Underground starch storage in Erica species of the Cape Floristic Region – differences between seeders and resprouters

Abstract

Concentrations of starch in roots of seeder species of Erica from the Cape Floristic Region, South Africa were found to be considerably less than in resprouters. Shoot starch was highly variable but mean values were similar in both seeder and resprouter species of Erica. Three distinct patterns of starch storage in roots were recognized. All seeder species fell within definitions of Categories 1 (narrow major and minor parenchymatous rays, one to two cells wide with no inter-ray storage) or 2 (thick major rays up to seven cells wide and thin minor rays with small amounts of inter-ray storage) whereas resprouter species were consistently within Categories 2 or 3 (broad major and minor rays, up to eight cells wide and conspicuous inter-ray starch storage). Results are discussed in light of similar studies of the related Epacridaceae. ' Mixed ' species (i.e. with seeder or resprouter individuals present, often in distinct populations) were always classified as belonging to Category 2. Studies of populations of three ' mixed ' species confirmed that seeder forms had consistently lower amounts of root starch than resprouters. Rays of xylem parenchyma were the main sites for starch storage in roots of both seeders and resprouters and greater proportions of cross-sectional area of roots were consistently devoted to such storage tissues in resprouter forms of the three ' mixed ' species. Analyses of a number of seeder and resprouter Erica coccinea populations showed that differences in amounts of realised and potential root starch storage are best explained by the effect of regeneration behaviour rather than by among-population variability.

Relative importance of various regeneration mechanisms in different restoration stages of Quercus variabilis forest after selective logging

“…The rapid development of stump sprouts was more obvious in the early stage after logging, which was confirmed by other studies on other oaks (Lockhart and Chambers, 2007;Xue et al, 2013;Rong et al, 2013). Stump sprouting is a process that consumes energy and resources, as reflected by the sharp decline in starch content in the root system of the stump after sprouting (Bowen and Pate, 1993;Bell and Ojeda, 1999), and decrease in carbohydrate and nutrients in the stump and root system with increasing harvesting age (Lockhart and Chambers, 2007). Midgley (1996) proposed a trade-off between sprouting and height growth for stump sprouts; the production of new sprouts may influence the height increment of old sprouts.…”

When sex is not enough: ecological correlates of resprouting capacity in congeneric tropical forest shrubs

“…In the fire-prone shrublands of Australia and South Africa, resprouters have root starch concentrations 4-35 times higher than those of nonresprouters (Pate et al 1990;Bell 1996;Bell and Ojeda 1999). Furthermore, root reserves decrease when plants resprout after burn events (Bowen and Pate 1993).…”

Nonstructural Carbon in Woody Plants

“…Resprouting in trees after low but pervasive levels of disturbance is supported by both below-and aboveground reserves, whereas resprouting in shrubs and trees subject to frequent, severe disturbance is supported by belowground reserves (93). Mediterranean woody shrubs in fire-prone heathlands allocate and accumulate more NSC belowground than sympatric, obligate seeders do (6,58,140). Here, starch reserves have been identified as critical for resprouting and are stored in xylem parenchyma ray tissue of woody underground organs, such as burls, lignotubers, and roots (6,140).…”

“…Mediterranean woody shrubs in fire-prone heathlands allocate and accumulate more NSC belowground than sympatric, obligate seeders do (6,58,140). Here, starch reserves have been identified as critical for resprouting and are stored in xylem parenchyma ray tissue of woody underground organs, such as burls, lignotubers, and roots (6,140). Similarly, savanna trees, which persist through repeated top kill by resprouting, also store large amounts of NSC (e.g., sugars plus starch = 28-30% mass) belowground in specialized organs (i.e., lignotubers) (49,144).…”