Seed rain and soil seed bank compensatory roles on Nassella tenuis(Phil.)Barkworth seedling recruitment in ungrazed and grazed sites  

作　　者：Cintia Vanesa LEDER Dianela Alejandra CALVO Guadalupe PETER 

机构地区：[1]Universidad Nacional de Río Negro,Sede Atlántica,Centro de Estudios Ambientales desde la NorPatagonia(Center of Environmental Studies from North Patagonia(CEANPa),National University of Río Negro),Viedma 8504,Argentina [2]Universidad Nacional de Río Negro,Sede Atlántica,Centro de Estudios Ambientales desde la NorPatagonia-National Council of Scientific and Technical Research(CONICET)(Center of Environmental Studies from North Patagonia(CEANPa),National University of Río Negro),Viedma 8504,Argentina

出　　处：《Journal of Arid Land》2022年第5期550-560,共11页干旱区科学（英文版）

基　　金：supported by the National University of Río Negro(PI 40-C-654,PI 40-C-873)。

摘　　要：In semi-arid lands,vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix.Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation and soil compaction.Nevertheless,some species with anchorage mechanisms in their seeds might overcome this,such as Nassella tenuis(Phil.)Barkworth.This is an important species in grazing paddocks because it has an intermediate palatability and its relatively tolerant to grazing.These characteristics allow N.tenuis to increase its abundance in grazed sites.Our objective was to assess how grazing affects the key palatable species from seeds to seedlings:i.e.,seed rain,soil seed bank,and seedling recruitment in different microsites along a windward-leeward transect across shrub canopy.We hypothesized that:(1)the negative effects of grazing on N.tenuis fructification are reflected in its seed rain,soil seed bank,and seedling recruitment,especially in interpatches;(2)Nassella tenuis seed rain reduction,soil compaction by cattle in grazed sites,and removal of seeds by wind decrease its soil seed bank,especially in microsites exposed to the predominant wind;and(3)the decrease in N.tenuis soil seed bank and cover increase in annual species in grazed sites have negative effects on its seedling recruitment,especially in microsites exposed to predominant wind.We placed seed traps,collected soil samples,and monitored seedling recruitment in different locations around shrub canopy to address our hypotheses.Also,we established a manipulative experiment in which we sow N.tenuis seeds and followed its recruitment in different microsites.We compared the seed rain,soil seed bank,natural seedling recruitment,and sown seeds recruitment of N.tenuis between grazed and ungrazed sites.We analyzed differences between microsites along a windward-leeward transect across shrubs patches.Seed rain and soil seed bank had the same density in patches and interpatches both in ungrazed and grazed sites.But seed rain was higher,and soi

关 键 词：seed rain soil seed bank seedling recruitment MICROSITES GRAZING 

分 类 号：Q948[生物学—植物学]