Wyniki wyszukiwania - BazTech

1

Responses of Physiological Characteristics of Annual C4 Herbs to Precipitation and Wind Changes in Semi-Arid Sandy Grassland, Northern China

Sun Shanshan, Liu Xinping, He Yuhui, Lv Peng, Chelmeg, Zhang Lamei, Wei Shuilian

Polish Journal of Ecology

|

2020

|

Vol. 68, nr 2

121--131

EN

The effects of changing precipitation and wind regimes on plant physiology are increasingly drawing attention of eco-physiologists. In the manipulative experiment we studied the physiological mechanisms of annual C4 herbs in the semi-arid sandy land to understand the functional significance of their traits and responses to the changing environment, grass Setaria viridis, characterized by the moderate stem water content and low leaf water content, more effectively absorbed light energy and utilized water resources than two dominant dicot plants, Salsola collina and Bassia dasyphylla. Precipitation increase and wind reduction promoted photosynthesis of the three C4 herbaceous plants, and their photosynthetic rates were higher in the end of July than that in August. Precipitation increase and the 20% reduction in wind velocity could also enhance their stomatal conductance and transpiration rate. The transpiration rate was consistent with the change in stomatal conductance, exhibiting highly positive correlation. The interactive effects of precipitation increase and wind velocity reduction made great changes in photosynthetic rate of the S. collina, lifted the photosynthetic rate and water use efficiency of the S. viridis. Our results suggest that the C4 herbs have shown some degree of stress resistance, and they are able to acclimate better to frangible environment of semi-arid sandy land. Furthermore, the changing environments heighten photosynthesis of the C4 herbs, which is pretty important to strength the arid plant stress resistance, then contributed to the ecosystem community production and dry matter accumulation.

2

Genetic Diversity in Salix gordejevii Populations from Different Environmental Gradients in Horqin Sandy Land, Northern China

Huang Wen-Da, Zhao Xue-Yong, Zhao Xin, Luo Ya-Yong, Feng Jing, Su Na, He Yuan-Zheng

Polish Journal of Ecology

|

2019

|

Vol. 67, nr 3

175--185

EN

Salix gordejevii (Salicaceae) is a climax and dominant sand-fixing shrub species native to the northern China. We assessed S. gordejevii population genetic variation in different environmental gradients in Horqin Sandy Land, Northern China using inter-simple sequence repeat (ISSR) markers, and investigated the possible existence of relationships between genetic diversity and environmental gradients. The results showed that S. gordejevii populations in general have high genetic diversity. An analysis of molecular variation (AMOVA) revealed relatively high levels (> 89.91%) of within-population genetic variation. Based on cluster analysis, the 12 studied S. gordejevii populations can be clustered into three clades. Genetic diversity and differentiation of S. gordejevii populations are affected from different environmental gradients. Genetic diversity of all populations was affected by habitat environment change, and was well-correlated with the humidity gradients. These results have important implications for restoration and management of degraded ecosystems in arid and semi-arid areas.

3

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

Liu R., Zhao H., Zhao X.

Polish Journal of Ecology

|

2012

|

Vol. 60, nr 2

375-385

EN

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).

4

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

Luo Y., Zhao X., Zuo X., Zhang J., Liu R., Wang S.

Polish Journal of Ecology

|

2010

|

Vol. 58, nr 4

707-716

EN

To assess nitrogen (N) resorption patterns in semi-arid sandy land, N concentrations in green leaves (N[g]) and senesced leaves (N[s]) 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 N[g], N[s] and NUE experience two stages across habitats: first, there were low N[g] and N[s and high NUE in MD and SMD; second, there were high N[g] and N[s] 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 N[g] but on N[s] 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.