Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities ...Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon sources.Unlike the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown.We hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients.On the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased growth.We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output.We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon control.Important Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils.Consistent with our prediction,these effects were noticeable only when sufficient nutrients were present in the soil.Furthermore,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass.We interpret this to mean that when the amount of available nutrients is low,these nutrients are mainly used by the bacterial community.Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions,affecting plant resource allocation.展开更多
Aims Non-native invasive plants can alter soil chemistry through litter production and decomposition to facilitate their invasion.However,the important roles of these underlying processes in plant invasion remain poor...Aims Non-native invasive plants can alter soil chemistry through litter production and decomposition to facilitate their invasion.However,the important roles of these underlying processes in plant invasion remain poorly understood,particularly in tropical forest ecosys-tems.Here,we compared litter production,quality and decompos-ition of two invasive species(Broussonetia papyrifera and Cedrela odorata)and two co-occurring native species(Celtis mildbraedii and Funtumia elastica),and soil properties under them to elucidate their roles in the invasion of a tropical forest in Ghana.Methods Leaf litter production rates were determined using 36 mesh traps installed in the study area,while litter quality and soil physico-chemical properties were determined using standard protocols.A 6-month decomposition experiment using the litterbag technique was conducted to compare the decomposition rates of the species.Important Findings Litter production varied among the species and over time,with B.papyrifera producing 0.35-4.27 tons ha−1 y−1 from October to January;the other species produced 0.03^(-1).74 tons ha−1 y−1 over the same period.In the litterbag experiment,B.papyrifera recorded the lowest mass remaining(11-36%),followed by C.odorata(17-51%),F.elastica(31-55%)and C.mildbraedii(48-62%)in that order.Broussonetia papyrifera had the highest nitrogen(3.91%)and phosphorus(0.24%)but lowest lignin(12.20%)concentrations and the lowest C:N(10.87)ratio,indicating higher litter quality com-pared to the other species.Soil under B.paprifera was richest in phosphorus and nitrogen compared to the other species.Overall,our results indicate that the production of more nutrient-rich and rapidly decomposing leaf litter by B.papyrifera may constitute an important positive feedback mechanism driving its invasion and impacts in this tropical forest.展开更多
基金Sol Leshin UCLA-BGU Program,grant number 8721991.
文摘Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon sources.Unlike the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown.We hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients.On the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased growth.We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output.We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon control.Important Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils.Consistent with our prediction,these effects were noticeable only when sufficient nutrients were present in the soil.Furthermore,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass.We interpret this to mean that when the amount of available nutrients is low,these nutrients are mainly used by the bacterial community.Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions,affecting plant resource allocation.
文摘Aims Non-native invasive plants can alter soil chemistry through litter production and decomposition to facilitate their invasion.However,the important roles of these underlying processes in plant invasion remain poorly understood,particularly in tropical forest ecosys-tems.Here,we compared litter production,quality and decompos-ition of two invasive species(Broussonetia papyrifera and Cedrela odorata)and two co-occurring native species(Celtis mildbraedii and Funtumia elastica),and soil properties under them to elucidate their roles in the invasion of a tropical forest in Ghana.Methods Leaf litter production rates were determined using 36 mesh traps installed in the study area,while litter quality and soil physico-chemical properties were determined using standard protocols.A 6-month decomposition experiment using the litterbag technique was conducted to compare the decomposition rates of the species.Important Findings Litter production varied among the species and over time,with B.papyrifera producing 0.35-4.27 tons ha−1 y−1 from October to January;the other species produced 0.03^(-1).74 tons ha−1 y−1 over the same period.In the litterbag experiment,B.papyrifera recorded the lowest mass remaining(11-36%),followed by C.odorata(17-51%),F.elastica(31-55%)and C.mildbraedii(48-62%)in that order.Broussonetia papyrifera had the highest nitrogen(3.91%)and phosphorus(0.24%)but lowest lignin(12.20%)concentrations and the lowest C:N(10.87)ratio,indicating higher litter quality com-pared to the other species.Soil under B.paprifera was richest in phosphorus and nitrogen compared to the other species.Overall,our results indicate that the production of more nutrient-rich and rapidly decomposing leaf litter by B.papyrifera may constitute an important positive feedback mechanism driving its invasion and impacts in this tropical forest.
