Ecological drivers of root grafting in balsam fir natural stands

Quer, Elodie; Baldy, Virginie; DesRochers, Annie

doi:10.1016/j.foreco.2020.118388

Cited by 7 publications

(11 citation statements)

References 52 publications

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“…Our findings represent indirect evidence of positive interactions between trees via root grafts, which are reflected on tree allometry and network attributes. Nevertheless, it is noteworthy to highlight that quantifying size, age and functionality of grafts is still necessary to assess the relative contribution of functional grafts to resource transfer 9 – 11 , as they are detrimental to disentangle the cause-effects of grafting on tree growth and fitness. Age of grafts, as well as their size affect their functionality and thus, their ability to transfer resources between trees 9 .…”

Section: Resultsmentioning

confidence: 99%

“…Between the 1950s and the 1990s, they were mainly regarded as a phenomenon of random occurrence or a threat to forest stands due to their role as vectors of pathogen transmission in forest stands 4 and the only long-term accepted consequence of grafting as a positive trait was increased mechanical stability 2 , 3 , 5 . Now, the common perception of forest dynamics being ruled only by competition and survival of the fittest is being challenged by the discovery of mycorrhizal networks and the re-evaluation of root grafts as vectors of positive interactions amongst trees 6 – 11 .…”

Section: Introductionmentioning

confidence: 99%

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Cooperative root graft networks benefit mangrove trees under stress

et al. 2021

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The occurrence of natural root grafts, the union of roots of the same or different trees, is common and shared across tree species. However, their significance for forest ecology remains little understood. While early research suggested negative effects of root grafting with the risk of pathogen transmission, recent evidence supports the hypothesis that it is an adaptive strategy that reduces stress by facilitating resource exchange. Here, by analysing mangrove root graft networks in a non-destructive way at stand level, we show further 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 number of trees within grafted groups decreased. While trees do not actively ‘choose’ neighbours to graft to, our findings point to the existence of underlying mechanisms that regulate ‘optimal group size’ selection related to resource use within cooperating networks. This work calls for further studies to better understand tree interactions (i.e. network hydraulic redistribution) and their consequences for individual tree and forest stand resilience.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cooperative root graft networks benefit mangrove trees under stress

et al. 2021

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“…However, under equal climatic conditions, the observed stands showed different responses in terms of development of defoliation and mortality. The roots of trees from the species Abies can be physiologically fused [65], and the formation of silver fir biogroups is more common on limestone substrates than on silicate substrates [66], which could have facilitated a better supply of nutrients and water to trees at site B.…”

Section: Discussionmentioning

confidence: 99%

Silver Fir Decline in Pure and Mixed Stands at Western Edge of Spread in Croatian Dinarides Depends on Some Stand Structure and Climate Factors

et al. 2021

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Silver fir is one of the most threatened conifer species in Croatia, especially at the western edge of its spread in Croatian Dinarides, where the decline in fir trees has resulted in significant ecological and economic issues. The aim of this study was to determine, over an 18-year monitoring period, the relationships of silver fir crown defoliation with climatic factors and structural attributes. We further analyzed the tree retention time in a given defoliation class and transition dynamics between defoliation classes, as well as the survival/mortality of trees. Data on silver fir defoliation were analyzed in two different forest types: in pure silver fir and in mixed silver fir and common beech stands. The climatic factors, primarily vegetation period air temperature, potential evapotranspiration, and dry season water deficit, were correlated with crown defoliation. Regarding the structural attributes, in the mixed stand with predominantly smaller trees, crown defoliation increased with reduced diameter at breast height, crown diameter, social class, and crown illumination. In the pure fir stand, crown defoliation increased with reduced crown diameter, greater crown asymmetry, greater crown illumination, and on trees with a stork’s nest crown. The retention time in defoliation classes differed for research sites. Transition dynamics were different only for trees in the highest defoliation class (dead trees). At the end of the study period, silver fir mortality was higher in the pure fir stand. Increased silver fir defoliation and mortality can be expected in the future, particularly in overmature stands under prolonged drought stress. Permanent forest monitoring could ensure the high-quality data needed for adaptive management of fir stands that could positively influence the structure of these stands and, thus, improve their health status.

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“…In biogroups, the distances between trees are markedly smaller than those between neighbouring trees. Advantages of growing within a biogroup may also include the fusion of root systems in trees of the same species, leading to the forming a kind of a single organism, supported by the joint root system and the assimilative apparatus, resulting in more efficient utilization of moisture and minerals found in the soil [66][67][68]. Biocenotic admixtures, i.e., tree and shrub species introduced to stands, promote and enhance advantageous biocenotic conditions and contribute to the health and natural resistance of the forest, while additionally sustaining wildlife populations.…”

Section: Single-species and Mixed Planting Systemsmentioning

confidence: 99%

Afforestation of Transformed Savanna and Resulting Land Cover Change: A Case Study of Zaria (Nigeria)

2022

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This paper presents the effects of actions aiming at tree planting, and thus protection of the land belonging to Ahmadu Bello University (ABU) in Zaria (Nigeria) from erosion. This area is located within the northern limits of the Guinea savanna belt, which has been considerably transformed primarily for agricultural purposes. For years this area has been subjected to the destructive surface and gully erosion processes, which were documented both by field work and the analysis of high-resolution images presented by Google Earth. Land erosion leads to the silting of an impounding reservoir (Kubanni)—the primary water source for the university campus and the basis for its existence. Since 2000, the university has been actively involved in tree-planting efforts in the campus vicinity, executed mainly through the establishment of small plantations ranging in area from approximately 1 ha to 56 ha. Today, these measures have brought tangible effects such as increment of tree-planted expanses, as evidenced in the multitemporal analysis of the Landsat 7 ETM+ and Landsat 8 OLI satellite images. The increasing planted area protects both the soil and the reservoir. A marked stand increment (almost doubled) has been recorded, which is evident from the satellite imageries, and is presented on the land-use map produced with GIS technique for this project.

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Ecological drivers of root grafting in balsam fir natural stands

Cited by 7 publications

References 52 publications

Cooperative root graft networks benefit mangrove trees under stress

Cooperative root graft networks benefit mangrove trees under stress

Silver Fir Decline in Pure and Mixed Stands at Western Edge of Spread in Croatian Dinarides Depends on Some Stand Structure and Climate Factors

Afforestation of Transformed Savanna and Resulting Land Cover Change: A Case Study of Zaria (Nigeria)

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