Allometry of fine roots in forest ecosystems (original) (raw)
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Oecologia, 2009
Biodiversity eVects 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 diVerences in tree species diversity, while systematic analyses of the eVects of biodiversity on root systems are virtually non-existent. By investigating the Wne root systems in 12 temperate deciduous forest stands in Central Europe, we tested the hypotheses that (1) stand Wne root biomass increases with tree diversity, and (2) 'below-ground overyielding' of species-rich stands in terms of Wne root biomass is the consequence of spatial niche segregation of the roots of diVerent species. The selected stands represent a gradient in tree species diversity on similar bedrock from almost pure beech forests to mediumdiverse forests built by beech, ash, and lime, and highlydiverse stands dominated by beech, ash, lime, maple, and hornbeam. We investigated Wne root biomass and necromass at 24 proWles per stand and analyzed species diVerences in Wne root morphology by microscopic analysis. Fine root biomass ranged from 440 to 480 g m ยก2 in the species-poor to species-rich stands, with 63-77% being concentrated in the upper 20 cm of the soil. In contradiction to our two hypotheses, the diVerences in tree species diversity aVected neither stand Wne root biomass nor vertical root distribution patterns. Fine root morphology showed marked distinctions between species, but these root morphological diVerences did not lead to signiWcant diVerences in Wne root surface area or root tip number on a stand area basis. Moreover, diVerences in species composition of the stands did not alter Wne root morphology of the species. We conclude that 'below-ground overyielding' in terms of Wne root biomass does not occur in the species-rich stands, which is most likely caused by the absence of signiWcant spatial segregation of the root systems of these late-successional species.
Fine Root Architecture of Nine North American Trees
Ecological Monographs, 2002
The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in diameter. Because of the size class approach, the position of an individual root on the complex lateral branching system has often been ignored, and relationships between the form of the branching root system and its function are poorly understood.
PloS one, 2017
The potential benefits of planting trees have generated significant interest with respect to sequestering carbon and restoring other forest based ecosystem services. Reliable estimates of carbon stocks are pivotal for understanding the global carbon balance and for promoting initiatives to mitigate CO2 emissions through forest management. There are numerous studies employing allometric regression models that convert inventory into aboveground biomass (AGB) and carbon (C). Yet the majority of allometric regression models do not consider the root system nor do these equations provide detail on the architecture and shape of different species. The root system is a vital piece toward understanding the hidden form and function roots play in carbon accumulation, nutrient and plant water uptake, and groundwater infiltration. Work that estimates C in forests as well as models that are used to better understand the hydrologic function of trees need better characterization of tree roots. We ha...
2001
We compared the root systems of seven halophytic species that occur at different elevations on a salt marsh, in order to (i) test the hypothesis that variations in root system architecture reflect adaptation to inundation frequency or nitrogen limitation, and (ii) verify the theoretically predicted relationships between root diameter, link magnitude and root topology. Diameters and lengths of individual laterals were determined along root axes, and branching patterns were quantified by calculating a topological index (TI). 2. Chenopodiaceae (annual dicots) showed that with increasing elevation, the branch density and length of individual first-order laterals tended to increase, so that the relative length of the main axes decreased. Root branching of the Chenopodiaceae at lower elevations was herringbone-like, whereas species from higher elevations had smaller TIs because their branching patterns were more complex. 3. The Gramineae, too, showed a tendency to increased length of individual laterals with increasing elevation. However, TI was not related to elevation, did not indicate a herringbone structure for all species, and was within the same range of that of the Chenopodiaceae. 4. As root topology of the Chenopodiaceae is related to elevation, but that of the grasses is not, topology is not necessarily an important adaptive trait in all plant families that inhabit the salt marsh. Short first-and second-order laterals may represent a more general architectural adaptation to frequent inundation, with longer first-order laterals being favourable to competition for nutrients. 5. Diameters at the root base tended to decrease if root branching was herringbone-like (TI close to 1). Roots of first-order laterals were approximately one-third of the diameter of the main axes; second-order laterals were approximately half the diameter of the firstorder laterals. These ratios illustrate the value of using the developmental segment-ordering system in describing roots. The theoretically predicted relationship between root diameter and link magnitude was not present within individual orders of roots, whereas diameter did slowly increase with magnitude when combining different root orders. 6. In the absence of a clear relationship between root diameter and link magnitude, the predicted high carbon costs associated with herringbone root systems disappear, whereas the advantage of minimized inter-root competition remains. Consequently, herringbone root systems will be most efficient in terms of nutrients gained per carbon invested. However, dichotomous root systems offer a greater potential for exploring the soil, which contributes to the potential competitiveness of plants growing in nutrient limited habitats.
Journal of Forest Planning, 2003
Root biomass can represent a significant proportien of the total ecosystem biomass, although the difficulty in extracting the reots is eften a limit{ng factor when estimating the belowground biomass. The objective of this study is to create equations to estimate the roet variables from other tree variables for mizunara oak CQuercus crisPttla BLuME) in broad-leaved secondary forests, First, experimenta1 plots were established ln secondary forests dominated by mizunara oak and sample oak trees were felled just outside the plots. 'ihe biomass of each tree orgaii was measured and other reot variables such as root length, area and volume were also measured. Then, allocatien of the four root variables by root diameter classes was described, Regression equations by power functien were created between the four root variables and root diameter to estimate the missing root parts by root diameter classes ancl for the total reot systern. Root variables for missing parts were estimated frorn the diameter of broken root ends with regression equations between the four root variables and roet diameter for tetal root system. Finally, allometric regressions between root variables and ether tree variab]es were analyzed both by root diameter classes and for the tetal roet system. Diameter at beast height (DBH) preved to be a geod predictor of root variab]es fer different reot classes and for the tota1 root system, Diarneter at stump height (DSH) can be a usefu1 estimator if branching starts at DBH as it also shows high correlation with root systems. Kdywords: missing root, roet area, roet blomass, roet length, root volume water or nutrient uptake asOHM, 1979), Because it is difficult to classLly reots in the sarne way as to classify the abeveground parts, KARTzuMI (1974a) attempted to classify roets mechanically into six parts and BOHM (1979) reported that the common practice ef dividing tree roots into classes with different diameters is on aid to obtain information on the amount of fine, small, medium, and large reots in a reot system. Furthermore, VoGT (1989) $uggested that reot systems could be divided into several diameter classes based on their funct{on in tihe support, storage, transport and uptake J fon Rann. 9:85-95ceO03) NII-Electronic
Tamm Review: Deep fine roots in forest ecosystems: Why dig deeper?
Forest Ecology and Management, 2020
While the number of studies dealing with fine root dynamics in deep soils layers (depth > 1 m) has increased sharply recently, the phenology, the morphology, the anatomy and the role of deep fine roots are still poorly known in forest ecosystems. This review summarizes the current knowledge on fine root production, mortality and longevity in deep soil layers, mycorrhizal association with deep roots, and the role of deep fine roots on carbon, water and nutrient cycling in forest ecosystems. Plant species are known to be more deeply rooted in tropical ecosystems than in temperate and boreal ecosystems, but deep-rooted species are common in a wide range of climates. Deep fine roots are highly plastic in response to changes in environmental conditions and soil resources. Recent studies show that functional traits can be different for deep and shallow roots, with a possible functional specialization of deep fine roots to take up nutrients. With higher vessel diameter and larger tracheid, the anatomy of deep fine roots is also oriented toward water acquisition and transport by increasing the hydraulic conductivity. Deep fine roots can have a great impact on the biogeochemical cycles in many forests (in particular in tropical areas where highly weathered soils are commonly very deep), making it possible to take up water and nutrients over dry periods and contributing to store carbon in the soil. The biogeochemical models in forest ecosystems need to consider the specificity of deep root functioning to better predict carbon, water and nutrient cycling as well as net ecosystem productivity.