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Biomass fraction of graminoids and forbs in N-limited alpine grasslands: N:P stoichiometry

Zhang R., Gou X., Bai Y., Zhao J., Chen L., Song X., Wang G.

Polish Journal of Ecology

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2011

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Vol. 59, nr 1

105-114

EN

It is known that the dominance of graminoid species is promoted by N addition; however, there has been relatively little effort to examine the pattern induced by natural N fertility. Since nutriet use efficiency (NUE) is an important trait determining plant competitive ability, we expected that the species guild with higher NUE (lower nutrient content) may be more competitive on infertile soils. We explored the relationships between relative forbs biomass share, soil N and productivity by the linear regressi on analysis on a natural alpine meadow in northeast of Qinghai Tibetan Plateau (3600 m a.s.l.). To test the variety of leaf N:P stoichiometry, paired t test and general linear model multivariate (GLM) analysis were also used. We found that the leaf N:P ratios of the whole community were below 13 in studied sites, which may be consistent with the N limitation on the vegetation. Graminoids retained lower concentrations of leaf N and P than forbs in community on the N limited grassland. Consistent with our prediction, we found that the biomass fraction of graminoids declined with soil N content and aboveground production on the grassland. Different from the pattern along fertility gradients induced by N fertilization, our results showed that gr aminoids with lower internal nutrient content were able to resist low levels of nutrient availability on the natural alpine grassland when compared to forbs.

2

The impact of cattle and sheep grazing on grassland in Vel'ká Fatra National Park

Jendrisakova S., Kovacikova Z., Vargova V., Michalec M.

Journal of Water and Land Development

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2011

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no. 15

83-90

EN

The Vel'ká Fatra National Park (declared on 1 April 2002) is extending on an area of 40,371 ha and was established to protect well-preserved ecosystems. The Vel'ká Fatra (Greater Fatra) with the highest peak Ostredok (1592 m altitude) is a typical mountain territory and ranks among the highest mountain ranges in Slovakia. Grassland areas above the forest line ("hole" in Slovak) and highland relief are typical for Vel'ká Fatra where forests cover is 85% of the area. Large areas of grassland located on gently modelled ridges resulted from deforestation many centuries ago. The alpine meadows which are rich in rare plant communities cover the area of 2000 ha. In the past, these grasslands were used by cutting and grazing. Nowadays, the meadows are not mowed at all. The reasons are low numbers of ruminants in nearby farms, high cost and poor access roads that are eroded very much. Grazing with young cattle has been banned and consequently tall grasses expanded, swards thinned as well as avalanche risk increased. Currently, it is allowed to graze young cattle again, but farmers do not exploit this option very much. About 200 heifers and 2,500 sheep graze there, but only at the lowest areas of the mountains and for short periods of time. The grassland is dominated by Deschampsia caespitosa (L.) P. Beauv. and also by very rapidly expanding Calamagrostis epigejos (L.) Roth, Brachypodium pinnatum (L.) P. Beauv. and Cirsium arvense (L.) Scop. indicating a prolonged period of abandonment.

PL

Park Narodowy Vel'ká Fatra ustanowiony 1 kwietnia 2002 r. dla ochrony dobrze zachowanych ekosystemów zajmuje powierzchnię 40 371 ha. Vel'ká Fatra (Większa Fatra) z najwyższym szczytem Ostredok (1592 m n.p.m.) jest typowym obszarem górskim i zalicza się do najwyższych grzbietów górskich Słowacji. Charakterystyczne dla parku są ekosystemy trawiaste położone powyżej linii lasów ("hole" w języku słowackim), porastających 85% obszaru i wysokogórskie ukształtowanie terenu. Rozległe obszary trawiaste, usytuowane na łagodnie uformowanych grzbietach, są wynikiem wylesiania, które miało miejsce wiele wieków temu. Alpejskie łąki, bogate w zespoły rzadkich roślin, pokrywają powierzchnię 2000 ha. W przeszłości były wykorzystywane jako użytki zielone. Obecnie łąki nie są koszone. Powodem jest niewielka liczba przeżuwaczy w okolicznych gospodarstwach, wysoki koszt i uciążliwy transport na silnie zerodowanych drogach. Zakazano wypasu młodego bydła. W konsekwencji rozwinęły się zespoły wysokich traw, ruń została przerzedzona i zwiększyło się ryzyko lawinowe. Obecnie zezwala się ponownie na wypas młodego bydła, ale rolnicy nie korzystają powszechnie z tej możliwości. Wypasa się tam jedynie 200 jałówek i 2500 owiec jedynie w najniżej położonych terenach górskich przez krótki okres. Zespoły trawiaste są zdominowane przez Deschampsia caespitosa (L.) P. Beauv. i przez bardzo ekspansywne Calamagrostis epigejos (L.) Roth, Brachypodium pinnatum (L.) P. Beauv. and Cirsium arvense (L.) Scop., co wskazuje na wydłużony okres zaniechania użytkowania.

3

Trade-off of sexual and asexual recruitment in a dominant weed Ligularia virgaurea (Maxim.) In alpine grasslands (China)

Wu G., Hu T., Liu Z.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

81-86

EN

Ligularia virgaurea (Maxim.) is a typical naturally-occurring native noxious weed, widely distributed in alpine grasslands of the Tibetan Plateau, China. Three field sampling plots (30 m ' 50 m) dominated by L. virgaurea were selected to study its population colonization mode and the relationship between sexual- and clonalrecruitment in alpine meadow of the Qinghai-Tibetan Plateau, NW China. Field investigations were conducted on its soil seed bank, seed rain and the individuals of new recruitment (seedlings and ramets) to study its sexual and asexual recruitment. And, 46 individuals which produced the seeds were selected randomly to study their relationship between seed production and ramet production. Results showed that there were more ramets (26.23 ramets m[^-2]) and less seedlings (6.70 seedlings m[^-2]) and a mean value of seed rain was close to 8.04 seeds m[^-2], but the soil seed bank for this species was not found in study sites. Significantly negative correlations (r = -0.416, P <0.001) between seed number per individual and ramet number per adult individual were found for L. vrigaurea in studied alpine grasslands. Our results revealed that clonal reproduction was the main population colonization mode. In addition, there was a significantly negative relationship between seed production and ramets for this species.