Similarity and difference in vegetation structure of three desert shrub communities under the same temperate climate but with different microhabitats

Tao, Ye; Zhang, Yuan Ming; Downing, Alison

doi:10.1186/1999-3110-54-59

Cited by 19 publications

(12 citation statements)

References 26 publications

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“…For example, Loera et al () found that species of Ephedra occurring in particularly arid environments tend to have papery‐bracted strobili, suitable for wind‐dispersal (Hollander & Vander Wall, ). This is consistent narrow microsite preferences of some desert species of Ephedra , such as E. distachya L. (of Asia), which occurs in slightly wetter areas around sand dune bases (Tao et al, ), and many North American species, which often occur on dune tops, where they may experience less competition and can utilize their long tap roots to access deep water resources (Ickert‐Bond, personal observation). However, additional studies of Ephedra and other species are needed to compare seed morphology, dispersal patterns, and distances from microsites to better understand the relationships between long distance dispersal in deserts and microsite preferences and access (e.g., Guo et al, ).…”

Section: Dispersal Hypotheses and Hypothesis Testing Within And Amongsupporting

confidence: 72%

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

Harris

Ickert‐Bond

Rodríguez³

2018

J of Sytematics Evolution

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Here, we review progress and prospects to explicitly test for long distance dispersal biogeographic events. Long distance dispersal represents a “jump” across some kind of barrier, such as a topographic feature or a zone of unsuitable climate and may include repeated jumps, or stepping‐stone dispersals. Long distance dispersals were considered integral for explaining the organization of biodiversity at large and small scales by early biogeographers, such as Darwin and Wallace. Darwin, Wallace, and others envisioned that long distance dispersals were predictable events because the vectors for dispersal, such as animals, winds, and currents, behaved in non‐random ways. However, these early biogeographers found that dispersal was hard to observe, and, later, with the advent of the theory of Continental Drift, vicariance became regarded as a better scientific explanation for the arrangement of biodiversity, because it represented a falsifiable hypothesis. Thus, long distance dispersal was reduced to a nuisance parameter in biogeography; a random possibility that could never fully be ruled out in a scenario in which evidence supported vicariance. Today, there is strong interest to more fully integrate long distance dispersal into understanding the assembly and organization of biodiversity on earth. In this review, we discuss progress and prospects for explicitly testing long distance dispersal hypotheses including through uses of molecular, morphological, paleontological, and informatics methods. We focus on hypothesis testing of long distance dispersals involved in the assembly of the flora of North America, which is a robust preliminary study system on account of its extant and extinct biodiversity being well‐catalogued.

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Section: Dispersal Hypotheses and Hypothesis Testing Within And Amongsupporting

confidence: 72%

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

Harris

Ickert‐Bond

Rodríguez³

2018

J of Sytematics Evolution

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“…At the same time, high standard deviations indicate a high variability within each pasture due to varying topography and variability of rainfall. Nonetheless, the observed herbage offers were relatively low compared with studies in similar climatic contexts elsewhere (Sankey et al 2009;Behnke et al 2011;Sasaki et al 2012;Tao et al 2013), whereas the nutritive values were relatively high and constant throughout the studied years. Especially the latter observation is surprising, as in Central Asia the nutritive value of natural vegetation varies strongly with season and has been reported to be particularly low during winter and early spring (Yoshihara et al 2008;Glindemann et al 2009;Olson et al 2010;Sasaki et al 2012;Schönbach et al 2012;Bösing et al 2014;Ding et al 2014;Ma et al 2014;Müller et al 2014).…”

Section: Quantity and Quality Of Herbagementioning

confidence: 68%

Spatio-temporal patterns of herbage availability and livestock movements: A cross-border analysis in the Chinese-Mongolian Altay

et al. 2016

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Due to increasing population and the recent implementation of policies to intensify the use of land and water resources, the transhumant pastoral systems in the Chinese-Mongolian Altay-Dzungarian region are rapidly changing, leading to modifications of herd size, herd composition and spatial distribution of livestock grazing. This may have major consequences for the supply and quality of rangeland biomass. Despite similar topographic settings, the socio-political framework for Chinese and Mongolian pastoralists differs significantly, leading to differences in rangeland utilization. To substantiate these claims, the long-distance transhumance routes, frequency of pasture changes, daily grazing itineraries and size of pastures were recorded by means of GPS tracking of cattle and goats on 1,535 (China) and 1,396 (Mongolia) observation days. The status quo of the main seasonal pastures was captured by measuring the herbage offer and its nutritive value in 869 sampling spots. In the Altay-Dzungarian region, small ruminant herds covered up to 412 km (Mongolia) and grazed on up to nine pastures per year (China). In Mongolia, the herds' average duration of stay at an individual pasture was longer than in China, particularly in spring and autumn. Herbage allowance at the onset of a grazing period (kg dry matter per sheep unit and day) ranged from 34/17 to 91/95 (China/Mongolia). Comparing crude protein and phosphorous concentrations of herbage, in China, the highest concentrations were measured for spring and summer pastures, whereas in Mongolia, the highest concentrations were determined for autumn and winter pastures. Based on our data, we conclude that regulation of animal numbers and access to pastures seemingly maintained pasture productivity in China, especially at high altitudes. However, this policy may prohibit flexible adaptation to sudden environmental constraints. In contrast, high stocking densities and grazing of pastures before flowering of herbaceous plants negatively affected rangeland productivity in Mongolia, especially for spring and summer pastures.

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“…A few similar studies have been carried out previously in this area (Tao et al, 2013;. Typically, in these studies, the vegetation type (or its floristic composition) changes markedly in different microhabitats.…”

Section: Discussionmentioning

confidence: 90%

Patterns of biomass allocation in Haloxylon persicum woodlands and their understory herbaceous layer along a groundwater depth gradient

2017

Forest Ecology and Management

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a b s t r a c tTo investigate above-and belowground biomass allocation patterns and the relationship of root distribution between different functional groups (shrubs vs. herbs) along a groundwater depth gradient, an experiment was carried out in a Haloxylon persicum woodland. Four sites were selected along the groundwater depth gradient. At each site, five sample plots (20 Â 20 m) and 15 subplots (1 Â 1 m) were established for a vegetation inventory of Haloxylon persicum and the herbaceous layer. The vegetation inventory included plant density, canopy coverage, height, and basal stem diameter of H. persicum. Allometric equations were established for H. persicum based on the biomass of 22 excavated trees, which were then applied to inventory data to provide stand estimates of aboveground biomass (AGB), belowground biomass (BGB), and total biomass (TB) of H. persicum. The AGB of the herbaceous layer was measured in subplots (1 Â 1 m) and BGB was excavated and measured to a depth of 100 cm at 10-cm intervals. Our results indicated that the BGB-to-AGB ratio at the community level in the herbaceous layer increased notably along the gradient of declining groundwater depth. The depth of the soil horizon that contained 65% of the root surface area and 85% of the root biomass was shallower (0-2.5 m) in the deep end of the groundwater depth gradient than in the shallow end (0-3 m) of the gradient. H. persicum adjusted root distribution to capture water in the upper soil layers in response to the decline in groundwater depth. However, this adjustment was not sufficient to compensate for the decline in the water table: the BGB-to-AGB ratio showed no significant increase as AGB declined. On the contrary, herbaceous plants seemed better adapted to changes in the water table by effectively adjusting their BGB-to-AGB ratio. Use of BGB-to-AGB ratios that are specific to groundwater tables will significantly improve our estimates of BGB carbon stocks in these woodlands. Considering the scarcity of information on biomass stocks and partitioning in desert woodlands, our results might be applicable to other desert regions in Central Asia dominated by H. persicum.

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Similarity and difference in vegetation structure of three desert shrub communities under the same temperate climate but with different microhabitats

Cited by 19 publications

References 26 publications

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

Long distance dispersal in the assembly of floras: A review of progress and prospects in North America

Spatio-temporal patterns of herbage availability and livestock movements: A cross-border analysis in the Chinese-Mongolian Altay

Patterns of biomass allocation in Haloxylon persicum woodlands and their understory herbaceous layer along a groundwater depth gradient

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