological space and/or rates of processes, (2) the presence of structures (e.g., coarse woody debris) that may buffer some micro-environments from disturbances by functioning as a hospitable environment or as a reservoir for mycorrhizal fungi to sustain them into the next phase of stand development, and (3) chemical changes in soils during soil development which may result in distinct soil chemical environments. The response of the plants or change in the sustainability of carbon and nutrient cycles may be expressed more strongly at this smaller ecological space of an individual plant and furthermore must be frequently examined separately by the above-and belowground space of that individual. This paper will present three case studies from temperate and tropical forest ecosystems which suggest the importance of studying plant growth and nutrient and trace element cycling by stratifying sampling to encompass the mosaic patterns of existing spatial variability within the ecosystem. The examples show how individual plant species are able to create ecologically distinct spatial environments because of their distribution patterns within the landscape, how nutrient transfers in roots respond to the chemical variations in the soil, and how roots and mycorrhizal fungi are able to maintain themselves in the mosaic of coarse woody debris remaining on a site after the elimination of aboveground tree biomass.

Physical, Chemical, and Biological Properties of Soil under Decaying Wood in a Tropical Wet Forest in Puerto Rico

“…In fact, Vogt et al [14] noted that decaying logs acted as refuges for mycorrhizal fungi during dry periods or after disturbances. Therefore, it can be expected that decaying logs will contribute to keep the underlying soil moister than the soil that is covered only by the forest floor litter.…”

Spatial variability of throughfall water and chemistry and forest floor water content in a Douglas fir forest stand

“…Such studies have not been designed to sample the spatial heterogeneity that normally exists in a plot, because the questions driving the research required only a site average with preferably a small standard deviation (Vogt et al, 1995). Although this low-resolution research is necessary, it does overlook a rich abundance of information found at a higher resolution.…”

Competição por recursos do solo entre ervas daninhas e culturas

“…Para determinada distância entre raízes, o grau de competição aumenta com o aumento da difusão efetiva, resultando em maior potencial de competição por nitrato do que por K ou por íons relativamente imóveis, como P. O conceito de justaposição das zonas de depleção é menos aplicável para água e nutrientes dissolvidos, como o N, que são primariamente supridos para as raízes por fluxo de massa. Para esses nutrientes, a competição depende tanto da absorção de nutrientes quanto de água (VOGT et al, 1995).…”