The severe degradation of grasslands caused by overgrazing and other diverse human operations has become widespread in Inner Mongolia, China. In this study, the vegetations of several grasslands under different land-use conditions were compared to examine the relationships between the vegetation and the disturbance of the grassland. Floristic and life-form compositions of the stands representing the six different sites were researched by the quadrat method: a non-grazed grassland (G1), a lightly grazed grassland (G2), a path (P), an abandoned field (AF) and two artificial meadows (M1 and M2). P, AF, M1 and M2 were located in a part of the grazed grassland. AF, M1 and M2 had been tilled when planted. The dominant species found in G1 and G2 were Potentilla fragarioides, Poa annua, and Cleistogenes squarrosa. Artemisia annua, Chenopodium album, Cannabis sativa f. ruderalis and Calystegia hederacea were found in P and AF, being scarce in the grassland areas. Amaranthus retroflexus, Kochia scoparia and Setaria viridis, which are cosmopolitan weeds, were dominant only in AF. Leymus chinensis, Agropyron cristatum, Potentilla bifurca, and Potentilla tanacetifolia were widely observed across all the surveyed sites. The land-use change from grassland to path caused a decrease of perennial species and an invasion of annual species by heavy trampling. A similar vegetational change occurred with the land-use change from grassland to abandoned field due to the destruction of original vegetation by tillage. Human disturbance such as tillage and trampling also resulted in a decrease in the species with the tufted-and branchedform and an increase in the species with the erect-form. Tillage could produce a more serious impact on the grassland vegetation as compared to grazing. Flora of Inner Mongolian grasslands M. Ao et al.

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To achieve chemical control of aggressive creeping perennial weeds and avoid the disadvantages of conventional foliar applications, we established a winter soil‐injection method using soil‐active herbicides. Our previous study demonstrated the feasibility of the practical use of this method by showing that the regeneration from rhizomes or creeping root segments was inhibited by direct contact with chemicals in the soil. Then, a field trial was conducted on a population of Japanese knotweed. A stand of 148 plants growing on a railway bank was used for the experiment involving two herbicide treatments and an untreated control. In early March 2016, 1 L of chlorpropham (230 mg/L) or tebuthiuron (100 mg/L) was injected 15–25 cm deep into the base of each dead shoot clump. New shoot growth started in late April and became senescent in November. Aerial growth, determined as total shoot length and shoot number, significantly decreased throughout the season under both chemical treatments, without showing any injury symptoms (shoot dieback, leaf desiccation, or yellowing) that make unsightly views. In November, rhizome number was as low as 6 and 18% of the untreated control in the chlorpropham and tebuthiuron treatments, respectively. Sprouting and rooting abilities were reduced by treatment with tebuthiuron. Such marked reductions in rhizome number and viability, as well as the reduction in food reserves as estimated from diminished aerial growth, suggested probable substantial growth inhibition in the following season. Further improvement of the injection methodology would be attained from the consolidation of practical application data.

Increased infestation of aggressive creeping perennial weeds is a significant problem in urban vegetation management programs. These weeds produce vigorous biomass and extensive underground networks of either rhizomes or creeping roots that easily regrow from numerous buds. Foliar application of proper systemic herbicides has been a most effective way to suppress regrowth from underground creeping organs; however, killing the mature plants has disadvantages from aesthetic, economic, and ecological viewpoints. Therefore, we intended to test the possibility of soil‐injection of soil‐active herbicides for effective control of the perennial weeds which develop underground network systems. A pot experiment using combinations of seven species (seven rhizomatous and two having creeping roots) and five chemicals (four herbicides and a plant growth regulator) was conducted to assess whether and how chemicals diffused in soil affect the sprout and growth of buds on creeping organs. All the tested herbicides completely inhibited bud sprouting in one and more species when applied at median or high rates, while most of the flurprimidol‐applied segments sprouted but shoot elongation was significantly reduced. Characteristics of each herbicide were also reflected in the selectivity and features of new outgrowth. The results indicated that chemicals existing in soil were undoubtedly absorbed and affected bud activities. It is concluded that soil injection that delivers the probable soil‐active chemicals to subterranean creeping systems could be a promising technology for controlling noxious creeping perennials.

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