Agriculture Reference
In-Depth Information
shrublands. Cork oaks very often have an open crown and on these well-lit
understory sites the composition may be more typical of phrygana shrublands.
Oak seedlings that recruit in the understory often remain suppressed for decades;
however, they do resprout after fire, and it may be that a disturbance is required
for their successful emergence into the canopy, as is seen with oak recruitment into
pine woodlands (Pons & Pausas
2006
).
Shrublands Dominated by Small-leaved and/or Malacophyllous
Species (Phrygana)
Phrygana includes a wide range of shrublands, dominated by species with small or
narrow leaves, often very reduced or even absent (e.g. with photosynthetic stems),
or by species with malacophyllous leaves, that are soft, somewhat fleshy and
pliable (
Table 4.4
). Broadleaf malacophyllous shrubs are often semi-deciduous
and shed most leaves (sometimes even small branches) under water stress, and
some are seasonally dimorphic, replacing their large winter/spring leaves with
smaller, thicker summer leaves (in species of
Sarcopoterium
,
Cistus
,
Phlomis
and
Euphorbia
; Margaris
1977
; Christodoulakis
1989
; Orshan
1989
; Aronne & De
Micco
2001
). All these shrublands are often very rich in suffrutescents (chamae-
phytes), such as species of
Helianthemum
,
Fumana
,
Thymus
and
Teucrium
, which
may become dominant toward arid zones where they form scrublands with very
low amounts of fuel.
Many of these shrubs and subshrubs are shallow-rooted non-resprouters, and
they counterbalance their lower root allocation through (1) leaf traits that confer
higher drought resistance, e.g. high leaf mass per area, even in comparison with
sclerophyllous broadleaf evergreen resprouter species (Paula & Pausas
2006
), and
(2) a root structure that allows them to better explore the upper soil layer and to
transport water more efficiently than resprouter species (Paula & Pausas,
2011
).
These associations have many local names depending on the dominant species
and the language (
Box 4.1
). Phrygana is used in Greece and other eastern basin
countries (Margaris
1976
; Arianoutsou-Faraggitaki & Margaris
1982
) and
tomillar is a term more common in the west (Dufour-Dror
2002
). This association
often occurs on disturbed sites, such as those that were terraced in the past and
then abandoned, and in woodlands that were cleared, overgrazed and later aban-
doned (Diamantopoulos
et al.
1994
;P ยด rez
et al.
2003
; Baeza
et al.
2006
). They also
tend to occur on sites with acidic, low-nutrient soils forming typical heathland
(e.g. Ojeda
et al.
1996
,
2010
) but may appear as gap species in woodlands. Short
small-leaved subshrubs also occur in drier areas, forming a transition toward arid
or cold steppes.
Shrubs or subshrubs in these communities are shorter lived and smaller than
broadleaf sclerophyllous shrubs. Many of the dominant woody species recruit
after fire (
Table 4.4
) from dormant seeds with heat- or smoke-stimulated
germination (see
Chapter 3
). They include many legumes (species of
Ulex
,
Spar-
tium
,
Calicotome
,
Cytisus
,
Genista
,
Chamaespartium
and
Anthyllis
), Cistaceae
