1067-4136/05/3603- © 2005 Pleiades Publishing, Inc.
Russian Journal of Ecology, Vol. 36, No. 3, 2005, pp. 205–208. Translated from Ekologiya, No. 3, 2005, pp. 227–230.
Original Russian Text Copyright © 2005 by Yanovskii.
Succession is a dynamic process of the consecutive
change of biogeocenoses. The principal mechanism of
succession is the restoration of ecological equilibrium
between biotic communities and environmental factors.
The climax stage is the ﬁnal in the development of a
biogeocenosis, at which it achieves a state of long-term
dynamic equilibrium with the environment. The main
trait of climax communities is the level of biological
productivity, at which the annual production is equal to
the total expenditures for respiration, litter accumula-
tion, and consumption by animals. Hence, the biomass
of communities remains relatively stable.
Two types of successions are distinguished by rate:
gradual and spontaneous. Gradual progressive succes-
sions are characterized by relatively uniform, “evolu-
tionary” stabilization of interconnections and struc-
tures. Spontaneous successions occur upon an abrupt
harmful impact and are sometimes termed demutations,
in contrast to progressive successions. Two types of
successions are distinguished by the type of impact:
allogenous (i.e., initiated by external processes) and
autogenous (i.e., resulting from biotic processes within
the system). A typical allogenous succession is pyro-
genic demutation resulting from forest ﬁre (uncon-
trolled burning that spreads over the forest area).
The possibility and intensity of a ﬁre depend on
moisture content in the litter, moss, and plant debris.
Changes in this parameter under the inﬂuence of mete-
orological conditions are the main cause of ﬂuctuations
in the degree of ﬁre hazard. In addition, they depend on
the ratio of the aforementioned combustible materials
to the mass of growing herbaceous vegetation, which
accounts for a gradual seasonal change of ﬁre hazard
(Furyaev, 1996). Regularities in the occurrence and dis-
tribution of ﬁres merit special investigation. Here, it
should only be noted that pyrogenic demutation is spe-
ciﬁcally characterized by the high-temperature digres-
sion of the ecosystem, or ecodegradation. It is obvious
that ﬁres radically interfere with the vital activities of
an ecosystem. The ecological situation drastically
changes (this concerns both microclimate, and the state
and structure of the litter and soil), the biocenosis per-
ishes (both the ﬂora and fauna), and a major part of
organic matter is eliminated. This leads to instability of
the community and to improbability of the formation of
climax biogeocenoses. The subsequent restoration of
herbaceous vegetation is accompanied by expansion of
dense herbage, which markedly reduces the possibility
of renewal of woody plants. Moreover, the impact on
the fauna, whose diversity abruptly decreases, under-
mines the regulatory potential of the biogeocenosis.
Entomogenic demutation belongs to autogenous
processes. It takes its origin in the ecosystem proper,
and external factors only contribute to its realization.
The onset of entomogenic succession may be caused by
the weakening of the forest stand by a long severe
drought. A low-density population of an entomophage is
always present in the community and, having obtained a
stimulus such as abundant optimal food and favorable
climatic conditions, it realizes its growth potential. How-
ever, even in the case of total forest stand destruction, all
organic matter remains within the biogeocenosis and,
hence, the biomass remains unchanged. The structural
diversity of the system increases. Although the produc-
tivity of the forest decreases for some time, the ecosys-
tem retains its capacity for natural development.
Under certain conditions, insect population out-
breaks support the existence of climax communities. In
spruce forests of North America, phytophagous insects
and spruce form a natural self-maintained system.
Spruce budworm destroys large overmature trees and
clears the area for young trees, which are much less sus-
ceptible to damage (McDonald, 1965). As justly noted
by MacLean (1984), who analyzed the population out-
Role of the Forest Entomofauna
in Successional Processes
V. M. Yanovskii
Sukachev Institute of Forest, Siberian Division, Russian Academy of Sciences,
Krasnoyarsk, 660036 Russia
Received May 24, 2004
—Participation of the entomofauna in the succession of forest biogeocenoses is analyzed. In stable
ecosystems, insects serve as a mechanism providing for long–term ecological stability. In unstable ecosystems,
their activities are essentially negative and cause ecosystem degradation.
: succession, pyrogenic and entomogenic demutation, forest entomofauna, phytophages, entomoph-