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Nutrient Uptake and Allocation by Plants in Recent Mounds Created by Subterranean Rodent, Plateau Zokor Eospalax baileyi

Wu R., Wei X., Liu K., Zhong M., Liu Y., Pan D., Shao X.

Polish Journal of Ecology

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2017

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Vol. 65, nr 1

132--143

EN

To understand the nutrient absorption and adaptability of plant species that initially colonize mounds and the influences of the plateau zokor on the diversity of the plant community after 4 years' period, a series of experiments was conducted in an alpine meadow on the Qinghai-Tibetan Plateau. The contents of C and N and the flow of N in pioneer species were measured and tracked using the 15N isotope tracer method, and the species diversity on 4-year-old mounds was investigated. The results showed that (1) plateau zokors could influence the plant species on the mounds by creating gaps in the grassland; (2) Elymus nutans and Elsholtzia feddei, with high rates and efficiencies of nutrient absorption and transportation, were more competitive on the newly formed mounds than other species; (3) Elymus nutans played a dominant role in the plant community of the mounds; and (4) plateau zokors did not change the plant diversity after 4 years' period. These findings indicated that species colonizing the mounds experienced a process of competition when gaps were created by the rodents, that species with greater capabilities for resource acquisition and utilization had stronger competitiveness and vice versa, and that after a few years, the plant diversity on the mounds was almost similar to that of the undisturbed grassland.

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Determinants of plant species richness in different wetland types along a hydrological gradient: implication for conservation

Shi J., Ma K., Wang J., Zhang Y., Zhao J.

Polish Journal of Ecology

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2013

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Vol. 61, nr 4

645--654

EN

The loss of biodiversity caused by wetland degradation is a hot issue in ecology. It is known that hydrological degradation is the primary reason resulting in wetland degradation, but little is known about the relationship between plant species richness and environmental factors in different wetland types along a hydrological gradient. According to the gradient from high to low water level, wetland remnants in the Sanjiang Plain of northeast China were classified into three wetland types, which were permanently inundated marshes (PIM), seasonally inundated marshes (SIM) and wet meadows (WM) respectively. In this paper, we aimed to identify the determinants of plant species richness in the three wetland types and discern the transition of the determinants along a hydrological gradient. Plant species richness as well as area, habitat heterogeneity and resource availability was investigated in 51 wetland remnants, which were composed of 6 PIM, 25 SIM and 20 WM. Averagely, the area of wetland remnants occupied by PIM, SIM and WM was 0.35 ± 0.17 ha, 2.81 ± 2.88 ha and 1.34 ± 1.18 ha respectively. Aggregating the species in each wetland type, there were 67, 244 and 170 species recorded in PIM, SIM and WM. The determinants of species richness varied in different wetland types: standing water depth in PIM, area and water heterogeneity in SIM, and soil fertility and area in WM. With the decreasing water level, the influence of hydrological condition on species richness in the three wetland types declined while the impact of area and soil fertility gradually increased. Thus, hydrological condition was probably responsible for the transition of the determinants of species richness in different wetland types. Moreover, the habitat specialists of wetland would be lost when PIM or SIM degraded to WM. In order to conserve and restore plant diversity, specific measures should be taken including preventing area loss for all wetland remnants, managing the hydrological process for PIM and SIM, and regulating soil nutrient for WM.

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Simulated herbivory limits phenotypic responsesTo drought in Convolvulus demissus Choisy(Convolvulaceae)

Quezada Iván M., Gianoli Ernesto

Polish Journal of Ecology

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2006

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Vol. 54, nr 3

499-503

EN

Drought and herbivory are important stress factors for plants. When plants are subjected to any form of stress, phenotypic responses are elicited to reduce damage. Responses to drought include a decrease in leaf area and aerial biomass, and an increase in root/shoot ratio of biomass allocation. If plants are subjected to drought and herbivory at the same time, constrained responses are expected due to resource limitation. In a greenhouse experiment we analyzed the effect of simulated herbivory on the ability to respond to drought stress in seedlings of the Chilean perennial herb Convolvulus demissus (Convolvulaceae), which in natural populations may experience water deficit during dry summers as well as grazing by mammals. Plants subjected to drought showed the phenotypic responses theoretically expected. In contrast, plants subjected to a combined drought + herbivory treatment did not show those responses, being phenotypically similar to control plants. It is suggested that herbivory may limit responses to drought in C. demissus, hence magnifying the negative consequences on plant fitness of such abiotic factor.