CAJ | 학술논문

对黄土区苜蓿人工草地群落31年时间序列生态和生产功能演替过程进行了研究，结果显示，1）人工草地群落生态功能越来越趋向于天然草地。生态功能随群落结构变化显著，其变化过程大致可分为3个演替阶段，即2～6龄紫花苜蓿草地阶段、6～31龄苜蓿人工草地向长芒草天然草地演替的过渡阶段、31龄之后的长芒草次生天然草地阶段；苜蓿种群在6龄后开始退化演替，其重要值、群落多样性指数、均匀度指数和优势度指数逐渐减小，群落结构趋向于复杂化，生态稳定性相对增大，群落演替逐步向天然植被演化。2）苜蓿人工草地群落生产功能呈“倒 V”型变化趋势。群落生产力随演替年限延长先增大后减少，6龄苜蓿草地的年生物量最大，之后，年生物量逐渐下降。年生物量与苜蓿种群重要值相关系数最高，与多样性指数的直接通径系数最高，多样性指数和年生物量二者之间的相关性随人工草地生长年限延长呈“倒 V”型变化趋势，6龄苜蓿人工草地二者相关性最高，成为人工草地“生产”和“生态”功能的转折点。3）可通过灭杂、施肥、有效利用水分和探索适宜栽培种植方式来遏止人工草地向“生态稳定性”天然草地恢复的趋势，延缓其“生产稳定性”，以保持人工草地的生产、生态可持续。
대황토구목숙인공초지군락31년시간서렬생태화생산공능연체과정진행료연구，결과현시，1）인공초지군락생태공능월래월추향우천연초지。생태공능수군락결구변화현저，기변화과정대치가분위3개연체계단，즉2～6령자화목숙초지계단、6～31령목숙인공초지향장망초천연초지연체적과도계단、31령지후적장망초차생천연초지계단；목숙충군재6령후개시퇴화연체，기중요치、군락다양성지수、균균도지수화우세도지수축점감소，군락결구추향우복잡화，생태은정성상대증대，군락연체축보향천연식피연화。2）목숙인공초지군락생산공능정“도 V”형변화추세。군락생산력수연체년한연장선증대후감소，6령목숙초지적년생물량최대，지후，년생물량축점하강。년생물량여목숙충군중요치상관계수최고，여다양성지수적직접통경계수최고，다양성지수화년생물량이자지간적상관성수인공초지생장년한연장정“도 V”형변화추세，6령목숙인공초지이자상관성최고，성위인공초지“생산”화“생태”공능적전절점。3）가통과멸잡、시비、유효이용수분화탐색괄의재배충식방식래알지인공초지향“생태은정성”천연초지회복적추세，연완기“생산은정성”，이보지인공초지적생산、생태가지속。
The ecological and productive succession process of cultivated alfalfa grassland communities which were established 31 years ago on the Loess Plateau was studied.The sown alfalfa grassland evolved with time to display more and more characteristics of natural grassland.As the community structure developed,ecologi-cal indexes changed significantly and the change process could be divided into three stages.The first stage was alfalfa dominance from 2 to 6 years.The second stage was from 6 to 31 years,during which alfalfa grassland gradually transitioned to Stipa bungeana natural grassland.The third stage was S .bungeana secondary natural grassland after 31 years.The alfalfa grassland exhibited marked retrogressive succession from 6 years after es-tablishment.At this point the alfalfa important value,community diverstiy index,evenness index and domi-nance index gradually decreased.The community structure tended to complexity,the ecological stability in-creased and the community characteristics gradually evolved towards those of natural vegetation.The herbage production initially showed an increasing trend,reached a maximum after 6 years,and then gradually declined. The annual biomass production correlated well with alfalfa contribution,while the highest direct path coeffi-cient in a path coefficient analysis linked annual biomass production and the diversity index.As sown alfalfa grassland aged,the correlation between the annual biomass and the diversity index increased and then decreased and 6 years from sowing represented a turning point for productivity and ecological succession.By removing weeds,fertilization,effective use of water and exploring appropriate cultivation practices,the succession to natural grassland and “ecological stability”could be delayed and the productive phase prolonged.