Intrinsic and Extrinsic Controls of Fine Root Life Span

Chen, Han Y. H.; Brassard, Brian W.

doi:10.1080/07352689.2012.734742

Cited by 100 publications

(81 citation statements)

References 113 publications

(133 reference statements)

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“…This finding from our study was consistent with other studies of root dynamics in temperate forests, where fine root production is highest and lifespan is shortest during warmer seasons. In this case increased soil nutrient availability from higher rates of soil microbial decomposition, high photosynthetic and respiration rates can decrease tissue construction costs and increase fine root turnover, lowering fine root lifespan [37], [52], [60]. However, our results did not corroborate our hypothesis of correspondingly higher root tissue production and turnover throughout the fall as non-natives continued extended leaf production.…”

Section: Discussioncontrasting

confidence: 87%

Links between Belowground and Aboveground Resource-Related Traits Reveal Species Growth Strategies that Promote Invasive Advantages

et al. 2014

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Belowground processes are rarely considered in comparison studies of native verses invasive species. We examined relationships between belowground fine root production and lifespan, leaf phenology, and seasonal nitrogen dynamics of Lonicera japonica (non-native) versus L. sempervirens (native) and Frangula alnus (non-native) versus Rhamnus alnifolia (native), over time. First and second order fine roots were monitored from 2010 to 2012 using minirhizotron technology and rhizotron windows. 15N uptake of fine roots was measured across spring and fall seasons. Significant differences in fine root production across seasons were seen between Lonicera species, but not between Frangula and Rhamnus, with both groups having notable asynchrony in regards to the timing of leaf production. Root order and the number of root neighbors at the time of root death were the strongest predictors of root lifespan of both species pairs. Seasonal 15N uptake was higher in spring than in the fall, which did not support the need for higher root activity to correspond with extended leaf phenology. We found higher spring 15N uptake in non-native L. japonica compared to native L. sempervirens, although there was no difference in 15N uptake between Frangula and Rhamnus species. Our findings indicate the potential for fast-growing non-native Lonicera japonica and Frangula alnus to outcompete native counterparts through differences in biomass allocation, root turnover, and nitrogen uptake, however evidence that this is a general strategy of invader dominance is limited.

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Section: Discussioncontrasting

confidence: 87%

Links between Belowground and Aboveground Resource-Related Traits Reveal Species Growth Strategies that Promote Invasive Advantages

et al. 2014

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“…Moreover, the N‐induced increase in grass root biomass was less than the decrease in root biomass of forbs (i.e. increase 47.3% vs. decrease 58.9%), but the death of overall grass roots may also be reduced because grass roots generally have slower turnover than forb roots (Peek ; Chen & Brassard ). This may also explain no significant changes in root biomass of the community following chronic N amendment.…”

Section: Discussionmentioning

confidence: 99%

Differential responses of grasses and forbs led to marked reduction in below‐ground productivity in temperate steppe following chronic N deposition

et al. 2015

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Summary1. Enhanced deposition of atmospheric nitrogen (N) has profound impacts on ecosystem processes such as above-ground productivity and community structure in grasslands across the globe. But how N deposition affects below-ground processes of grasslands is less well known. 2. Here, we evaluated the effects of chronic N amendment at a relatively low rate (20 kg ha À1 year À1 ) on root traits (root productivity, root biomass, root/shoot ratio) in Inner Mongolia steppes by rhizotron and ingrowth core and soil monolith techniques at levels of individual species, functional groups and ecosystem. 3. For 8 years, N amendment suppressed above-ground net primary production (ANPP), photosynthetic rates and root biomass of forbs, but enhanced ANPP and root biomass of grasses. This led to an overall reduction in below-ground productivity of the grassland by 24-33%, while ANPP remained unchanged. 4. Nitrogen amendment acidified soil and subsequently increased extractable soil manganese (Mn) concentration. Nitrogen amendment increased foliar Mn concentrations in forb, but not grass species, leading to a significant inhibition of photosynthetic rates in forb species. 5. Synthesis. These findings highlight the importance of the differentiating responses of plant functional groups to long-term N deposition and the important consequences of these responses for below-ground productivity and long-term soil C sequestration.

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“…This suggests that the value of individual leaves or FRs and their (re)construction costs are relatively low (Eissenstat & Yanai ; Miller et al . ; Chen & Brassard ). This classification allowed us to analyse ‘order of organ’ (OoO) as an equivalent factor for both roots and shoots in our statistical models.…”

Section: Introductionmentioning

confidence: 99%

Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

2017

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Summary Optimal defence allocation theory (ODT) is one of the most prominent theoretical frameworks to explain the allocation of defence compounds within plants. It predicts that the most valuable and vulnerable plant organs have the highest levels of chemical defence. The ODT has been well worked out and experimentally tested for shoot defences, but not for root defences. To assess if ODT principles apply similarly to roots and shoots, we examined glucosinolates in above‐ground and below‐ground organs of nine plant species belonging to two families. In order to evaluate whether ODT equally applies to shoot and root organs, we designed a conceptual model in which above‐ground and below‐ground organs were assigned to orders of importance to plant performance. We hypothesized that organs constituting the plant's core structure are better protected than more distal organs. The nine plant species were cultivated, and their roots and shoots were harvested and divided into three orders for glucosinolate analysis. Using a specialist (Delia radicum) and a generalist (Amphimallon solstitiale) root herbivore, we also experimentally tested the hypothesis that the generalist herbivore prefers to feed on fine roots (FRs) with a low glucosinolate concentration, while the specialist prefers taproots (TRs) with a high glucosinolate concentration. We found that both in roots and shoots, the higher ordered core structural organs (TRs and stems) had the highest levels of glucosinolates. Below‐ground, TRs and lateral roots were better protected than the more distal, and less costly, FRs in seven out of nine species tested. The specialist root herbivore preferred feeding on the highly defended TRs, which is in line with what has been found for above‐ground specialist herbivores. Moreover, the glucosinolate concentration in roots overall was significantly higher than that in shoots. Synthesis. These results support the hypothesis that Optimal defence allocation theory (ODT) generally applies to glucosinolate allocation in above‐ground and below‐ground organs and may mainly serve to maintain the integrity of the main plant structure. Moreover, it suggests that above‐ground and below‐ground insect herbivores independently exert similar selection pressures on defence allocation patterns in roots and shoots.

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Intrinsic and Extrinsic Controls of Fine Root Life Span

Cited by 100 publications

References 113 publications

Links between Belowground and Aboveground Resource-Related Traits Reveal Species Growth Strategies that Promote Invasive Advantages

Links between Belowground and Aboveground Resource-Related Traits Reveal Species Growth Strategies that Promote Invasive Advantages

Differential responses of grasses and forbs led to marked reduction in below‐ground productivity in temperate steppe following chronic N deposition

Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

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