沙漠公路防护林主要植物种凋落物的分解特征

发布时间：2018-01-14 22:34

本文关键词：沙漠公路防护林主要植物种凋落物的分解特征　出处：《新疆大学》2017年博士论文　论文类型：学位论文

【摘要】：塔里木沙漠公路沿线气候条件极端干旱、水资源匮乏、地下水矿化度高、风沙活动强烈、沙丘流动性极强。塔里木沙漠公路作为联通新疆南北疆的交通要道,是世界上穿越流动沙漠最长的等级公路。沙漠公路两侧建立了就地利用高矿化度地下水滴灌,以高抗逆性的柽柳属(Tamarix Linn.)、沙拐枣属(Calligonum L.)和梭梭属(Haloxylon Bunge)灌木和小乔木为主要造林树种的生物防沙体系,即塔里木沙漠公路防护林。塔里木沙漠公路防护林所处的特殊地理环境,使得防护林凋落物分解所释放的养分成为植物营养和土壤肥力的主要来源。本文以塔里木沙漠公路防护林内乔木状沙拐枣(Calligonum arborescens)、梭梭(Haloxylon ammodendron)和多枝柽柳(Tamarix ramosissima)的凋落物为研究对象,于2012年~2014年通过野外定点监测、原位分解试验、定点控制试验和室内凋落物样品分析,研究了塔里木沙漠公路防护林三种主要植物种凋落物的凋落量及其组成随定植年限增加的动态变化特征;分析了不同凋落物类型、不同定植年限防护林地、不同林龄凋落物和不同控制措施对凋落物的质量残留率、分解速率、分解过程中元素(C、N、P、K、Ca、Mg、木质素和纤维素)及元素比值动态变化特征的影响。揭示了塔里木沙漠公路防护林凋落物的凋落动态,探讨了控制措施对凋落物分解的影响;阐明了塔里木沙漠公路防护林凋落物分解过程、养分迁移模式及主要影响因素。主要结论如下:塔里木沙漠公路1995年、1998年、2001年、2004年和2006年定植防护林的年总凋落量分别为7.93 t·hm-2、6.19 t·hm-2、10.54 t·hm-2、9.10 t·hm-2、8.31 t·hm-2。各定植年限防护林三种植物的年凋落量均以柽柳最高,且秋季最高。凋落物组成均以梭梭同化枝、柽柳枝和沙拐枣同化枝的凋落量最高,占年总凋落量的70.58%~88.93%。不同定植年限防护林,总凋落量和主要凋落组分凋落量的月动态趋势皆呈三峰型,峰值出现在3~5月、7月、9~11月,最高值均出现在11月。其余凋落物组成呈不规则变化且峰值出现的时间有所差异,梭梭老枝和柽柳叶为5~7月,梭梭果为9~10月,沙拐枣果为6~7月,柽柳花和沙拐枣花凋落在5~8月。沙漠公路防护林组成物种的遗传和生态学特性、生理过程和气候条件影响凋落量及其组成的凋落动态。在塔里木沙漠公路不同定植年限防护林地,三种凋落物的分解速率从高到低分别为多枝柽柳枝(0.24~0.32 g·g-1·a-1),乔木状沙拐枣同化枝(0.17~0.23 g·g-1·a-1),梭梭枝(0.13~0.18 g·g-1·a-1)。三种凋落物分解速率最低值均出现在1995a防护林地;分解速率最高值,多枝柽柳枝和乔木状沙拐枣同化枝出现在2004a防护林地,梭梭枝出现在2001a防护林地。防护林定植年限通过凋落物分解的微环境直接或间接影响凋落物分解。凋落物初始C、P、K和Mg含量是分解前期的主要控制因子;初始木质素、纤维素含量,C/N和N/P比值是分解中期和后期的主导因子。在720d的分解过程中,三种凋落物的C元素呈净释放模式,N和P元素呈富集-释放模式,K元素呈释放-富集模式,梭梭枝和乔木状沙拐枣同化枝的Ca和Mg元素呈净富集模式,多枝柽柳枝的Ca和Mg元素呈释放-富集模式。木质素和纤维素含量呈先升高后降低的变化趋势,木质素在分解后期低于初始浓度,纤维素始终高于初始浓度。沙漠公路防护林凋落物的元素迁移动态主要受到凋落物基质质量、元素自身特性、分解阶段和分解环境等的综合影响。不同控制措施以及不同林龄凋落物的地表和埋深处理,凋落物分解速率最高为梭梭同化枝,多枝柽柳枝次之,最低为乔木状沙拐枣同化枝。不同控制措施对凋落物分解速率的影响有所差异,对照组乔木状沙拐枣同化枝、梭梭同化枝和多枝柽柳枝凋落物分解速率分别为0.53 g·g-1·a-1、0.94 g·g-1·a-1、0.55 g·g-1·a-1。各控制措施中,沙埋10cm三种凋落物的分解速率(0.92~1.69 g·g-1·a-1)最高,矿化度29.7g·L-1水灌溉的分解速率(0.31~0.54 g·g-1·a-1)最低。沙埋(0.69~1.69 g·g-1·a-1)、灌水周期7d(0.69~1.34 g·g-1·a-1)、施用磷钾复合肥(0.57~1.25 g·g-1·a-1)和淡水灌溉(0.59~1.12 g·g-1·a-1)显著提高三种凋落物的分解速率。控制措施通过改变凋落物分解的微环境从而影响凋落物分解速率,水分是主要影响因素。凋落物的初始N含量和C/N、木质素/N比值是不同控制措施下凋落物分解速率的主要控制因素,凋落物初始养分含量能较好的预测初期分解速率,凋落物难分解物质是控制后期分解速率的主要因素,不同控制措施下凋落物分解各阶段主要控制因素有所差异。凋落物420d的分解过程中,不同控制措施对凋落物分解过程中元素迁移模式的影响有所异同。其中,淡水灌溉处理下乔木状沙拐枣同化枝和多枝柽柳枝在分解中后期呈现出P富集。高矿化度水灌溉处理下梭梭同化枝和多枝柽柳枝在分解中后期呈现出Ca富集。沙埋处理下乔木状沙拐枣同化枝在分解前期呈现出N富集,沙埋10cm处理下三种凋落物呈现出P富集。施用氮肥处理下三种凋落物呈现出N富集,梭梭同化枝呈现出Ca富集。施用磷钾复合肥处理下乔木状沙拐枣同化枝在分解前期和中期呈现出N富集,三种凋落物皆呈现出P和K富集。灌水周期处理下乔木状沙拐枣和梭梭同化枝呈现出Mg释放。覆膜处理下多枝柽柳枝呈现出P释放;梭梭同化枝呈现出Ca富集。控制措施在一定程度上促使元素出现了富集现象,增加了凋落物的养分归还量。分解过程中木质素含量呈上升-下降趋势,因凋落物质量和控制措施的作用在不同时间出现下降的拐点,乔木状沙拐枣同化枝和多枝柽柳枝在分解后期低于初始值,梭梭同化枝木质素始终高于初始值;三种凋落物的纤维素含量呈波动上升趋势且始终高于初始值。不同林龄凋落物,7a乔木状沙拐枣和梭梭同化枝的分解速率最高,15a多枝柽柳枝凋落物分解速率最高。不同林龄凋落物的分解速率,初始C和N含量为分解前期主要限制因素,木质素和纤维素为分解后期主导因素。不同林龄三种凋落物的C、P、K和Mg元素皆呈释放模式,N元素主要呈释放模式,Ca元素主要呈富集-释放模式。各林龄三种凋落物的木质素含量呈上升-降低趋势,因凋落物类型的差异,乔木状沙拐枣同化枝在分解120d后低于初始值,梭梭同化枝和多枝柽柳枝始终高于初始值;纤维素含量呈波动上升趋势且始终高于初始值。本研究表明,在极端干旱的沙漠人工防护林,凋落物初始化学性质是凋落物分解速率的主要内在决定因素,水分和养分条件影响着凋落物的分解速率和养分归还。本文研究结果不仅对揭示特殊生境下沙漠人工防护林凋落物的凋落动态、分解速率和养分循环等有重要的理论意义,而且为沙漠人工防护林土壤性质的改善、土壤肥力的提高,防护林稳定和可持续发展管护措施的优化提供了数据支撑和科学依据。
[Abstract]:Climatic conditions along the Tarim desert highway of extreme drought, shortage of water resources, groundwater with high mineralization, sand dune activity is strong, liquidity is very strong. The Tarim desert highway as Unicom northern South Xinjiang traffic hub, is the world's longest flow across the desert. The desert road on both sides of the road were established using local high salinity groundwater drip irrigation, with high resistance of Tamarix (Tamarix Linn.), Calligonum (Calligonum L.) and Haloxylon (Haloxylon Bunge) of shrubs and small trees as the main afforestation tree species in biological defense system, namely the Tarim Desert Highway Shelterbelt. The special geographical environment of Tarim Desert Highway Shelterbelt in the making of protective forest litter substances released by the decomposition of nutrients has become a major source of plant nutrition and soil fertility. The Tarim desert highway shelter forest Calligonum arborescens (Calligonum arborescens), Soso (Haloxylon ammodendron) and tamarixramosissima (Tamarix ramosissima) litter as the research object, in 2012 ~2014 years through the field measurement, the in situ decomposition test, analysis of point control test and indoor litter samples, dynamic characteristics of the Tarim desert highway anti litter of three main plant species in forest litter and its composition with the increase in age; analysis of different litter types, different planting years of protection forest, different ages and different litter quality control measures on litter decomposition rate, residual rate, decomposition process elements (C, N, P, K, Ca, Mg, lignin and cellulose) and the influence of elements the ratio of dynamic characteristics. To reveal the litter dynamic of Tarim Desert Highway Shelterbelt litter, discusses the impact of control measures on litter decomposition; the Tarim Desert Highway Shelterbelt. The decomposition process, and the main influence factors of nutrient transfer model. The main conclusions are as follows: the Tarim desert highway in 1995, 1998, 2001, 2004 and 2006 years, the total amount of litter planting protection forest were the annual litter capacity of 7.93 T T - hm-2,6.19 hm-2,10.54 T - hm-2,9.10 T - hm-2,8.31 t - hm-2. of the three kinds of protection forest planting years plants are the highest and highest in autumn. Tamarisks, litter composition in Haloxylon ammodendron assimilating branches of litterfall Tamarix and Calligonum, willow assimilating branches of the highest, accounted for 70.58%~88.93%. of different planting period of protection forest total annual litterfall, month dynamic trend of the total amount of litter and litter components of litter were all three peaks. The peak in July, 3~5 months, 9~11 months, the highest value appeared in November. The remaining litter composition changes irregularly and the peak time difference, old branch and tamarisk willow Haloxylon is 5~7 month, 9~10 month for Haloxylon fruit, Calligonum fruit is 6~7 month, Tamarix flowers and flower litter Shaguai in 5~8 months. Genetic composition and ecological characteristics of species of Desert Highway Shelterbelt, physiological processes and climate conditions affect litterfall and litter dynamic composition. In the Tarim desert highway shelter forest in different planting years, three kinds of litter decomposition rate from high to low are much from (0.24~0.32 - g-1 - G and A-1), Calligonum arborescens (0.17~0.23 g assimilating branches of g-1 A-1 (0.13~0.18 g), Haloxylon g-1 branch A-1). Three kinds of litter decomposition rate was the lowest value appeared in 1995a protection forest; the decomposition rate of the highest value, branched willows and tamarisk Calligonum arborescens assimilating branches appear in 2004a protection forest, shelter forest in 2001a branch of Haloxylon ammodendron. Micro environment protection forest plantation by litter decomposition directly or indirectly affect the litter decomposition of litter. The initial C, P, K and Mg content decomposition The main control factors of early; initial lignin, cellulose content, C/N and N/P ratio is the dominant factor of decomposition of middle and late in the decomposition process of 720d, C elements in three kinds of litter showed a net release mode, N and P elements showed enrichment release pattern, K elements are released - enrichment pattern of Haloxylon ammodendron the branches and branches of Ca assimilation of Calligonum arborescens and Mg elements showed a net accumulation model, multi Ca and Mg elements from switchgrass was released - enrichment mode. The lignin and cellulose content showed a trend of first increase and then decrease, the decomposition of lignin in the late lower than the initial concentration of cellulose is always higher than the initial concentration of element migration. Dynamic desert highway shelter forest litter is mainly affected by litter substrate quality, elements of their own characteristics, the comprehensive effects of decomposition stage and decomposition environment. Different control measures and the surface of different age and depth of litter, litter The highest decomposition rate of H.ammodendron assimilation twigs, branches of Tamarix switchgrass times, a minimum of Calligonum arborescens. Different effects of assimilating branches of different control measures on litter decomposition rates, control group of Calligonum arborescens assimilating branches, branches and branches of Tamarix ammodendron assimilation willow litter decomposition rate was 0.53 G - g-1 - G - a-1,0.94 g-1 - a-1,0.55 G - g-1 - a-1. of the control measures, the decomposition rate of sand burying 10cm three kinds of litter (0.92~1.69 G - g-1 - A-1) the highest decomposition rate of mineralization of 29.7g L-1 water irrigation (0.31~0.54 G - g-1 - A-1). The lowest sand burial (0.69~ 1.69 g g-1 A-1) irrigation cycle 7d (0.69~1.34 g, g-1 A-1), the application of phosphorus and potassium compound fertilizer (0.57~1.25 G - g-1 - A-1) and fresh water irrigation (0.59~1.12 G - g-1 - A-1) significantly increased the decomposition rate of three kinds of litter decomposition rate. From the influence of litter micro environmental measures by changing litter decomposition control Rate of water is the main influencing factors. The initial N content and C/N litter lignin, the ratio of /N is mainly to control the rate of decomposition of different control measures of litter factors, initial litter nutrient content can predict better initial decomposition rate of litter decomposition, difficult substances are the main factors controlling the late decomposition rates, different control the measures of litter decomposition in each stage of the main controlling factors of difference. The decomposition process of litter 420D, effects of different control measures in the process of decomposition of migration pattern elements on litter have similarities and differences. Among them, fresh water irrigation treatment under Calligonum arborescens and Tamarix Tamarix switchgrass in assimilating shoots in the decomposition of the late show high P enrichment. Salinity water irrigation treatments of H.ammodendron assimilation twigs and multi Tamarix switchgrass the decomposition of the late show Ca enrichment. Sand buried under the treatment of Calligonum arborescens assimilating branches at the early stage of the decomposition showing a rich N Set, sand buried under 10cm treatment of three kinds of litter showed P enrichment. Nitrogen fertilizer under three kinds of litter showed N enrichment, H.ammodendron assimilation twigs showing Ca enrichment. The application of phosphorus and potassium compound fertilizer treatment of Calligonum arborescens in decomposition of assimilating branches of prophase and metaphase N showed enrichment, three kinds of litter all had P and K enrichment. The irrigation cycle under the treatment of Calligonum arborescens and H.ammodendron assimilation twigs showing Mg release. Tamarix ramosissima under mulching treatment showed a willow P release; H.ammodendron assimilation twigs showing Ca enrichment. The control measures in a certain extent to element enrichment phenomenon, increase litter nutrient return the content of lignin. The decomposition process showed increasing decreasing trend, because of litter quality and control measures of the effect of decreasing inflection point at different time, Calligonum arborescens assimilating branches and multi Tamarix bowing in the late stage of decomposition lower than the initial value, sacsaoul Assimilating branches of lignin is always higher than the initial value; the cellulose content of three kinds of litter in a rising trend and is higher than the initial value. Different age of litter, 7a Calligonum arborescens and Haloxylon ammodendron assimilating branches of the decomposition rate of the highest, 15A branched Tamarix litter decomposition rate is highest. The decomposition rate of litter in different age, initial C and the content of N is the early stage of the decomposition of the main limiting factors, lignin and cellulose for the decomposition of late dominant factors. Different ages of three litter C, P, K and Mg elements were all release pattern, N element was mainly release mode, Ca elements mainly in the accumulation release mode. By age three litter the lignin content showed increasing decreasing trend, due to differences in litter types of Calligonum arborescens in assimilating shoots after 120d decomposition is lower than the initial value of H.ammodendron assimilation twigs and multi tamarisk willow is always higher than the initial value of cellulose content showed fluctuations; The increase trend and is higher than the initial value. This study shows that in the artificial forest protection desert extreme drought, litter initial chemical properties are inherent factors determine the litter decomposition rate, nutrient and moisture conditions affect the decomposition rate and nutrient return of litter. The research results not only reveal the special habitats of litter dynamics artificial protection desert forest litter, decomposition rate has important theoretical significance and nutrient cycling, and soil properties of artificial forest protection desert improvement, improve soil fertility, provide data support and scientific basis for optimizing the stability and sustainable development of protection forest management and protection measures.

【学位授予单位】：新疆大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S714

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