29 research outputs found
Biomass and morphology of fine roots in temperate broad-leaved forests differing in tree species diversity: is there evidence of below-ground overyielding?
Biodiversity effects on ecosystem functioning in forests have only recently attracted increasing attention. The vast majority of studies in forests have focused on above-ground responses to differences in tree species diversity, while systematic analyses of the effects of biodiversity on root systems are virtually non-existent. By investigating the fine root systems in 12 temperate deciduous forest stands in Central Europe, we tested the hypotheses that (1) stand fine root biomass increases with tree diversity, and (2) âbelow-ground overyieldingâ of species-rich stands in terms of fine root biomass is the consequence of spatial niche segregation of the roots of different species. The selected stands represent a gradient in tree species diversity on similar bedrock from almost pure beech forests to medium-diverse forests built by beech, ash, and lime, and highly-diverse stands dominated by beech, ash, lime, maple, and hornbeam. We investigated fine root biomass and necromass at 24 profiles per stand and analyzed species differences in fine root morphology by microscopic analysis. Fine root biomass ranged from 440 to 480 g mâ2 in the species-poor to species-rich stands, with 63â77% being concentrated in the upper 20 cm of the soil. In contradiction to our two hypotheses, the differences in tree species diversity affected neither stand fine root biomass nor vertical root distribution patterns. Fine root morphology showed marked distinctions between species, but these root morphological differences did not lead to significant differences in fine root surface area or root tip number on a stand area basis. Moreover, differences in species composition of the stands did not alter fine root morphology of the species. We conclude that âbelow-ground overyieldingâ in terms of fine root biomass does not occur in the species-rich stands, which is most likely caused by the absence of significant spatial segregation of the root systems of these late-successional species
Effects of two contrasting canopy manipulations on growth and water use of London plane (Platanus x acerifolia) trees
Aims: Two contrasting canopy manipulations were compared to unpruned controls on London plane trees, to determine the effects on canopy regrowth, soil and leaf water relations.
Methods: âCanopy reductionâ, was achieved by removing the outer 30 % length of all major branches and âcanopy thinningâ, by removing 30 % of lateral branches arising from major branches.
Results: Total canopy leaf areas recovered within two and three years of pruning for the canopy-thinned and reduced trees respectively. Canopy reduction increased mean leaf size, nitrogen concentration, canopy leaf area density and conserved soil moisture for up to 3 years, whereas canopy thinning had no effects. Another experiment compared more severe canopy reduction to unpruned trees. This produced a similar growth response to the previous experiment, but soil moisture was conserved nearer to the trunk. Analysis of 13C and 18O signals along with leaf water relations and soil moisture data suggested that lower boundary layer conductance within the canopy-reduced trees restricted tree water use, whereas for the canopy-thinned trees the opposite occurred.
Conclusions: Only canopy reduction conserved soil moisture and this was due to a combination of reduced total canopy leaf area and structural changes in canopy architecture
The Continuous Incorporation of Carbon into Existing Sassafras albidum Fine Roots and Its Implications for Estimating Root Turnover
Fine root traits in adult trees of evergreen and deciduous taxa from low and high elevation in the Alps
Variation in the morphology of fine roots in Cryptomeria japonica determined by branch order-based classification
The effects of temperature and drought on autumnal senescence and leaf shed in apple under warm, east mediterranean climate
Root plasticity maintains growth of temperate grassland species under pulsed water supply
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