Comparison of water quality in two catchments with different forest types in the headwater region of the Hun River, Northeast China

In the headwater catchments of the Hun River,Northeast China, secondary forests(SF) have been replaced by plantations since the 1960 s. Concern has been growing over this loss and the decline in water quality caused by the plantations. To test the effects of plantations on water quality, we selected two separate catchments covered by SF and Pinus koraiensis plantations(KP) to monitor physical and chemical properties of various hydrological variables including throughfall, stemflow,through-litterfall and runoff(flowing out of outlets of the catchments). The physical properties of water declined after water flowed through the two catchments as compared with rainwater. The pH of runoff in both catchments also dramatically decreased. The concentrations of Cl^-, NO_3^- and NH_4^+ in the runoff from the two catchments were similar(concentrations of Cl-and NH_4^+ in both catchments were similar to those in rainwater). Total P concentration in runoff of the SF catchment was higher than that of the KP catchment(P concentrations in both catchments were also higher than in rainwater) because P concentrations in litter and soil of the SF catchment were higher than those in the KP catchment. In summary, the rainwater became acidic in both catchments, but the responses of most water quality variables were similar in the two catchments, suggesting that appropriate ratios of KP in SF are feasible for secondary forest recovery and for preserving water quality(KP did not cause a decline in quality) in the headstream regions in Northeast of China.

Review of regional carbon counting methods for the Chinese major ecological engineering programs

In order to improve environment and relieve poverty, China has launched a series of major ecological engineering programs since the 1980 s. These include the Natural Forest Conservation Program, the Sloping Cropland Conversion Program, the Desertification Combating Program, and the Protection Forest System Construction Program. There is a growing need to quantify the contributions of these programs to regional carbon stocks.However, the lack of widely accepted, robust methods is one of the key obstacles to quantification. The objective of this study was to review existing methods for quantifying regional carbon stocks and then recommend suitable ones for the Chinese ecological engineering programs. We expect that the recommended methods can be applied to elsewhere in the world where there are similar characteristics and objectives.

武功山山地草甸生态系统土壤无机磷垂直地带性分布特征

利用土壤无机磷形态分级方法,以江西省武功山山地草甸为研究对象,分析不同海拔高度(1 600~1 900m)和不同土壤深度(0-20和20-40cm)下,土壤无机磷形态的含量与分布特征,及无机磷各形态与有效磷的相关性。结果表明,1)武功山山地草甸土壤无机磷含量的变化范围在175.48~524.06mg·kg-1,无机磷总量随海拔高度的升高而显著增加(P【0.05),随土层深度的加深而显著减少,呈现表聚性;2)无机磷中水溶性磷、Al-P、Fe-P、O-P、Ca-P的变化范围分别是0.423~4.781、16.27~90.72、54.13~344.34、19.66~90.32、15.12~76.21mg·kg-1。各无机磷形态均随海拔升高呈现垂直分布规律,且具有表聚性。同一海拔及土层上,水溶性磷【Ca-P【O-P【Al-P【Fe-P;3)有效磷含量与Al-P占无机磷总量的百分比呈极显著相关(P【0.01),说明Al-P是该区域土壤有效磷的潜在来源。本研究既揭示了武功山山地草甸土壤无机磷形态的垂直地带性分布特征及其与有效磷的相关性,确定了土壤磷素有效性的潜在来源,同时也可为武功山山地草甸生态系统的植被恢复提供理论依据。

武功山山地草甸土壤磷素分布格局及其与土壤酸度的关系

磷是植物生长的限制性营养因子，以江西省武功山山地草甸为研究对象，分析不同海拔高度（1600～1900 m）和不同土壤深度（0～20 cm和20～40 cm）条件下，土壤全磷、有效磷、活性酸度（ pH值）、水解性总酸度及交换性酸度的空间分布特征，以及土壤酸度与土壤有效磷的相关性。结果表明：（1）武功山山地草甸土壤有效磷和全磷含量随海拔升高而显著增加，有效磷与全磷的变异范围分别为：3．71～17．78 mg/kg及0．46～1．37 g/kg；土壤有效磷与全磷含量呈显著相关性；（2）土壤pH值随海拔升高无显著性变化，土壤交换性酸度和水解性总酸度均随海拔升高而显著增加；（3）土壤有效磷含量与土壤交换性酸度及水解性总酸度显著正相关。研究揭示了武功山山地草甸土壤磷素和土壤酸度的空间分布格局及其相关性，同时也为武功山山地草甸生态系统的植被恢复提供理论依据。

A modelling method for large-scale open spaces orientated toward coordinated control of multiple air-terminal units

The temperature distribution is always assumed to be homogeneous in a traditional singleinput-single-output(SISO)air conditioning control strategy.However,the airflow inside is more complicated and unpredictable.This study proposes a zonal temperature control strategy with a thermal coupling effect integrated for air-conditioned large-scale open spaces.The target space was split into several subzones based on the minimum controllable air terminal units in the proposed method,and each zone can be controlled to its own set-point while considering the thermal coupling effect from its adjacent zones.A numerical method resorting to computational fluid dynamics was presented to obtain the heat transfer coefficients(HTCs)under different air supply scenarios.The relationship between heat transfer coefficient and zonal temperature difference was linearized.Thus,currently available zonal models in popular software can be used to simulate the dynamic response of temperatures in large-scale indoor open spaces.Case studies showed that the introduction of HTCs across the adjacent zones was capable of enhancing the precision of temperature control of large-scale open spaces.It could satisfy the temperature requirements of different zones,improve thermal comfort and at least 11%of energy saving can be achieved by comparing with the conventional control strategy.

中国科学院清原森林生态系统观测研究站塔群平台的功能和应用

森林生态系统结构与生态服务功能关系是森林生态学和林学的永恒研究主题。受传统森林调查方法及技术手段的限制,对复杂地形下森林生态系统结构和功能的监测及二者关系的研究面临诸多挑战。在中国科学院野外站网络重点科技基础设施建设项目的支持下,中国科学院清原森林生态系统观测研究站在独立流域内建成了以观测塔群(三座观测塔覆盖各自子流域代表性森林类型)为主体,集激光雷达(LiDAR)、通量仪器、水文站网、固定标准地和数据中心为综合体的"次生林生态系统塔群激光雷达监测平台"(简称塔群平台)。塔群平台采用激光雷达扫描获取森林点云数据,描述森林生态系统的全息三维结构;依托独立流域/子流域内的通量监测系统、水文监测站网和通量源区内的长期固定标准地,可保证碳-水过程观测的可靠性,并用于验证复杂地形下的通量监测技术与方法,揭示森林生态水文与碳交换过程,准确估算森林生态系统主体生态服务功能(水源涵养和固碳)。所有"塔-站"数据通过无线网络实时汇集于数据中心,便于数据监视、管理与共享。此外,塔群平台将侧重研究森林生态系统结构量化的新方法和新指标,探索复杂地形森林生态系统中H2O/CO2/痕量气体通量观测的理论与方法,为阐明森林结构与功能的关系、服务于森林生态系统管理提供基础数据。