南方红壤丘陵区水土保持生态服务功能提升研究进展——以江西省兴国县塘背河小流域为例

[目的]总结和探讨南方红壤丘陵区水土保持生态服务功能的提升途径,为该区水土保持生态建设、脱贫致富和社会经济可持续发展提供科学借鉴。[方法]以江西省兴国县塘背河小流域为例,基于相关科学研究和文献资料,在综合考虑不同生态服务功能之间的关系基础上,开展以水土保持服务功能提升为核心的关键技术研究。[结果]在系统梳理塘背河小流域治理成效的基础上,指出崩岗侵蚀、林分结构单一和林下流、规模化经果林开发导致的局部水土流失恶化和生态系统脆弱等问题依然存在,亟需从前期侧重遏制水土流失为主的生态修复转向生态系统服务功能整体提升为主的新阶段,这是南方红壤丘陵区普遍存在的问题。[结论]建议以生态系统服务提升为核心目标,从不同服务之间权衡与协同关系和水土保持服务的空间流动等基础科学问题研究入手,研发水土保持生态服务功能提升关键技术(包括权衡与协同土壤保持与生物多样性、水源涵养和固碳增汇等服务功能之间的关系),并构建生态和社会经济协调发展的生态服务功能提升综合模式,打造塘背河小流域"升级版"和"扩展板",以促进研究成果的转化,服务南方红壤丘陵区生态环境保护与可持续高质量发展。     

南海北部陆坡金鼻眶灯鱼秋季摄食节律

中层鱼是深海食物网的重要组成部分,其摄食节律的研究对探讨以中层鱼为核心的能量流动与物质循环具有重要意义。本研究利用2014年10月南海北部陆坡海域拖网调查数据,对中层鱼优势种金鼻眶灯鱼(Diaphus chrysorhynchus)秋季的摄食节律进行了研究。结果表明:(1)金鼻眶灯鱼取样体长范围为28~110 mm,集中于50~59 mm体长组,各时间段摄食等级与体长间均不存在正相关;(2)金鼻眶灯鱼在18:00左右上浮摄食,次日05:30左右达到摄食高峰,为连续摄食,5个取样时间段平均摄食等级范围为1.50~2.57,呈增长趋势;(3)差异性分析表明,金鼻眶灯鱼傍晚与夜间或清晨间摄食等级差异性显著,表现在18:30~19:30时间段与01:00~02:00、04:45~05:50或06:30~07:30三个时间段间(P=0.041;P=0.000;P=0.007),另03:30~04:30与04:45~05:50时间段间摄食等级也存在极显著差异(P=0.005);(4)金鼻眶灯鱼各时间段摄食等级频率呈波浪形变化,4级频率在06:30~07:30时间段达到最高峰;0级频率在黄昏18:30~19:30时最高,01:00~02:00降为0,03:30~04:30上升到黄昏时的一半,此后连续下降。总体而言,金鼻眶灯鱼傍晚至次日清晨连续摄食,连续排遗,摄食集中于清晨。综上所述,金鼻眶灯鱼是一种昼夜垂直迁移、夜间连续摄食与排遗的浮游动物食性鱼类,其在南海陆坡水域能量流与物质流中起着承上启下的作用。     

Biotypic and pest status differences between Hungarian and South African populations of Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Homoptera: Aphididae)

Russian wheat aphid, Diuraphis noxia (Kurdjumov) is a severe pest of cereals in South Africa and in the USA. In order to reduce D noxia damage, intensive resistance breeding programs have been undertaken, resulting in D noxia-resistant cultivars that are now widely used in South Africa and in the USA. However, there appear to be differences in the ability of different populations of D noxia to damage these resistant cereal cultivars. To determine whether different biotypes of D noxia are present, damage to eight wheat cultivars was compared when they were exposed to either Hungarian or South African aphid strains. It appeared that the Hungarian CVS MV Magdaléna, MV Magvas, and MV 17 were susceptible to D noxia from both Hungary and South Africa. The susceptible South African CV Betta was also severely damaged regardless of the country of origin of the aphids. None of the cultivars resistant in South Africa (Caledon, SST 333, SST 972 and Halt) were, however, resistant to Hungarian populations of D noxia. These cultivars, which carry resistance genes originating from the breeding lines PI 262660, PI 137739 and PI 372129, were severely damaged by the Hungarian D noxia. Apart from the highly resistant CV Halt, the resistant cultivars used in this study were developed in South Africa, with the biotype present there. Damage to all cultivars tested was significantly more severe in response to Hungarian than to South African D noxia, indicating that a more damaging aphid biotype occurs in Hungary. However, D noxia has not yet become a pest of wheat in Hungary, possibly due to a difference in cultural practices.     

Functional connectivity defined through cost-distance and genetic analyses: a case study for the rock-dwelling mountain vizcacha (<Emphasis Type="Italic">Lagidium viscacia</Emphasis>) in Patagonia,Argentina

Landscape connectivity can have profound consequences for distribution and persistence of populations and metapopulations. Evaluating functional connectivity of a landscape for a species requires a measure of dispersal rates through landscape elements at a spatial scale sufficient to encompass movement capabilities of individuals over the entire landscape. We evaluated functional connectivity for a rock-dwelling mammal, the mountain vizcacha (Lagidium viscacia), in northern Patagonia. Because of the strict association of mountain vizcachas with rocks, we hypothesized that connectivity for this species would be influenced by geology. We used molecular genetic estimates of gene flow to test spatially explicit models of connectivity created with GIS cost-distance analysis of landscape resistance to movement. We analyzed the spatial arrangement of cliffs with join counts and local k-function analyses. We did not capture and genotype individuals, but sampled at the population level through non-invasive collection of feces of mountain vizcachas. The model of landscape connectivity for mountain vizcachas based on geology was corroborated by the pattern of genetic structure, supporting the hypothesis that functional connectivity for mountain vizcachas is influenced by geology, particularly by the distribution of appropriate volcanic rocks. Analysis of spatial arrangement of cliffs indicated that occupied cliffs are clustered and confirmed that rivers act as barriers to dispersal for mountain vizcachas. Our methods could be used, within certain constraints, to study functional landscape connectivity in other organisms, and may be particularly useful for cryptic or endangered species, or those that are difficult or expensive to capture.     

Modification of the effective mesh size for measuring landscape fragmentation to solve the boundary problem

Patch-based landscape metrics can be biased by the boundaries and the extent of a reporting unit if the boundaries fragment patches. We call this the “boundary problem”. The effective mesh size m _eff is a convenient method to quantify landscape fragmentation, that is based on the probability that two points chosen randomly in a region will be connected, e.g., not be separated by roads, railroads, or urban development. The cutting-out (CUT) procedure, used in the original computation of m _eff, suffers from the boundary problem because the boundaries of the reporting units are considered to be additional barriers. Therefore, m _eff will be underestimated, particularly if reporting units are embedded within the broader landscape. In this paper, we present a solution to overcome this limitation by a new method called “cross-boundary connections” (CBC) procedure. It attributes the connections between two points that are located in different reporting units to both reporting units. We systematically compare the CBC procedure to the CUT procedure and show that the boundary problem is intrinsic to the CUT procedure, while the CBC procedure is independent of the size and administrative boundaries of reporting units. In addition, we elucidate the superior performance of the new procedure in the case study of South Tyrol where m _eff is being used for sustainability reporting on the level of municipalities. The new CBC procedure eliminates the bias due to the boundaries and the size of reporting units in measuring landscape fragmentation through m _eff.     

Seasonal variations in sexual behavior, testosterone, testicular size and semen characteristics, as affected by social dominance, of tropical hair rams (Ovis aries)

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behavior and testosterone concentration (T4) in dominant and subordinate Pelibuey rams. Six groups of three animals were evaluated every 2 weeks over a 12 month period. Dominant (D), medium (M) and subordinate (S) animals in each group were identified through a food competition test every 15 days. All rams ejaculated and produced semen throughout the year. A linear hierarchy was clearly established and maintained during the year. S rams had lower levels (P < 0.05) of semen volume, sperm concentration and testicular volume than D rams, regardless of season. Scrotal circumference was not influenced (P > 0.05) by their social position. D rams were more affected by the photoperiod, decreasing (P < 0.05) reaction times, increasing (P < 0.05) T₄ and producing more (P < 0.05) sperm per ejaculation than S rams during short days (14.65 ± 1.22 vs 26.92 ± 1.65 s; 8.68 ± 0.44 vs 7.37 ± 0.40 ng/mL and 3.37 ± 0.17 vs 2.04 ± 0.16 sperm/10⁹, respectively). Semen volume and sperm concentration were significantly (P < 0.05) greater during short days in all rams, regardless of their social status, with the exception of sperm concentration in D rams where no variation was found. M rams displayed variable values in the range between the D and S rams. It was concluded that the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year and that seasonal variation within the variables affected the social ranks differently.     

Aggressiveness of Phytophthora infestans and phenotypic analysis of resistance in wild Petota accessions in Ecuador

The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated potato species (sect. Petota ) and the level of resistance of nine Petota species were assessed in the highland tropics of Ecuador. For this, isolates of P. infestans were inoculated on whole plants of Petota species in the field and net house and six epidemiological components – infection frequency (IF), incubation period (IP), latent period (LP), lesion size (LS), lesion growth rate (LGR), and relative area under the lesion expansion curve (RAULEC) – were measured during a single infection cycle. Additionally, host specificity was determined by testing for a significant host by pathogen interaction using the same components. The results showed significant differences among isolates of the EC-1 clonal lineage for IP, IF, and RAULEC. Significant differences among isolates were not found for the other components measured. There were significant differences in resistance among the accessions of Petota hosts tested. RAULEC, LGR, LP, and LS were in general more adequate in differentiating among the more resistant and more susceptible accessions but the importance of each component varied with host species. There was slight and inconsistent evidence for the existence of host specificity in some isolates of Petota hosts. IP was the only component for which a significant host by isolate interaction was observed and in most cases the isolates had the greatest aggressiveness on their hosts of origin.     

Weed population dynamics during the groundnut crop cycle in the wet tropical zone of Kombe (Congo)

Weed competition in crops constitutes the main limiting factor for groundnut crop yields in the Congolese humid zone. In order to control the problems related to weed interference in the crop, the most appropriate weeding period for good production has been investigated. The critical period of weed interference has been determined from a groundnut crop experiment weeded at different times during two crop cycles. The data obtained allowed the authors to propose a suitable weeding regime that would reduce the costs and frequencies of weeding and enable local farmers to plan their work more effectively.     

DROUGHT MANAGEMENT IN SOUTH AUSTRALIA

<正> 1. Introduction The revived concern for environmental hazards implicit in the contemporary debatesupon Global Change questions, the Ozone Hole and the International Decade of NaturalDisaster Reduction, raises once more the question of disaster relief. Much of the ensuingconcerm for disaster relief however has focused upon technical questions of supplying aid in     

南水北调大型泵结构设计研究

值此南水北调工程正式开工，回顾了我国大型泵的发展历史；介绍了国外典型大型泵的结构，具有转速高、齿轮传动，配套电机体积小，泵站建设总投资少等优点；阐述了吸取国外先进经验改进我国大型泵结构设计的必要性及可行性；提出要加大科研力度，使大型泵设计实现第二次革命，推动排灌事业的发展．