A dwarf bamboo(Pleioblastus chino) and winter browsing by Japanese hare(Lepus brachyurus) combine to limit establishment of transplanted native tree seedlings in an abandoned agricultural field

Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplanted native tree species （Quercus myrsinifolia, Quercus serrata, Aphananthe aspera, and Rhus sylvestris） by experimentally manipulating the vegetation cover, which was mainly dominated by dwarf bamboo （Pleioblastus chino）, and herbivore access to the planting sites on farmland that had been abandoned for 15 years at the start of the study. Few transplanted seedlings of any species survived under intact vegetation cover, irrespective of herbivore presence. In gaps in the vegetation cover, winter browsing by Japanese hare （Lepus brachyurus） damaged all species. However, lower browsing frequency and higher resprouting ability after grazing of the seedlings enabled both Quercus species to survive better than the other species. These results indicate that dwarf bamboo and the hare jointly limit the establishment of native trees in old fields. If active afforestation by transplanting seedlings at sites dominated by dwarf bamboo is planned, a combination of vegetation removal, selection of suitable species, and temporary seedling protection will be most effective.

Enriching plant diversity in grasslands by large-scale experimental sward disturbance and seed addition along gradients of land-use intensity

Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research.Furthermore,enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology.In grasslands,many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegeta-tion.We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands.Additionally,the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems.Here,we present details of the experimen-tal design and report results from the first vegetation survey 1 year after disturbance and seed addition.Moreover,we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity.Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany.Grasslands were under regular agricul-tural use,but varied in the type and the intensity of management,thereby representing the range of management typical for large parts of Central Europe.The disturbance treatment consisted of disturbing the top 10 cm of the sward using a rotavator or rotary harrow.Seed addition consisted of sowing a high-diversity seed mixture of regional plant species.These species were all regionally present,but often locally absent,depending on the resident vegetation composi-tion and richness of each grassland.Important Findings Seven months after sward disturbance,respective plots had significantly increased in bare soil,seedling species richness and number of seed-lings.Seed addition had increased plant species richness,but only in combination with sward disturbance.The increase in species richness,when both seed addition and disturbance was applied,was higher at high land-use intensity and low resident diversity.Thus,we show that at least the early recruitment of many species is possible also at high land-use intensity,indicating the potential to restore and enhance bio-diversity of species-poor agricultural grasslands.Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.

Interactions among dwarf bamboo, litter and consumption by small vertebrates place multiple constraints on the establishment of native tree seedlings in a Japanese agricultural landscape

Aims Faunal assemblage alterations due to anthropogenic impacts have changed herbivore-vegetation relationships in various ecosystems,but the influences of small vertebrates on revegetation processes remain unclear.In a peri-urban agricultural landscape in eastern Japan that lacks large ungulates but supports small generalist herbivores,fewer native seedlings have become established in thickets dominated by native dwarf bamboo,Pleioblastus chino(Franch.et Sav.)Makino.The mechanisms limiting tree seedling establishment are unknown.Our aim here was to evaluate the influence of interactions among the dwarf bamboo,its litter cover and small vertebrate herbivores on the micro-site conditions governing the establishment of native tree seedlings from different successional stages in an old field in temperate Japan.Methods First,seedling emergence and survival of seeded Pinus densiflora Siebold et Zucc.,Celtis sinensis Pers.,Aphananthe aspera(Thunb.)Planch.,Quercus serrata Murray,Quercus myrsinifolia Blume and Castanopsis sieboldii(Makino)Hatus.ex T.Yamaz.et Mashiba were observed in a factorial design that accounted for the presence or absence of dwarf bamboo and its litter cover,as well as the exclu-sion or access of small vertebrate fauna,in 2009 and 2010.To identify small vertebrate herbivores that reduced the emergence or survival of tree seedlings in the first experiment,reseeding experi-ments using P.densiflora,C.sinensis,A.aspera and Q.myrsinifolia were conducted by video trapping in 2011 and video and still-cam-era trapping in 2012.Important Findings The abiotic conditions under the dwarf bamboo were lethal to early-to mid-successional P.densiflora,C.sinensis,A.aspera and Q.serrata but led to better survival-although spindly growth-of late-succes-sional Q.myrsinifolia and C.sieboldii.The main consumers and the plants they found palatable differed between the bamboo thickets and the intervening gaps.Predation by mice appeared to have severely limited the emergence of all species,particularly in the bamboo thick-ets but occasionally in the gaps,whereas litter cover slightly mitigated this limitation.However,bamboo litter cover reduced the emergence of P.densiflora in the gaps.Chinese bamboo partridge(Bambusicola thoracicus Temminck),an introduced game bird,selectively and severely fed on the cotyledons-and probably seeds-of A.aspera and moderately preyed upon those of P.densiflora in the gaps.Apparent consumption of seedlings in the gaps by the Japanese hare(Lepus brachyurus Temminck)suppressed the growth of all species but apparently did not severely affect emergence and survival.Thus,the net balance of positive and negative interactions at the bamboo thicket scale(i.e.the presence of dominant dwarf bamboo cover or intervening gaps and the herbivore behaviours in these two environments)and at the microsite level(i.e.litter cover)shapes the early establishment patterns of native tree seedlings,and this balance differs among tree seedling species.