The aquatic environment capacity possesses the largest tolerance to pollutants. We can improve the calculating precision using the conceptual net method. Its basic ways involved in calculation include the following as...The aquatic environment capacity possesses the largest tolerance to pollutants. We can improve the calculating precision using the conceptual net method. Its basic ways involved in calculation include the following aspects: first, to establish the flow continuity equation, flow motion equation, water quality equation and other mathematical models; at the same time, to conceptualize the reservoir studied, divide the reservoir into several functional areas, and use the one-dimensional section-beginning calculation model to calculate all cross-sections of each functional area; then, to superimpose the environmental capacity of each functional section to get the aquatic environment capacity of the entire two-dimensional space; and finally, to introduce how to make use of the conceptual net to calculate the aquatic environment capacity in terms of the actual reservoir's situation.展开更多
Set-nets are common alongshore fishing gear used in Haizhou Bay, which rely on flow to catch fish. The catch per unit effort(CPUE) of set-net is affected by spatial-temporal and environmental factors but no research h...Set-nets are common alongshore fishing gear used in Haizhou Bay, which rely on flow to catch fish. The catch per unit effort(CPUE) of set-net is affected by spatial-temporal and environmental factors but no research has been conducted on this subject. In this study, we used generalized additive models(GAMs) to explore the influence of spatial-temporal and environmental factors on CPUEs of species aggregated, small yellow croaker(Larimichthys polyactis), and octopus(Octopus variabilis) based on logbooks investigations conducted at 4 stations in an alongshore area of Haizhou Bay from 2011 to 2012. The results showed that all CPUEs exhibited significant spatial-temporal differences at various scales. Aggregated CPUE was high when the sea surface temperature(SST) was 15-18℃ and 20-23℃, which was mainly determined by life history traits of the octopus and small yellow croaker(optimal SSTs 14-17℃ and 19-24℃, respectively). Chlorophyll-a concentration had significant influences on the aggregated, small yellow croaker and octopus CPUEs at optimal ranges of 3.8-6.2 mg m^(-3), 4.2-4.8 mg m^(-3) and 4.5-5.5 mg m^(-3), respectively. Flow through the net had positive relationships with CPUEs. The approximate logarithmic trends in regression curves had a critical point of 2.5 Mm^3 d^(-1), which was the dividing point that differentiated whether the major factor affecting CPUEs was the flow velocity or the fishery resource. Our results from this study will help guide fishery production and improve catch rate of set-net fishing in Haizhou Bay.展开更多
In order to identify the relationship between diurnal changes in the net photosynthetic rate（Pn） of Pueraria lobata and environmental factors,diurnal changes in the Pn of leaves of two P.lobata cultivars were measur...In order to identify the relationship between diurnal changes in the net photosynthetic rate（Pn） of Pueraria lobata and environmental factors,diurnal changes in the Pn of leaves of two P.lobata cultivars were measured using a CIRAS-1 portable photosynthesis measurement system（PP-Systems,UK）.The results show that diurnal changes in Pn of both cultivars could be interpreted as double-peak curves,indicating the occurrence of an obvious midday depression.Further analyses indicate that the correlation between Pn and stomatal conductance was positive and extremely significant（p 〈 0.01）.The correlations of Pn with intercellular CO2 concentration and transpiration rate were positive and significant（p 〈 0.05）,while the correlations of Pn with air and leaf temperatures were negative and significant（p 〈 0.05）.The results indicate that among the factors affecting photosynthetic properties,some can be grouped as stomatal limitations while others are non-stomatal limitations.展开更多
热带地区土地利用变化深刻影响了区域碳收支状况。为加强对热带亚洲北缘碳源/汇格局认知,本研究基于涡度相关方法获取西双版纳热带雨林和橡胶林多年的气象和碳通量数据,定量评价环境因素对西双版纳不同热带森林净生态系统碳交换的影响...热带地区土地利用变化深刻影响了区域碳收支状况。为加强对热带亚洲北缘碳源/汇格局认知,本研究基于涡度相关方法获取西双版纳热带雨林和橡胶林多年的气象和碳通量数据,定量评价环境因素对西双版纳不同热带森林净生态系统碳交换的影响。结果表明:热带雨林多年平均净生态系统碳交换(NEE)为-157.9 g C/(m^(2)·a)(-1.6 t C/(hm^(2)·a));橡胶林为-491.9 g C/(m^(2)·a)(-4.9 t C/(hm^(2)·a)),均呈现碳汇效应。在季节尺度上,热带雨林和橡胶林净生态系统碳交换变化特征相反,其中,热带雨林在干季的NEE(-148.3 g C/(m^(2)·season))强于雨季(-9.6 g C/(m^(2)·season)),橡胶林雨季NEE(-376.9 g C/(m^(2)·season))强于干季(-115.0 g C/(m^(2)·season)),NEE在干季受物候因素影响,在雨季主要受空气温度和饱和水汽压差调控。日尺度上,热带雨林与橡胶林的NEE均呈单峰变化曲线,日均NEE分别为-0.4 g C/(m^(2)·d)和-1.4 g C/(m^(2)·d),两种森林的NEE日变化主要受光合有效辐射(PAR)调控,橡胶林相比于热带雨林具有更强的光合能力;上午时段是两种森林主要的固碳时段,下午的高温抑制了森林的净碳吸收。研究结果揭示了相同环境条件对热带雨林与橡胶林净生态系统碳交换的差异性影响,为预估未来不同土地利用情景下的热带森林区域碳平衡状况提供参考。展开更多
常绿阔叶林在维持生物多样性和生态系统功能方面发挥着关键作用,同时对气候变化和人类活动的影响高度敏感。然而,全球常绿阔叶林的净初级生产力(net primary productivity,NPP)和降水利用效率(precipitation use efficiency,PUE)的空间...常绿阔叶林在维持生物多样性和生态系统功能方面发挥着关键作用,同时对气候变化和人类活动的影响高度敏感。然而,全球常绿阔叶林的净初级生产力(net primary productivity,NPP)和降水利用效率(precipitation use efficiency,PUE)的空间分布格局及其驱动机制仍不明确。为此,本研究基于全球272个常绿阔叶林实测NPP数据,使用随机森林模型预测了全球常绿阔叶林NPP和PUE的空间分布格局,并从气候和土壤物理性质分析NPP和PUE的驱动机制。结果表明:全球NPP预测值为909.08~3213.11 g C·m^(-2)·a^(-1),PUE预测值为0.22~5.79 g C·m^(-2)·mm^(-1);NPP和PUE在全球范围内展现出相似的地理空间分布趋势,在海拔低于400 m的区域,两者均呈上升趋势,而在海拔超过400 m后则出现下降;温度和降水是NPP、PUE变化的主要驱动因素,而土壤物理性质对其影响较小;NPP在降水量为1200 mm时与降水的关系发生变化,温度在19℃以下时降水对NPP的影响更显著;PUE对温度和降水的响应也存在阈值效应,降水<2500 mm或温度<24℃时PUE较高。降水和温度对NPP和PUE的协同作用受到两因素相互叠加的影响。研究结果为全球常绿阔叶林碳水循环模型提供了关键参数,有助于提升其在气候变化情景下的空间预测能力。展开更多
作为重要的蓝碳生态系统之一,红树林是减缓气候变化的天然、长期有效碳汇。气候变暖为红树林北移提供机遇,然而其固碳能力还需深入探究。本文利用长时间序列涡度通量观测技术,探究了浙南幼龄红树林湿地在日尺度和季节尺度上的净生态系...作为重要的蓝碳生态系统之一,红树林是减缓气候变化的天然、长期有效碳汇。气候变暖为红树林北移提供机遇,然而其固碳能力还需深入探究。本文利用长时间序列涡度通量观测技术,探究了浙南幼龄红树林湿地在日尺度和季节尺度上的净生态系统碳交换量(NEE)变化特征,并分析了关键环境驱动因子。结果表明,浙南红树林湿地NEE在日变化上呈现“U型”趋势,季节变化明显。CO_(2)吸收通量于夏季达到最大值,其他季节随着温度的降低逐渐减弱。浙南幼龄红树林湿地NEE与光合有效辐射、风速呈显著正相关,而与气压、饱和水汽压差呈显著负相关。基于涡度NEE年累积数据,量化浙南幼龄(3年生)红树林碳汇能力为291 g C·m^(-2)·a^(-1),表明浙南幼龄红树林具备了一定的碳汇能力。展开更多
基金supported by the Key Laboratory of Hydraulic and Water Transport Engineering under the State of Ministry of Education (2006B02)
文摘The aquatic environment capacity possesses the largest tolerance to pollutants. We can improve the calculating precision using the conceptual net method. Its basic ways involved in calculation include the following aspects: first, to establish the flow continuity equation, flow motion equation, water quality equation and other mathematical models; at the same time, to conceptualize the reservoir studied, divide the reservoir into several functional areas, and use the one-dimensional section-beginning calculation model to calculate all cross-sections of each functional area; then, to superimpose the environmental capacity of each functional section to get the aquatic environment capacity of the entire two-dimensional space; and finally, to introduce how to make use of the conceptual net to calculate the aquatic environment capacity in terms of the actual reservoir's situation.
基金funded through the Special Fund for Agro-Scientific Research in the Public Interestthe Special Public Welfare Industry (agriculture) Research-Research and Demonstration of Fisheries Fishing Technology and Fishing Gear (No. 201203018)the National Natural Science Foundation of China (No. 31402350)
文摘Set-nets are common alongshore fishing gear used in Haizhou Bay, which rely on flow to catch fish. The catch per unit effort(CPUE) of set-net is affected by spatial-temporal and environmental factors but no research has been conducted on this subject. In this study, we used generalized additive models(GAMs) to explore the influence of spatial-temporal and environmental factors on CPUEs of species aggregated, small yellow croaker(Larimichthys polyactis), and octopus(Octopus variabilis) based on logbooks investigations conducted at 4 stations in an alongshore area of Haizhou Bay from 2011 to 2012. The results showed that all CPUEs exhibited significant spatial-temporal differences at various scales. Aggregated CPUE was high when the sea surface temperature(SST) was 15-18℃ and 20-23℃, which was mainly determined by life history traits of the octopus and small yellow croaker(optimal SSTs 14-17℃ and 19-24℃, respectively). Chlorophyll-a concentration had significant influences on the aggregated, small yellow croaker and octopus CPUEs at optimal ranges of 3.8-6.2 mg m^(-3), 4.2-4.8 mg m^(-3) and 4.5-5.5 mg m^(-3), respectively. Flow through the net had positive relationships with CPUEs. The approximate logarithmic trends in regression curves had a critical point of 2.5 Mm^3 d^(-1), which was the dividing point that differentiated whether the major factor affecting CPUEs was the flow velocity or the fishery resource. Our results from this study will help guide fishery production and improve catch rate of set-net fishing in Haizhou Bay.
基金supported by the "Eleventh Five-year" National Science and Technology Support Program of China (Grant No. 2009BADA7B04 Grant No. 2008BAD95B03the National Science and Technology Major Project of China (Grant No. 2009ZX09308-002)
文摘In order to identify the relationship between diurnal changes in the net photosynthetic rate（Pn） of Pueraria lobata and environmental factors,diurnal changes in the Pn of leaves of two P.lobata cultivars were measured using a CIRAS-1 portable photosynthesis measurement system（PP-Systems,UK）.The results show that diurnal changes in Pn of both cultivars could be interpreted as double-peak curves,indicating the occurrence of an obvious midday depression.Further analyses indicate that the correlation between Pn and stomatal conductance was positive and extremely significant（p 〈 0.01）.The correlations of Pn with intercellular CO2 concentration and transpiration rate were positive and significant（p 〈 0.05）,while the correlations of Pn with air and leaf temperatures were negative and significant（p 〈 0.05）.The results indicate that among the factors affecting photosynthetic properties,some can be grouped as stomatal limitations while others are non-stomatal limitations.
文摘热带地区土地利用变化深刻影响了区域碳收支状况。为加强对热带亚洲北缘碳源/汇格局认知,本研究基于涡度相关方法获取西双版纳热带雨林和橡胶林多年的气象和碳通量数据,定量评价环境因素对西双版纳不同热带森林净生态系统碳交换的影响。结果表明:热带雨林多年平均净生态系统碳交换(NEE)为-157.9 g C/(m^(2)·a)(-1.6 t C/(hm^(2)·a));橡胶林为-491.9 g C/(m^(2)·a)(-4.9 t C/(hm^(2)·a)),均呈现碳汇效应。在季节尺度上,热带雨林和橡胶林净生态系统碳交换变化特征相反,其中,热带雨林在干季的NEE(-148.3 g C/(m^(2)·season))强于雨季(-9.6 g C/(m^(2)·season)),橡胶林雨季NEE(-376.9 g C/(m^(2)·season))强于干季(-115.0 g C/(m^(2)·season)),NEE在干季受物候因素影响,在雨季主要受空气温度和饱和水汽压差调控。日尺度上,热带雨林与橡胶林的NEE均呈单峰变化曲线,日均NEE分别为-0.4 g C/(m^(2)·d)和-1.4 g C/(m^(2)·d),两种森林的NEE日变化主要受光合有效辐射(PAR)调控,橡胶林相比于热带雨林具有更强的光合能力;上午时段是两种森林主要的固碳时段,下午的高温抑制了森林的净碳吸收。研究结果揭示了相同环境条件对热带雨林与橡胶林净生态系统碳交换的差异性影响,为预估未来不同土地利用情景下的热带森林区域碳平衡状况提供参考。
文摘常绿阔叶林在维持生物多样性和生态系统功能方面发挥着关键作用,同时对气候变化和人类活动的影响高度敏感。然而,全球常绿阔叶林的净初级生产力(net primary productivity,NPP)和降水利用效率(precipitation use efficiency,PUE)的空间分布格局及其驱动机制仍不明确。为此,本研究基于全球272个常绿阔叶林实测NPP数据,使用随机森林模型预测了全球常绿阔叶林NPP和PUE的空间分布格局,并从气候和土壤物理性质分析NPP和PUE的驱动机制。结果表明:全球NPP预测值为909.08~3213.11 g C·m^(-2)·a^(-1),PUE预测值为0.22~5.79 g C·m^(-2)·mm^(-1);NPP和PUE在全球范围内展现出相似的地理空间分布趋势,在海拔低于400 m的区域,两者均呈上升趋势,而在海拔超过400 m后则出现下降;温度和降水是NPP、PUE变化的主要驱动因素,而土壤物理性质对其影响较小;NPP在降水量为1200 mm时与降水的关系发生变化,温度在19℃以下时降水对NPP的影响更显著;PUE对温度和降水的响应也存在阈值效应,降水<2500 mm或温度<24℃时PUE较高。降水和温度对NPP和PUE的协同作用受到两因素相互叠加的影响。研究结果为全球常绿阔叶林碳水循环模型提供了关键参数,有助于提升其在气候变化情景下的空间预测能力。
文摘作为重要的蓝碳生态系统之一,红树林是减缓气候变化的天然、长期有效碳汇。气候变暖为红树林北移提供机遇,然而其固碳能力还需深入探究。本文利用长时间序列涡度通量观测技术,探究了浙南幼龄红树林湿地在日尺度和季节尺度上的净生态系统碳交换量(NEE)变化特征,并分析了关键环境驱动因子。结果表明,浙南红树林湿地NEE在日变化上呈现“U型”趋势,季节变化明显。CO_(2)吸收通量于夏季达到最大值,其他季节随着温度的降低逐渐减弱。浙南幼龄红树林湿地NEE与光合有效辐射、风速呈显著正相关,而与气压、饱和水汽压差呈显著负相关。基于涡度NEE年累积数据,量化浙南幼龄(3年生)红树林碳汇能力为291 g C·m^(-2)·a^(-1),表明浙南幼龄红树林具备了一定的碳汇能力。
