火烧对黔中喀斯特山地马尾松林分的影响

Influence of fire on stands of Pinus massoniana in a karst mountain area of central Guizhou province

采用样地比较法在黔中喀斯特山地上覆第四纪粘土的马尾松人工次生林内,研究了林火对马尾松林分的影响,结果表明过火马尾松林不同部位的受害率为树皮(95.51%)>树枝(71.49%)>树冠(62.95%),不同层片的植物死亡率为草本层(100.00%)>灌木层(30.43%)>乔木层(29.09%)。马尾松树皮受害率不因径级而变化、树枝和树冠受害率及植株死亡率随径级增高而降低,灌木层物种或全部死亡、或部分死亡、或全部存活,草本层物种或死亡、或萌生。过火马尾松林地生物量的潜在损失量(68.7755 t/hm2)>直接损失量(12.1818 t/hm2)、直接损失率22.41%,直接损失量中乔木层(6.9382 t/hm2)>枯物层(3.3441 t/hm2)>灌木层(2.4964 t/hm2)>草本层(0.8861 t/hm2),直接损失率中草本层或枯物层(100.00%)>灌木层(33.36%)>乔木层(23.59%)。过火马尾松林不同层片的Patrick指数、Gleason指数、Simpson指数和Hurlbert指数损失量为草本层>灌木层>乔木层、潜在损失量>直接损失量,直接损失率中乔木层的相应值为14.29%、14.29%、17.85%、-11.29%,灌木层的相应值为26.76%、26.76%、37.63%、-18.53%,草本层为100.00%。

The effects of fire on artificial secondary forests of Pinus massoniana with an average diameter at breast height（DBH） from 5.5958 cm to 19.3900 cm,average height from 4.11 m to 18.60 m,and average density from 500 clumps hm-2 to 2400 clumps hm-2,were investigated by comparison of burnt and non-burnt plots in a karst mountain area covered by Quaternary clay in central Guizhou province,China.The percentage damage to P.massoniana trees differed among plant organs and followed the order bark（95.51%） branches（71.49%） crown（62.95%）.The percentage plant death in different forest layers was highest in the herbaceous layer（100%）,intermediate in the arbuscular layer（30.43%） and lowest in the arboreous layer（29.09%）.With increasing DBH of P.massoniana in the arboreous layer,the percentage damage to bark was unchanged,whereas damage to branches and the crown decreased,and the percentage death of plants also decreased.At P.massoniana DBH5 cm,the percentage damage to bark,branches and the crown,percentage plant death and direct loss of biomass were all 100%,whereas at DBH≥25 cm the percentage damage to bark,branches and the crown were 85.00%,25.00% and 15.00%,respectively,and percentage plant death and direct loss of biomass were zero.In the arbuscular layer,either all individuals of a plant species died,such as P.massoniana,Betula alnoides and Camellia oleifera,all plants survived,such as Prunus serrulata,Myrsine africana and Rhamnus leptophylla,or only some plants died,such as Cunninghamia lanceolata,Castanea seguinii and Aralia chinensis.Plant species in the herbaceous layer either died or germinated after death of aboveground branches and leaves because of fire.In burnt forest,the potential biomass loss（68.7755 t/hm2） was higher than direct biomass loss（12.1818 t/hm2;percentage direct loss 22.41%）.Direct biomass loss differed among the layers and followed the order arboreous layer（6.9382 t/hm2） litter layer（3.3441 t/hm2） arbuscular layer（2.4964 t/hm2） herbaceous layer（0.8861 t/hm2）;in terms of the corresponding percentage direct biomass loss,the order was herbaceous layer（or litter layer,100.00%） arbuscular layer（33.36%） arboreous layer（23.59%）.Decreases in the Patrick,Gleason,Simpson and Hurlbert indices followed the order herbaceous layer arbuscular layer arboreous layer,and reflected potential losses were higher than direct losses of plant diversity in the different layers of burnt forests.The range and average values of direct diversity loss in the arboreous layer indicated by the Patrick,Gleason,Simpson and Hurlbert indices were 0—1 and 0.1429,0—0.1669 and 0.0238,0—1.0000 and 0.1586,and-0.1098—0 and-0.0166,respectively;the corresponding range and average values of percentage direct biodiversity loss were 0—100 and 14.29,0—100 and 14.29,0.66—100 and 17.85,and-18.61—-3.98 and-11.29,respectively.The range and average values of direct loss of diversity in the arbuscular layer as measured by these indices were 0—5 and 1.8571,0—0.6948 and 0.4301,0—0.2987 and 0.1115,and-0.3477—0 and-0.1241,respectively;the corresponding range and average values of percentage direct biodiversity loss were 0—42.86 and 26.76,0—42.85 and 26.76,0—86.35 and 37.63,and-52.00—0 and-18.53,respectively.The range and average values of direct diversity loss in the herbaceous layer indicated by these indices were 2—6 and 3.8000,1.8205—5.4614 and 3.4589,0.2593—0.8313 and 0.5300,and 0.1728—0.7619 and-0.4863;the percentage direct loss was 100.00% for all of the indices.The average burn height of the arboreous layer was negatively correlated to DBH,positively correlated to density and percentage damage to branches,the crown and entire plants,and uncorrelated with percentage damage to bark.The arboreous layer showed higher burn heights than those of the arbuscular layer,and their correlation was negative,and was negatively correlated to potential or direct loss of biomass and positively correlated to percentage direct loss of biomass.Burn height was positively correlated to direct loss or percentage direct loss of biomass,and negatively correlated to potential loss of biomass in the arbuscular layer.Direct loss or percentage direct loss of biomass with the Patrick and Gleason indices was not obviously correlated to burn height in the arboreous layer and was positively correlated to burn height in the arbuscular layer.Burn height was positively correlated to direct loss,and negatively correlated to percentage direct loss,of biomass with the Simpson index in the arboreous layer,and positively correlated to direct loss and percentage direct loss of biomass with the Simpson index in the arbuscular layer.No obvious correlation between burn height of the arboreous or arbuscular layer and direct loss or percentage direct loss of biomass with the Hurlbert index was detected.