214 E.A. Mikhailova et al. Agriculture, Ecosystems and Environment 80 2000 213–226
native ecosystems. It is estimated that there are not more than 70 plant species spread over 1440 million ha
of presently cultivated landscape in the world Al- tieri, 1999, a sharp contrast with the diversity of plant
species found within 1 m
2
of a native grassland in the Kursk region of Russia, which can contain as many as
77 plant species Alekhin, 1934. Tilman 1999 ar- gues that greater plant biodiversity leads to a greater
stability in the ecosystems using a long-term study in Minnesota grasslands.
Conversion of native grassland to cropland with- out adequate fertilization usually leads to deteriora-
tion in soil properties Ponomareva and Nikolaeva, 1965; Afanasyeva, 1966; Mikhailova et al., 2000.
Mikhailova et al. 2000 showed that cultivation of chernozems in the Kursk region of Russia can lead
to SOC and N losses well beyond the plow layer 0–30 cm, down to 80 cm in a continuously cropped
field and down to 130 cm in a continuously fallow field. This finding implies that the CO
2
emission from the chernozem soils as a result of cultivation
may be much higher than predicted by some esti- mates. Studies on the soil biota of these grassland
ecosystems showed that soil macrofauna biodiversity decreased in the following sequence: native grass-
landperiodically-cut grazedhay fieldpasturebarley fieldlong-term continuous fallow Pokarzhevskij
et al., 1989; Pokarzhevskii and Krivolutskii, 1997.
Managing native grasslands for pasture or hay col- lection can maintain some of their unique botanical
composition, soil quality and minimize CO
2
emission from this soil type as a result of cultivation. There is
ample data to suggest that limited harvesting, by an- imal or mechanical means, has beneficial effects on
grassland ecology. Bekker et al. 1997 in a study of 38 grassland sites in western Europe concluded that
lack of management resulted in the loss of grassland species from both the vegetation and the soil seed bank
due to invasion of woodland species. Renzhong and Ripley 1997 also noted that species diversity was
greatest at an intermediate grazing intensity and least in lightly managed areas of Leymus chinensis grass-
land on the Songnen plain of northeastern China. Both of these studies indicate, however, that over-grazing
or intensive management resulted in degradation of grasslands. The effects of grazing and hay collection
on soil organic C and N are less understood. A review of a world-wide 236-site data set on effects of grazing
on soil and vegetation found no clear relationship be- tween species composition, root biomass, SOC and N
Milchunas and Lauenroth, 1993. These inconclusive findings demonstrate the complexity of interactions in
grassland ecosystems.
The viability of native grasslands can be sustained by providing an economic incentive for keeping these
lands intact or under limited utilization. The ex- ceptional botanical richness of these sites Alekhin,
1934 has not been ignored by Kursk entrepreneurs, who have been using plants collected from the native
grasslands to produce an alcoholic balsam named ‘Streletskaya Steppe’. Local farmers use these na-
tive grasslands as pasture and hay collection fields. High positive correlation between nutritional quali-
ties of pasture and milk products has been found in other parts of the world Licitra et al., 1997, where
botanical richness is comparable to that found in the grasslands of the Kursk region of Russia. The char-
acterization of pastures by species, forage and soil quality can be used to evaluate potential economic
uses for example, production of unique milk and cheese products of the native grasslands.
This research encompasses a field study in the V.V. Alekhin Central-Chernozem Biosphere State Reserve
in the Kursk region of Russia. The study addresses the following questions: i How does plant composition
change with different management regimes in native grasslands? and ii How does management of native
grasslands affect soil and forage properties?
2. Materials and methods
2.1. Field sites The Streletskyi section of the V.V. Alekhin
Central-Chernozem Biosphere State Reserve of Rus- sia is located approximately 18 km south of the city of
Kursk 51
◦
N 36
◦
E Vinogradov, 1984. Three fields were sampled in the summer of 1998. These sites are
about 264 m above mean sea level Ryabov, 1979. 2.1.1. Native grassland field
No agricultural activity has been allowed on this area since 1935. Before 1935, this land was used as a
pasture for at least 300 years Maleshin and Zolotuhin, 1994. Dominant species include meadow bromegrass
E.A. Mikhailova et al. Agriculture, Ecosystems and Environment 80 2000 213–226 215
Bromus riparius Rehm., wild oats Stipa pennata L., narrow-leaved meadow grass Poa angustifolia
L., intermediate wheatgrass Elytrigia intermedia Host Nevski, meadow-sweet rose Filipendula vul-
garis Moench and green strawberry Fragaria viridis Duch.. Soil organic carbon is derived dominantly
from C-3 type plant species, as indicated by
13
C val- ues of −25
‰
Mikhailova et al., 2000. Even though strictly protected from any human and domestic an-
imal interference, this field is considered somewhat ‘artificial’ by the local botanists, who insist that peri-
odic vegetation burning and wild animal grazing are ‘natural’ components of this system Sobakinskih,
pers. commun..
2.1.2. Grazedhay field with 4 years of annual harvest followed by 1 year rest referred as
periodically-cut grazedhay field Originally native grassland, this field has been used
for hay collection for at least 50 years. From 1981 until 1990, hay was harvested for 3 years in a row
followed by 1 year of rest. Since 1990, the field has been managed with 4 years of annual harvest fol-
lowed by 1 year of rest. It is used as a pasture during the spring season 1 cow per hectare and received
no additional fertilization throughout its management history Pokarzhevskii and Krivolutskii, 1997. This
management regime was chosen by the Biosphere Re- serve to simulate closely the natural cycle of periodic
vegetation burning and occasional animal presence. In this experiment, sampling occurred for the first
year after rest.
2.1.3. Yearly-cut grazedhay field Originally a native grassland site, this field has been
used for yearly hay collection for at least 50 years.
Table 1 Monthly precipitation and temperature values at the V.V. Alekhin Central-Chernozem Biosphere State Reserve
a
Month 1998
Long-term mean Precipitation mm
Temperature
◦
C Precipitation
b
mm Temperature
c ◦
C April
55 7
39±21 6±2
May 14
14 54±33
14±2 June
32 19
66±31 17±2
July 86
20 79±45
19±1 August
65 17
66±36 18±1
a
V.V. Alekhin Central-Chernozem Biosphere State Reserve, 1947–1998.
b
50-year average and standard deviation.
c
47-year average and standard deviation.
It is used as a pasture during the spring season 1 cow per hectare, but receives no additional fertiliza-
tion Pokarzhevskii and Krivolutskii, 1997. Hay is harvested twice per year: at the end of June or the
beginning of July, and in September Mikhailova and Ivanov, 1977. According to long-term observations,
the maximum number of flowering plants occurs at the end of June and this time is characterized by the high-
est above-ground plant biomass, thus, determining the hay harvest period Zmyhova, 1979.
The climate in the region is temperate, moderately cold with a mean annual precipitation of 587 mm and
a mean annual air temperature of 5.4
◦
C Alekhin, 1947–1997, V.V. Alekhin Central-Chernozem Bio-
sphere State Reserve, 1947–1997. Table 1 shows the weather conditions during the growing season of
1998 and the long-term averages.
All sampled sites have soils developed on deep loess deposits. They are classified as fine-silty, mixed, frigid
Pachic Hapludolls Soil Survey Staff, 1998, corre- sponding to the highly carbonated chernozem, leached
chernozem and faunal-pedoturbated chernozem com- plex in the Russian Soil Classification System.
2.2. Sampling procedure The three fields were sampled on July 20–21 of
1998. Hay harvest should have begun 1–2 weeks ear- lier, but it was delayed by rainy weather. Farmers har-
vested sites immediately after sampling for this study. The weather conditions of 1998 are common once in
4 years. May and June were quite dry and many plants had already flowered before the onset of July rains.
Based on plant composition, eight representative sam- pling sites were selected by a botanist in each of the
216 E.A. Mikhailova et al. Agriculture, Ecosystems and Environment 80 2000 213–226
fields. Two adjacent quadrats of 0.25 m
2
each were placed at each of the eight sampling sites within the
field, and plant species found within these areas were identified. Plant species names were verified and up-
dated to accepted taxa when necessary according to Czerepanov 1995. Botanical descriptions were kept
separate for the two quadrats within each site, but the plant samples were combined for further labora-
tory analysis for two quadrats total of 16 quadrats for each of the sampling sites resulting in eight sam-
ples per field. All plant material including roots was manually collected within the quadrats and separated
into live plant material, dead plant biomass and roots. Samples were combined for further laboratory anal-
ysis for two quadrates for each of the sampling sites resulting in eight samples of live plant material, dead
plant material, and roots per field.
Soil samples were collected from 0–10 cm depth in- crement at each of the eight sampling sites and com-
bined to form one composite soil sample representing each field. Bulk density measurements were done in
the native grassland and yearly-cut grazedhay fields.
2.3. Laboratory methods Soil samples were air dried, manually crushed, and
passed through a 2-mm mesh sieve. Particle-size distri- bution was determined for each sample by the pipette
method after pretreating for carbonates and soluble salts with 1 M NaOAc adjusted to pH 5, and removal
of organic matter with 30 H
2
O
2
Gee and Bauder, 1986. Oven-dry bulk densities were determined for
each sampled site. Soil pH was measured in a 1:1 soilwater suspension
McLean, 1982. Exchange acidity was determined us- ing BaCl
2
-triethanolamine buffered at pH 8 accord- ing to Method S1840 of the Cornell Nutrient Analysis
Laboratory CNAL Greweling and Peech, 1965. Ex- changeable cations were obtained with 1 M NH
4
OAc at pH 7.0 using a Zero-Max E2 vacuum extractor as de-
scribed in Method S2030 of the CNAL McClenahan and Ferguson, 1989. Cation-exchange capacity was
determined by summation of cations. Exchangeable Al was extracted with 1 M KCl and analyzed by the induc-
tively coupled argon emission plasma ICAEP, JY70 Type II using Method S2510 of the CNAL McClena-
han and Ferguson, 1989. Total N and soil organic C were determined by dry combustion-mass spectrome-
try using a Robo-prep-Tracemass system, Europa Sci- entific Cheshire, UK. Total elemental analysis of soil
by wet ash digestion HNO
3
–HClO
4
was performed according to Ritter et al. 1978.
Plant samples were thoroughly mixed, dried at 60
◦
C for 72 h, and ground to a 1 mm particle size in a cyclone mill Udy Corp., Fort Collins, CO in prepa-
ration for chemical analyses. Whole-plant N con- centration was determined by dry combustion-mass
spectrometry using a Robo-prep-Tracemass system, Europa Scientific Cheshire, UK. Samples 0.5 g
were analyzed sequentially for neutral detergent fiber NDF, acid detergent fiber ADF, and acid deter-
gent lignin using procedures described by Van Soest et al. 1991, except that the filter bag technique was
used with the ANKOM
200220
fiber analyzer. Sodium sulfite and heat-stable a-amylase was used on all
samples. In vitro true digestion IVTD concentration was determined according to Cherney et al. 1997,
using the rumen buffer fluid described by Marten and Barnes 1980 and using the Daisy II
200220
in vitro incubator and the ANKOM
200220
fiber analyzer. The buffer contained urea. Ruminal fluid inoculum was
obtained from a nonlactating, rumen-fistulated Hol- stein cow, fed on a medium quality orchard grass
hay diet for ad libitum intake. Samples 0.25 g were incubated for 48 h at 39
◦
C, followed by treating the undigested residue with neutral detergent. Total ele-
mental analysis of forage was performed according to Greweling 1976. All measured concentrations are
expressed on a dry matter basis.
All statistical calculations in this study were performed using the Minitab® statistical software
program Ryan and Joiner, 1994.
3. Results and discussion
