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Types of resprouters

February 2nd, 2018 No comments

Many plants resprout after disturbance; there is a diversity of way in which a plant can resprout as there is a diversity of bud-bearing structures that form bud banks [1,2]. We can classify resprouters as follows [1,2]:

Basal resprouters

  • Species resprouting from buds located belowground in non-woody (fleshy or fibrous) swellings like bulbs, corms, non-woody rhizomes, stem tubers, root tubers or belowground caudex. They are specially common (but not exclusive) in monocots and ferns, and are characteristic of the geophyte growth form. They occur in many ecosystems, often tied to seasonal stresses. They are abundant in many fire-prone ecosystems, with remarkable examples of species with fire-stimulated flowering [3].
  • Species resprouting from an specialized underground woody structure like a basal burl (lignotuber, xylopodium) or a woody rhizome. They define the geoxyle growth form (see below) and are strongly tied to fire-prone ecosystems.
  • Species that resprout from a non-specialized basal structure like roots and the root crown. They occur in many ecosystems, not only fire-prone ones.

Aerial resprouters (aeroxyles)

  • Some trees resprout from buds located along the stems, even after relative intense fire (crown-fire); these are epicormic resprouters [2]. The buds are protected from the heat of the fire by a thick bark [4] or are well sunken in the stem (eucalypts). They are typical of some fire-prone ecosystems [2].
  • Some plants (e.g., palms, tree ferns, cycads) resprout after fire from the stem apex: apical resprouters. This is not a typical resprouting from dormant buds, but from the original apical bud that survived thanks to the protection by leaf bases and scales.

The term geoxyle was used by some early botanists [5,6] for a plant growth form with large woody underground structures and with an aboveground biomass of only a few years’ duration. Latter, the term geoxylic suffrutice was proposed for these plants with deciduous or short-lived shoots with a massive underground structure [7] (also termed ‘underground trees’). Consequently, the term geoxyles can be applied to any plant with a massive underground woody structure (e.g., xylopodium, lignotuber, woody rhizomes [1]), and suffrutescent geoxyles to those with herbaceous seasonal stems, typically lignified at the base. Many savanna plants are suffrutescent geoxyles (e.g., Fig. 1). Many mediterranean plants are shrub geoxyles like the lignotuberous species ([6] and Fig. 2), or the shrubby oaks that have woody rhizomes (Quercus coccifera, Q. gambelli). Given the large underground structure of geoxyles, they are very good postfire resprouters and live mostly in fire-prone ecosystems; i.e., the geoxyle growth form is likely an adaptation to fire-prone environments [1,9].

Fig. 1. Andira laurifolia (suffrutescent geoxyle, underground tree) showing the underground woody rhizomes (from Warming 1893 [10]). See also Fig. 3 below.

Fig. 2. Arctostaphylos glandulosa (shrub geoxyle) showing the lignotuber (from Jepson 1916 [11])

 

Fig. 3. Seasonal dynamics of a suffrutescent geoxyles with a woody rhizome and seasonal shoots. From [12].

 

References

[1] Pausas J.G., Lamont B.B., Paula S., Appezzato-da-Glória B., Fidelis A. 20.18 Unearthing belowground bud banks in fire-prone ecosystems. New Phytologist  [doi | pdf | suppl. | BBB database]

[2] Pausas J.G. & Keeley J.E. 2017. Epicormic resprouting in fire-prone ecosystems. Trends in Plant Science 22: 1008-1015. [doi | sciencedirect | pdf]

[3] Fire-stimulated flowering

[4] Pausas, J.G. 2015. Bark thickness and fire regime. Funct Ecol 29:317-327. [doi | pdf | suppl.]

[5] Lindman C.A.M. 1914. Nagra bidrag till fragan: buske eller trad? K. Vetenskapsakademiens Arsbok 12, Upsala. (mentioned in [6])

[6] Du Rietz GE. 1931. Life-forms of terrestrial flowering plants. Acta Phytogeogr. Suecica 3: 1-95.

[7] White F. 1977. The underground forest of Africa: a preliminary review. Singapore Gardens’ Bulletin 24: 57-71.

[8] Paula S., Naulin P.I., Arce C., Galaz C. & Pausas J.G. 2016. Lignotubers in Mediterranean basin plants. Plant Ecology 217: 661-676. [doi | pdf | suppl.]

[9] Lamont BB, He T, Pausas JG. 2017. South African geoxyles evolved in response to fire; frost came later. Evolutionary Ecology 31: 603–617. [doi | pdf | suppl.]

[10] Warming E. 1893. Lagoa Santa: étude de géographie botanique. Revue Générale de Botanique 5: 145-158, 209-233. 

[11] Jepson WL. 1916. Regeneration in manzanita. Madroño 1: 3-12.

[12] Bond WJ. 2016. Ancient grasslands at risk. Science 351: 120-122.

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