Landscape changes and their ecological effects of Miaodao Archipelago with human disturbances and under natural conditions in the past 30 years

The modern landscape patterns of islands usually show obvious spatial heterogeneity and complex ecological effects due to the vulnerability of ecosystems with natural characteristics under increasing human activities. In this work, we studied the variation in landscape pattern of the Miaodao Archipelago in Bohai Sea, North China, from 1990 to 2019, and an evaluation index system was established to explore the impacts of natural conditions and human disturbances on the ecological effects in the pressure-state-response(PSR) framework. Empirical analysis was conducted on the natural conditions, human disturbances, and ecological effects. The results show that forest was the main component of the landscape pattern in the archipelago. Both of the areas offorest and construction land were increasing, and the areas of cropland and grassland were declining. Other landscape types changed slightly, and the landscape fragmentation was increasing. The natural condition exhibited positive effects while human disturbance showed negative effects on the local ecology. Human disturbances come mainly from shoreline use while the natural conditions were mainly from the elevation change. The ecological effects were resulted mainly from the net primary productivity and water yield.     

Water discharge variability of Changjiang （Yangtze） and Huanghe （Yellow） Rivers and its response to climatic changes

Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.     

AN ILLUSTRATIVE STUDY ON LOCAL LANDSCAPEAND ITS LONG-TERM CHANGES BASED ON IKONOS AND HISTORICAL AERIAL PHOTO

Nowadays, the research works on landscape at fine scales using high-resolution images are uncommon.This research is based on the analysis of the combination of remote sensing data (1KONOS imagery acquired in 2002 and historical aerial photo taken in 1942). In the paper, the ecotopes in Qiujiadou and Xishao villages in Yixing City of Jiangsu Province in 1942 and 2002 were compared and landscape changes as well as the causes of the considerable changes were analyzed. It was found that the ecotope changes were at greater level in some aspects such as water surface and perennial vegetation coverage etc. This study at fine scale is globally significant for the rural areas, especially for the subsistence agricultural land, which occupies larger percentage in the earth. And it analyzes the structure of landscape based on a new landscape classification system--stratifications method.     

Forest structure of a maple old-growth stand: a case study on the Apennines mountains (Southern Italy)

In Europe, very small forest areas can be considered to be old-growth, and they are mainly located in Eastern Europe. The typical structures of old growth forests infrequently occur in Mediterranean mountainous environments, since they have been affected by human activities for centuries. This study focused on a remote and almost pure Italian maple stand located in southern Italy, which has not been managed for long time due to its inaccessibility. The effects of natural evolution on the forest stand were evaluated through the analysis of the spatial and chronological structure and the regeneration patterns, then estimating the amounts and quality of deadwood occurrence. Across the whole stand, all the trees with DBH (diameter at breast height) larger than 50 cm (LLT, large living trees) were measured (DBH and height) and age was also determined through a dendrochronological approach. The diameters observed ranged between 50 and 145 cm with ages of 120 to 250 years. The Latham index calculated for trees within the sample plot highlighted a multilayered canopy with a dominant layer of large living trees (age > 120 years). The size-class distribution of stems had a reverse-J shape, and basal area was 52 m² ha^-1. Deadwood was exclusively constituted by standing dead trees and CWD and its volume was on average 31 m³ ha^-1.Pure Italian maple forests are generally rare in Europe, and it was unexpected to find a forest stand characterized by a so complex structure with old growth attributes. The study of complex forest stand, even if small, could give precious information on the forest evolution, clarifying also diverse auto-ecological traits of tree species that usually are not common in our forests.     

Impacts of land use change on landscape patterns in mountain human settlement: The case study of Hantai District(Shaanxi,China)

Mountain area is an important geographical unit of land,and its ecology is sensitive and fragile.Over the past few decades,human activities have caused dramatic changes in land use in mountainous areas,which caused changes in landscape patterns and impacts on the ecological environment.It is unknown how the mechanism of land use affects the landscape pattern at different scales.The Hantai District,a typical human settlement in the mountain area in Shaanxi,China,was chosen as the study area.Based on the remote sensing images,the mathematical models and landscape indexes were adopted to evaluate the impact of land use change from 1998 to 2017 on the landscape pattern at different scales,and its main driving forces were analyzed.The results showed that the urbanized land expanded largest from 15.39%to 24.30%,and cultivated land experienced the largest decline from 43.54%to 35.35%.Changes in land use have made the patch morphology of most land types developed from a natural random to a sawtooth shape,and its spatial pattern evolved from a ruleset to a fragmented expansion.This reflects the continuous strengthening of human intervention in the process of regional development.Under the jurisdiction of Hantai District,the biggest change in landscape pattern is in Hanzhong City and Qili Town.The improved economy and increasing population and urbanization rate were the main factors that cause these changes.This research could provide necessary information for understanding the evolution mechanism of land resources in mountainous human settlements for mountainous areas with significant geomorphic differentiation.     

Assessment of tectonic control on the development of low mountains moderate relief in the Outer Carpathians(Southern Poland)

Inherited tectonic structures, ongoing tectonic deformation, and variations in relative rock uplift rates play an important role in conditioning the processes of relief development. Their influence among other factors, such as climate and lithology, can be quantified using landscape analysis, and geomorphometric indices, in particular. The usage of landscape analysis in recent years is increasing systematically due to the constant improvement of the digital elevation models and GIS software that significantly facilitate this approach. In this study, we aim to recognize the influence of tectonic structures and processes on relief development in the low mountains with moderate relief of the So?a River catchment in the Western Outer Carpathians. To this end, we calculated geomorphometric indices(river longitudinal profile, stream-length gradient index, minimum bulk erosion, relief ratio, circulatory ratio, elongation ratio, and hypsometric integral) for the So?a River and its 47 sub-catchments using a 25-m spatial resolution Digital Terrain Elevation Data Level 2. Additionally, we identified lineaments and knickpoints and correlated the computed results with local and regional fault networks, variations in lithology, and climate fluctuations. Obtained results indicate a significant impact of inherited tectonicstructures on the relief development of the So?a River catchment, i.e., directions of principal ridges and valleys follow the orientation of main folds and faults recorded in this area. Anomalously high values of minimum bulk erosion, river gradient, and streamlength gradient index allowed us to define two areas with higher relative uplift rates: 1) the So?a Gorge and 2) the Beskid ?ywiecki Mts. Polish Outer Carpathians are generally considered as an area of low strain rate and low seismic activity. However, the possibility of neotectonic processes should be considered in geohazard estimations. Observed bends in the direction of river valleys that do not correspond with changes in lithology could be related to active strikeslip faults. These are probably the reactivated basement structures, copied in the thin-skinned nappe cover, as a result of the accommodation of the Mur-?ilina Fault Zone resulting from the tectonic push of the Alcapa(Alpine-Carpathian-Pannonian) microplate against the European plate. Thus, the role of recent tectonic activity in relief development of the So?a River catchment even though appears to be subsidiary at the most, should not be excluded.     

潍坊市北部沿海地区海咸水入侵灾害及防治对策

潍坊市北部的寿光、寒亭、昌邑等沿海地区,80年代初期就已形成地下水水位下降漏斗,导致海咸水对淡水含水层的入侵.本文根据监测资料,对该区海咸水入侵发展现状、危害程度及形成原因进行了探讨,并提出了防治对策.     

Variations of suction and suction stress of unsaturated loess due to changes in lignin content and sample preparation method

Unsaturated loess in natural sites loses stability as the overburden load continuously increases. Traditional soil modifiers such as cement and fly ash affect the surrounding environment. A new type of material, i.e., lignin, is environmentally friendly and able to increase the strength of loess. However, the engineering characteristics of the improved loess under unsaturated conditions are not yet clear. In this study, the soil-water characteristic curves(SWCCs) of lignin-improved loess samples were determined from 0 k Pa to 700 k Pa using a pressure plate instrument, and then, they were fitted using the van Genuchten(VG) model and the Fredlund and Xing(FX) model. In addition, the effects of the lignin content and sample preparation methods on the SWCCs were investigated to determine the optimal lignin content and a suitable sample preparation method for loess foundations. As the lignin content increases, the matric suction and residual water content of the improved loess increase. The suction stress increases with the increasing lignin contents of 1%-2%. At lignin contents of 3%-4%, the suction stress begins to decrease and the samples prepared using the slurry method has a lower suction stress than that prepared using the wet mixing method. The air entry value(AEV) increases with increasing lignin content. In addition, scanning electron microscopy(SEM) was used to investigate the microstructural variations. It was found that after the addition of lignin, the entrapment of the loess particles by the lignin fibers created some larger particles and smaller pore diameters, which in turn led to poor connectivity of the loess pores. These changes cause the matric suction of the modified loess to increase.     

Shifts of sediment bacterial community and respiration along a successional gradient in a typical karst plateau lake wetland(China)

Bacteria are important regulators of carbon cycling in lakes and are central to sediment ecosystem processes. However, the sediment microbial communities and their respiratory responses to the lake wetland succession are poorly understood. In this study, we collected sediment samples from four different succession points(the Potamogeton lucens zone, the Scirpus tabernaemontani zone, the Scirpus triqueter zone, and the Juncus effusus zone) in the Caohai Wetland of the Guizhou Plateau(China). The bacterial communities at these succession points were studied using a high-throughput sequencing approach. The sediment microbial respiration(SR) was measured using static chambers in the field and basal respiration(BR) was determined in the laboratory. The results show that the dominant bacterial taxa in the sediment was Proteobacteria(34.7%), Chloroflexi(17.8%), Bacteroidetes(7.3%), Acidobacteria(6.6%), and Cyanobacteria(6.1%). Principal coordinate analysis showed that the microbial community structure differs significantly at different sampling points along the successional gradient, indicating that the bacterial community structure is sensitive to the lake wetland succession. Different hydrological regimes and soil characteristics such as NH_4~+-N, Fe~(2+), Mn~(2+), and sediment organic carbon(SOC) content may be important factors responsible for the differences in the sediment microbial characteristics of the different successional stages in the Caohai wetland. Additionally, it was found that the SR increased significantly from the P. lucens zone to the J. effusus zone, but BR had the opposite response. The shifts in the bacterial community structure along the successional gradient may be the main reason for the observed differences in sediment respiration.     

Frozen ground and periglacial processes relationship in temperate high mountains: a case study at Monte Perdido-Tucarroya area(The Pyrenees,Spain)

Seasonally frozen ground,mountain permafrost and cryogenic geomorphological processes are important components of the Pyrenean high mountains.This work presents the results of a study on the distribution of frozen ground in a marginal and paraglacial environment of temperate mountains.An inventory was made of landforms and indicators of frozen ground,and frozen ground was mapped accordingly.During 2014 and 2016 ground temperatures and thermal regimes were monitored,basal temperatures of snow-cover(BTS)were measured and a thermal map was drawn.Differential thermal behaviours were detected among different elevations and slope orientations.Periglacial processes are the most widespread,in which frost weathering and nivation,together with gelifluction and cryoturbation,are the most efficient processes;the latter two are generally linked to the presence of frozen ground.The fall in air and ground temperatures with altitude,slope orientations,and snowpack thickness and evolution determine ground thermal regimes.In the study area,three types of thermal regimes were established:climate-controlled,snowcover-controlled,and frozen ground-controlled.Seasonally frozen ground occurs across a broad range of elevation between 2650 and 3075 m asl,whereas possible permafrost only occurs above 2750 m asl.     

Changes in spatial variations of sap flow in Korean pine trees due to environmental factors and their effects on estimates of stand transpiration

It is difficult to scale up measurements of the sap flux density (Js) for the characterization of tree or stand transpiration (E) due to spatial variations in JS and their temporal changes. To assess spatial variations in the sap flux density of Korean pine (Pinus koraiensis) and their effects on E estimates, we measured the Js using Granier-type sensors. Within trees, the Js decreased exponentially with the radial depth, and the Js of the east aspects were higher than those of the west aspects. Among trees, there was a positive relationship between Js and the tree diameter at breast height, and this positive relationship became stronger as the transpiration demand increased. The spatial variations that caused large errors in E estimates (i.e., up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors. However, changes in these variations did not generate substantial errors in the E estimates. For our study periods, the differences in the daily E (E _D) calculated by ignoring radial, azimuthal and tree-to-tree variations and the measured E _D were fairly constant, especially when the daily vapor pressure deficit (D__D) was higher than 0.6 kPa. These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations (radial, azimuthal and tree-to-tree variations) when considering E estimates.     

Estimation of natural mortality coefficient from fish abundance and catch data using Virtual Population Analysis (VPA)

1 Introduction Natural mortality coefficient (M) is one of the key population parameters common to most analyses in fish stock assessment. Many mathematical models of fish stock dynamics include M directly or indirectly. However, until now M is the least known among the four factors affecting fish stock variation: recruitment, growth, natural death and fishing death (Quinn and Deriso, 1999). There is an extensive literature concerning the impact of errors in M on stock assessment (Mertz and…     

The impact of catastrophic natural disaster on land-use changes of Qingping town and the selection of suitable land for settlement construction

A Ms 8.0 large earthquake occurred in Sichuan,China on May 12,2008(hereafter called 5.12 Earthquake),and then a large debris flow happened in the quake-hit Qingping Township of Mianzhu county on August 13,2008(hereafter called 8.13 Debris Flow).The influence of two disasters on the changes in land use were analyzed by using highresolution aerial photos and satellite remote sensing images taken before and after the 5.12 Earthquake and 8.13 Debris Flow,the selection of suitable construction land were studied by learning experiences and lessons from the selection of resettlement areas and through field surveys and with land use transfer model and analytical model in combination with RS and GIS.The results showed that the influence of the 5.12 Earthquake on ecological environment was far greater than that of the 8.13 Debris Flow;there were more salient conflicts between population and land after the earthquake.Sites for post-disaster reconstruction should not be in disaster-prone areas or in gully-facing areas.Suitable land for settlement construction in I-1~I-5 low-hazard zones is optimal settlement areas for post-disaster reconstruction.     

Land use and land cover changes in small Carpathian catchments between the mid-19~(th) and early 21~(st) centuries and their record on the land surface

Land use and land cover(LULC) changes and their impact on the mountain environment were studied in six catchments(～10 km~2 each) in the Polish Western Carpathians from the mid-19~(th) century to the early 21~(st) century. The analysis of cadastral and orthophoto maps indicates that during the investigated period, the forest area increased, quantified by an annual change index(Annch), between +0.12% to +0.27%, with a decrease of arable land index to –0.45% and –2.28% in the analysed catchments. LULC changes were accompanied by a continuous increase in settlement developments(residential and farming houses) by 50%-140% as well as significant changes related to their spatial distribution. Abandonment of arable land and forest succession have resulted in the geomorphological transformation of hillslopes, which predominantly includes a decrease in used road density, their transformation to road cuts and gorges. Overpopulation and the domination agriculture in the past caused the expansion of unpaved roads density and then the fragmentation of hillslopes, as well as the development of agricultural terraces.     

Effects of salinity on embryonic and larval development of Chinese mitten crab Eriocheir sinensis(Decapoda: Brachyura) and salinity-induced physiological changes

To investigate the effects of salinity on early development of Chinese mitten crab(Eriocheir sinensis),and the salinity tolerance mechanism of embryos,different developmental stages of embryos(gastrula,eyespot and pre-hatching stage),and hatched stage I zoea and megalopa,were exposed to a range of salinities(1,5,10,15(control),20,25,30,35 and 40).Hatching,survival and molting were monitored.Effects of 24-hour hypersaline(35)and hyposaline(1)stress on egg diameter,water content,Na~+/K~+-ATPase(NKA)activity,and crustacean hyperglycemic hormone(CHH)gene mRNA expression in embryos and megalopa,are reported.Embryos are more tolerant of low(≤5)than high(≥25)salinities,with optimum ranges for gastrula and pre-hatching stage embryos being 5-20,and for eyespot embryo and stage I zoea,10-20.Most megalopa can molt to the first juvenile instar by day 5 at salinities between 1 and 40,whereas molting of megalopa stages was delayed at 40.Hypersaline conditions resulted in a loss of moisture,reduction of egg volume,and a significant increase in NKA activity and CHH mRNA expression at some developmental stages.Hyposaline conditions did not affect moisture content or egg volume,but resulted in decreased NKA activity and CHH mRNA expression in embryos.For megalopa stages,NKA activity was significantly upregulated following both hypo-and hypersaline stress.Our results suggest high salinity will inhibit development and hatching of E.sinensis embryos,and low salinity will affect the survival of their stage I zoea.Increased NKA activity in embryos and megalopa stages might indicate a hyporegulation response under hypersaline conditions.These findings provide useful information for spawning ground protection of indigenous E.sinensis and enrich the knowledge of embryonic tolerance mechanisms of hyperregulating crustaceans following osmotic stress.     

Age-related changes of leaf traits and stoichiometry in an alpine shrub(Rhododendron agglutinatum) along altitudinal gradient

Leaf morphological and stoichiometric characteristics are considered to represent both the interior inheritable characters in the plant and its adaptations to specific exterior environments. Rhododendron agglutinatum,an evergreen alpine shrub species,occupies a wide range of habitats above timberline in the Miyaluo Natural Reserve,southwestern China. Along an altitudinal gradient ranging from 3700 to 4150 m,we measured leaf morphological characters including leaf dry matter content(LDMC),leaf dry mass per unit area(LMA),and one leaf area(OLA),as well as carbon(C) and nutrient(N,P) contents in leaves of three different age groups(juvenile leaves,mature leaves and senescent leaves). We also calculated the stoichiometric relationships among carbon and nutrients(C/N,C/P and N/P). Results showed thatboth age and altitude affected the leaf morphological and stoichiometric properties of R. agglutinatum. Mature leaves possessed the highest LDMC,LMA and C contents both on a dry mass basis and on a unit area basis. Younger leaves possessed higher contents of nutrients. OLA as well as ratios between carbon and nutrients(C/N,C/P) increased with ages. Juvenile leaves possessed lowest ratio between nitrogen and phosphorus. In juvenile leaves,nutrients increased with altitudinal elevation,whereas other traits decreased. In mature leaves,nutrients and their ratios with carbon showed consistent trends with juvenile leaves along increasing altitude,whereas LMA and carbon on a unit area basis showed opposite trends with juvenile leaves along increasing altitude. In senescent leaves,only content of phosphorus on a unit area basis and N/P were found linearly correlated with altitude. Our results demonstrated a clear pattern of nutrient distribution with aging process inleaves and indicated that a high possibility of N limitation in this region. We also concluded that younger leaves could be more sensitive to climate changes due to a greater altitudinal influence on the leaf traits in younger leaves than those in elder leaves.     

Morphological changes and allometric growth in hatcheryreared Chinese loach Paramisgurnus dabryanus(Dabry de Thiersant, 1872)

The length-weight relationship and allometric growth patterns of hatchery-reared Chinese loach, Paramisgurnus dabryanus(Dabry de Thiersant, 1872), were determined from hatching to 60 days after hatching. A best power model was estimated for the length-weight relationship during the early life stages. Positive allometric growth for the head segment, trunk length, tail length and eye diameter was also found in the early life stages, while body depth, tail depth, tail fi n length, pectoral fi n length and barbel length displayed a negative coeffi cient. During the subsequent early developmental stage, the growth coeffi cients showed a clear and common tendency towards isometry for all measured body ratios. The allometric growth changes in Chinese loach during the early stage are possibly the result of selective organogenesis directed towards survival priorities.     

岩溶微古地貌对岩溶白云岩的储层控制作用——以大牛地奥陶系马五_(1+2)段岩溶储层水平井解释为例

针对鄂尔多斯盆地大牛地气田马五1+2段储层致密、岩溶作用强烈、非均质性强,直井单井产能低,调整为水平井开采后获得良好的开发前景等特点,根据岩心、物性及薄片观察等资料,分析马五1+2段水平井钻遇试气成果,储层发育及录井气测异常厚度等对不同微古地貌的水平井导眼段及水平井进行测井解释,识别并确定水平段储集类型,研究岩溶微古地貌对岩溶白云岩储层控制作用。结果表明:研究区岩溶相带发育明显,纵向上岩溶储层受岩溶相带的控制明显,马五13、马五14、马五2处于垂直渗流带,整体受泥质充填较弱,储集性能较好,为储集有利相带;岩溶斜坡微古地貌处地表水的渗滤作用表现明显,白云岩发育大量的溶蚀孔隙、溶缝,泥质充填程度较弱,具有良好的储集性能,是古岩溶储层发育和气藏形成的有利部位;岩溶高地储集空间易被溶蚀、充填,故物性与斜坡相比较差。     

The in vitro effects of steroids,human chorionic gonadotropin and cyanoketone on germinal vesicle breakdown of striped mullet (Mugil cephalus L.) oocytes

The in vitro effects of steroids, human chorionic gonadotropin (HCG) and cyanoketone on germinal vesicle breakdown (GVBD) of striped mullet (Mugil cephalus L.) oocytes were investigated. All concentrations of HCG (5,10,50 I.U./ml), progesterone and pregnenolone at the highest concentrations(lug/ml) were moderately effective in inducing GVBD, whereas 17β-estrodiol, cortisol, testosterone, 11β-hydroxyandrostenedione and 11-ketotestosterone did not stimulate GVBD. 17α, 20βdihydroxy-4-pregnen-3-one (17α, 20βdiOHprog) and deoxycorticosterone (DOC) were the most potent steroids in stimulating final oocyte maturation. The results indicate that C21 hydroxylated steroids are potent inducers of final maturation in mullet. Further, co-incubations with 17β-estradiol, cortisol and testosterone did not alter the maturation-inducing effects of HCG or 17α,20βdiOHprog. Cyanoketone, a blocker of 3βHSD activity, was only partially effective in blocking GVBD induced by HCG. This suggests that Δ5 (pregnenolone derived) and Δ4 steroids may be involved in final oocyte maturation in this species.     

华贵栉孔扇贝稚贝盐度适应性的研究

通过室内实验研究了水温28.5～29.4℃、pH值7.6～8.1条件下,华贵栉孔扇贝Chlamys nobilis(Reeve)稚贝(壳高9.77±0.19mm)对不同盐度的适应性。结果表明:华贵栉孔扇贝稚贝适宜生存盐度为24.27~37.18,最适生存盐度为26.91~32.13,适宜生长盐度为24.56~37.09,最适生长盐度为26.91~29.52。在适宜生存盐度范围内,当盐度变化超出最适范围时,低盐端变化对相对成活率、壳高日增长率、体重日增长率影响比高盐端明显。