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1

Spatial heterogeneity of soil seed banks in sandy grasslands under fencing and grazing in Horqin sandland, Northern China

100%
Zuo X., Zhao X., Zhao H., Zhang T., Wang S., Knops J., Kochsiek A.
Polish Journal of Ecology
|
2013
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tom 61
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nr 2
Understanding composition, structure and spatial heterogeneity in soil seed banks is important for the management of grassland ecosystem. Although the effect of fencing and grazing on vegetation composition is widely known, information on species composition, seed density and spatial heterogeneity of soil seed banks in sandy grasslands under fencing and grazing is still lacking. We measured the species composition and seed density of soil seed banks in fenced grassland, grazed grassland and grazed shrubby grassland in Horqin Sand Land, Northern China. By applying the geostatistical methods, we assessed how fencing and grazing affected spatial heterogeneity of soil seed banks in sandy grasslands. Total seed density and species richness in soil seed banks were lower in fenced grassland than in either grazed grassland or grazed shrubby grassland. Seed density and species richness of annual species in soil seed banks were also lower in fenced grassland than in either grazed grassland or grazed shrubby grassland, while those of perennial species showed a reverse trend. The analysis of spatial autocorrelation ranges, fractal dimensions and distribution pattern maps from geostatistical methods showed that spatial heterogeneity of seed density and species richness in soil seed banks were also lower in fenced grassland than in either grazed grassland or grazed shrubby grassland. Continuous fencing increases the seed density and species richness of perennial species in soil seed banks, as well as results in a decrease in spatial heterogeneity of seed density and species richness in soil seed banks. So, continuous fencing should be considered to restore the degraded sandy grasslands in management of semiarid grassland ecosystems.
2

Influence of grazing exclusion on soil macro-invertebrate diversity in degraded sandy grassland (Inner Mongolia, China)

100%
Liu R.-T., Zhao H.-L., Zhao X.-Y.
Polish Journal of Ecology
|
2012
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tom 60
|
nr 2
In arid and semi-arid areas, heavy grazing combined with climate change cause land degradation (e.g., desertification). Grazing management is essential for ecosystem recovery and desertification control in these areas, including Northern China’s Horqin Sandy Land. However, the recovery of soil faunal community during grazing exclusion is unknown. We examined plant and soil macro-invertebrate community structure together with soil properties in three treatments in a representative degraded Horqin sandy grassland: exclosure for 15 and 10 years (15EX and 10EX) and long-term continuous grazing (CG). The vegetation cover and height increased significantly and soil bulk density decreased significantly along the gradient from CG to 15EX, but there were no significant differences in soil pH, electrical conductivity, organic carbon and total nitrogen. Soil macro-invertebrate abundance, group richness and diversity increased along the gradient from CG to 15EX, with significant differences in invertebrate abundance and group richness between CG and 15EX; there was no significant differences between CG and 10EX. There were no significant differences in soil macro- invertebrate diversity and evenness between these three treatments. These results suggested that grazing exclusion for at least 15 years might be necessary for the recovery of these fauna. The vegetation height and the soil electrical conductivity, organic carbon, and total nitrogen determined the distribution and community structure of soil macro-invertebrates. Some faunal groups lived in specific habitats due to strong adaptation to different management practices. For example, the Thomisidae, Philodromidae, Salticidae, and Rhopalidae tended to live in habitats with tall vegetation. The Lygaeidae, Miridae, Teneberionidae, and Linyphiidae adapted to live in soil with low soil organic carbon and nitrogen (ungrazed grassland).
3

Carbon accumulation in the bulk soil and different soil fractions during the rehabilitation of desertified grassland in Horqin Sandy Land (Northern China)

100%
Li Y., Zhao X., Wang S., Zhang F., Lian J., Huang W., Mao W.
Polish Journal of Ecology
|
2015
|
tom 63
|
nr 1
Desertification, which affects more than two-thirds of the world's arid and semi-arid regions, is a significant global ecological and environmental problem. There is a strong link between desertification of the drylands and emission of CO₂ from soil and vegetation to the atmosphere. The Horqin Sandy Land is a severely desertified area in China's agro-pastoral ecotone due to its fragile ecology, combined with unsustainable land management. We estimated changes of organic carbon content in the bulk soil (0–5 cm), in the light-fraction of soil organic matter (based on density fractionation), and in the various particle-size fractions in areas with mobile sand dunes after implementing grazing exclusion (12 and 27 years) and tree and shrub planting (22 and 24 years). Carbon stocks in the bulk soil and all soil density and particle-size fractions increased significantly in the exclosure and plantation plots. The average rates of carbon accumulation in the bulk soil in the exclosure and plantation plots were 16.0 and 17.8 g m⁻² y⁻¹, respectively, versus corresponding values of 2.3 and 7.1 g m⁻² y⁻¹ for the light fraction, 4.3 and 8.0 g m⁻² y⁻¹ for the coarse fraction, 5.0 and 3.4 g m⁻² y⁻¹ for the fine sand, 4.5 and 4.2 g m⁻² y⁻¹ for the very fine sand, and 1.8 and 1.8 g m⁻² y⁻¹ for the silt clay fraction. The older the exclosure and plantation, the more carbon accumulated in the bulk soil and in each fraction. The carbon pool exceeded the level in non-desertified grasslands after 27 years of grazing exclosure and 24 years of the shrub plantation. Our results suggest that both grazing exclusion and planting trees and shrubs can restore desertified grassland, creating a high potential for sequestering soil carbon, but that the plantations appeared to accumulate soil carbon faster than the exclosures.
4

Seasonal changes of soil nitrogen mineralization along restoration gradient of sandy grassland, Northern China

80%
Lv P., Zuo X., Sun S., Zhang J., Zhao S., Hu Y.
Polish Journal of Ecology
|
2020
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tom 68
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nr 4
5

Leaf nitrogen resorption pattern along habitats of semi-arid sandy land with different nitrogen status

80%
Luo Y., Zhao X., Zuo X., Zhang J., Liu R., Wang S.
Polish Journal of Ecology
|
2010
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tom 58
|
nr 4
To assess nitrogen (N) resorption patterns in semi-arid sandy land, N concentrations in green leaves (Ng) and senesced leaves (Ns) of 35 species of shrubs and herbages were measured along habitats of decreasing soil total N (0.54 to 0.041 g g⁻¹ d.w. of top soil level) in Horqin Sandy Land (Inner Mongolia, China). These habitats are following: inter-dune grassland (IDG), fixed sand dune (FD), semi-fixed sand dune (SFD), semi-mobile sand dune (SMD), and mobile sand dune (MD) were considered. Results showed that Ng and Ns (i.e. nitrogen resorption proficiency, NRP) increased and leaf nitrogen use efficiency (NUE) decreased significantly with increasing soil N status across the above habitas, but nitrogen resorption efficiency (NRE) was not affected. The levels of Ng, Ns and NUE experience two stages across habitats: first, there were low Ng and Ns and high NUE in MD and SMD; second, there were high Ng and Ns and low NUE in IDG, FD and SFD. Plants from IDG, FD and SFD had incomplete N resorption during foliar senescence, but plants from MD and SMD had complete N resorption. Leaf NRE was determined by life forms which had no significant effect on Ng but on Ns and NUE. For all plants in the five habitats, NRE and NUE decreased with the sequence of grass, herb, shrub, while Ns showed a contrary tendency. Plants from strong N limitation habitats did not show higher NRE, but showed higher NRP and leaf NUE, so NRP was a more sensitive indicator of changes in N status than NRE. In conclusion, Leaf N resorption patterns were mainly determined by soil N status across habitats, and there were some consistent patterns among life forms.
6

Variations in foliar nutrient resorption efficiency of different plant growth forms in a temperate sandy grassland

80%
Mao W., Li Y., Cui J., Zuo X., Zhao X.
Polish Journal of Ecology
|
2011
|
tom 59
|
nr 2
Foliar nutrient resorption is an important strategy which allows leaf nutrients to be reused rather than lost with leaf fall, particularly in nutrient-poor ecosystems where even small nutrient losses can have significantly negative impacts on plant survival, competitive ability, and fitness. However, plants vary greatly in nitrogen (N) and phosphorus (P) resorption among plant growth forms during leaf senescence, which may be vital to understand the role of plant growth forms in ecosystem functioning. Green and senesced leaf N and P concentrations of 39 plant species in sandy grassland (Horqin Sand Land) of northern China were analyzed to detect variations of nutrient resorption efficiency among plant growth forms. The results showed that nitrogen resorption efficiency (NRE) ranged from 29% to 74%, with an average (± SD) of 50.3 ± 11.2%, and phosphorus resorption efficiency (PRE) varied among species between 46% and 82%, with a mean (± SD) of 68.4 ± 6.9%, suggesting that nutrient resorption is a vital nutrient conservation strategy in this ecosystem. In addition, NRE and PRE differed significantly among the dominant plant growth forms in this sandy grassland. NRE for N-fixing species and graminoids were significantly lower relative to NRE for shrubs and forbs, but mean PRE of graminoids was significantly higher than those of N fixers, shrubs and forbs. These data give indirect evidence that the differentiation of N and P conservation serve as an important mechanism permitting the co-existence of growth forms in arid systems.
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