Pioneer (先駆種): earlier successional species

tending to be sun tree and/or generalist

Climax species (極相種)

tending to be shade tree and/or specialist

Sussceesion is translated into 'sen-i (センイ, 遷移)'
[ secondary succession | Usu | chronosequence | facilitation ]

The mechanisms of succession explained by Grime's triangle (グライムの三角形による遷移機構の説明)

Primary succession (一次遷移)

Xeric succession (乾性遷移)

Mesic succession (湿性遷移)

Secondary succession (二次遷移)

Post-mined peatland
Revegetation on skislope

landscape of skislope
problems on skislope establishment
skislope
skislope establishment

Revegetation after coal mining
Revegetation after wildfire

In the early stages

1

2

3

4

secondary vegetation made by human activities (代償植生) (s.s.), e.g., agricultural lands, artificial forests and satoyama

↔ old-growth, primary or primeval forest

Three factors on climax

1. Stability: self-maintaining = mature plant community
2. Convergence: final stages of succession in a given area
3. Regional prevalence: characterized as principal, undisturbed plant community in a given region
   directional change → succession
   non-directional change → cyclic change or fluctuation

CC = 2a/(2a + b + c)
a: number of species observed in both the times (years), b: number of species observed only in the first time, c: number of species observed in the next time

PS = 2Σmin(x_i, y_i)/Σ(x_i + y_i) × 100
x_i, y_i: percentage cover of ith species in times (years) x and y, min(x_i, y_i): minimum percentage cover of ith species in the two years

D = Σ_i=1^s[n(x, y, t₂) – n(x, y, t₁)]²
s: number of species present within the plots,
n_i: within-quadrat average covers of the species
x, y: grid coordinates

        Species  t1   t2  t2 - t1  Square
        1        10  20     10      100
        2         5   5      0        0
        3         .   5      5       25
        4         1   .      1        1
        5         1   .     -1        1
        Sum                         127

∴ D = 127

V_i = max_j=1ⁿ(|P_ij – P_(i–1)j|)
for i = 2, …, N and species j = 1, …, n. The n is number of species considered in the respective sere (being dominant at some time) and N is number of years. Values P_ij refer to the cover of a species in the first year and P_ij generally to the cover of a species j in the i-th year.

DS = (Σ_i=1ⁿl_id_i)/n × v
l: longevity (annual or therophyte = 1 (biennial = 2), perennial (geophytes, hemicryptophytes, chamaephytes) = 10, nanophanerophytes = 50, megaphanerophytes = 100)
d: relative dominance: (C' + H')/2 or (F' + D' + C')/3
n: number of species in the minimum area
v: cover percentage, 100% = 1
Empirically DS is effective between the successional stages of grasslands and sun tree forests. However, DS does not indicate succesional stages well at the late successional stages becasue DS does not change greatly due to the dominance of N, M and MM.

SI = cΣ_i=1ⁿ(d_i·l)
_d: relative dominance of basal area (range: 0-1), _l: estimated tree age in the dominat stand on each species, _c: crown area (100% = 1) d : relative dominance based on basal area (ranging from 0 to 1); l: life span which was estimated by the ages of massive stems of each species or species group in its dominating stands; c: cover of canopy (ranging from 0 to 1, where means 100% in cover) which would affect shade-tolerances of undergrowth).

Examples

Fig. Hypothetical procedures to obtain successional sere by chronosequence approach. This is the case of post-fire stand. [Above] Circles indicate the areas that received fire. Squares indicate plots established in the post-fire areas. Numerals indicate the ages after fire. [Below] The sequential changes in species composition. Species A is dominant five years after fire, and then gradually decreases the abundance. Species B is the most common in area where it has passed for 20 years since the last fire. If we assume that the species composition change in time, we determine species A is a pioneer after fire in the region.

Ex. Sakurajima Island, Kyushu, Japan (Tagawa 1964)
Ex. skislopes (Tsuyuzaki 2005)

Problems on the assumption of chronosequence

• The intensity, scale and frequency of disturbances are not always same.

Facilitation vs competition

Stress gradient hypothesis, SGH (ストレス勾配仮説)

Fig. Stress gradient hypothesis (Bertness & Callaway 1994)
often estimated by relative neighbor effect

(Maestre et al. 2009)

Revised SGH

competitive
stress tolerant

resource (e.g., nutrients)
non-resource (e.g., frost)

Fig. Revised SGH

(Successional) facilitation

Types of facilitation

Direct

A. Ameliorate harsh environmental conditions = Resource modification

1. Adjust light and temperature by shading
2. Increase soil moisture
3. Increase soil nutrients
4. Adjust soil aerobic conditions

B. Alter the characteristics of soil substrates

1. Bulk density, and macropores
2. Nurse logs
3. Seed trap effect by diverse microtopography

C. Epiphytes (e.g., orchids, ferns, mosses, algae)

1. Autotrophic: obligate, facultative
2. Heterotrophic: parasitic (asymmetrical effect)
3. Auto-heterotrophic continuum (hemiparasites)

Indirect

1. Eliminate potential competitors
2. Introduce beneficial organisms, e.g., mycorrhizae and pollinators
3. Protect from herbivores by physical modification of environment

• Tsuyuzaki, S. 1987. Origin of plants recovering on the volcano Usu, northern Japan, since the eruptions of 1977 and 1978. Vegetatio 73: 53-58
• Tsuyuzaki, S. 1989. Analysis of revegetation dynamics on the volcano Usu, northern Japan, deforested by 1977-78 eruptions. American Journal of Botany 76: 1468-1477
• Tsuyuzaki, S. 1994. Fate of plants from buried seeds on volcano Usu, Japan, after the 1977-78 eruptions. American Journal of Botany 81: 395-399
• Tsuyuzaki, S. 2009. Causes of plant community divergence in the early stages of volcanic succession. Journal of Vegetation Science 20: 959-969

Quiz

1. Give some examples of arrested succession and discuss the mechanisms.
2. A city lot is undergoing succession. Your goal is to reestablish a forest community. Under each of the following (example) conditions, what would you do? a) succession has been arrested by strong dominance of an exotic shrub such as Scot's bloom; b) there are serious barriers to immigration; c) soils have become compacted over the years; d) all of the above. Assess the nature of the succession if left alone, then determine if you will be accelerating, deflecting, or correcting the succession tract. Give brief examples of your tactics.
3. Name some stochastic events and give examples about how they might alter succession.
4. Contrast facilitation with inhibition as succession mechanisms. What does each predict concerning the order and structure of succession? Are these concepts mutually exclusive?
5. List five major factors or processes that would produce a plant association distinct from the climatic climax type in an region where you like.
6. List five factors that have influenced the landscape of Lake Toya.