InSitu 95: Paper No 11
"Methods of selection work to improve the resistance factor of
protective forests in Russia arid zone"
by: H.Mattis
Introduction
The principal targets for protective afforestation in Russia
are regions with severe soil and climatic conditions, that is there is
a lack of moisture, frequently recurring droughts, dry winds, freezing
winters, salinity and alkalinity of the soils, and a susceptibility of
the tree species to diseases and pests. All these factors create
difficulties for the establishment of effective and resistant
shelterbelts.
At the same time shelterbelts exert an extensive and positive
effect on agriculture in arid zone of the contry. Shelterbelts
contribute to increased yield of agricultural crops, protect the soil
from water erosion and wind erosion, and so on.
This paper summarizes the experience of the All-Russia
Scientific Research Institute of Agroforestry Amelioration (VNIALMI)
in breeding tree species that are utilized in Russia.
Breeding of Introduced Species
VNIALMI carries out the selection of the most resistant species
in arboreta located in three regions. These arboreta, located in the
arid zone, differ in regard to the tree growing conditions. The
arboretum in the Central Povolzh'e (Samara city) was established in
1950 on ordinary loamy chernozems, has a mean annual temprature of 3.7
C (maximum +40 C, minimum -45 C), a relative humidity of 46% and a
total precipitation of 395mm. The arboreta in the Lower Povolzh'e
(Volgograd and Kamyshin) were established in 1910 and 1962 on chestnut
soils, have a mean temperature of 5.4 to 7.6 C (maximum 41 to 43 C,
minimum -35 to -39 C), a relative humidity of 40 to 41% and a total
precipitation of 350 to 386mm. The arboretum in Western Siberia
(Kulunda, Altai Territory) was established in 1977 on chestnut
light-loamy soils, with a mean annual temperature of 1.9 C (maxium
+41 C, minimum -50 C), a relative humidity of the air of 50% and a
total precipitation of 270mm.
Of 281 species, hybrids and cultivars tested at Central
Povolzh'e, the most promising for afforestation in the chernozem
steppe were found to be: Betula pendula Roth, Quercus robur L, Larix sibirica
Ledeb, Pinus sylvestris L, Populus pyromidalis X P. chinensis,
P. pyramidalis X P. nigra, and P. balsamifera X P. berolinensis.
Of the 734 species, hybrids and forms that were tested in the
Lower Povolzh'e arboreta, the most promising for field shelterbelts
were: Robinia pseudoacacia L, Ulmus pumila L, Quercus robur L, Pyrus
communis L, Gledistia triancanthos L, and Fraxinus lanceolata Borkh;
for anti-erosion plantations: Crataegus species, Caragana arborescens
Lam, Amorpha fruticosa L, Cotinus coggygira Scop and Ribes aureum
Pursh; while for pasture-protecting shelterbelts: Crataegus monogyna
Jacq, Colligonum sp., Halloxylon aphyllum (Minw.) Iijm, and Tamarix
sp.
Of 120 species, hybrids and forms tested in Western Siberia,
the most promising have been acknowledged as: Betula pendula Roth,
Pinus sylvestris L. and Ulmus laevis Pall. When the ground water is
available to the roots, the greatest growth and a high winter
hardiness were shown by the poplar hybrids: Populus pyramidalis X P.
berolinensis and P. nigra X P. berolinensis X P. canadensis.
Plus Tree Selection
The principal features, used for the superior populations,
species and cultivars are drought, salt and frost resistance, as well
as resistance to pest and diseases.
Since in most regions there are no native populations of woody
plants, the selection of the plus individuals or populations for
protective afforestation is carried out in estabished old shelterbelt
plantings, which during the process of their growth have undergone a
systematic exposure to extreme conditions and, survived.
Such a combination of unfavourable weather conditions has
occurred during the past 20 years over an extensive area of the
European part of Russia. The severe snowless winters of 1968/69 and
1971/72 and the severe droughts in 1972 and 1975 resulted in massive
dieback of shelterbelts in the South-East of the European territory of
the country. After such extereme years almost all of the shelterbelts
were candidates for the selection of superior trees and shrubs. The
serviving individuals and entire plantations provide a valuable gene
pool for producing improved, hardy shelterbelt plantations.
In addition, the native forests and "kolkas" which grow in
depressed sectors of the topography are used in the improvement
program. Their range occasionally extends into the regions of
shelterbelt planting. These populations of tree species are also of
considerable importance for breeding and seed peoduction purpeses. It
is the sections of the natural forests on upland, dry sites that are
targeted for the selection of parental (plus) populations and
individual trees, even though in their growth and condition they are
inferior to the sections of the stand growing on the bottom or on the
lower part of the slope of the ravines.
Finally, individual long-lived trees that have survived under
severe conditions and which are growing in old forest belts, tree
plantations, park and farms, should provide the basis for establishing
seed plantations for protective afforestation.
The plus trees that have been selected are marked with a ring
and numbered, and registration plates are placed on them. Vegetatively
and seed propagated test planting of these plus trees are established.
After prolonged evaluation of their perfomance, conclusions are made
concerning the quality of the selected gene pool. The best clones and
populations are planted in seed orchards. The new progeny is more
resistant and long-lived under severe growing conditions.On the basis
of this method, VNIALMI has selected individual specimens of oak, elm,
locust, pine and other trees, which are distinguished by a high
resistance to drought, salinity, frost and diseases in the dry steppe
and in semi-desert.
Breeding of Hybrids
Further improvement in the ameliorative effect and longevity
of shelterbelts under steppe conditions may be achieved by the
introduction of hybrids of tree species. Work on hybridization in the
field was initiated at the VNIALMI research station at Kamyshin in
1939 by A.V.Al'benski. At the present time hybrids of oak, pine, elm, ash
and poplar have been developed that are especially promising for
shelterbelt planting. As has been shown by studies conducted over many
years, the majority of these species have superior growth and form.
In the hybridization of oaks the pedunculate oak (Quercus
robur L) was taken as the maternal tree, while the red oak (Q. rubra L) was
taken as the pollinator. In the hybrids, the growth in height during
the initial years was 1.5 times as great as in the parental species.
At an age of 18 years the difference in height was 23.7 to 77.6%,
while the difference in diameter ranged from 10.2 to 100.0%. On the
basis of the intensity of transpiration, the accumulation of dry
matter and the water-retaining capacity of the leaves, the hybrids occupy an
intermediate position in comparison with both of the control species.
Their heat tolerance is higher than that in the pedunculate and red
oaks. In addition, the hybrids obtained have shown improved resistance
to infection by vascular mycisis (a widely distributed disease of
oak).
For the hybridization of pines, the Scots pine (Pinus
sylvestris L) and Crimean pine (P. Pallasiana Lamb.) were used. Both
species were used as maternal trees and as pollinators. They are
widely utilised for the afforestation of light soils, and in this case
the Scots pine grows more rapidly, while the Crimean pine is more
salt-tolerant. the average height of a 20 year old hybrid is 18 to 20%
higher than that of either of the maternal species. The hybrid also
surpasses the maternal species by 18% D.B.H. On the basis of the
intensity of transpiration the hybrids occupied an intermediate
position between the parental species.
In the hybridization of elms, the Siberian elm (Ulmus pumila
L)which was introduced from Central Asia, was used as the maternal tree.
This species is distinguished by its rapid growth, drought and salt
resistance, but is not fully frost hardy. The progeny obtained from
the pollination of this species with the pollen of the smooth-leaves elm
(U. carpinifolia Rupp) and the "common" elm (U. laevis Pall.) markedly
exceeded the parental species in their growth. The heterosis in growth
was retained also in the third seed generation. The drought resistance
in the hybrids obtained was also higher than in the parental specias.
Of special importance to field shelterbelt afforestation is
the poplar (Populus sp.), which is distinguished by its rapid growth and
great height. The hybrids with a pyramidal form allow one to allocate
a minimal area to the shelterbelts and especially valuable for
afforestation on irrigated lands. Twenty six crossing combinations of
this tree were carried out by A.V.Al'benski and his students from
1933.
The most successful of these were: white X Bolle (P.alba X
P. bolleana); pyramidal X Berlin (P. pyramidalis X P. berolinensis);
pyramidal X Chinese (P. pyramidalis X P. chinensis), Balsam and Berlin
(P. balsamifera X berolinensis), and Moscow and "krasnonervnyi"
No. 1191. All of these successfully survived the severe winter of
1968/1969 and extremely dry summer of 1972, and they had an
indisputable superiority over the parental species on the basis of
their morphological features.
Organization of Forest Seed Production
Shelterbelt planting in Russia is carried out over a large
territory with various soil and climatic conditions. On the basis of
the directions of the breeding work and the organization of the forest
seed production, three large regions are distinguished:
1) forest-steppe and chernozem steppe, 2) dry steppe, and
3) semi-desert.
The first two regions have concentrated on establishment of
field shelterbelts and water-regulating forest belts in agricultural
fields, anti-erosion forest plantations in ravines and gullies and
afforestation of lands that have a low productivity (sands, waste
piles, quarries, etc.).
In the forest-steppe and chernozem steppe regions, which are
characterized by comparatively good forest growth conditions, it is
necessary to introduce into the shelterbelt plantations tall trees
that form open and permeable belts, which exert the best effect on the
microclimate of the fields. To these belong the pine (Pinus sp.),
larch(Larix sibirica), oak, birch, Norway maple (Acer platanoides), linden
(Tillia sp.) and poplar (Populus sp.). Seed plantations of these tree
species are established with consideration given to the overall
requirement for protective afforestation. Seed orchards in this region
are established from progeny of the better local and the tested
introduced populations. By the establishment of special seed orchards
there is a more reliable seed supply, a reduction in the damage caused
by pests and diseases and some improvement in the gene pool of the
most drought, salt and frost resistant.
In the dry steppe regions with dark-chestnut soil the belts of
trees on the fields are mainly oak (Quercus sp.) and their hybrids. On
chestnut and light-chestnut soils, the best are Siberian elm (Ulmus
pumila), locust (Robiniapseudo acacia), ash (Fraxinus), hawthorn
(Crataegus), olive (Elaeagnus) and golden currant (Ribes aureum),
while on light soils pine (Pinus) is mainly used. The seed plantations are
also established with consideration given to the overall requirements
of trees and their function in the region.
In the semi-desert zone if the country the principal type of
shelterbelt planting is pasture plantations. For the creation of
ameliorative plantations of green caponies for relaxation of animals,
drought and salt resistant shrubs, such as saxaul (Haloxylon),
"dzhuzgun" (Colligonum) and tamarisk (Tamariz) are utilized.
Furthermore, in order to improve their productivity, woody foliage
plants such as winterfat (Eurotia), saltwort (Salsola) and others are
planted. Seeds are obtained from established seed plantations from a
quality-controlled gene pool of these species.
Conclusions
1. A basic condition for the growing of long-lived shelterbelt
plantations within the arid treeless zone involves the utilization of
a particular composition of woody plants, which may be introdused
species, that are most completely adapted to the soil and climatic
conditions of a particular geographical locality.
2. Additional improvement in the resistance of artificial
plantations may be attained by:
(a) the plus tree selection of the principal tree species that
are used for protective afforestation;
(b) interspecific hybridization of the tree species;
(c) the proper selection of the direction of the shelterbelt
planting (field or pasture-protecting, anti-erosion,
sand-consolidating, etc.) and the correct organization of the
silvicultural seed production in different natural conditions
in the the arid zone.
3. For the establishment of maternal seed plantations, use is
made of a genetically valuable gene pool, that is distinguished by an
elevated resistance to drought, frost, the salt content in the soil,
pests and diseases.