EGI OpenIR
基于氢氧同位素示踪法探测新疆防护林、 农作物、 核桃树体系水分来源与竞争
Alternative TitleApplication of Hydrogen and Oxygen Isotopes to Study the Source of Water and Competition in Shelter-Forest-Crop Systems in the Xinjiang Oasis
郭辉
Subtype硕士
Thesis Advisor赵英
2019-06-30
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline农学硕士
Keyword杨树防护林 玉米 核桃树 棉花 氢氧同位素 生态平衡 Shelter poplar Cotton Walnut Corn Hydrogen isotope Oxygen isotope Ecological balance
Abstract新疆干旱区水资源缺乏,风沙侵蚀严重,农田防护林作为绿洲生态保护屏障,防风固沙,在该区生态系统中扮演着重要角色。 然而,传统上,间套种植的人工林对农田作物存在水分养分的竞争,导致农作物产量下降。因此由人为因素导致大量防护林衰退、 死亡。本研究通过运用氧同位素焦点法与 SIAR 模型,结合人工添加氘同位素,量化本区间套作的防护林与人工经济林根系分布和主要用水范围, 分析潜在竞争区域及防护林对农作物水分负面影响程度。研究结果对新疆绿洲地区防护林的合理管护与绿洲生态平衡有重要意义。策勒绿洲大水漫灌的杨树-玉米-核桃树体系中,研究发现:玉米在拔节期与吐丝期主要吸收浅层土壤水分(0-40 cm) , 贡献率分别为 60%、 58%;核桃树水分主要来源于玉米根部之下土壤中, 7 月和 8 月根系主要吸水区间 80-100 cm、60-80cm, 40 cm 土层以下贡献率为 75%,并且根系分布范围超过深 200 cm,可延申到距树干 5m 之外。但其有大约 35%水分来自土壤表层(0-40 cm),其巨大的耗水量对玉米的水分竞争不可避免;杨树根系水分利用具有很强的可塑性,漫灌前主要利用距地表 140 cm 之下土层水分(140-200 cm 贡献率为 43%,主要水分利用层为 140-160 cm),漫灌后用水量逐渐向上迁移(0-40 cm 土层贡献率为36%, 100-120 cm 为主要吸水区间)。在莫索湾绿洲滴灌的棉花-杨树试验中,结果表明:棉花在膜下滴灌方式下主要吸收表层土壤水,蕾期主要利用 0-20 cm 的土壤水,花铃期主要利用 20-40cm 土壤水;而杨树在漫灌前主要利用深层 40 cm 以下土壤水,在灌溉后水分来源虽有向上迁移倾向,但仍大约有 60%的水分源于土壤 40 cm 以下。 δD 同位素示踪发现杨树根系垂向可生长到土层 200-400 cm 范围,水平延伸至棉田内 5-8m,在 5 m 内棉花必定面临着杨树的水分与养分竞争。本文通过应用人工添加氘同位素与自然稳定同位素,克服了传统上自然同位素无法准确量化干旱区植物根系分布与误差较大的不足,最终较为精确的量化植物水分利用与根系分布,对之后同位素在生态水文学中的应用具有借鉴意义。
Other AbstractIn the arid region of Xinjiang, water resources are scarce and wind-sand erosion isserious. As an oasis ecological protection barrier, farmland shelter forest plays animportant role in the ecosystem of the region. Traditionally, however, intercroppedplantations compete for water and nutrients in farmland crops, resulting in a decline incrop yields. As a result, a large number of shelterbelts have declined and died due tohuman factors. In this study, the root distribution and main water area of intercroppedshelterbelts and artificial economic forests were quantified by using oxygen isotopefocus method and SIAR model combined with deuterium isotope addition, and thenegative effects of potential competition areas and Shelterbelts on crop water wereanalyzed. The results are of great significance to the rational management and protectionof shelterbelts and the ecological balance of oases in Xinjiang oasis region.In Cele oasis’ poplar (Populus)-corn (Zea.) -walnut (Juglans) agroforest system, weevaluate whether walnut and poplar developed towards deeper soil layers or extendedbelow the corn-rooting zone. We found the main depth water uptake of cornwas shallowsoil strata in jointing period and silking-filling period, walnuts focused on deep horizonsbelow the corn rooted soil volume, and poplars showed great plasticity in deep andshallow soil strata depending on soil moisture status. And walnuts and poplars root canrespectively extend 200 and 400 cm deep soil.In Mosuowan oasis’ poplar-cotton (Gossypium) agroforest system. The shelterbelts,constructed from poplar, compete with crops for water, and thereby cause economicloss for farmers. We used direct inference of a stable oxygen isotope (δ18O) and theSIAR model to analyse the most common water uptake depth water uptake depth ofcotton at different growth stages under mulched drip irrigation, and poplar’s waterutilization strategy before and after irrigation. Results showed cotton primarily relieson soil water from a depth of 0-40 cm, taking up water from the 0-20 cm layer in budstage, and from the 20-40 cm layer in boll stage. However, poplar mainly utilized soil water from below 40 cm, and the depth of soil water used by poplar graduallydecreased after irrigation. We identified poplar roots in soil at 200-400 cm deep,extending 5-8 m into the cotton field. This reflected that poplar must compete for waterand nutrition within this 5 m, especially the inner 3 m. This research increases ourunderstanding of potential areas of water competition between poplar and crops andsuggests reasonable management for shelter forest to maintain oasis ecologicalbalance.In this research, by using artificial addition of deuterium isotopes and natural stableisotopes, we overcome the shortcomings of traditional natural isotopes that can notaccurately quantify the root distribution and eliminate the huge variance of plants inarid areas, and finally quantify the water use and root distribution of plants moreaccurately, which has reference significance for the application of isotopes ineco-hydrology.
Subject Area水土保持与荒漠化防治
Language中文
Document Type学位论文
Identifierhttp://ir.xjlas.org/handle/365004/15352
Collection中国科学院新疆生态与地理研究所
研究系统
Affiliation中国科学院新疆生态与地理研究所
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
郭辉. 基于氢氧同位素示踪法探测新疆防护林、 农作物、 核桃树体系水分来源与竞争[D]. 北京. 中国科学院大学,2019.
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