本文關(guān)鍵詞： 桂西南 負(fù)載量 馬尾松人工林 調(diào)控措施 空間連續(xù)性　出處：《中南林業(yè)科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：本研究以廣西南寧市典型人工林為研究對象,在對各林型內(nèi)可燃物進(jìn)行分類,采樣調(diào)查、室內(nèi)分析和模型預(yù)測的基礎(chǔ)上,通過研究不同樹種、灌木、草本、凋落物和腐殖質(zhì)層等可燃物在空間上的分布規(guī)律和負(fù)載量特征,探討不同林型單元內(nèi)的可燃物屬性、結(jié)構(gòu)和潛在林火行為特征。在對馬尾松純林、馬尾松-大葉櫟混交林和大葉櫟純林可燃物負(fù)載量空間分布與樹冠火行為關(guān)系分析的基礎(chǔ)上,運用可燃物空間連續(xù)性指數(shù)評估模型,對不同林型可燃物垂直連續(xù)性和水平連續(xù)性進(jìn)行計算,評估了針葉林和針闊混交林樹冠火發(fā)生和蔓延的可能性,提出了阻滯樹冠火轉(zhuǎn)化和蔓延的調(diào)控措施。研究得出如下主要結(jié)論:(1)馬尾松純林枝葉負(fù)載量最高,松櫟混交林居中,大葉櫟純林最低;馬尾松純林灌木層可燃物負(fù)載量也高于松櫟混交林和大葉櫟純林;各類別可燃物中,冠層大枝占比最高,1000h枯枝占比最低;馬尾松純林中易燃可燃物負(fù)載量最高(16.29 t/hm2),其次是松櫟混交林(15.64 t/hm2),大葉櫟純林最低(9.00 t/hm2),易燃可燃物是關(guān)鍵的引燃物,與森林火災(zāi)風(fēng)險密切相關(guān),馬尾松林潛在樹冠火風(fēng)險最高,其次是松櫟混交林,大葉櫟純林極難發(fā)生樹冠火。(2)采用表面積加權(quán)算法的蔓延速度(MRE=5.43%)和火焰長度(MRE=14.27%)預(yù)測效果較好,采用負(fù)載量加權(quán)算法的反應(yīng)強度(MRE=4.07%)和火線強度(MRE=16.29%)預(yù)測效果較好。(3)反應(yīng)強度與可燃物負(fù)載量正相關(guān),與含水率負(fù)相關(guān);可燃物負(fù)載量、風(fēng)速和坡度對于蔓延速度均有增益效果,但當(dāng)可燃物負(fù)載量增大到一定量(高點)后,蔓延速度不再增加,三個林型可燃物負(fù)載量的(蔓延速度限制)高點分別為30～32t/hm2、40t/hm2和20t/hm2;風(fēng)速對于蔓延速度貢獻(xiàn)要大于坡度,同樣風(fēng)速下,馬尾松林火蔓延速度最高,其次是松櫟混交林,大葉櫟林最低。(4)基于環(huán)境因子、可燃物性質(zhì)和空間位置以及林火特征,將森林燃燒等級劃為低、中、高三級,推算了不同燃燒等級下的火強度、可燃物消耗量和火焰高度。整體來看,馬尾松在各等級燃燒條件下所釋放能量密度均較高,發(fā)生樹冠火后可燃物燒損量也最大,而大葉櫟純林無法形成樹冠火,僅能在0～1m區(qū)間提供適宜的地表火燃燒條件,對森林生態(tài)系統(tǒng)影響最小。(5)基于Byram模型,根據(jù)平地?zé)o風(fēng)條件下火焰燃燒狀態(tài)、可燃物分層和冠層平均枝下高,建立了可燃物垂直連續(xù)性指數(shù)和水平連續(xù)性指數(shù)及等級。應(yīng)用連續(xù)性評估模型對馬尾松林和松櫟混交林的可燃物空間連續(xù)性進(jìn)行了定量評估,可燃物的垂直連續(xù)性高低決定地表火能否轉(zhuǎn)化為樹冠火,而水平連續(xù)性高低決定樹冠火是否能大面積蔓延。結(jié)果表明,馬尾松林可燃物整體垂直連續(xù)性指數(shù)和水平連續(xù)性指數(shù)較高,均達(dá)到了高度連續(xù),松櫟混交林可燃物整體垂直連續(xù)性為低等級連續(xù),其水平連續(xù)性為高等級連續(xù)。(6)根據(jù)火焰高度分級和Byram模型,推導(dǎo)了可燃物連續(xù)性負(fù)載量閾值計算公式,分別計算了馬尾松林和松櫟混交林不同單元內(nèi)0～3m區(qū)間可燃物垂直連續(xù)性負(fù)載量閾值,并以此為依據(jù),制定了具體的可燃物調(diào)控措施,根據(jù)二次評估結(jié)果,篩選了不同林型的最佳調(diào)控方案(馬尾松純林采取方案一中的3m修枝高度,松棟混交林采取方案一中的3m修枝高度,亦可視具體情況調(diào)整為4m修枝高度),可兼顧森林生態(tài)系統(tǒng)穩(wěn)定性維持、用材林目標(biāo)樹種生物量提高和森林潛在火災(zāi)風(fēng)險控制多目標(biāo)協(xié)同管理。
[Abstract]:In this study, Guangxi Nanning City, a typical plantation as the research object, in the combustible in each forest type classification, sampling survey, laboratory analysis and prediction model based on the study of different trees, shrubs, herbs, distribution of litter and humus layer and other combustible materials in space and the load characteristics. The attribute of combustibles in different forest types in the unit, structure and potential fire behavior characteristics. In the pure forest of Pinus massoniana, Pinus massoniana and Castanopsis fissa mixed forest and pure forest of castanopsisfissa fuel load based analysis of the relationship between the distribution and crown fire behavior, the use of combustible space continuity index evaluation model for different forest type of fuel vertical continuity and continuity are calculated, the assessment of possibility of coniferous forest and mixed forest crown fire occurrence and spread, and put forward the control measures into the block crown fire and spread application research. The main conclusions are as follows: (1) the highest load of branches of pure pine forest, pine and oak mixed forest center, Li Chunlin leaves the lowest; Pinus forest shrub layer is higher than the amount of fuel load and oak pine mixed forest of Castanopsis fissa plantations; various types of combustible materials, the highest proportion of big canopy, litter accounted for the lowest 1000h flammable materials; pure forest load was the highest (16.29 t/hm2), followed by pine oak mixed forest (15.64 t/hm2), castanopsisfissa pure forest is the lowest (9 t/hm2), is the key to the ignition of flammable combustible material, and is closely related to the risk of forest fires, the highest potential in masson pine forest crown fire risk, followed by Oak pine mixed forest, Castanopsis fissa plantations can hardly occur crown fire. (2) using surface area weighted algorithm (MRE=5.43%) and the rate of spread of flame length (MRE=14.27%) better prediction effect by reactive load intensity weighted algorithm (MRE=4.07%) and fire intensity (MRE=16.29 %) better forecasting effect. (3) the reaction intensity and fuel load of positive correlation, negative correlation with water content; fuel load, wind speed and slope for the spread has gain effect, but when the fuel load increased to a certain amount (high), the spread rate no longer increased three Lin type fuel load (spread speed limit) high were 30 ~ 32t/hm2,40t/hm2 and 20t/hm2; the wind speed for spreading speed is bigger than the slope under the same wind velocity, masson pine forest fire spread fastest, followed by the oak pine mixed forest, Castanopsis fissa forest was the lowest. (4) based on the environmental factor, the combustible material and space the location and characteristics of forest fire, forest fire will be classified as low grade, grade, grade, fire intensity under different combustion calculated, fuel consumption and flame height. Overall, Masson conditions in the energy released in the combustion of each grade were density The high occurrence of crown fire after the fuel consumption is the largest, and the pure forest of Castanopsis fissa cannot form a crown fire, only in the interval from 0 to 1m provide a suitable surface fire combustion conditions, with minimal impact on forest ecosystem. (5) based on the Byram model, according to the ground without wind flame burning state, combustible layered and canopy height under branch, established fuel vertical continuity index and horizontal continuity index and the rating. Combustible space application continuity evaluation model of Masson pine forest and pine oak mixed forest continuity were assessed quantitatively, fuel vertical continuity decides the surface fire can be transformed into crown fire. While the level of continuity determines whether a large area of crown fire spread. The results showed that the Masson pine forest combustible overall vertical continuity index and horizontal continuity index was higher, reached the height of continuous, pine and oak mixed forest combustibles The overall vertical continuity for the low level continuously, its level of continuity for high grade continuous. (6) according to the classification of flame height and Byram model, deduces the combustible continuous load threshold formula, forest and pine oak mixed forest of Pinus massoniana in different units is 0 ~ 3M between fuel vertical continuity load threshold respectively. The calculation, and on this basis, developed a combustible specific control measures, according to the two assessment results, the optimum control scheme of different forest types (pure pine forest program one 3m in the height of pruning, pine mixed forest, take a program of 3M pruning height, depending on the particular circumstances of adjustment is also 4m), can take into account the pruning height to maintain the stability of forest ecosystem, forest tree biomass and improve target timber forest fire risk control potential multi-objective collaborative management.

【學(xué)位授予單位】：中南林業(yè)科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：S762
，

本文編號：1540131