scholarly journals N : P stoichiometry and habitat effects on Mediterranean savanna seasonal root dynamics

2019 ◽  
Vol 16 (9) ◽  
pp. 1883-1901 ◽  
Author(s):  
Richard K. F. Nair ◽  
Kendalynn A. Morris ◽  
Martin Hertel ◽  
Yunpeng Luo ◽  
Gerardo Moreno ◽  
...  
Keyword(s):  
Root Biomass ◽  
Root Length Density ◽  
Root Traits ◽  
Early Spring ◽  
Tree Canopy ◽  
Nutrient Ratios ◽  
Individual Plant ◽  
Root Dynamics ◽  
Water Shortages ◽  
Ingrowth Cores

Abstract. Mediterranean grasslands are highly seasonal and co-limited by water and nutrients. In such systems, little is known about root dynamics which may depend on individual plant properties and environment as well as seasonal water shortages and site fertility. Patterns of root biomass and activity are affected by the presence of scattered trees, grazing, site management, and chronic nitrogen deposition, all of which can affect nutrient ratios and potentially cause development of nitrogen : phosphorus (N : P) imbalances in ecosystem stoichiometry. In this study we combined observations from minirhizotrons with root measurements from direct soil cores and ingrowth cores, along with measures of above-ground biomass to investigate seasonal root dynamics and root : shoot ratios in a Mediterranean tree–grass “savanna”. We investigated responses to soil fertility, using nutrient manipulation (N∕NP addition) and spatial microhabitat treatments between open-pasture and microhabitats under the tree canopy. Root dynamics over time were also compared with indices of above-ground growth drawn from proximal remote sensing. Results show distinct differences in root dynamics and biomass between treatments and microhabitats. Root biomass was higher with N additions, but did not differ from the control with NP additions in early spring. By the end of the growing season root biomass had increased with NP in open pastures but not higher than N added alone. In contrast, root length density (RLD) in pastures responded stronger to the NP than N-only addition, while beneath trees root biomass tended to be higher with only N. Even though root biomass increased, the root : shoot ratio decreased under nutrient treatments. Timing of root and shoot growth was reasonably well paired, although in autumn root growth appeared to be substantially slower than “regreening” of the system. We interpret these differences as a shift in community structure and/or root traits under changing stoichiometry induced by the fertilization. We also consider seasonal (phenology) differences in the strength and direction of effects observed.

scholarly journals Combined effects of altered N:P stoichometry and trees on Mediterranean savanna root dynamics

2018 ◽  
Author(s):  
Richard Nair ◽  
Martin Hertel ◽  
Yunpeng Luo ◽  
Gerardo Moreno ◽  
Markus Reichstein ◽  
...  
Keyword(s):  
Community Structure ◽  
Root Biomass ◽  
Vegetation Index ◽  
Near Infrared ◽  
Root Length Density ◽  
Root Traits ◽  
Tree Canopy ◽  
Root Dynamics ◽  
Ingrowth Cores ◽  
Normalised Difference Vegetation Index

Abstract. Mediterranean grasslands are highly seasonal and co-limited by water and nutrients. In such systems little is known about root dynamics which may depend on plant habit and environment as well seasonal water shortages and site fertility. This latter factor is affected by the presence of scattered trees and site management including grazing, as well as chronic nitrogen deposition, which may lead to N:P imbalance. In this study we combined observations from minirhizotrons collected in a Mediterranean tree-grass ecosystem (Spanish Dehesa), with root measurements from direct soil cores and ingrowth cores, and above-ground biomass to investigate seasonal root dynamics and root:shoot ratios. We investigated responses to soil fertility, using a nutrient manipulation (N / NP additions) and microhabitats effects between open pasture and under tree canopy locations. Root dynamics over time were compared with indices of above-ground growth drawn from proximal remote sensing (Normalised Difference Vegetation Index and Green Chromatic Coordinate derived from near-infrared enabled digital repeat photography). Results show distinct differences in root dynamics and biomass between treatments and microhabitats. Root biomass was higher with N additions, but not with NP additions in early spring, but by the end of the growing season root biomass had increased with NP in open pastures but not higher than N alone. In contrast, root length density (RLD) in pastures responded stronger to the NP than N only treatment, while beneath trees RLD tended to be higher with only N. Even though root biomass increased, root:shoot ratio decreased under nutrient treatments.We interpret these differences as a shift in community structure and/or root traits under changing stoichiometry and altered nutrient limitations. The timing of maximum root cover, as assessed by the minirhizotrons, did not match with above-ground phenology indicators at the site as root growth was low during autumn despite the greening up of the ecosystem. In other periods, roots responded quickly to rain events on the scale of days, matching changes in above-ground indices. Our results highlight the need for high resolution sampling to increase understanding of root dynamics in such systems, linkage with shifts in community structure and traits, and targeting of appropriate periods of the year for in-depth campaigns.

Root dynamics of southern Ohio oak-hickory forests: influences of prescribed fire and landscape position

2001 ◽  
Vol 31 (4) ◽  
pp. 644-653 ◽  
Author(s):  
William J Dress ◽  
Ralph EJ Boerner
Keyword(s):  
Soil Temperature ◽  
Root Biomass ◽  
Biomass Accumulation ◽  
Growing Season ◽  
Sampling Interval ◽  
Fine Root Biomass ◽  
Landscape Position ◽  
Root Production ◽  
Root Dynamics ◽  
Ingrowth Cores

This study compares standing root biomass from sequential root cores and new root production in ingrowth cores in three watersheds: an unburned control watershed, a watershed burned once in 1996, and a watershed burned for three consecutive years (1996–1998). Based on root cores collected on six sampling dates from April through November 1998, maximum standing live root biomass occurred approximately 1 month earlier in the growing season in the site burned three times, presumably because of increased soil temperature after the fires. Standing live fine root biomass was significantly lower in the site burned three times in three of the six sampling dates (April, June, and November) and when averaged over the whole growing season. Most of this effect was due to lesser root biomass in the most mesic landscape position. New root production was measured during three ingrowth core intervals: April to August 1998, August to November 1998, and August 1998 to November 1999. Net production was significantly greater in sample plots in xeric landscape positions during each sampling interval. Overall, differences in standing root biomass were inversely correlated with fire-induced changes in N mineralization and increased soil temperature after burning shifted the phenology of root biomass accumulation earlier in the growing season.

scholarly journals Drought Avoidance Traits in a Collection of Zoysiagrasses

HortScience ◽  
2018 ◽  
Vol 53 (11) ◽  
pp. 1579-1585 ◽  
Author(s):  
David Jespersen ◽  
Brian Schwartz
Keyword(s):  
Root Length ◽  
Root Biomass ◽  
Root Length Density ◽  
Warm Season ◽  
Specific Root Length ◽  
Root Traits ◽  
Plant Performance ◽  
Factors Affecting ◽  
Drought Avoidance ◽  
Turfgrass Quality

Drought avoidance is dictated by a collection of traits used to maintain tissue hydration levels and turgidity during water-limited conditions. These traits include deeper and more extensive rooting and the closure of stomata to limit the transpiration of water from leaves. Zoysiagrasses are a group of warm-season turfgrasses, including Zoysia japonica and Zoysia matrella, that are valued for their turfgrass quality; however, they are susceptible to drought relative to other warm-season turfgrass species. The objectives of the study were to determine 1) differences in drought avoidance among a collection of zoysiagrasses and 2) which drought avoidance traits contributed to these differences. Fifteen zoysiagrass genotypes were exposed to either drought or control conditions in a greenhouse environment. Overall performance was assessed by evaluating turfgrass quality and percentage green cover. Drought avoidance was estimated by measuring leaf hydration levels and drought avoidance traits [including stomatal conductance (gS)]; root traits such as total root biomass, specific root length (SRL), and root length density (RLD) were measured. Compared with commercial cultivars Meyer, Palisades, or Zeon, some experimental genotypes maintained greater turfgrass quality during drought, with experimental genotype ‘09-TZ-54-9’ having a quality rating of 7.8 after 20 days of drought compared with 5.3 in ‘Zeon’, 5.2 in ‘Meyer’, and 5.0 in ‘Palisades’. A range of belowground traits such as root biomass was also found to be associated with drought avoidance, with experimental ‘09-TZ-53-20’ having 1.03 total grams, and 2.39 total grams in ‘10-TZ-1254’, compared with 1.14, 1.66, and 3.44 total grams in ‘Meyer’, ‘Zeon’, and ‘Palisades’, respectively. Significant differences in drought avoidance were found among the 15 genotypes, with both belowground rooting traits and aboveground factors affecting transpiration influencing plant performance.

Effects of harvesting on fine root biomass and decomposition in an Engelmann spruce – subalpine fir forest

2003 ◽  
Vol 33 (5) ◽  
pp. 847-853 ◽  
Author(s):  
Sylvia E Welke ◽  
Graeme D Hope ◽  
Gary A Hunt
Keyword(s):  
Root Biomass ◽  
Fine Root ◽  
Timber Harvesting ◽  
High Elevation ◽  
Fine Root Biomass ◽  
Nutrient Concentrations ◽  
Root Dynamics ◽  
Subalpine Fir ◽  
Root Longevity ◽  
Engelmann Spruce

The effect of timber harvesting on the biomass, nutrient standing crop, and decomposition of fine roots (<2 mm) was studied in a high elevation, Engelmann spruce (Picea engelmannii Parry ex Engelm.) – subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forest. Root dynamics were compared in openings of different sizes. The sequential core method was used to collect fine root samples over 4 years. Differences in fine root biomass between opening sizes were most significant for the active fine root portion and were most pronounced in the fall compared with the spring. Active fine root biomass was significantly lower in the 10-ha clearcuts (164 kg/ha) compared with control plots (275 kg/ha). Furthermore, active fine root biomass was often lower in the 1.0-ha opening than in the 0.1-ha and control plots. A similar trend was established for inactive fine root biomass, although this was not consistent over sampling years. Nutrient concentrations of K, but no other elements, were higher in control plots. Nutrient standing crops, however, followed trends observed in fine root biomass. In the 10-ha clearcuts, the largest changes in fine root biomass occurred at the edge of the opening. The findings suggest that small (<10 ha) cutblocks may maintain greater fine root longevity.

scholarly journals Root Phenotyping for Drought Tolerance: A Review

Agronomy ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 241 ◽  
Author(s):  
Allah Wasaya ◽  
Xiying Zhang ◽  
Qin Fang ◽  
Zongzheng Yan
Keyword(s):  
Drought Tolerance ◽  
Crop Yield ◽  
Root Length ◽  
Root Length Density ◽  
Canopy Temperature ◽  
Specific Root Length ◽  
Root Traits ◽  
Three Dimensions ◽  
Invasive Approach ◽  
Root Phenotyping

Plant roots play a significant role in plant growth by exploiting soil resources via the uptake of water and nutrients. Root traits such as fine root diameter, specific root length, specific root area, root angle, and root length density are considered useful traits for improving plant productivity under drought conditions. Therefore, understanding interactions between roots and their surrounding soil environment is important, which can be improved through root phenotyping. With the advancement in technologies, many tools have been developed for root phenotyping. Canopy temperature depression (CTD) has been considered a good technique for field phenotyping of crops under drought and is used to estimate crop yield as well as root traits in relation to drought tolerance. Both laboratory and field-based methods for phenotyping root traits have been developed including soil sampling, mini-rhizotron, rhizotrons, thermography and non-soil techniques. Recently, a non-invasive approach of X-ray computed tomography (CT) has provided a break-through to study the root architecture in three dimensions (3-D). This review summarizes methods for root phenotyping. On the basis of this review, it can be concluded that root traits are useful characters to be included in future breeding programs and for selecting better cultivars to increase crop yield under water-limited environments.

scholarly journals Effects of warming and fertilization interacting with intraspecific competition on fine root traits of Picea asperata

2020 ◽  
Author(s):  
Dan-Dan Li ◽  
Hong-Wei Nan ◽  
Chun-Zhang Zhao ◽  
Chun-Ying Yin ◽  
Qing Liu
Keyword(s):  
Root Growth ◽  
Climate Warming ◽  
Tree Growth ◽  
Root Length ◽  
Root Biomass ◽  
Fine Root ◽  
Root Traits ◽  
Root Surface ◽  
Root Branching ◽  
Picea Asperata

Abstract Aims Competition, temperature, and nutrient are the most important determinants of tree growth in the cold climate on the eastern Tibetan Plateau. Although many studies have reported their individual effects on tree growth, little is known about how the interactions of competition with fertilization and temperature affect root growth. We aim to test whether climate warming and fertilization promote competition and to explore the functional strategies of Picea asperata in response to the interactions of these factors. Methods We conducted a paired experiment including competition and non-competition treatments under elevated temperature (ET) and fertilization. We measured root traits, including the root tip number over the root surface (RTRS), the root branching events over the root surface (RBRS), the specific root length (SRL), the specific root area (SRA), the total fine root length and area (RL and RA), the root tips (RT) and root branching events (RB). These root traits are considered to be indicators of plant resource uptake capacity and root growth. The root biomass and the nutrient concentrations in the roots were also determined. Important Findings The results indicated that ET, fertilization and competition individually enhanced the nitrogen (N) and potassium (K) concentrations in fine roots, but they did not affect fine root biomass or root traits, including RL, RT, RA and RB. However, both temperature and fertilization, as well as their interaction, interacting with competition increased RL, RA, RT, RB, and nutrient uptake. In addition, the SRL, SRA, RTRS and RBRS decreased under fertilization, the interaction between temperature and competition decreased SRL and SRA, while the other parameters were not affected by temperature or competition. These results indicate that Picea asperata maintains a conservative nutrient strategy in response to competition, climate warming, fertilization, and their interactions. Our results improve our understanding of the physiological and ecological adaptability of trees to global change.

scholarly journals Relationships between Root Traits and Soil Physical Properties after Field Traffic from the Perspective of Soil Compaction Mitigation

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1697
Author(s):  
Matthieu Forster ◽  
Carolina Ugarte ◽  
Mathieu Lamandé ◽  
Michel-Pierre Faucon
Keyword(s):  
Physical Properties ◽  
Bulk Density ◽  
Soil Compaction ◽  
Root Length Density ◽  
Root Traits ◽  
Air Permeability ◽  
Soil Physical Properties ◽  
Soil Reinforcement ◽  
Soil Functions ◽  
Crop Species

Compaction due to traffic is a major threat to soil functions and ecosystem services as it decreases both soil pore volume and continuity. The effects of roots on soil structure have previously been investigated as a solution to alleviate compaction. Roots have been identified as a major actor in soil reinforcement and aggregation through the enhancement of soil microbial activity. However, we still know little about the root’s potential to protect soil from compaction during traffic. The objective of this study was to investigate the relationships between root traits and soil physical properties directly after traffic. Twelve crop species with contrasting root traits were grown as monocultures and trafficked with a tractor pulling a trailer. Root traits, soil bulk density, water content and specific air permeability were measured after traffic. The results showed a positive correlation between the specific air permeability and root length density and a negative correlation was found between bulk density and the root carbon/nitrogen ratio. This study provides first insight into how root traits could help reduce the consequences of soil compaction on soil functions. Further studies are needed to identify the most efficient plant species for mitigation of soil compaction during traffic in the field.

Fine root growth dynamics in teak (Tectonagrandis Linn. F.)

1986 ◽  
Vol 16 (6) ◽  
pp. 1360-1364 ◽  
Author(s):  
S. K. Srivastava ◽  
K. P. Singh ◽  
R. S. Upadhyay
Keyword(s):  
Root Growth ◽  
Root Biomass ◽  
Fine Root ◽  
Growth Dynamics ◽  
Temporal Variations ◽  
Fine Root Biomass ◽  
Tropical Region ◽  
Root Bark ◽  
Root Mass ◽  
Root Dynamics

Temporal variations in the spatial distribution of fine root mass were studied in a 19-year-old teak plantation in a dry tropical region. The soil block method was used to investigate fine root dynamics. Quantification of fine root mass was achieved in terms of live teak roots (separated by diameter), dead teak roots, teak root bark, herb roots, and fragmented soil organic matter. The annual mean fine root biomass was 5420 kg•ha−1 and the net production was 5460 kg•ha−1•year−1. The bulk of the root mass was distributed at a depth of 10–30 cm and roots ≤2 mm constituted one-half or more of the total root biomass. Maximum live root growth occurred during the rainy season. All root sizes showed similar bimodal seasonal patterns, but the maximum:minimum ratio generally declined with greater root size.

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