Community disassembly and invasion of remnant native grasslands under fluctuating resource supply

1. Native vegetation fragments embedded in anthropogenic landscapes are increasingly threatened by land-use intensification. Managing disturbance regimes and nutrient inputs may help maintain species diversity in such remnants. Yet it is unclear the extent to which changes in resource availability due to reduced capture by resident plants and/or increased supply rates may trigger native community disassembly and exotic invasions. 2. We examined how mowing disturbance and N fertilizer addition affected plant community recovery after a burning event in a remnant corridor of tussock pampa grassland in Argentina. The percentage cover and richness of native and exotic plant functional groups were monitored over four years. According to the ‘fluctuating resource theory’, we expected invasion to be highest when both light and N availability were increased simultaneously. 3. Mowing delayed recovery by dominant C4 tussock grasses and promoted subordinate, native C3 grasses and exotic legumes, th...

1. 嵌入人为景观（anthropogenic landscapes）中的本土植被片段（native vegetation fragments）正日益受到土地利用集约化（land-use intensification）的威胁。对干扰制度（disturbance regimes）与养分输入（nutrient inputs）进行管理，或有助于维持此类残存片段中的物种多样性（species diversity）。然而目前尚不清楚，因本土植物对资源的捕获能力下降以及/或者养分供给速率提升所导致的资源可获得性变化，会在多大程度上触发本土群落解体（community disassembly）与外来物种入侵（exotic invasions）。2. 我们针对阿根廷一处丛生禾草潘帕斯草原（tussock pampa grassland）残存廊道（remnant corridor）展开研究，探究了刈割干扰（mowing disturbance）与氮肥添加（N fertilizer addition）如何影响火烧事件（burning event）后的植物群落恢复（plant community recovery）。研究持续四年，监测了本土与外来植物功能群（plant functional groups）的盖度百分比（percentage cover）与物种丰富度（richness）。依据波动资源理论（fluctuating resource theory），我们预期当光照与氮素可获得性同时提升时，外来物种入侵程度将达到最高。3. 刈割延缓了优势C4丛生禾草的恢复进程，并促进了从属地位的本土C3禾草与外来豆科植物的生长，th...