Status and Dynamics of the Kobresia pygmaea Ecosystem on the Tibetan Plateau

Miehe, Georg; Miehe, Sabine; Kaiser, Knut; Liu, Jianquan; Zhao, Xinquan

doi:10.1579/0044-7447(2008)37[272:sadotk]2.0.co;2

Cited by 142 publications

(116 citation statements)

References 3 publications

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“…This similarity in the phenological plasticity in response to environmental change has important implications for community stability-the patterns of coexistence of the two dominant plant families on the TP seem to be maintained [29], although their phenologies have advanced.…”

Section: Discussionmentioning

confidence: 97%

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Zhou

Yao

et al. 2014

Biol. Lett.

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Worldwide, many plant species are experiencing an earlier onset of spring phenophases due to climate warming. Rapid recent temperature increases on the Tibetan Plateau (TP) have triggered changes in the spring phenology of the local vegetation. However, remote sensing studies of the land surface phenology have reached conflicting interpretations about green-up patterns observed on the TP since the mid-1990s. We investigated this issue using field phenological observations from 1990 to 2006, for 11 dominant plants on the TP at the levels of species, families (Gramineae-grasses and Cyperaceae-sedges) and vegetation communities (alpine meadow and alpine steppe). We found a significant trend of earlier leaf-out dates for one species (Koeleria cristata). The leaf-out dates of both Gramineae and Cyperaceae had advanced (the latter significantly, starting an average of 9 days later per year than the former), but the correlation between them was significant. The leaf-out dates of both vegetation communities also advanced, but the pattern was only significant in the alpine meadow. This study provides the first field evidence of advancement in spring leaf phenology on the TP and suggests that the phenology of the alpine steppe can differ from that of the alpine meadow. These findings will be useful for understanding ecosystem responses to climate change and for grassland management on the TP.

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Section: Discussionmentioning

confidence: 97%

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Zhou

Yao

et al. 2014

Biol. Lett.

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“…The Kobresia pastures are characterized by productive vegetation with a dense root system (Miehe et al, 2008). Its high root/shoot biomass results in 90 % of the carbon assimilation being allocated into the ground of the pastures.…”

Section: Introductionmentioning

confidence: 99%

Field 13CO2 pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a Kobresia meadow

Zou

Zhao

et al. 2014

Biogeosciences

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Abstract. Livestock exclosure has been widely used as an approach for grassland restoration. However, the effects of exclosures on grasslands are controversial and can depend on many factors, such as the grassland ecosystem types, evolutionary history and so on. In this study, we conduct field experiments to investigate the variations of the ecosystem function in response to livestock exclosure in a Kobresia humilis meadow with 6 years of grazing exclosure on the QinghaiTibetan Plateau. We focused on two ecosystem functions: plant community structure and ecosystem carbon cycling. The plant aboveground productivity, plant diversity and the composition of plant functional groups of the meadow were addressed as the indicators of the plant community structure. The 13 C isotope pulse labeling technique was applied to evaluate the alterations of ecosystem carbon cycling during a short term. The results showed that the plant community structure was changed after being fenced in for 6 years, with significantly decreased aboveground productivity, species loss and varied composition of the four plant functional groups (grasses, sedges, legumes and forbs). Using the pulse labeling technique, we found a lower cycling rate of 13 C in the plant-soil system of the fenced plots compared with the grazed sites during the first 24 h after labeling. A higher proportion of recovered 13 C in the plant-soil system migrated into the soil as root exudates immediately after labeling at both fenced and control grazed sites, with a significantly lower proportion in the fenced site, coinciding with the lower proportion of 13 C lost from soil respiration. Thirtytwo days after labeling, 37 % of the recovered 13 C remained in the soil of the fenced plots, with significant differences compared to in the grazed plots (47 %). In addition, less 13 C (5 vs. 7 %) was lost by soil respiration in the fenced plots during the chase period of 32 days. Overall, our study suggests that livestock exclosures have negative effects on the plant community structure and partitioning patterns of the photoassimilated carbon in the Kobresia meadow, and the effects on photoassimilated carbon cycling are likely to result from the variations of community structures in the ecosystem.

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“…Alpine steppes cover an area of 800,000 km 2 in the northwest of the Tibetan Plateau (Zhang 1988;Miehe et al 2011), and Kobresia pastures cover an area of 450,000 km 2 in the southeast (Miehe et al 2008). Those Kobresia pastures are partly secondary grasslands after forests had been cleared since the mid-Holocene (Kaiser et al 2007;Miehe et al 2009Miehe et al , 2014.…”

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confidence: 99%

Land use change decreases soil carbon stocks in Tibetan grasslands

Qiao

Cao

et al. 2015

Plant Soil

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Backgrounds and aims Land use is an important factor affecting soil organic carbon (SOC) dynamics and can produce positive C climate feedback, but its effects remain unknown for Tibetan ecosystems. Methods Recent land use changes have converted the traditional winter Kobresia pastures of nomads in the northeastern Tibetan Plateau to Elymus pastures or even to cropland. Detailed SOC measurements up to 30-cm depth were combined with analysis of δ 13 C, δ 15 N, bulk density, microbial C, and N contents in three land use types. Results Bulk density was decreased by conversion from Kobresia pasture to cropland but increased by conversion to Elymus pasture. The loss of 1 % of SOC caused by land use change leads to δ 13

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Status and Dynamics of the Kobresia pygmaea Ecosystem on the Tibetan Plateau

Cited by 142 publications

References 3 publications

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow

Land use change decreases soil carbon stocks in Tibetan grasslands

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Status and Dynamics of the Kobresia pygmaea Ecosystem on the Tibetan Plateau

Cited by 142 publications

References 3 publications

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Field &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a &lt;i&gt;Kobresia&lt;/i&gt; meadow

Land use change decreases soil carbon stocks in Tibetan grasslands

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Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow