应用浮游植物生物完整性指数评价长江上游河流健康

2013年11月-2014年6月对长江上游宜宾至江津段五个断面的浮游植物进行了四次调查,共鉴定出浮游植物6门38属95种。对13个备选指标进行分布范围、判别能力及Pearson相关性分析,构建了适合长江上游的浮游植物生物完整性指数(P-IBI)指标体系,即香农多样性指数、Margalef丰富度指数、Pielou均匀度指数、浮游植物密度、硅藻密度百分比等参数指标。采用3分制法、4分制法和比值法分别对生物指标计分,评价结果显示:高庄桥、羊石处于"健康"状态;白沙处于"亚健康"状态;而江安、德感处于"亚健康"向"一般"过渡状态。综合来看,三种评价方法所反映各样点的健康状况基本一致,只是4分制法和比值法在划分评价等级上更细致,评价结果更精确。Pearson相关性分析显示:TN、pH与P-IBI值呈显著负相关(P0.05)。     

有色黏虫板对柑橘木虱的监测及防治研究进展

柑橘黄龙病是柑橘生产中的重大病害,随着其在全球范围内的传播蔓延,该病已成为近年来柑橘生产和研究中普遍关注的热点。柑橘木虱(Diaphorina citri Kuwayama)是传播柑橘黄龙病菌(Candidatus Liberibacter asiaticus)的主要虫媒,对柑橘木虱种群的准确监测与有效防控是控制柑橘木虱传播黄龙病的关键所在。有色黏虫板是一种利用昆虫趋色性,对小型飞行昆虫进行监测与诱杀的重要物理防治手段。有色黏虫板同样适用于监测和诱捕柑橘木虱,但黏虫板的颜色、光源、气候条件、悬挂黏虫板的植物种类及其挥发性信息化合物成分等都会影响黏虫板对柑橘木虱的诱集效果。本文在综合国内外柑橘木虱防控技术的基础上,将近年来利用有色黏虫板,监测与防控柑橘木虱的最新进展进行综述,并对有色黏虫板的发展前景给予展望。     

槟榔科学研究近况分析

概述世界槟榔种植区域分布、面积和产量，及2015年度国内外在槟榔生理生化、生防菌、栽培管理、加工和利用等方面取得的研究进展，并对目前槟榔研究技术瓶颈和发展趋势进行了分析。     

A stochastic surplus production model in continuous time

Surplus production modelling has a long history as a method for managing data‐limited fish stocks. Recent advancements have cast surplus production models as state‐space models that separate random variability of stock dynamics from error in observed indices of biomass. We present a stochastic surplus production model in continuous time (SPiCT), which in addition to stock dynamics also models the dynamics of the fisheries. This enables error in the catch process to be reflected in the uncertainty of estimated model parameters and management quantities. Benefits of the continuous‐time state‐space model formulation include the ability to provide estimates of exploitable biomass and fishing mortality at any point in time from data sampled at arbitrary and possibly irregular intervals. We show in a simulation that the ability to analyse subannual data can increase the effective sample size and improve estimation of reference points relative to discrete‐time analysis of aggregated annual data. Finally, subannual data from five North Sea stocks are analysed with particular focus on using residual analysis to diagnose model insufficiencies and identify necessary model extensions such as robust estimation and incorporation of seasonality. We argue that including all known sources of uncertainty, propagation of that uncertainty to reference points and checking of model assumptions using residuals are critical prerequisites to rigorous fish stock management based on surplus production models.     

Efficiency of fisheries is increasing at the ecosystem level

Managing fisheries presents trade‐offs between objectives, for example yields, profits, minimizing ecosystem impact, that have to be weighed against one another. These trade‐offs are compounded by interacting species and fisheries at the ecosystem level. Weighing objectives becomes increasingly challenging when managers have to consider opposing objectives from different stakeholders. An alternative to weighing incomparable and conflicting objectives is to focus on win–wins until Pareto efficiency is achieved: a state from which it is impossible to improve with respect to any objective without regressing at least one other. We investigate the ecosystem‐level efficiency of fisheries in five large marine ecosystems (LMEs) with respect to yield and an aggregate measure of ecosystem impact using a novel calibration of size‐based ecosystem models. We estimate that fishing patterns in three LMEs (North Sea, Barents Sea and Benguela Current) are nearly efficient with respect to long‐term yield and ecosystem impact and that efficiency has improved over the last 30 years. In two LMEs (Baltic Sea and North East US Continental Shelf), fishing is inefficient and win–wins remain available. We additionally examine the efficiency of North Sea and Baltic Sea fisheries with respect to economic rent and ecosystem impact, finding both to be inefficient but steadily improving. Our results suggest the following: (i) a broad and encouraging trend towards ecosystem‐level efficiency of fisheries; (ii) that ecosystem‐scale win–wins, especially with respect to conservation and profits, may still be common; and (iii) single‐species assessment approaches may overestimate the availability of win–wins by failing to account for trade‐offs across interacting species.     

Impact of grassland contract policy on soil organic carbon losses from alpine grassland on the Qinghai–Tibetan Plateau

Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi‐household management pattern (MMP: grassland shared by several households without enclosures) and a single‐household management pattern (SMP: grassland enclosed and used by only one household). In 2016, 50 MMP and 54 SMP winter pastures on the Qinghai–Tibetan Plateau were sampled to assess the differences in soil organic carbon (SOC) between the two management patterns. Results showed that average SOC was significantly greater under MMP than under SMP, with an estimated 0.41 Mg C/ha/yr lost due to SMP following the new grassland contract. Based on the government's grassland policy, four grassland utilization scenarios were developed for both summer and winter pastures. We found that if the grassland were managed under SMP, likely C losses ranged between 0.31 × 10⁷ and 6.15 × 10⁷ Mg C/yr across the Qinghai–Tibetan Plateau relative to MMP, which more closely resembles pre‐1990s grassland management. Previous estimates of C losses have only considered land use change (with cover change) and ignored the impacts driven by land management pattern changes (without cover change). The new data suggest that C losses from the Qinghai–Tibetan Plateau are greater than previously estimated, and therefore that the grassland contract policy should be reviewed and SMP households should be encouraged to reunite into the MMP. These findings have potential implications for land management strategies not only on the Qinghai–Tibetan Plateau but also other grazing regions globally where such practices may exist.     

运用机载LiDAR数据对橡胶林地上生物量估测的采样尺度效应分析

气候变化下,森林生物量遥感监测是当前研究的热点,机载LiDAR作为重要的遥感信息源,其采样大小对生物量估测精度有着一定的影响。以机载LiDAR数据为信息源,以44块30m×30m的方形橡胶林实测样地数据为基础,对机载激光雷达数据进行不同尺寸采样(共21个采样尺寸,边长从10m至30m,间隔为1m),提取不同采样尺寸下的激光雷达参数,并与橡胶林地上生物量建立PLSR模型,就机载激光雷达采样大小对橡胶林地上生物量估测精度的影响进行研究。研究表明:当采样尺寸小于18m时,估测精度随着采样尺寸的增大而增大;而当采样尺寸大于18m时,估测精度随着采样尺寸的增大而减小,进而趋于平缓。结果虽然呈现出一定的规律性,但是差异并不是很明显。当采样尺寸为18m时估测效果最佳,模型决定系数(R^2)为0.718,均方根误差(RMSE)为17.830 t/hm^2;交叉验证精度P和RMSEcv分别为82.741%和18.874t/hm^2。相较于实际样地(30m)尺寸下的估测结果,18m采样尺寸下的R^2提高了1.989%,RMSEcv降低了2.611%。因此,生物量的估测精度受机载激光雷达数据采样尺寸大小的影响,在生物量估测过程中需结合研究对象和研究区的实际情况对采样尺寸进行选择,从而提高生物量估测精度。     

An acoustic based approach to evaluate the effect of different diet lengths on feeding behavior of Litopenaeus vannamei

Studying shrimp feeding behavior is challenging and, traditionally, studies have been using direct visual observation or video recordings with image analysis under laboratory conditions. Passive acoustics monitoring (PAM) is a non-invasive approach to study feeding behavior of penaeids, as their mandibles emit clicking sounds during feed ingestion. Considering the wide variation available in shrimp diet lengths, our knowledge is still limited about their effects on feeding behavior. The present study was designed to use acoustics to evaluate the feeding behavior of Litopenaeus vannamei fed different diet lengths. A commercial pelleted diet with similar diameter (2.4 mm) and three different lengths was used as treatments “small” (2.35 mm), “medium” (4.26 mm) and “large” (8.42 mm). Three separate trials were performed with fastened shrimp (20 g), using omnidirectional hydrophones and external audio recorders. Our approach started with the characterization of the click acoustic parameters produced by three shrimps when fed the different diet lengths in anechoic chambers (15 L). We then analyze the number of clicks produced per pellet and duration of the clicking activity when shrimp fed a single pellet in individual tanks (1 L). Finally, the acoustic energy of feeding activity and feed consumption, as well as theirs relationship to predict feed intake was evaluated in aquaria (70 L) with five shrimps. The acoustic parameters of isolated clicks were not affected by the different diet lengths, however, doubling the length of the pellet resulted in doubling the number of clicks emitted during feeding activity. The duration of clicking activity per pellet indicated that small pellets are consumed 2.9 and 4.7 times faster than medium and large pellets, respectively. Furthermore, feeding acoustic energy of small pellets decreased rapidly after feed offer, as their faster consumption probably contributed to shrimps achieved satiety earlier than larger diets. Feed consumption was similar among diets length, but significantly correlated with the feeding acoustic energy emitted by L. vannamei, which is a breakthrough in feeding behavioral research. The results highlight the potential and possibilities of an acoustic approach to estimate feed consumption, as well as an alternative to traditional methods in feeding behavioral studies to improve efficiency of feed management.     

王正非林火蔓延模型改进研究

王正非林火蔓延模型是目前国内比较先进的森林火灾蔓延模型,但是由于林火行为的复杂性,此模型在准确率和普适性方面仍存在许多不足。本文结合已有的成果进一步改进王正非模型,增加了可燃物湿度对林火蔓延速度的影响,改进了林火初始速度的计算方式。针对各种坡度对林火蔓延行为的影响给出了一个计算公式。与改进前相比,改进后的模型使其对林火蔓延情况的预估更为精准。     

基于无人机LiDAR的天然林与人工林林隙提取

为研究主动遥感进行森林地物分类和林隙提取的效果,分别在天然林和人工林中比较了无人机激光雷达(Li DAR)数据的阈值法、逐像元法和面向对象法3种方法的分类精度和适用性。选取天然林(黑龙江省哈尔滨市帽儿山林场)和人工林(内蒙古自治区赤峰市旺业甸林场)两处试验区,应用阈值法、逐像元法和面向对象法3种方法,对两个试验区采集的无人机Li DAR数据进行林隙、非林隙、其他类型划分。研究结果表明,面向对象法在天然林和人工林试验区中的分类精度和Kappa系数均最高,天然林为82. 43%、0. 73,人工林为91. 74%、0. 88;逐像元法次之,天然林为76. 62%、0. 64,人工林为78. 68%、0. 68;阈值法的分类精度和Kappa系数差异较大,在天然林中的精度极低,为50. 54%、0. 27,人工林的精度较高,为79. 12%、0. 69。面向对象法和逐像元法在天然林和人工林普遍适用,均可以达到理想的分类精度和Kappa系数。阈值法在天然林的精度较低,更适合于人工林的分类,即林分高度趋于一致,且建筑、道路等其他类型干扰较少的区域。天然林的最佳分类方法为面向对象法,人工林的最佳分类方法为阈值法。