Dynamic Changes of Stipa bungeana Steppe Species Diversity as Better Indicators for Soil Quality and Sustainable Utilization Mode in Yunwu Mountain Nature Reserve, Ningxia, China

Abstract

Due to serious degradation of typical Stipa bungeana steppe community on the Loess Plateau, a 26-year (1982-2007) experiment has been carried out by methods of forbidden grazing, cutting, and rotational grazing. Our results show that the process of succession of long-term enclosed S. bungeana community can be divided into two stages: 1980-1996, the forward succession stage, when the species diversity and biomass reach the peak (33.7 species/m 2 and 1349.41 g/m 2 , respectively); 1997-2007, the slow succession stage, when the gradually thickening of litter layer (litter depth reaches 3-5 cm) directly causes the reduction of species diversity and biomass to 19.1 species/m 2 and 863.19 g/m 2 , respectively. While under the cutting and rotational grazing methods, grassland succession can be divided into four stages: 1st-5th year, the continuing growth stage; 6th-9th year, the vigorous competing stage; 10th-15th year, the aggregation growth stage of constructive species with biomass reaching the peak (1444.19 g/m 2 ); and 16th-23rd year, stable growth stage of constructive species, which form sub-climax and are eventually dominated by S. bungeana, with the species diversity and biomass of 25-27 species/m 2 and 956.76-1165.35 g/m 2 , respectively. The constructive species suddenly change in the 24th year, and the population of S. grandis increases rapidly to 21 m À2 accounting for 25% of the total plant population. Long-term enclosure leads to decreased species diversity and biomass and is not beneficial for grassland renewing. The species diversity and biomass of degraded grassland continuously decrease to 10 species/m 2 and 392.1 g/m 2 due to long-term artificial failure and transitionally grazing, leading to harden soil with slow rainfall infiltration, where plants can only sustain life under the drought condition. Therefore, reasonable cutting and rotational grazing are the methods of choice for the gradual increase of species diversity and promotion of the natural renewal and forward succession of the grassland on Loess Plateau. These results provide reliable information for the diversity dynamic change as better indictors of soil quality and sustainable utilization mode.Keywords: Nature reserve; Soil quality; Species diversity dynamics; Stipa bungeana steppe; Sustainable utilization mode IntroductionGrassland is one of the globally important terrestrial ecosystems, and the increase in species diversity and productivity of grassland community depends greatly on the long-term management [1][2][3][4][5][6][7]. More research indicates that the species diversity of grassland has important ecology functions [8][9][10][11][12], species diversity is positively related to productivity, especially aboveground biomass [13][14][15]. Stipa bungeana steppe is a major community of middle temperate semi-arid typical grassland in the Eurasian section, widely distributes in western China and Loess Plateau region, and is mainly used for grazing and cutting. Typical grassland has important position in the temperate steppe in Chin...

Screening Indian Mustard Genotypes for Phytoremediating Arsenic‐Contaminated Soils

“…The As accumulation was higher in shoot than in the root, implying that a considerable amount of As was translocated to the aerial plant parts. A similar observation was also previously reported [5,11,[50][51][52][53][54][55][56][57][58][59][60][61].…”

Ethylene glycol tetra-acetic acid and salicylic acid improve anti-oxidative ability of maize seedling leaves under heavy-metal and polyethylene glycol 6000-simulated drought stress

“…Many researches showed that under drought stress, the activity of anti-oxidative enzymes changes dramatically in seedlings and the MDA content strongly increased, showing that insufficient water supply caused significant adverse effects on seedling growth and development (Guo et al 2007;Shao et al 2008;Chao et al 2010;Basile et al 2011;Doganlar & Atmaca 2011;Ippolito et al 2011;Manchanda & Garg 2011;Fellet et al 2012;Kalavrouziotis & Koukoulakis 2012;Minutolo et al 2012;Rahman et al 2012;Song et al 2012Song et al , 2013. It has been pointed out through numerous studies (Aganchich et al 2007;Ephrath et al 2011;Guan et al 2011;Cheng et al 2012;Encina et al 2012;Kalavrouziotis & Koukoulakis 2012;Garg & Bhandari 2013;Minggagud & Yang 2013) that in many crops, heavy metal and drought stress cause changes in the secretion of organic acids such as EGTA and SA. These compounds can form stabilized complexes with some heavy metal ions during the process of chelating, thus transforming toxic heavy metal ions into low-toxic and non-toxic chelating complexes and alleviating the toxic effects of high concentrations of heavy metal ions on plants (Guo et al 2007;Chao et al 2010;Singh & Chaturvedi 2012;Song et al 2012Song et al , 2013.…”

“…Soil is of vital importance to plant growth and development, providing all kinds of nutritious elements (Chao et al 2010;Cheng et al 2012;Mattana et al 2012;Simõ es et al 2012;Zhang et al 2012;Košir et al 2013;Lantieri et al 2013;Richter et al 2013;Zhang et al 2013). However, with the rapid industrial and agricultural development worldwide, soil pollution by heavy metals has become a serious issue.…”

“…Compared with other food crops, maize needs relatively large amounts of water in the process of its growth. Therefore, the issue of maize production under water deficit has increasingly been taken into account (Aganchich et al 2007;Ephrath et al 2011;Guan et al 2011;Cheng et al 2012;Encina et al 2012; Kalavrouziotis & Koukoulakis 2012;Baker et al 2013).…”

“…The accumulation of MDA in leave and root cells has long been considered as a sign of reduced stress resistance or tolerance or even plant damage. Application of exogenous organic acids, such as ethylene glycol tetra-acetic acid (EGTA) and salicylic acid (SA), have been reported to exert certain alleviative effects on plant growth and development under heavy metal and drought stress (Aganchich et al 2007;Chao et al 2010;Ephrath et al 2011;Guan et al 2011;Cheng et al 2012;Encina et al 2012;Kalavrouziotis & Koukoulakis 2012;Baker et al 2013). The aim of this paper was to study the physiological responses of maize seedling to two different types of stress: (1) heavy metal stress by exposure to different concentrations Cd 2þ , Hg 2þ , and Pb 2þ ; and (2) drought stress induced by the application of PEG6000.…”