CAJ | 학술논문

以大针茅为建群种的草原是蒙古高原典型草原地带广泛分布的地带性植物群落。近几十年来，由于不合理的利用，大针茅草原出现不同程度的退化。氮素是半干旱草原植物生长的限制性因素，氮素的添加有利于退化草原的恢复，但在氮素影响下草原植物根系特征变化的相关研究很少。本研究分别选取内蒙古锡林郭勒典型草原区的轻度退化和重度退化草地，进行氮素添加实验（0，30，50，80 g／m2），研究在不同退化程度的草地中大针茅根系特征对氮素添加的响应。结果表明，在重度退化草地中，氮素的添加显著促进了大针茅的根系生长和地上部分生长，根系长度、面积、体积、深度以及地上高度均随氮素添加量的增加而显著增加，根系长度、面积、体积呈极显著正相关关系，根系深度与地上高度呈显著正相关关系；轻度退化草地中大针茅根系特征对氮素添加的响应不显著。比较2个样地，在无氮素添加的条件下，重度退化草地中大针茅的根系直径显著低于轻度退化草地；在高氮素（80 g／m2）添加条件下，重度退化草地中的大针茅根系长度、面积、体积、地上高度与根系深度显著高于轻度退化草地。重度退化草地中土壤氮素的增加，促使大针茅根系主要通过增加根系长度扩大在土壤中的空间分布。
이대침모위건군충적초원시몽고고원전형초원지대엄범분포적지대성식물군락。근궤십년래，유우불합리적이용，대침모초원출현불동정도적퇴화。담소시반간한초원식물생장적한제성인소，담소적첨가유리우퇴화초원적회복，단재담소영향하초원식물근계특정변화적상관연구흔소。본연구분별선취내몽고석림곽륵전형초원구적경도퇴화화중도퇴화초지，진행담소첨가실험（0，30，50，80 g／m2），연구재불동퇴화정도적초지중대침모근계특정대담소첨가적향응。결과표명，재중도퇴화초지중，담소적첨가현저촉진료대침모적근계생장화지상부분생장，근계장도、면적、체적、심도이급지상고도균수담소첨가량적증가이현저증가，근계장도、면적、체적정겁현저정상관관계，근계심도여지상고도정현저정상관관계；경도퇴화초지중대침모근계특정대담소첨가적향응불현저。비교2개양지，재무담소첨가적조건하，중도퇴화초지중대침모적근계직경현저저우경도퇴화초지；재고담소（80 g／m2）첨가조건하，중도퇴화초지중적대침모근계장도、면적、체적、지상고도여근계심도현저고우경도퇴화초지。중도퇴화초지중토양담소적증가，촉사대침모근계주요통과증가근계장도확대재토양중적공간분포。
Stipagrandis forms zonal plant communities widely distributed in the typical steppe region of the Mongolian plateau.In recent decades,due to the over-utilization,theS.grandisgrassland has shown different degrees of degradation.Nitrogen is a limiting factor for plant growth in semi-arid grassland.N addition is ben-eficial to the recovery of degraded grassland,but research on the influence of N addition to root characteristics of grassland plants is rarely undertaken.In order to study the response of root characteristics ofS.grandisto N addition in grassland with different degrees of degradation,two sites (lightly degraded and heavily degraded grassland)were selected in Xilingol typical grassland region of Inner Mongolia,and a 2-year N addition experi-ment was performed (0,30,50,80 g/m2 NH4NO3).In the heavily degraded grassland,N addition led to a sig-nificant increase in root growth of S.grandis.Root length,surface area,volume,root depth and above-ground height were all significantly increased with increased nitrogen input rates,and these measures of plant response were all significantly correlated.In the lightly degraded grassland,however,the root characters ofS. grandiswere not responsive to N.Comparing the two sites,root diameter in heavily degraded grassland was significantly lower than that in lightly degraded grassland when no N was added.Root length,area,volume, above-ground height and root depth in heavily degraded grassland was significantly higher than that in lightly degraded grassland under high N (80 g/m2 )conditions.In heavily degraded grassland,with increased level of soil N,the root system ofS.grandisacquires N for development by increasing root length to colonise a greater soil volume.