This paper studies the effects of land cover changes on distributions andcirculations of nutrients in a terrestrial ecosystem, taking Jianou Niukenglong Grassland EcosystemExperimental Station as a case study. During ...This paper studies the effects of land cover changes on distributions andcirculations of nutrients in a terrestrial ecosystem, taking Jianou Niukenglong Grassland EcosystemExperimental Station as a case study. During a two year experiment from 1994 to 1996, the land covertypes were changed from desert slopeland to grasslands, in particular, Chamaecristarotundifolia(pers) green + Pasdum thunbergii and Glycine max var. + Pasalum thunbergii. In order tostudy land cover change effects on nutrients in the terrestrial ecosystem, we selected organicmaterials (OMs), nitrogen (N), phosphorus (P), potassium (K) and aluminum (Al) to study theirchanges in total soil nutrient concentrations, nutrient reserves in soil, distributions andreservations of nutrients in distinct grassland communities and overall nutrient contents reservedin terrestrial ecosystem, and their circulation with land cover change. The experimental resultsindicate that with the increase of vegetation coverage, the total concentrations of N, P and K growrapidly in the soil, but that of Al decreases markedly. The increases of the total concentrations ofN, P and K were mainly the consequences of changes of the factors that affect soil evolution, e.g.,soil moisture, and changes of soil evolution processes, e.g., weathering rate and the decrease ofsoil erosion. These changes were caused by land coverage growth from desert slopeland to grassland.With the change of the land cover types and the increase of land coverage, the activity of Alaccelerated as well, and the vertical penetration and lateral penetration of Al have been increased.Therefore, the loss of Al within the experimental terrestrial ecosystem was inevitable, and thetotal concentration and reserve of Al in soil have become smaller and smaller, in spite of thegrowth of grass absorbing some amounts of Al. The Al reserve has increased in vegetation, but it hasdeclined in total terrestrial ecosystem. Land cover change also affects the circulations ofnutrients in the terrestrial ecosystem and for the purpose of study on nutrient circulations, wechoose to study plant absorption, litter and reservation of nutrients to establish an index toindicate the situations of nutrient circulations within terrestrial ecosystems. The results indicatethat in the two land cover types (two grassland ecosystems), the sequence of nutrient circulationindices are N > K > P > Al in Chamaecrista rotundifolia(pers) green + Pasalum thunbergii and P > N >K > Al in Glycine max var. + Pasalum thunbergii. On the basis of the study, we can conclude thatland cover change affects both distributions and circulations in the terrestrial ecosystem, and thatdifferent changes have distinct influences on distributions and circulations. Some nutrients wereaffected differently in some contents.展开更多
基金Key project of Institute of Geographic Sciences and Natural Resources Research for basic research No.CXIOG-E01-01+2 种基金 Natural Science Foundation of Henan Province No.031105170 Key Young Teachers Program in Colleges and Universities of Henan Province
文摘This paper studies the effects of land cover changes on distributions andcirculations of nutrients in a terrestrial ecosystem, taking Jianou Niukenglong Grassland EcosystemExperimental Station as a case study. During a two year experiment from 1994 to 1996, the land covertypes were changed from desert slopeland to grasslands, in particular, Chamaecristarotundifolia(pers) green + Pasdum thunbergii and Glycine max var. + Pasalum thunbergii. In order tostudy land cover change effects on nutrients in the terrestrial ecosystem, we selected organicmaterials (OMs), nitrogen (N), phosphorus (P), potassium (K) and aluminum (Al) to study theirchanges in total soil nutrient concentrations, nutrient reserves in soil, distributions andreservations of nutrients in distinct grassland communities and overall nutrient contents reservedin terrestrial ecosystem, and their circulation with land cover change. The experimental resultsindicate that with the increase of vegetation coverage, the total concentrations of N, P and K growrapidly in the soil, but that of Al decreases markedly. The increases of the total concentrations ofN, P and K were mainly the consequences of changes of the factors that affect soil evolution, e.g.,soil moisture, and changes of soil evolution processes, e.g., weathering rate and the decrease ofsoil erosion. These changes were caused by land coverage growth from desert slopeland to grassland.With the change of the land cover types and the increase of land coverage, the activity of Alaccelerated as well, and the vertical penetration and lateral penetration of Al have been increased.Therefore, the loss of Al within the experimental terrestrial ecosystem was inevitable, and thetotal concentration and reserve of Al in soil have become smaller and smaller, in spite of thegrowth of grass absorbing some amounts of Al. The Al reserve has increased in vegetation, but it hasdeclined in total terrestrial ecosystem. Land cover change also affects the circulations ofnutrients in the terrestrial ecosystem and for the purpose of study on nutrient circulations, wechoose to study plant absorption, litter and reservation of nutrients to establish an index toindicate the situations of nutrient circulations within terrestrial ecosystems. The results indicatethat in the two land cover types (two grassland ecosystems), the sequence of nutrient circulationindices are N > K > P > Al in Chamaecrista rotundifolia(pers) green + Pasalum thunbergii and P > N >K > Al in Glycine max var. + Pasalum thunbergii. On the basis of the study, we can conclude thatland cover change affects both distributions and circulations in the terrestrial ecosystem, and thatdifferent changes have distinct influences on distributions and circulations. Some nutrients wereaffected differently in some contents.
