Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and obser...Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and observation of fine roots of seven species including the Euphorbiaceae, Theaceae, Melastomataceae, Lauraceae and Fagaceae families was carried out. The results showed that： （1） Pioneer tree roots in the first stage of natural succession were of two types, one characterized by taproot system with bulky plagiotropic branches; the other characterized by flat root system with several tabular roots. The late mesophilous tree roots were characterized by one obvious taproot and tactic braches roots up and down. Shrub species roots were characterized by heart fibrous root type featured both by horizontally and transversally growing branches. Root shapes varied in different dominant species at different stages of succession. （2） Roots of the different species varied in the external features-color, periderm and structure of freshly cut slash. （3） In a set of successional stages the biomass of tree roots increased linearly with the age of growth. During monsoon, the total root biomass amounted to 115.70 t/ha in the evergreen broadqeaved forest; 50.61 t/ha in needle and broad-leaved mixed forest dominated by coniferous forest; and 64.20 t/ha in broad-and needle-leaved mixed forest dominated by broad-leaved heliophytes, and are comparable to the underground biomass observed in similar tropical forests. This is the first report about roots characteristics of forest in the lower sub-tropical area of Dinghushan, Guangdong, China.展开更多
There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusive...There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusively planted as monocultures in the Pengzhou forest farm in the western mountainous area of Sichuan Province. This study aimed to assess the spatial and ecological characteristics of middle-aged Cunninghamia lanceolata(Lamb.) Hook. and Cryptomeria fortunei Hooibr. in the Pengzhou forest farm. The relationships and differences between stand growth characteristics and forest soil composition were assessed on the two forests planted simultaneously within the same area and exposed to the same environmental conditions. Cr. fortunei grew sparse, and slower than Cun. lanceolata. Principal component analysis indicated that the soil properties in the Cr. fortunei plantation were better than those in the Cun. lanceolata plantation. Redundancy analysis revealed that the differences in stand structure were affected significantly by the total nitrogen content and pH value. Thus, we propose that Cr. fortunei is planted for priority consideration in the subtropical high mountain area. Further, tending operations and application of fertilizers need to be conducted in Cun. lanceolata forests. Based on theoretical and experimental data, the present study explains why local farmers are more willing to plant Cr. fortunei, and thus provides a useful theoretical reference for the development of sustainable plantations in the future.展开更多
In tropical montane areas, water limitation is a common occurrence, and both pioneer and forests species experience water stress during the dry season. Adjustments of leaf area during periods of drought allow for the ...In tropical montane areas, water limitation is a common occurrence, and both pioneer and forests species experience water stress during the dry season. Adjustments of leaf area during periods of drought allow for the maintenance of the water supply and physiological functions of the remaining leaves. Here, we compared leaf blade water relations between pioneer and forest tree species. Leaf pressure-volume (P-V) curves were determined from samples taken prior to the dry season, to assess how leaves of the different species were adapted to prepare for and endure water deficits. The following parameters were calculated: osmotic potential at full (Ψπ(100)) and zero (Ψπ(0)) turgor, relative water content at zero turgor (RWC0), volumetric elastic modulus (ε) as well as apoplasm (A) and symplasm (S) water content and their ratio (A/S). Although the pioneer and forest species occupied contrasting habitats, and both groups were clearly differentiated with respect to their water transport capability and water use efficiency, their leaf tissue water relations showed clear differences across species but not between the groups. Some species underwent leaf shedding and accumulated xylem embolisms during the dry season, and their leaves had high cell elasticity. Consequently, these species presented large cell volume changes with turgor loss. Conversely, species with rigid leaves were able to undergo lower leaf turgor with only small changes in cell volume during drought, which might aid to preserve leaf cell function, maintain water uptake, and consequently avoid accelerated leaf senescence and shedding during the dry season.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30270282) and the Science Foundation of Guangdong Province (No. 003031), China
文摘Representative pioneer tree root systems in the subtropical area of South China were examined with regard to their structure, underground stratification and biomass distribution. Excavation of skeleton roots and observation of fine roots of seven species including the Euphorbiaceae, Theaceae, Melastomataceae, Lauraceae and Fagaceae families was carried out. The results showed that： （1） Pioneer tree roots in the first stage of natural succession were of two types, one characterized by taproot system with bulky plagiotropic branches; the other characterized by flat root system with several tabular roots. The late mesophilous tree roots were characterized by one obvious taproot and tactic braches roots up and down. Shrub species roots were characterized by heart fibrous root type featured both by horizontally and transversally growing branches. Root shapes varied in different dominant species at different stages of succession. （2） Roots of the different species varied in the external features-color, periderm and structure of freshly cut slash. （3） In a set of successional stages the biomass of tree roots increased linearly with the age of growth. During monsoon, the total root biomass amounted to 115.70 t/ha in the evergreen broadqeaved forest; 50.61 t/ha in needle and broad-leaved mixed forest dominated by coniferous forest; and 64.20 t/ha in broad-and needle-leaved mixed forest dominated by broad-leaved heliophytes, and are comparable to the underground biomass observed in similar tropical forests. This is the first report about roots characteristics of forest in the lower sub-tropical area of Dinghushan, Guangdong, China.
基金funded by the National Key Research and Development Program of China(Grant No.2016YFD060020302)the Doctoral Graduate Student’s Academic Visit Fund of Sichuan University
文摘There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusively planted as monocultures in the Pengzhou forest farm in the western mountainous area of Sichuan Province. This study aimed to assess the spatial and ecological characteristics of middle-aged Cunninghamia lanceolata(Lamb.) Hook. and Cryptomeria fortunei Hooibr. in the Pengzhou forest farm. The relationships and differences between stand growth characteristics and forest soil composition were assessed on the two forests planted simultaneously within the same area and exposed to the same environmental conditions. Cr. fortunei grew sparse, and slower than Cun. lanceolata. Principal component analysis indicated that the soil properties in the Cr. fortunei plantation were better than those in the Cun. lanceolata plantation. Redundancy analysis revealed that the differences in stand structure were affected significantly by the total nitrogen content and pH value. Thus, we propose that Cr. fortunei is planted for priority consideration in the subtropical high mountain area. Further, tending operations and application of fertilizers need to be conducted in Cun. lanceolata forests. Based on theoretical and experimental data, the present study explains why local farmers are more willing to plant Cr. fortunei, and thus provides a useful theoretical reference for the development of sustainable plantations in the future.
文摘In tropical montane areas, water limitation is a common occurrence, and both pioneer and forests species experience water stress during the dry season. Adjustments of leaf area during periods of drought allow for the maintenance of the water supply and physiological functions of the remaining leaves. Here, we compared leaf blade water relations between pioneer and forest tree species. Leaf pressure-volume (P-V) curves were determined from samples taken prior to the dry season, to assess how leaves of the different species were adapted to prepare for and endure water deficits. The following parameters were calculated: osmotic potential at full (Ψπ(100)) and zero (Ψπ(0)) turgor, relative water content at zero turgor (RWC0), volumetric elastic modulus (ε) as well as apoplasm (A) and symplasm (S) water content and their ratio (A/S). Although the pioneer and forest species occupied contrasting habitats, and both groups were clearly differentiated with respect to their water transport capability and water use efficiency, their leaf tissue water relations showed clear differences across species but not between the groups. Some species underwent leaf shedding and accumulated xylem embolisms during the dry season, and their leaves had high cell elasticity. Consequently, these species presented large cell volume changes with turgor loss. Conversely, species with rigid leaves were able to undergo lower leaf turgor with only small changes in cell volume during drought, which might aid to preserve leaf cell function, maintain water uptake, and consequently avoid accelerated leaf senescence and shedding during the dry season.
