岷江上游辐射松人工林种质资源及土壤生物肥力评价

【作者】 李梅；

【导师】 罗承德；

【作者基本信息】 四川农业大学 ， 森林培育， 2009， 博士

【摘要】 已有干旱河谷植被恢复与重建侧重于通过表形对抗性树种的引种和筛选,有关基因水平的种质资源研究,以及林地土壤生物肥力（Soil bio-fertility）恢复与重建研究略显不足,以至生态恢复与重建的效果不甚明显。结合岷江上游干旱河谷土壤生态环境特性以及应正在实施的生态建设工程等需求,对岷江上游干旱河谷区的引种辐射松（Pinus radiata D.Don）进行了种质资源评价,进而通过辐射松与乡土树种油松（Pinustabulaeformis）的抗旱性比较评价了辐射松在引种地的生态适应性,以及评价引种辐射松造林对林地土壤生物肥力的影响。于汶川和理县1998～2004年间营造的辐射松人工林中,以典型抽样采集21份辐射松新梢针叶样本,运用SSR分子标记技术进行群落亲缘关系研究,评价辐射松人工林种质资源;以取自四川省阿坝州林科所（汶川县）营养袋育2a生引种辐射松、乡土树种油松幼苗,在四川农业大学温室大棚内以土壤盆栽方式按单因素试验设计进行较为系统的干旱梯度胁迫比较实验,研究其抗旱特性和机理;在岷江上游干旱河谷区的茂县、汶川和理县以空间代替时间,于环境条件等基本一致,而造林时期不同的林分中,选取10个不同林龄的辐射松林,林内设置20m×20m固定样地,进行土壤微生物与土壤酶特性和人工林土壤生物肥力研究。为岷江上游干旱河谷及相似区域的植被恢复与重建、低效林改造、迹地更新等生态建设提供优树选择和促进岷江上游引种辐射松林分种质资源管理提供一定的科学依据。具体研究结果如下。（1）SSR分子标记技术对21份供试材料分析结果显示,以遗传相似系数GS0.8041为阈值,将21份材料分为3大类:第一大类为17个地理种源的辐射松,包括材料1～6、材料10～19和材料21,按引种地划分这17份供试材料覆盖了引自美国、澳大利亚、墨西哥和新西兰的辐射松,其中引自新西兰辐射松的供试材料达11个;第二大类为3个地理种源的辐射松,它们是材料7～9,均为引自新西兰的辐射松;第三大类仅为1个引自新西兰的辐射松,即材料20。表明近20a来,岷江上游引种辐射松的种质资源主要以来自新西兰的辐射松材料为主。以遗传相似系数GS0.8247为阈值,以上3大类中仅第一大类可进一步分为3个亚类（Ⅰ₁,Ⅰ₂,Ⅰ₃）。其中,Ⅰ₁由材料1～6组成,而材料1和2、材料3和4无法区分,或差异不在所检测的SSR位点之内,可分别视为基因型相同;Ⅰ₂由材料10～12组成;Ⅰ₃由材料13～19和材料21组成,而材料15和17无法区分,可视为基因型相同。结果表明SSR分子标记技术能有效揭示岷江上游干旱河谷引种辐射松人工林群落内种质资源的亲缘关系,也表明群落的种质资源遗传多样性较高,适宜性较广,利于种群繁衍。但3对样本材料（材料1和2、材料3和4、材料15和17）无法区分其遗传差异,或差异不在所检测的SSR位点之内,说明群落内的引种种源存在部分基因型相同,但却异名的现象,这不利于辐射松种质资源的评价、保存与开发利用。（2）对引种辐射松幼苗和乡土树种油松幼苗进行梯度干旱胁迫比较研究,随干旱胁迫时间的延长,盆栽辐射松、油松幼苗的土壤含水量均呈不断下降趋势,且表现为胁迫前期下降速率快于后期。辐射松幼苗在处理24d时,土壤含水量为6.45%,失水率66.55%,日均失水2.77%;处理48d时,土壤含水量为4.48%,失水率76.76%,日均失水1.60%,此时幼苗干枯死亡。油松幼苗在处理24d时,土壤含水量为4.72%,失水率79.79%,日均失水3.32%;处理56d时土壤含水量降至3.21%,失水率82.26%,日均失水1.47%,此时幼苗逐渐死亡。表明辐射松、油松幼苗具较强抗旱性,但辐射松幼苗抗旱能力不及油松幼苗。整个干旱胁迫期间,两树种幼苗针叶形态均通过增加角质层、表皮、下皮层厚度来减少体内水分流失,以减少蒸腾;通过缩小自身叶肉细胞体积减轻失水带来细胞收缩产生的机械损伤,通过减小气孔开度减缓体内水分蒸腾速度,保持体内水分以利度过干旱。辐射松针叶角质层、表皮、下皮层厚度和组织紧密度分别增加了16.33%、72.23%、80.16%和88.02%;油松针叶的上述指标则分别增加了53.06%、74.91%、29.14%和73.85%。辐射松针叶的绿色折叠组织厚度和气孔开度分别下降了34.55%和45.11%;油松则分别下降了39.51%和32.62%。表明两树种叶片的解剖形态对干旱胁迫都具有较强的适应特性,但它们适应干旱的程度有所不同。（3）两树种幼苗在抵御干旱胁迫过程中,叶片相对含水量、水分饱和亏缺、叶保水力（失水速率）等指标均表现出较大的变化,但变化程度有差异。随干旱胁迫时间的延长,它们的相对含水量呈极显著降低,水分饱和亏缺均表现为上升,叶保水力（失水速率）在胁迫前期均快速下降,但随胁迫时间延长（24d后）,辐射松幼苗叶保水力值呈迅速升高趋势（回升率94.84%）,油松幼苗的该值升幅较小（回升率14.75%）。结果说明两树种均能通过降低相对含水量,增加细胞浓度以抵御干旱,而从水分饱和亏缺、叶保水力（失水速率）指标看,油松幼苗的抗旱性优于辐射松幼苗。（4）干旱胁迫对两树种幼苗体内的质膜透性（PMP）、丙二醛（MDA）、游离脯氨酸（Pro）、可溶性糖（WSS）、叶绿素含量（chla、chlb、chlab）等生化指标表现出较大影响。随干旱胁迫程度加剧,两树种相对电导率都分别有所增加,辐射松在处理56d时与对照比增加了58.43%,油松增加了54.14%,胁迫前期增加不显著,后期各处理间差异达显著水平;MDA含量随干旱胁迫时间延长均表现为先略下降,后有所上升的趋势;Pro、WSS、ABA含量在整个干旱胁迫实验期间均有增加,方差分析Pro、WSS、ABA增加达显著水平。表明两树种幼苗对干旱胁迫的机制基本一致。（5）在岷江上游干旱河谷引种辐射松林地按造林时间不同选取立地条件相似的10个固定样地,进行土壤有机质含量的时间序列研究:以样地Ⅰ（1991年造林）和样地Ⅱ（1992年造林）的有机质含量最高,样地Ⅸ（2004年造林）最低,并且各样地土壤有机质含量以秋季最高,春季和冬季次之,夏季含量最低。表明该区土壤有机质含量有随造林时间延长而增加的趋势。（6）微生物总量有随造林时间的增长而增加的趋势。样地Ⅱ的微生物总量最大(4.96×10⁶个·g^-1干土),样地Ⅷ（2003年造林）最低(1.33×10⁶个·g^-1干土)。微生物总量值由大到小的顺序为:Ⅱ（1992年造林,植被盖度10%）＞Ⅰ（1991年造林,植被盖度20%）＞Ⅲ（1998年造林,植被盖度70%）＞Ⅶ（2003年造林,植被盖度25%）＞Ⅳ（1998年造林,植被盖度15%）＞Ⅴ（1999年造林,植被盖度15%）＞Ⅸ（2004年造林,植被盖度10%）＞Ⅹ（2005年造林,植被盖度2%）＞Ⅵ（2002年造林,植被盖度30%）＞Ⅷ（2003年造林,植被盖度5%）。也就是说随着造林时间的延长,林地土壤微生物总量和土壤生物肥力有提高的趋势。但因植被盖度的影响,个别样地特别是新造林地的土壤微生物总量与造林时间并未表现出完全的一致,表明影响土壤生态性质的因素存在复杂性。（7）微生物类群中各类微生物占微生物总量的比例为细菌（54.81～75.13%）＞放线菌（24.87～46.38%）＞固氮菌（3.03～5.06%）＞真菌（0.03～0.14%）。总趋势显示微生物总量、细菌数量、放线菌数量和真菌数量均为秋季最多,春季和冬季次之,夏季最少。各样地土壤酶活性的季节动态变化有差异,但总体表现为秋季最高。各样地酶类活性表现为样地Ⅰ、Ⅱ的蔗糖酶活性与过氧化氢酶活性最高,Ⅹ最低;Ⅳ的酶活性最高,Ⅷ最低;Ⅰ的磷酸酶活性最高,Ⅸ最低。4种土壤酶活性均表现为土壤上层＞下层。其中,脲酶活性在土壤上层是下层的1.102～3.251倍;磷酸酶活性在土壤上层是下层的1.389～5.471倍;蔗糖酶活性在土壤上层是下层的1.315～2.546倍;过氧化氢酶活性在土壤上层是下层的1.022～1.673倍。表明土壤酶类的活性各有特点,但总体趋势仍表现出造林时间越长,土壤酶活性越高,越利于土壤质量的改善。相关性分析结果显示:细菌与放线菌、固氮菌、过氧化氢酶均达极显著正相关水平,相关系数分别为0.818、0.812、0.806、0.691;细菌与蔗糖酶达显著正相关水平,相关系数为0.691;放线菌与固氮菌、蔗糖酶呈极显著正相关,相关系数分别为0.843、0.798,与过氧化氢酶呈显著正相关,相关系数为0.637;过氧化氢酶与蔗糖酶呈显著正相关,相关系数为0.681。表明土壤微生物数量与土壤酶活性之间总体上存在着很好的正相关性。（8）对表征土壤生物肥力的土壤有机质、土壤微生物与土壤酶进行主成分分析,第一主成分线性组合主要是有机质、脲酶、蔗糖酶、过氧化氢酶、细菌、放线菌等变量,占信息总量的44.96%,其特征值达4.047;第二主成分线性组合主要是真菌、固氮菌、细菌、放线菌等变量,占信息总量的27.74%,其特征值为2.497;第三主成分主要是磷酸酶、蔗糖酶等变量,占信息总量的17.33%,其特征值为1.560。前3个主成分累积贡献率达90.04%,表明可以其评价土壤生物肥力,综合评价结果为Ⅱ＞Ⅰ＞Ⅲ＞Ⅳ＞Ⅵ＞Ⅶ＞Ⅴ＞Ⅹ＞Ⅸ＞Ⅷ。说明岷江上游干旱河谷引种辐射松造林后,林地土壤微生物量与酶活性均表现出增加的趋势和改善林地土壤质量的趋势。更多还原

【Abstract】 Many previous studies have been widely emphasized the introduction and selection of species with high resistibility during vegetation restoration and rebuilding in dry valley. Few attentions have paid to soil bio-fertility,which greatly limited the effects of restoration and rebuilding practice.Therefore,the evaluation of germplasm resource of P.radiata plantation in the upper reach of Minjiang River were studied in combined with soil characters and the urgent needs of ecological constitution,and through the varieties of seedlings resistibility between P.radiata and P.tabulaeformis,the evaluation of the soil bio-fertility and community relationships of Pinus radiata plantations was studied also. The results were expected to provide effective theory for vegetation restoration and rebuilding,low-effect forest modification,and community succession in the upper reach of Mingjiang River and other regions,and provide scientific data for germplasm resource management of introduced P.radiata plantation.Ten plantations with different forest age were selected under the same environmental conditions in Maoxian.Wenchuan and Lixian in the upper reach of Minjiang River,20 m×20 m sampling plots in each plantation were selected for soil microbial and soil enzyme research.21 typical fresh leaf samples were collected to community relationships research by SSR molecular method.2-year-old seedlings of P.radiata and P.tabulaeformis from Aba institute of forestry research were used for drought stress experiment in the greenhouse in Sichuan Agricultural University. The results as follows:（1） The results from SSR molecular method to 21 sampling material indicated that three groups could be formed by the limited genetic similarity coefficient GS0.8041.The 1^st Group included the P.radiata from 17 geomorphic resources,including material 1-6, 10-19 and 21,which introduced from the USA,Australian,Mexico and New Zealand,11 samplings were introduced from New Zealand.The 2^nd Group included the P.radiata from three geomorphic resources,including material 7-9,which introduce from New Zealand. The 3^rd Group included only one P.radiata（material 20） from New Zealand.GroupⅠcould be divided into three sub-groups（Ⅰ₁,Ⅰ₂,Ⅰ₃） by the limited genetic similarity coefficient GS0.8247.GroupⅠ₁,groupⅠ₂ and groupⅠ₃ included the samples 1-6,the samples 13-19 and the sample 21,respectively.Samples 1-4 could be looked as the same gene type and sample 15 and 17 could also be looked as the same gene type.The results suggested that SSR molecular method could effectively reveal the relationships among the introduced P.radiata plantations in the upper Minjiang River,which also indicated that P. radiata communities could be beneficial to gene flow and population reproduction due to high genetic diversity.However,the plantations were not called the same name although which with the same gene type,which was not facility to the evaluation,conservation and exploration of P.radiata germplasm resource. （2） Soil water content decreased with the increase of drought stress time in planting both P.radiata and P.tabulaeformis seedlings in the greenhouse experiment,showing more rapid in the early period.After 24d treatment,soil water content was 6.45%,water loss rate was 66.55%,daily loss rate 2.77%in planting P.radiata seedlings.After 48d treatment,the seedling died,soil water content was 4.48%,water loss rate 76.76%,daily loss rate 1.60%.After 24d treatment,soil water content was 4.72%,water loss rate was 79.79%,daily loss rate 3.32%in planting P.tabulaeformis seedlings.After 56d treatment, the seedling died,soil water content was 3.21%,water loss rate 82.26%,daily loss rate 1.47%.The results suggested that the seedlings of P.radiata had lower drought resistibility compared to that in P.tabulaeformis seedlings.The seedling of both species reduced the transpiration rate by increasing the depth of horn,pellicle and hypoderm and decreasing stomata conductance during the whole drought stress period.Needle horn,pellicle,and hypoderm and organize density of P.radiata increased to 16.33%,72.23%,80.16%and 88.02%,while 53.06%,74.91%,and 73.85% for P.tabulaeformis,respectively.The depth of green collapsed organism and stomata conductance of P.radiata needles were decreased to 34.55%and 45.11%,while 39.51 and 32.62%for P.tabulaeformis,respectively.Although both species showed high adaptation by analyzed needle anatomies character,their adaptive types were different,their adaptive degrees of drought were different.（3） The relative water content,water saturation deficient,water conservation ability of seedling needles were different between species.The relative water content of needles was significantly decreased as drought stress proceeded,but water saturation deficient increased.Water conservation ability decreased more rapidly in the early period of drought stress,but increased after 24d for P.radiata seedlings with 94.84%ascend ratio,14.75% for P.tabulaeformis.The results indicated that both species could resist to drought by decreasing relative water content,although water saturation deficient,water conservation ability of seedling needles were higher for P.radiata than that for P.tabulaeformis.（4） Drought stress had significant effects on PMP,MDA,Pro,WSS,Chla,Chlb and Chlab of seedlings.The relative conductance increased with increasing drought stress, 58.43%for P.radiata and 54.14%for P.tabulaeformis after 56d drought treatment.The content of MDA decreased in the early period of drought treatment,and then increased in the later period.The content of Pro,WSS and ABA increased with the increasing drought stress.The results indicated that the mechanism of drought stress of the both species seedlings were similar.（5） Ten plantations with different forest age were selected in the upper reach of Minjiang River,and the soil organic matter content was studied:the maximum number was inⅠandⅡsampling plots and the minimum number inⅨsampling plots,the soil organic matter content was exhibited obvious seasonal varieties with highest in autumn,then spring and winter,lowest in summer also.The results suggested that the soil organic matter content was increased with the increase of plantation time.（6） Microbe number increased with the increase of plantation time with the maximum number(4.96×10⁶·g^-1) inⅡsampling plots and minimum(1.33×10⁶·g^-1) number inⅧsampling plots,showed the order as:Ⅱ（1992 plantation,coverage 10%）＞Ⅰ（1992 plantation,coverage 20%）＞Ⅲ（1998 plantation,coverage 70%）＞Ⅶ（2003 plantation, coverage 25%）＞Ⅳ（1998 plantation,coverage 15%）＞Ⅴ（1999 plantation,coverage 15%）＞Ⅸ（2004 plantation,coverage 10%）＞Ⅹ（2005 plantation,coverage 2%）＞Ⅵ（2002 plantation,coverage 30%）＞Ⅷ（2003 plantation,coverage 5%）.This suggested that the soil microbe number and bio-fertility were increased with the increase of plantation time. However,some specific plantations especially for new plantation were not similarity with the orderliness which indicated that the factors which affecting ecological characteristics of soil were complex.（7） The ratio of microbial community in the total as the order:bacteria（54.81～75.13%）＞actinomycetes（24.87～46.38%）＞azotobacteria（3.03～5.06%）＞fungus（0.03～0.14%） with maximum in autumn,then in spring and winter,minimum in summer.The seasonal dynamics of soil enzyme activity in the sampling plots were different,and the general tendency was highest in autumn.Invertase and catalase activity were highest inⅠandⅡsampling plots,Ⅹwere lowest;urea activity was highest inⅣplantation,and lowest inⅧplantation;phosphatase activity was highest inⅠplantation,the lowest inⅨplantation.The topper soil was higher in the four plantations than that in lower soil.The results suggested that soil enzyme activity increased with the increase of plantation time, which be beneficial to the improvement of soil quality.Bacteria were correlated positively with actinomycetes（0.818）,azotobacteria（0.812）, catalase（0.806） and invertase（0.691）.Actinomycetes were positively correlated with azotobacteria（0.843）,catalase（0.637） and invertase（0.798）.Catalase was correlated positively with invertase（0.681）.The results suggested the significant positive relationships between microbe number and soil enzymes.（8） PCA statistics in soil organic matter,soil microbe number and soil enzyme indicated that:the first components are soil organic matter,invertase,urea,catalase, bacteria and actinomycetes,which accounted for 44.96%of total information,the characteristics value was 4.047;the second components were bacteria,azotobacteria, fungus and actinomycetes,which accounted for 27.74%of total information,the characteristics value was 2.497;the third components were phosphatase and invetase, which accounted for 17.33%of total information,the characteristics value was 1.560.The accumulated contribution rate of the total of three components was 90.04%,suggesting that the parameters could be indicators in evaluating soil bio-fertility.As the result of it,the order of synthetic evaluation in soil bio-fertility for sampling plots were:Ⅱplantation＞ Ⅰplantation＞Ⅲplantation＞Ⅳplantation＞Ⅵplantation＞Ⅶplantation＞Ⅴplantation＞Ⅹplantation＞Ⅸplantation＞Ⅷplantation.The results suggested that introduced P.radiata plantation could be beneficial to the improvement of soil quality in the upper reach of Minjiang River since soil organic matter,microbe number and enzyme increased with the increase of plantation time.更多还原