scholarly journals Roots of Cooperation: Can Root Graft Networks Benefit Trees Under Stress?

2020 ◽  
Author(s):  
Alejandra Vovides ◽  
Marie-Christin Wimmler ◽  
Falk Schrewe ◽  
Thorsten Balke ◽  
Martin Zwanzig ◽  
...  
Keyword(s):  
Forest Ecology ◽  
Adaptive Strategy ◽  
Pathogen Transmission ◽  
Hydraulic Redistribution ◽  
Optimal Size ◽  
Negative Effects ◽  
Individual Tree ◽  
Mangrove Root ◽  
Root Grafting ◽  
Root Grafts

Abstract The occurrence of natural root grafts, the functional union of roots of the same or different trees1–3, is common and shared across tree species2. However, their significance for forest ecology remains little understood. While early research suggested negative effects of root grafting (i.e. increases the risk of pathogen transmission)4,5, recent evidence supports the hypothesis that it is an adaptive strategy that reduces stress6–8 by facilitating resource exchange9,10. Here by analysing mangrove root graft networks, we show evidence of cooperation-associated benefits of root grafting. Grafted trees were found to dominate the upper canopy of the forest, and as the probability of grafting and the frequency of grafted groups increased with a higher environmental stress, the mean group size (number of trees within groups) decreased. While root networks could form randomly (i.e. trees do not actively ‘choose’ neighbours to graft to)11,12, the increased frequency and reduced group sizes in higher-stress environments point to the existence of underlying mechanisms that regulate ‘optimal size’ group selection related to resource use within cooperating groups8,13,14. This work calls for further studies to better understand tree interactions (i.e. network hydraulic redistribution)15 and their consequences for individual tree and forest stand resilience and water-use efficiency.

scholarly journals Genome-Wide Dissection of the CRF Gene Family in Brassica napus Indicates that BnaCRF8s Specifically Regulate Root Architecture and Phosphate Homeostasis against Phosphate Fluctuation in Plants

2020 ◽  
Vol 21 (10) ◽  
pp. 3660
Author(s):  
Sheliang Wang ◽  
Hao Zhang ◽  
Lei Shi ◽  
Fangsen Xu ◽  
Guangda Ding
Keyword(s):  
Brassica Napus ◽  
Plant Growth ◽  
Root Architecture ◽  
Time Course ◽  
Primary Root ◽  
Adaptive Strategy ◽  
Negative Effects ◽  
Response Factors ◽  
Pi Homeostasis ◽  
Genome Wide

Phosphorus (P) is an essential macronutrient required for plant growth and development. The involvement of cytokinin response factors (CRFs) in phosphate (Pi) homeostasis and lateral root (LR) initiation in Arabidopsis has been revealed. However, little is known in oil crops. Here, we performed genome-wide dissection of the CRF family in Brassica napus to identify 44 members, which were evolutionally classified into 6 subgroups. Among them, four BnaCRF8 genes were strongly upregulated by P deprivation, and were selected to be further investigated. Time course qRT-PCR analyses showed that four BnaCRF8 genes were enhanced dramatically after 12 h of P stress. Analyses of the subcellular localization in tobacco leaves indicated that BnaA7.CRF8 and BnaC2.CRF8 were localized in the nucleus. The expression of BnaCRF8 genes had constant negative effects on primary root growth and LR initiation and growth, and it reduced Pi acquisition and plant growth in Arabidopsis. Moreover, the expression of Pi homeostasis-related genes was modulated in BnaA7.CRF8 overexpression plants. These results suggest that BnaCRF8 genes might negatively regulate root architecture and plant growth through transcriptional modification of Pi homeostasis-related components. Overall, this study suggests that upregulation of BnaCRF8 genes might be a smart adaptive strategy to cope with continuous Pi deficiency in the environment.

Architectural approach to analysis of North American temperate deciduous forests

1982 ◽  
Vol 12 (4) ◽  
pp. 835-847 ◽  
Author(s):  
L. Oosterhuis ◽  
R. A. A. Oldeman ◽  
T. L. Sharik
Keyword(s):  
North American ◽  
Forest Ecology ◽  
Deciduous Forests ◽  
Forest Community ◽  
Individual Tree ◽  
Architectural Analysis ◽  
Plot Sampling ◽  
Temperate Deciduous ◽  
Temperate Deciduous Forests ◽  
The Individual

The architectural approach to the analysis of forest structure and dynamics, which originated in the tropics, has increasingly been applied to temperate forests during recent years, especially in Europe. However, few examples are available for this continent. To test the usefulness in North American temperate deciduous forests, an architectural analysis was conducted in a series of Appalachian oak forest stands. Central to the analysis are profile diagrams and plans of forest sample plots, five of which are presented here in detail. The interpretation of the diagrams focuses on the growth and development of the individual tree as well as the forest community, and thereby reveals certain phenomena which may not be detected by traditional plot sampling techniques. The architectural approach adds a new dimension to the existing array of research methods and its application is expected to be of great value in basic and applied studies of forest ecology.

Frequency of root grafting in naturally and artificially regenerated stands of Pinus banksiana: influence of site characteristics

2010 ◽  
Vol 40 (5) ◽  
pp. 861-871 ◽  
Author(s):  
Emilie Tarroux ◽  
Annie DesRochers
Keyword(s):  
Pinus Banksiana ◽  
Sandy Soils ◽  
Stand Density ◽  
Stand Development ◽  
Site Characteristics ◽  
Root Grafting ◽  
Naturally Regenerated Stands ◽  
Root Grafts ◽  
High Level ◽  
Western Boreal Forest

We investigated the frequency of root grafting in naturally and artificially regenerated stands of jack pine ( Pinus banksiana Lamb.) in the western boreal forest of Quebec, Canada. Twelve 30–60 m2 plots were hydraulically excavated to determine effects of site characteristics on frequency and timing of root grafting. Naturally regenerated stands had grafted tree percentages similar to artificially regenerated stands (21%–71% across plots) but greater numbers of root grafts per tree (naturally regenerated, 0.73 graft·tree–1; artificially regenerated, 0.52 graft·tree–1). Mean percentages of grafted trees, number of grafts per tree, and the speed of graft formation were greater in sandy soils (61%, 0.71 graft·tree–1 and 2.43 years, respectively) compared with clay soils (44%, 0.54 graft·tree–1 and 2.97 years, respectively). Proximity of trees was a better predictor of root grafting than stand density, despite many root grafts being found with distant trees (>2 m) in artificially regenerated stands. Our results suggested that root grafts form early in stand development. Even if trees are initially separate entities, this relatively high level of root grafting produces stands where trees are extensively interconnected.

scholarly journals Transpiration and water potential of young Quercus petraea (M.) Liebl. coppice sprouts and seedlings during favourable and drought conditions

2017 ◽  
Vol 63 (No. 7) ◽  
pp. 313-323 ◽  
Author(s):  
Stojanović Marko ◽  
Szatniewska Justyna ◽  
Kyselová Ina ◽  
Pokorný Radek ◽  
Čater Matjaž
Keyword(s):  
Forest Management ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Weather Conditions ◽  
Growing Season ◽  
Adaptive Strategy ◽  
Quercus Petraea ◽  
Leaf Water ◽  
Individual Tree ◽  
Drought Conditions

Increased frequency and intensity of drought events consequently affect oak high forests with the process of further decline, compromised growth and questionable natural regeneration. To overcome such difficulties, new adaptive strategies are required. Coppicing, as the oldest way of forest management, might provide some solutions. In our study two contrasting management systems, sessile oak coppice and high forest, were compared at the initial stages of regeneration and forest development. The transpiration of young oak sprouts and seedlings was monitored using sap flow systems during the 2015 growing season. The study of transpiration also included leaf water potential measurements during three measurement campaigns with contrasting weather conditions. Coppice sprouts transpired significantly more than seedlings on the individual tree and stand level during the entire growing season 2015; particularly large differences were observed during drought conditions. Coppice sprouts experienced lower water limitations due to the voluminous and deeper root system as indicated by leaf water potential results. Presented results attribute young coppices as one of the promising adaptable forest management types with a better adaptive strategy at the extreme sites under water limiting conditions.

scholarly journals Assessing costs of carrying geolocators using feather corticosterone in two species of aerial insectivore

2015 ◽  
Vol 2 (5) ◽  
pp. 150004 ◽  
Author(s):  
Graham D. Fairhurst ◽  
Lisha L. Berzins ◽  
David W. Bradley ◽  
Andrew J. Laughlin ◽  
Andrea Romano ◽  
...  
Keyword(s):  
Tree Swallows ◽  
Migratory Connectivity ◽  
Fitness Costs ◽  
Negative Effects ◽  
Individual Tree ◽  
Future Studies ◽  
Aerial Insectivore ◽  
Barn Swallows ◽  
Energetic Expenditure ◽  
Feather Corticosterone

Despite benefits of using light-sensitive geolocators to track animal movements and describe patterns of migratory connectivity, concerns have been raised about negative effects of these devices, particularly in small species of aerial insectivore. Geolocators may act as handicaps that increase energetic expenditure, which could explain reported effects of geolocators on survival. We tested this ‘Energetic Expenditure Hypothesis’ in 12 populations of tree swallows ( Tachycineta bicolor ) and barn swallows ( Hirundo rustica ) from North America and Europe, using measurements of corticosterone from feathers (CORT f ) grown after deployment of geolocators as a measure of physiology relevant to energetics. Contrary to predictions, neither among- (both species) nor within-individual (tree swallows only) levels of CORT f differed with respect to instrumentation. Thus, to the extent that CORT f reflects energetic expenditure, geolocators apparently were not a strong handicap for birds that returned post-deployment. While this physiological evidence suggests that information about migration obtained from returning geolocator-equipped swallows is unbiased with regard to levels of stress, we cannot discount the possibility that corticosterone played a role in reported effects of geolocators on survival in birds, and suggest that future studies relate corticosterone to antecedent factors, such as reproductive history, and to downstream fitness costs.

scholarly journals Natural root grafting in Picea mariana to cope with spruce budworm outbreaks

2016 ◽  
Vol 46 (8) ◽  
pp. 1059-1066 ◽  
Author(s):  
Roberto L. Salomón ◽  
Emilie Tarroux ◽  
Annie DesRochers
Keyword(s):  
Tree Growth ◽  
Picea Mariana ◽  
Boreal Forests ◽  
Negative Impact ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Carbon Supply ◽  
Root Grafting ◽  
Root Grafts

Spruce budworm (Choristoneura fumiferana Clem.) outbreaks cause extensive mortality and growth reductions throughout boreal forests in eastern North America. As tree vulnerability to defoliation remains partially unexplained by tree and stand attributes, we hypothesized that root grafting might attenuate the negative impact of severe defoliation in tree growth. Two experimental sites in the Abitibi-Témiscamingue region dominated by black spruce (Picea mariana Mill.) were harvested and hydraulically excavated to study tree growth in 36 trees in relation to root grafting and the last spruce budworm outbreak using dendroecological methods. Root grafts reduced the negative effects of defoliation by maintaining stable growth in connected trees during epidemic periods. Among dominant trees, growth releases immediately after the outbreak were uniquely observed in grafted trees. Among suppressed trees, grafted trees tended to grow more than non-grafted trees when defoliation severity was the highest. Carbohydrate transfers through root grafts and enhanced efficiency to acquire resources may explain the better performance of grafted trees under scenarios of limited carbon supply. This study reinforces the growing body of literature that suggests root grafting as a cooperative strategy to withstand severe disturbances and highlights the key role of root grafting in stand dynamics to cope with periodic outbreaks.

Time Series and Postglacial Forest Ecology

1981 ◽  
Vol 15 (3) ◽  
pp. 265-277 ◽  
Author(s):  
David G. Green
Keyword(s):  
Time Series ◽  
Forest Ecology ◽  
Forest Succession ◽  
Fire Frequency ◽  
Forest Composition ◽  
Mixed Composition ◽  
Individual Tree ◽  
Tree Communities ◽  
Pollen Records

AbstractForest ecology suffers from a lack of long-term community records. Preserved pollen data are richer in such information than is generally realized. By applying suitable statistical techniques to pollen records, one can learn much about competition, succession, and population dynamics in past tree communities. In this study, preserved pollen records from Everitt Lake, Nova Scotia, are analyzed as time series. Time domain studies reveal the post-fire responses of individual tree taxa. Correlograms yield models of past forest succession patterns. The models explain some effects of changing fire frequency, thus suggesting mechanisms by which fire, competition, and climate combine to produce long-term forest composition changes. Frequency domain studies suggest relationships between disturbance cycles, stand composition, and forest mosaics. Fire frequencies are seen to be highest where fire-dependent species abound and most regular where tree stands have uniform, not mixed, composition.

Root grafting in Radiata pine stands in the Australian Capital Territory

1970 ◽  
Vol 18 (3) ◽  
pp. 251 ◽  
Author(s):  
JP Wood ◽  
EP Bachelard
Keyword(s):  
Radiata Pine ◽  
Australian Capital Territory ◽  
Australian Capital ◽  
Seedling Roots ◽  
Initial Spacing ◽  
Root Grafting ◽  
Pine Stands ◽  
Root Grafts ◽  
Live Tree ◽  
Shallow Soils

Root grafting, as indicated by the number of living stumps in thinned stands, is widespread in radiata pine stands in the Australian Capital Territory. Grafting begins when the stands are about 10 years old and increases rapidly to at least 25 years. That live stumps are connected to live trees by root grafts was shown by excavation. Neither initial spacing of trees nor thinning influenced the incidence of root grafting but shallow soils appeared to inhibit it. The radioisotope 86Rb and the dye acid fuchsin were used to demonstrate movement of materials through root grafts from living stumps to living trees; this occurred at rates of 5-25 cm per hour. No movement in the opposite direction nor from live tree to live tree was detected. No evidence was obtained of living stumps affecting the growth of associated trees. Techniques for grafting seedling roots, and preliminary experiments on the movement of substances through such grafts, are described.

Direct Evidence of Ancient Symbiosis Using Trace Fossils

2008 ◽  
Vol 14 ◽  
pp. 271-287 ◽  
Author(s):  
Leif Tapanila
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Spatial Competition ◽  
Adaptive Strategy ◽  
Negative Effects ◽  
Symbiotic Associations ◽  
Negative Change ◽  
Intimate Association ◽  
Host Taxon ◽  
Levels Of Integration

Symbiotic associations are a poorly studied aspect of the fossil record, owing largely to the taphonomic biases that inhibit direct observation that two organisms shared an intimate association in life. A symbiosis between an infesting animal and a skeleton-producing host can form a bioclaustration cavity that directly preserves the association and has a high preservation potential. Identification of ancient mutuals and parasites must reject the null hypothesis of commensalism by demonstrating that the symbiosis correlates with a positive or negative change in host fitness as compared to a non-symbiotic relative of the host taxon. Reviews of the Paleozoic record of marine symbionts show that the majority are hosted by colonial animals, especially corals and calcareous sponges. These hosts include structural forms that have moderate to high levels of integration and can support bioclaustrations between clonal units, mitigating the negative effects of symbionts, and perhaps facilitating the symbiosis.The fossil record is biased toward recording long-lasting, widespread, equilibrated associations. By contrast, parasitisms that are especially negative to the host are expected to be fossilized rarely. The symbiotic associations that form bioclaustrations may also represent an endolithic adaptive strategy in response to biological antagonisms, such as predation and spatial competition. The Late Ordovician rise in symbiotic bioclaustrations joins burrows and borings as trace fossil examples of infaunalization strategies that accompany the Ordovician faunal radiation.

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