The Pattern of Understory Plant Diversity and Soil Physicochemical Properties in the Severely Burned Areas of Forests
To investigate the changes in plant biodiversity and soil physicochemical properties in severely burned forest areas,we selected sample plots from different recovery periods(2.5-16.0 years)after intense burning in Lankeshan Provincial Nature Reserve in Xijiang,Guangdong and Beiling Mountain forest farms,as well as plots from a forest park that had never been burned(control group).We recorded detailed information on plant species,their numbers,and coverage within the sample plots,and calculated plant diversity indices.Concurrently,we measured the physicochemical properties of the topsoil(0-10 cm)and the particle size distri-bution of macroaggregates(wet sieving)and micro-aggregates.The results showed that,(1)After severe burning,the number of understory plant species,their abundance,Margalef richness index,and Shannon-Wiener diversity index were all lower than those in the control plots that had not been burned.The understory plant species and abundance significantly decreased after burning.Over time,the burned plots showed an initial increase followed by a decrease in the number of understory plant species,Shannon-Wiener index,Pielou evenness index,and litter depth.However,Margalef richness index and Fisher's α showed an overall increas-ing trend.Most soil physicochemical properties were positively correlated with Simpson dominance index and habitat Fisher's α but negatively correlated with other diversity indices;however,these correlations were not significant.(2)With an increase in the recovery period after burning,soil pH,total potassium,total phos-phorus,and available phosphorus generally first increased and then decreased.Meanwhile,available potassi-um,total nitrogen,hydrolyzable nitrogen,cation exchange capacity showed an initial decrease followed by an increase.(3)As the recovery period after burning increased,the content of stable macroaggregates(>0.50 mm and>0.25 mm)in the soil increased initially and then decreased.Severe burning helped increase the con-tent of macroaggregates and soil stability in the short term.The content of micro-aggregates(≤0.25 mm)de-creased initially and then increased with the lengthening of recovery time.The short-term recovery process after burning enhanced the erosion-resistant stability of fine soil particles.
fire recoverybiodiversityforestsoil physico-chemical propertieswater stable macroag-gregatesmicro-aggregates
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