C3 plant Reaumuria soongorica and C4 plant Salsola passerina are super xerophytes and coexist in a mixed community in either isolated or associated growth, and interspecific facilitation occurs in associated growth. I...C3 plant Reaumuria soongorica and C4 plant Salsola passerina are super xerophytes and coexist in a mixed community in either isolated or associated growth, and interspecific facilitation occurs in associated growth. In the present study, the root traits including root distribution, root length（RL）, root surface area（RSA）, root weight（RW） and specific root length（SRL） of both species in two growth forms were investigated to clarify their response to facilitation in associated growth. Six isolated plants of each species, as well as six associated plants similar in size and development were selected during the plant growing season, and their roots were excavated at 0–10, 10–20, 20–30, 30–40 and 40–50 cm soil depths at the end of the growing season. All the roots of each plant were separated into the two categories of fine roots（2 mm diameter） and coarse roots（≥2 mm diameter）. Root traits such as RL and RSA in the fine and coarse roots were obtained by the root analyzing system WinRHIZO. Most of the coarse roots in R. soongorica and S. passerina were distributed in the top 10 cm of the soil in both growth forms, whereas the fine roots of the two plant species were found mainly in the 10–20 and 20–30 cm soil depths in isolated growth, respectively. However, the fine roots of both species were mostly overlapped in 10–20 cm soil depth in associated growth. The root/canopy ratios of both species reduced, whereas the ratios of their fine roots to coarse roots in RL increased, and both species had an increased SRL in the fine roots in associated growth. In addition, there was the increase in RL of fine roots and content of root N for S. passerina in associated growth. Taken together, the root growth of S. passerina was facilitated for water and nutrient exploration under the interaction of the overlapped roots in both species in associated growth, and higher SRL allowed both species to more effectively adapt to the infertile soil in the desert ecosystem.展开更多
Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive to many global change factors.Despite the importance of fine root turnover in plant C alloca...Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive to many global change factors.Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics and the tremendous research efforts in the past,our understanding of it remains limited.This is because the dynamics processes associated with soil resources availability are still poorly understood.Soil moisture,temperature,and available nitrogen are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch and at the ecosystem level.In temperate forest ecosystems,seasonal changes of soil resource availability will alter the pattern of carbon allocation to belowground.Therefore,fine root biomass,root length density(RLD)and specific root length(SRL)vary during the growing season.Studying seasonal changes of fine root biomass,RLD,and SRL associated with soil resource availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover.The objective of this study was to understand whether seasonal variations of fine root biomass,RLD and SRL were associated with soil resource availability,such as moisture,temperature,and nitrogen,and to understand how these soil components impact fine root dynamics in Larix gmelinii plantation.We used a soil coring method to obtain fine root samples(≤2 mm in diameter)every month from May to October in 2002 from a 17-year-old L.gmelinii plantation in Maoershan Experiment Station,Northeast Forestry University,China.Seventy-two soil cores(inside diameter 60 mm;depth intervals:0-10 cm,10-20 cm,20-30 cm)were sampled randomly from three replicates 25 m×30 m plots to estimate fine root biomass(live and dead),and calculate RLD and SRL.Soil moisture,temperature,and nitrogen(ammonia and nitrates)at three depth intervals were also analyzed in these plots.Results showed that the average standing fine root biomass(live and dead)was 189.1 g·m^(-2)·a^(-1),50%(95.4 g·m^(-2)·a^(-1))in the surface soil layer(0-10 cm),33%(61.5 g·m^(-2)·a^(-1)),17%(32.2 g·m^(-2)·a^(-1))in the middle(10-20 cm)and deep layer(20-30cm),respectively.Live and dead fine root biomass was the highest from May to July and in September,but lower in August and October.The live fine root biomass decreased and dead biomass increased during the growing season.Mean RLD(7,411.56 m·m^(-3)·a^(-1))and SRL(10.83 m·g^(-1)·a^(-1))in the surface layer were higher than RLD(1474.68 m·m^(-3)·a^(-1))and SRL(8.56 m·g^(-1)·a^(-1))in the deep soil layer.RLD and SRL in May were the highest(10621.45 m·m^(-3) and 14.83m·g^(-1))compared with those in the other months,and RLD was the lowest in September(2198.20 m·m^(-3))and SRL in October(3.77 m·g^(-1)).Seasonal dynamics of fine root biomass,RLD,and SRL showed a close relationship with changes in soil moisture,temperature,and nitrogen availability.To a lesser extent,the temperature could be determined by regression analysis.Fine roots in the upper soil layer have a function of absorbing moisture and nutrients,while the main function of deeper soil may be moisture uptake rather than nutrient acquisition.Therefore,carbon allocation to roots in the upper soil layer and deeper soil layer was different.Multiple regression analysis showed that variation in soil resource availability could explain 71-73%of the seasonal variation of RLD and SRL and 58%of the variation in fine root biomass.These results suggested a greater metabolic activity of fine roots living in soil with higher resource availability,which resulted in an increased allocation of carbohydrate to these roots,but a lower allocation of carbohydrate to those in soil with lower resource availability.展开更多
This paper investigated spatial distribution of Zanthoxylum bungeanum fine roots,which were sampled by excavating monoliths.The results showed that the root length density,surface area,volume as well as biomass were d...This paper investigated spatial distribution of Zanthoxylum bungeanum fine roots,which were sampled by excavating monoliths.The results showed that the root length density,surface area,volume as well as biomass were decreased with an increase in depth from 20 cm to 100 cm.The roots mainly distributed in 0～40 cm in the verticality,and the root length density,surface area,volume as well as biomass amounted to 72.0%,65.6%,59.2% and 57.5% of the corresponding total amount.Minimum and maximum of specific root length were respectively exhibited at 0～10 cm and 70～80 cm in the verticality.In addition,the root horizontal distribution reached to 110 cm,however most fine roots distributed within 50 cm and the horizon.And the root length density and biomass accounted for 71.5% and 76.4% of the total amount respectively.The minimum and the maximum of specific root length were exhibited at 10～20 cm and 70～80 cm in the horizon.展开更多
基金support by the National Natural Science Foundation of China (91025026, 31070359)the National Basic Research Program of China (Y31JA61001)
文摘C3 plant Reaumuria soongorica and C4 plant Salsola passerina are super xerophytes and coexist in a mixed community in either isolated or associated growth, and interspecific facilitation occurs in associated growth. In the present study, the root traits including root distribution, root length（RL）, root surface area（RSA）, root weight（RW） and specific root length（SRL） of both species in two growth forms were investigated to clarify their response to facilitation in associated growth. Six isolated plants of each species, as well as six associated plants similar in size and development were selected during the plant growing season, and their roots were excavated at 0–10, 10–20, 20–30, 30–40 and 40–50 cm soil depths at the end of the growing season. All the roots of each plant were separated into the two categories of fine roots（2 mm diameter） and coarse roots（≥2 mm diameter）. Root traits such as RL and RSA in the fine and coarse roots were obtained by the root analyzing system WinRHIZO. Most of the coarse roots in R. soongorica and S. passerina were distributed in the top 10 cm of the soil in both growth forms, whereas the fine roots of the two plant species were found mainly in the 10–20 and 20–30 cm soil depths in isolated growth, respectively. However, the fine roots of both species were mostly overlapped in 10–20 cm soil depth in associated growth. The root/canopy ratios of both species reduced, whereas the ratios of their fine roots to coarse roots in RL increased, and both species had an increased SRL in the fine roots in associated growth. In addition, there was the increase in RL of fine roots and content of root N for S. passerina in associated growth. Taken together, the root growth of S. passerina was facilitated for water and nutrient exploration under the interaction of the overlapped roots in both species in associated growth, and higher SRL allowed both species to more effectively adapt to the infertile soil in the desert ecosystem.
基金supported by the National Natural Science Foundation of China (No.30130160).
文摘Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive to many global change factors.Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics and the tremendous research efforts in the past,our understanding of it remains limited.This is because the dynamics processes associated with soil resources availability are still poorly understood.Soil moisture,temperature,and available nitrogen are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch and at the ecosystem level.In temperate forest ecosystems,seasonal changes of soil resource availability will alter the pattern of carbon allocation to belowground.Therefore,fine root biomass,root length density(RLD)and specific root length(SRL)vary during the growing season.Studying seasonal changes of fine root biomass,RLD,and SRL associated with soil resource availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover.The objective of this study was to understand whether seasonal variations of fine root biomass,RLD and SRL were associated with soil resource availability,such as moisture,temperature,and nitrogen,and to understand how these soil components impact fine root dynamics in Larix gmelinii plantation.We used a soil coring method to obtain fine root samples(≤2 mm in diameter)every month from May to October in 2002 from a 17-year-old L.gmelinii plantation in Maoershan Experiment Station,Northeast Forestry University,China.Seventy-two soil cores(inside diameter 60 mm;depth intervals:0-10 cm,10-20 cm,20-30 cm)were sampled randomly from three replicates 25 m×30 m plots to estimate fine root biomass(live and dead),and calculate RLD and SRL.Soil moisture,temperature,and nitrogen(ammonia and nitrates)at three depth intervals were also analyzed in these plots.Results showed that the average standing fine root biomass(live and dead)was 189.1 g·m^(-2)·a^(-1),50%(95.4 g·m^(-2)·a^(-1))in the surface soil layer(0-10 cm),33%(61.5 g·m^(-2)·a^(-1)),17%(32.2 g·m^(-2)·a^(-1))in the middle(10-20 cm)and deep layer(20-30cm),respectively.Live and dead fine root biomass was the highest from May to July and in September,but lower in August and October.The live fine root biomass decreased and dead biomass increased during the growing season.Mean RLD(7,411.56 m·m^(-3)·a^(-1))and SRL(10.83 m·g^(-1)·a^(-1))in the surface layer were higher than RLD(1474.68 m·m^(-3)·a^(-1))and SRL(8.56 m·g^(-1)·a^(-1))in the deep soil layer.RLD and SRL in May were the highest(10621.45 m·m^(-3) and 14.83m·g^(-1))compared with those in the other months,and RLD was the lowest in September(2198.20 m·m^(-3))and SRL in October(3.77 m·g^(-1)).Seasonal dynamics of fine root biomass,RLD,and SRL showed a close relationship with changes in soil moisture,temperature,and nitrogen availability.To a lesser extent,the temperature could be determined by regression analysis.Fine roots in the upper soil layer have a function of absorbing moisture and nutrients,while the main function of deeper soil may be moisture uptake rather than nutrient acquisition.Therefore,carbon allocation to roots in the upper soil layer and deeper soil layer was different.Multiple regression analysis showed that variation in soil resource availability could explain 71-73%of the seasonal variation of RLD and SRL and 58%of the variation in fine root biomass.These results suggested a greater metabolic activity of fine roots living in soil with higher resource availability,which resulted in an increased allocation of carbohydrate to these roots,but a lower allocation of carbohydrate to those in soil with lower resource availability.
文摘This paper investigated spatial distribution of Zanthoxylum bungeanum fine roots,which were sampled by excavating monoliths.The results showed that the root length density,surface area,volume as well as biomass were decreased with an increase in depth from 20 cm to 100 cm.The roots mainly distributed in 0～40 cm in the verticality,and the root length density,surface area,volume as well as biomass amounted to 72.0%,65.6%,59.2% and 57.5% of the corresponding total amount.Minimum and maximum of specific root length were respectively exhibited at 0～10 cm and 70～80 cm in the verticality.In addition,the root horizontal distribution reached to 110 cm,however most fine roots distributed within 50 cm and the horizon.And the root length density and biomass accounted for 71.5% and 76.4% of the total amount respectively.The minimum and the maximum of specific root length were exhibited at 10～20 cm and 70～80 cm in the horizon.
