Management implications of intrapopulation and interpopulation genetic variation in Norway spruce

Dušan Gömöry & Ladislav Paule

Technical University in Zvolen, Faculty of Forestry, T.G. Masaryka 24, 960 53 Zvolen, Slovakia

Questions addressed:

•what is the natural spatial genetic structure in a virgin forest as a standard for evaluation of effects of management?

•how natural and artificial regeneration in commercial forests affect genetic structures and levels of genetic variation?

Spatial genetic structure of a Norway spruce virgin forest

Object: National Nature Reserve Zadná Poľana, Central Slovakia (1,200-1,458 m a.s.l., Norway spruce virgin forest) transect 40 x 150 m, 200 trees sampled

Genetic analysis: 14 isozyme systems, 23 genesData analysis:

Relatedness: Bayesian approach (Brunel & Rodolphe 1985): P{Ai/(x, y)} = P{(x, y)/Ai}.P(Ai) / (∑i P{(x, y)/Ai}.P(Ai))

Spatial autocorrelation: Moran’s I for 15 distance classes with equal sample sizes

X Y Genotype frequency

observed expected

12.3

18.2

12.8

‑4.2

31.0

30.5

12.4

87.4

103.8

103.5

112.3

126.1

127.4

123.4

0.005

0.010

0.010

0.005

0.010

0.010

0.005

1.6092E‑10

7.7993E‑15

7.7993E‑15

5.1889E‑08

1.2831E‑12

1.2831E‑12

5.5114E‑08

Deviation of observed genotype frequencies from thoseexpected under Hardy-Weinberg equilibrium

Clustering offamily groups

Distribution of the percentage and numberof related pairs over 5 m distance classes

half sibs(one common parent)

full sibs(both parents common)

Spatial autocorrelation of genotypes - distribution of Moran’s I-indices over distance classes with equal sample sizes

bars – number of significant Moran’s indices, line – average of I over all alleles

clonal groups pooled all trees

Effects of the regeneration method on genetic structures of Norway spruce

Objects: 6 virgin forests (nature reserves) 4 naturally regenerated stands

4 stands established through reforestationGenetic analysis: 6 isozyme systems, 8 genesData analysis: genetic variation: allelic richness (mean number of alleles per locus

gene diversity (expected Hardy-Weinbergheterozygosity)genotype variation (observed heterozygosity)

genetic differentiation: genetic distances (Nei 1978)

allelic richness

2

2.2

2.4

2.6

2.8

3

3.2

n_a

virgin forests

naturally regenerated

reforested

gene diversity

0.2

0.25

0.3

0.35

0.4

0.45

H_e

virgin forests

naturally regenerated

reforested

heterozygosity

0.2

0.25

0.3

0.35

0.4

H_o

virgin forests

naturally regenerated

reforested

-2

-1

0

1

2

-5 -4 -3 -2 -1 0 1 2 3 4 5 6

axis 1 (55.3 %)

axis

2 (

18.5

%)

virgin forests natural regeneration reforestation

genetic differentiation

Conclusions:

Virgin forest• considerable deviation from HW proportions• spatial family structure• spatial clumping of genes

conclusion: equilibria and random distributions are not necessarily obligatory attributes of a natural state

Effects of management• no differences between natural forests and naturally regenerated commercial forests• decreased levels of the genetic variation in the forests originating from reforestation• increased differentiation in this group

possible consequences:• reduced effective population size• inbreeding in subsequent generation• reduced adaptability