【作者】 胡进耀；

【导师】 杨冬生； 胡庭兴；

【作者基本信息】 四川农业大学 ， 森林培育， 2009， 博士

【摘要】 按不同采伐时间和坡位选择下坡位巴山水青冈成熟林（成熟林Ⅰ）、中上坡位巴山水青冈成熟林（成熟林Ⅱ）、近熟林、中龄林、幼龄林5个样地。从林地的物种组成、多样性变化、建群种幼苗的光合生产力差异、凋落量及凋落物水文生态功能差异、土壤水源涵养功能差异、土壤肥力差异、土壤碳库等方面较为系统地研究了我国特有的巴山水青冈林皆伐后自然更新过程中群落生态特性的变化。结果如下:（1）四种林型丰富度指数、Simpson指数和综合指数变化的趋势基本一致,成熟林≈近熟林＜中龄林＜幼龄林。各个样地的均匀度与Shannon-Wiener指数变化趋势一致,成熟林Ⅰ、近熟林与幼龄林的均匀度最低,中龄林与成熟林Ⅱ达到最高。物种多样性的研究结果可以用中度干扰理论解释。对中上坡位和下坡位巴山水青冈成熟林乔木的径级结构与自然干扰研究表明,下坡位由于光照较少,对下层乔木限制较大,但由于湿度等原因,幼树数量仍比中上坡位多。各样地物种多样性与土壤养分、物理性质等有显著的相关性,且大多数成负相关,为它们之间的复杂关系提供了新的证据。（2）下坡位成熟林干基干折与枯立木数量较多,中上坡位成熟林干中干折和掘根比例高于下坡位成熟林。下坡位成熟林每年的死亡率是18.8棵,/hm²（5-20 cm DBH 16.8,＞20 cm DBH 2.1）。每年各茎级的死亡率在1.4%左右（5-20cm DBH 1.6%,＞20cm DBH 0.7%）。较长寿命期望值是71yr（5-20cm DBH 61yr,＞20cm DBH 149yr）。周转的时间5-20cm DBH需要61yr,＞20cm DBH149yr。中上坡位成熟林每年的死亡率是10.2棵/hm²（5-20cm DBH 7.6,＞20cm DBH 2.7）。每年各茎级的死亡率在0.66%左右（5-20cm DBH 0.68%,＞20cm DBH 0.59%）。较长寿命期望值是152yr（5-20cm DBH 147yr,＞20cm DBH169yr）。周转时间是:5-20cm DBH 147yr,＞20cmDBH169yr。（3）下坡位成熟林、中上坡位成熟林、幼龄林三个样地中,幼龄林中巴山水青冈幼苗的净光合速率最高,其次是下坡位成熟林（成熟林Ⅰ）,中上坡位成熟林（成熟林Ⅱ）最小。三个样地的巴山水青冈幼苗光合能力随生长季节变化的规律是一致的:生长盛期>生长初期>生长末期,且后两个阶段光合指标波动较大,CO₂补偿点也较高。巴山水青冈幼苗的光合日变化为单峰型曲线。说明水分和光照与巴山水青冈幼苗更新密切相关,肥力的影响是次要的,下坡位比中上坡位更适合巴山水青冈幼苗生长。（4）五个样地中,凋落物层年凋落量大小关系为:成熟林＞近熟林＞中龄林＞幼龄林;含水量成熟林＞近熟林＞中龄林＞幼龄林,与凋落量情况一致。从坡位上来说,年凋落量和含水量成熟林Ⅰ＞成熟林Ⅱ;巴山水青冈林具有明显的凋落高峰期,呈现单峰曲线。各样地一年中凋落量大小的顺序是:11月＞9月＞7月＞5月。各样地的蓄积量多少与年凋落量有一些差异。用浸泡法测定五个样地的凋落物的持水性能,结果表明,从凋落物持水率的角度来看,幼龄林的凋落物持水率最高,而成熟林Ⅱ的凋落物持水率最低。综合凋落物层蓄积量、持水率和自然含水率三个方面的结果:最大持水量:成熟林Ⅰ＞成熟林Ⅱ＞近熟林＞中龄林＞幼龄林;最大拦蓄量:成熟林Ⅱ＞成熟林Ⅰ＞近熟林＞中龄林＞幼龄林;有效拦蓄量:成熟林Ⅱ＞成熟林Ⅰ＞近熟林＞中龄林＞幼龄林。（5）在0-20cm和20-40cm土层中,土壤容重的特征是成熟林Ⅰ＜近熟林＜成熟林Ⅱ＜中龄林<幼龄林,非毛管孔隙度的大小则与此相反,成熟林Ⅰ的非毛管空隙度最高,反映其具有良好的土壤结构。巴山水青冈林下土壤持水率大小存在一定差异,其大小依次是成熟林Ⅰ＞近熟林＞成熟林Ⅱ＞中龄林＞幼龄林,0-20cm土壤持水能力要高于20-40cm。各样地0-20cm土壤排水能力均高于20-40cm土壤,成熟林Ⅱ的排水能力高于成熟林Ⅰ。巴山水青冈林0-20cm土层的初渗值均高于20-40cm土层的初渗值,各样地之间初渗值的关系是成熟林Ⅰ>近熟林>成熟林Ⅱ>中龄林>幼龄林,其中成熟林Ⅱ和近熟林比较接近、中龄林和幼龄林较为接近。（6）各林型的土壤自然含水率变化特点如下:时间变化特点,为7月＞5月＞11月＞9月;林型类型变化特点,为成熟林Ⅰ＞近熟林>成熟林Ⅱ＞中龄林>幼龄林,且各生长季节间变化幅度为成熟林Ⅱ＞成熟林Ⅰ＞近熟林＞中龄林＞幼龄林;从土层深度差异分析发现,0-20 cm自然含水率均高于20-40cm土层。各林型之间0-20cm土壤自然含水率的变化值幅度大于20-40cm土层。在同一样方内,0-20 cm和20-40 cm两层土壤之间自然含水率差异最大的是成熟林Ⅱ,最小的是幼龄林,其后依次是近熟林、成熟林Ⅰ和中龄林。各生长季节样地间0-20cm、20-40cm土层土壤有机质、全氮、碱解氮、铵态氮、硝态氮、全磷、速效磷、全钾、速效钾含量均为成熟林Ⅰ＞近熟林＞成熟林Ⅱ＞中龄林＞幼龄林,且0-20cm土层含量高于20-40cm土层,不同生长季节土壤养分含量存在明显的差异,均为9月＞5月＞11月＞7月。巴山水青冈成熟林及其天然次生林0-40 cm土层土壤物理性质与养分含量之间相关性较好。容重与碱解氮、铵态氮、硝态氮、全磷、速效磷、全钾和速效钾含量呈显著或极显著负相关;全氮与容重负相关,而与总孔隙、毛管孔隙、非毛管孔隙、通气孔隙度、毛管持水量、非毛管持水量、初渗系数和稳渗系数呈正相关,但相关性不显著;毛管持水量与全氮、碱解氮、全磷、速效磷和全钾呈正相关,非毛管持水量与所有的养分指标都呈正相关,但均不显著;毛管持水量与铵态氮、硝态氮和速效钾呈显著正相关;土壤有机质与容重负相关,与毛管持水量极显著正相关,与其它物理指标呈显著正相关:其余各养分与土壤物理性质之间均呈显著或者极显著正相关关系。（7）土壤有机碳总量（C_T）、土壤水溶性碳含量(C_WS)、土壤活性有机碳（C_A）在各生长季节均为成熟林Ⅰ＞近熟林＞成熟林Ⅱ＞中龄林＞幼龄林,且各样地0-20cm土层土壤有机碳总量均高于20-40cm土层,而且不同生长季节各样地土壤有机碳总量具有相同的变化规律,表现为9月＞5月＞11月＞7月。7月份巴山水青冈5个样地0-20cm土层,土壤容重、总孔隙、毛管孔隙、通气孔隙度、毛管持水量和初渗系数总体上均与土壤水溶性有机碳(C_WS)、活性有机碳（C_A）、稳态碳(C_UA)、水溶性有机碳与有机碳总量的比值(C_WS/C_T)、稳定态碳与有机碳总量的比值(C_UA/C_T)、碳库活度（A）、碳库管理指数（CPMI）之间存在显著或极显著相关（仅非毛管孔隙与CUA相关性不显著）,而与活性有机碳（C_A）含量与有机碳总量（C_T）的比值（C_A/C_T）之间相关性不显著;非毛管持水量与所有额碳库指标的相关性均不显著,非毛管孔隙和稳渗系数与C_UA/C_T和A相关性不显著;土壤容重与C_WS、C_A、C_UA、C_A/C_T、A、CPMI之间呈负相关关系,而与C_UA/C_T呈正相关关系;总孔隙、非毛管孔隙、初渗系数、稳渗系数与C_WS、C_A、C_UA、C_A/C_T、A、CPMI之间呈正相关,而与C_UA/C_T呈负相关。（8）巴山水青冈成熟林及3个天然更新林之间土壤脲酶活性、土壤蔗糖酶活性、土壤磷酸酶活性、过氧化氢酶在各月份的变化特点为成熟林Ⅰ＞近熟林＞成熟林Ⅱ＞中龄林＞幼龄林,且各样地0-20cm土层土壤酶活性均高于20-40cm土层。不同时期各样地土酶活性具有一定的差异,表现为9月＞7月＞5月＞11月。（9）巴山水青冈林地土壤呼吸作用变化存在明显的季节动态,且为单峰型,即从4月开始,土壤呼吸作用逐渐增强,至8月土壤呼吸作用达到全年最强高,土壤呼吸速率月均值达到2.78μmol·m^-2·s^-1,此后土壤呼吸作用逐渐减弱。巴山水青冈林土壤呼吸作用日动态表现为单峰型曲线形式,一般14:00-15:00土壤呼吸作用最强,而凌晨5:00左右土壤呼吸作用最弱。土壤呼吸作用强弱日变化动态与5cm土壤温度动态一致,而稍滞后于地表温度日变化动态。皆伐迹地幼龄林土壤呼吸速率日变化幅度高于巴山水青冈林地。幼龄林土壤呼吸速率最高值出现在14:00左右,而林地出现在15:00-16:00之间,最小值都出现在凌晨5:00左右;与原始林地相比,幼龄林土壤呼吸速率比林地早约1h达到最高峰值,温度与土壤呼吸速率极显著相关（p＜0.01）。研究结果说明,坡位对于巴山水青冈幼苗更新和生长有很大的影响,下坡位比中上坡位更适合巴山水青冈幼苗生长。保护巴山水青冈林对于提高林下地表枯落物层水文生态功能,增加林地土壤水源涵蓄功能和减少地表径流损失,提高林地土壤自然含水量、养分含量,提高土壤酶活性,增加各形态碳素含量和碳库指数,改善上壤结构等方面有重要的作用和意义。适当地干扰可增加水青冈林的生物多样性,但会减弱水青冈林的生态功能。研究结果为保护巴山水青冈林及巴山水青冈天然次生林更新过程中林地土壤的科学管理提供依据,也为巴山水青冈造林提供参考。更多还原

【Abstract】 Five plots including Fagus pashannica mature forest in downhill position, F. pashannica mature forest, near-mature forest, half-mature forest, young forest in midhill and uphill position, were selected. The changes of ecological characteristics of F. pashannica forest after clear cutting in the process of natural regeneration was studied systematically, from the aspects of forest species component, diversity changes, photosynthetic productivity differences of constructive species seedlings, hydrological and ecological functional differences of litter fall and litter production, soil water conservation capacity, soil fertility, and soil carbon pool. The results were as follows:（1）The changes of richness index, Simpson index and comprehensive index of four forest type showed the similar trend: mature forest≈near-mature forest＜half-mature forest＜young forest. The evenness of each sample plot showed a similar trend with the changes of the Shannon-Wiener index: mature forestⅠ, near-mature forest, and young forest had the lowest evenness, while half-mature forest and mature forestⅡhad the highest.Research results of species diversity can be explained with Intermediate Disturbance Hypothesis. Studies on diameter structure and diseased tree of F. pashannica mature forest in the uphill and downhill position indicated that less light on downhill restricted arbor in lower tree layer, but the sapling quantity was more than that in the in midhill and uphill position due to humidity reasons. Species diversity of each sample plot was significantly correlated （mainly a negative correlation） with soil nutrient and physical property, it can provide new evidence for their complex relationship.（2） 18.8 trees ha^-1yr^-1 （5-20 cm DBH 16.8,＞20 cm DBH 2.1） were damaged in lower slope position mature stand. mortality rate per year of various size classes was about 1.4%（5-20 cm DBH 1.6%,＞20 cm DBH 0.7%）.The expectation of further life was 71yr orerall（5-20 cm DBH 61yr,＞20 cm DBH 149yr）.Turnover time was 61 yr （5-20 cm DBH） and 149yr （＞20 cm DBH）.10.2 trees ha^-1yr^-1（5-20 cm DBH 7.6,＞20 cm DBH 2.7）were damaged in middle and upper slope position mature stand. mortality rate per year of various size classes was about 0.66%（5-20 cm DBH 0.68%,＞20 cm DBH 0.59%）.The expectation of further life was 152yr orerall（5-20 cm DBH 147yr,＞20 cm DBH169yr）, Turnover time was 147yr （5-20 cm DBH） and 169yr （＞20 cm DBH）.（3） The order of net photosynthetic rate of F. pashannica seedlings in sample plots was: young forest＞mature forest in the downhill （mature forestⅠ）＞mature forest in the midhill and uphill position （mature forestⅡ）. The variation of F. pashannica seedlings photosynthetic capacity with growing season was conformable: fast growth stage＞early growth stage＞last growth stage, and photosynthesis index had a large fluctuation and a high CO₂ compensation point during the early and last stage. Diurnal variation of photosynthes of of F. pashannica seedlings was single peak type. These indicated that water and light were closely related with F. pashannica regeneration, and downhill was more suitable than uphill for growth of F. pashannica seedling.（4） The annual litter production of litter layer, as well as water content in five sample plots was in the sequence of mature forest＞near-mature forest＞half-mature forest＞young forest. From the slope position, the litter production and water content of mature forestⅠwas more than that of mature forestⅡ. F. pashannica forest had obvious litter fastigium, and was single peak type. The sequence of annual litter production of each sample plot was: November＞September＞July＞May. Cumulation in each sample plot was a little different with the annual litter production. Determination results of water retention property of the litter by infusion method showed that young forest had the highest water retention property, while the mature forestⅡhad the lowest. The results about comprehensive litter layer cumulation, water retention ratio and natural water content were as follows: （1）the maximum water capacity: mature forestⅠ＞mature forestⅡ＞near-mature forest＞half-mature forest＞young forest; （2） the maximum water amount of interception: mature forestⅡ＞mature forestⅠ＞near-mature forest＞half-mature forest＞young forest; （3）the modified water amount of interception: mature forestⅡ＞mature forestⅠ＞near-mature forest＞half-mature forest＞young forest.（5） Soil capacity characteristic at 0-20cm and 20-40cm soil layers was: mature forestⅠ＜near-mature forest＜mature forestⅡ＜half-mature forest＜young forest; non-capillary porosity was just opposite to this, mature forestⅠhad the highest non-capillary porosity, reflected that mature forestⅠhad well soil structure. There were differences in undergrowth soil water retention property of F. pashannica forest, the order was: mature forestⅠ＞near-mature forest＞mature forestⅡ＞half-mature forest＞young forest, and water retention property at 0-20cm＞at 20-40cm. Soil drainability at 0-20cm in each sample plot was all higher than that at 20-40cm, initial infiltration capacity was: mature forestⅠ＞near-mature forest＞mature forestⅡ＞half-mature forest＞young forest, among which initial infiltration capacity of mature forestⅡwas close to near-mature forest, and half-mature forest was close to young forest.（6） Changes of natural water content characteristic in every forest type were as follows: （1）time changes characteristic: July＞May＞November＞September. （2） forest type changes characteristic: mature forestⅠ＞near-mature forest＞mature forestⅡ＞half-mature forest＞young forest, and changes during every growing season was: mature forestⅡ＞mature forestⅠ＞near-mature forest＞half-mature forest＞young forest. The difference analysis of soil depth detected that natural water content at 0-20cm was higher than that at 20-40cm; and the change range of natural water content at 0-20cm was also higher than that at 20-40cm during every forest type. In the same quadrat, the most difference in natural water content between 0-20cm and 20-40cm was mature forestⅡ, and then the near-mature forest, mature forestⅠ, half-mature forest, the lowest was young forest.During each growing season, the contents of soil organic matter, total nitrogen, available nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, total potassium and available potassium in 0-20cm and 20-40cm soil layer were all: mature forestⅠ＞near-mature forest＞ mature forestⅡ＞half-mature forest＞young forest, and these contents in 0-20cm were higher than these in 20-40cm, soil nutrient contents in different growing season were different, were: September＞May＞November＞July.F. pashannica mature forest and natural secondary forest’s soil physical properties and nutrient content had a better correlation in 0-40cm soil layer. Bulk density was significantly or very significantly correlated with alkaline hydrolytic nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, total potassium, available potassium. Total nitrogen was negative correlated with bulk density, and positive correlated with total pore, capillary pore, non-capillary pore, aeration porosity, capillary water capacity, non-capillary water capacity, primary permeability coefficient and stable permeability coefficient, but the correlation was not significant. Capillary water capacity was positive correlated with total nitrogen, alkaline hydrolytic nitrogen, total phosphorus, available phosphorus, total potassium, non-capillary water capacity positive correlated with all nutrient indexes, but the correlation was not significant. Capillary water capacity was positive correlated with ammonium nitrogen, nitrate nitrogen and available potassium. Soil organic matter was negative correlated with bulk density, it was very significantly correlated with capillary water capacity, and significantly correlated with other physical parameters. Other nutrients were significantly or very significantly positive correlated with soil physical properties.（7） In every season, the content of total organic carbon（C_T）, free carbon(C_WS) and activity organic carbon（C_A） of soil displayed the character that mature forestⅠ＞near-mature forest＞mature forestⅡ＞half-mature forest＞young forest, and in every sample field, the content of total organic carbon in the 0-20cm soil layer was always higher than that in the 20-40cm soil layer, and every sample plot in different seasons had the same variational rule about total organic carbon: September＞May＞November＞July.In the five sample plots at 0-20cm soil layer of F. pashannica forest in July, soil volume, total pore, capillary pore, aeration porosity capillary interstice, capillary water capacity and initial infiltration index generally were significantly or very significantly correlated with C_WS, C_A, C_UA, C_WS / C_T, C_UA/ C_T, A and CPMI, but not significantly related with C_A/ C_T, there was no significant positive correlations between non-capillary water capacity and carbon pool index; non-capillary pore and steady infiltration index were not significantly correlated with C_UA/ C_T and A; soil volume was negative correlated with C_WS、C_A、C_UA、C_A/C_T、A、CPMI, while positive correlated with C_UA/C_T; total pore, non-capillary pore, initial infiltration index and steady infiltration index were significant positive related with C_WS、C_A C_UA、C_A/C_T、A、CPMI, and negative correlated with C_UA/C_T.（8） The change characteristics of soil urease activity, soil saccharase activity, soil phosphatase activity and catalase in every month among F. pashannica mature forest and three natural regeneration forests of were: matured forestⅠ＞near-mature forest＞mature forestⅡ＞half-mature forest＞young forest, and the soil enzyme activity at 0-20cm soil layer was higher than that at 20-40cm. The soil enzyme activity of each sample plot at different times had some differences, registered as September＞ July＞May＞November.（9） The changes of soil respiration had a obvious seasonal dynamics and was the single-peak type, which was, from the beginning of April, soil respiration gradually increased, and at August, reached the highest throughout the year (Mean of soil respiration rate reached 2.78μmol·m^-2·s^-1), and then gradually reduced. Daily changes of soil respiration showed a form of the single-peak curve, generally, the strongest appears between 14:00 and 15:00, and the weakest appears around 5:00 in the early morning. Daily changes of soil respiration were same with 5cm soil temperature changes, but slightly lagged behind the dynamic changes in surface temperature. Soil respiration rate of clear cutting was higher than F. pashannica forest, The maximum value of soil respiration rate of the clear cutting appeared at 14:00, while in the forest at 15:00-16:00, and the minimum both appeared around 5:00 in the early morning; compared with forest, the clear cutting reached the highest value about 1 hour ahead, and temperature was significantly related with soil respiration rate （p＜0.01）.Research results showed that slope position had great influence on F pashannica seedling regeneration and growth, and downhill was more suitable than midhill and uphill position for growth of F. pashannica seedling. Protection of F. pashannica played a very significant role in enhancing hydrology and ecological functions of surface litter layer, increasing the water retention ability, reducing surface runoff loss of soil, improving natural water content of soil, soil nutrient content, soil enzyme activity and soil structure, increasing carbon content and carbon pool index. Proper disturb can enhance biodiversity of F. pashannica, but will weaken its ecological functions. Our study can provide evidence for F. pashannica protection, soil forest scientific management of its natural secondary forest and its forestation.更多还原