Early response of understory vegetation to the mass dieback of Norway spruce in the European lowland temperate forest

Spruce-dominated forests are commonly exposed to disturbances associated with mass occurrences of bark beetles.The dieback of trees triggers many physical and chemical processes in the ecosystem resulting in rapid changes in the vegetation of the lower forest layers.We aimed to determine the response of non-tree understory vegetation to the mass dieback of Norway spruce(Picea abies)in the first years after the disturbance caused by the European spruce bark beetle(Ips typographus)outbreak.Our study area was the Białowieża Biosphere Reserve covering the Polish part of the emblematic Białowieża Forest,in total 597km^(2).The main data source comprised 3,900 phytosociological relevés(combined spring and summer campaigns)collected from 1,300 systematically distributed forest sites in 2016–2018–the peak years of the bark beetle outbreak.We found that the understory responded immediately to mass spruce dieback,with the most pronounced changes observed in the year of the disturbance and the subsequent year.Shade-tolerant forest species declined in the initial years following the mass spruce dieback,while hemicryptophytes,therophytes,light-demanding species associated with non-forest seminatural communities,as well as water-demanding forest species,expanded.Oxalis acetosella,the most common understory species in the Białowieża Forest,showed a distinct fluctuation pattern,with strong short-term expansion right after spruce dieback,followed by a gradual decline over the next 3–4 years to a cover level 5 percentage points lower than before the disturbance.Thus,our study revealed that mass spruce dieback selectively affects individual herb species,and their responses can be directional and non-directional(fluctuation).Furthermore,we demonstrated that the mass dieback of spruce temporarily increases plant species diversity(α-diversity).

CHINA'S VEGETATION/ECOSYSTEM RESPONSE TO GLOBAL CHANGE: RESEARCH PROGRESS & PROSPECTS

This paper presents the latest developments in the re search progress on mechanisms by which natural plants and crops respond to the doubled concentration of CO2 in the atmosphere, resultant climatic change and the modeling of vegetation and eco-systems in China. In addition, it points out that the future study on global change and terrestrial ecosystems should stress m(?)iti-disciplinary teamwork and inter-discipline penetration. Finally, the paper emphasizes 10 research realms in the field to be enhanced in the future.

Evaluating the Dependence of Vegetation on Climate in an Improved Dynamic Global Vegetation Model

The capability of an improved Dynamic Global Vegetation Model （DGVM） in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model- DGVM （CLM3.0-DGVM） with a submodel for temperate and boreal shrubs, as well as other revisions such as the ＂two-leaf＂ scheme for photosynthesis and the definition of fractional coverage of plant functional types （PFTs）. Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of di？erent vege- tation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.

The dynamic response of forest vegetation to hydro- thermal conditions in the Funiu Mountains of western Henan Province

This paper uses HJ-1 satellite multi-spectral and multi-temporal data to extract forest vegetation information in the Funiu Mountain region. The S-G filtering algorithm was employed to reconstruct the MODIS EVI（Enhanced Vegetation Index） time-series data for the period of 2000–2013, and these data were correlated with air temperature and precipitation data to explore the responses of forest vegetation to hydrothermal conditions. The results showed that：（1） the Funiu Mountain region has relatively high and increasing forest coverage with an average EVI of 0.48 over the study period, and the EVI first shows a decreasing trend with increased elevation below 200 m, then an increasing trend from 200–1700 m, and finally a decreasing trend above 1700 m. However, obvious differences could be identified in the responses of different forest vegetation types to climate change. Broad-leaf deciduous forest, being the dominant forest type in the region, had the most significant EVI increase.（2） Temperature in the region showed an increasing trend over the 14 years of the study with an anomaly increasing rate of 0.27℃/10a; a fluctuating yet increasing trend could be identified for the precipitation anomaly percentage.（3） Among all vegetation types, the evergreen broad-leaf forest has the closest EVI-temperature correlation, whereas the mixed evergreen and deciduous forest has the weakest. Almost all forest types showed a weak negative EVI-precipitation correlation, except the mixed evergreen and deciduous forest with a weak positive correlation.（4） There is a slight delay in forest vegetation responses to air temperature and precipitation, with half a month only for limited areas of the mixed evergreen and deciduous forest.

Effect of arsenic contaminated irrigation water on Lens culinaris L.and toxicity assessment using lux marked biosensor

Contamination of irrigation water represents a major constraint to Bangladesh agriculture,resulting in elevated levels in the terrestrial systems.Lux bacterial biosensor technology has previously been used to measure the toxicity of metals in various environmental matrices.While arbuscular mycorrhizal fungi have their most significant effect on phosphorus uptake,but showed alleviated metal toxicity to the host plant.The study examined the effects of arsenic and inoculation with an arbuscular mycorrhizal fungus,Glomus mosseae,on lentil （Lens culinaris L.cv.Titore）.Plants were grown with and without arbuscular mycorrhizal inoculum for 9 weeks in a sand and terra-green mixture （50：50,V/V） and watered with five levels of arsenic （0,1,2,5,10 mg As/L arsenate）.The results showed that arsenic addition above 1 mg/L significantly reduced percentage of mycorrhizal root infection.On further analysis a close relationship was established with the vegetative and reproductive properties of lentil （L.culinaris） plants compared to the percentage bioluminescence of the soil leachate.However,arbuscular mycorrhizal fungal inoculation reduced arsenic concentration in roots and shoots.Higher concentrations of arsenic （5,10 mg As/L arsenate） reduced the mycorrhizal efficiency to increase phosphorus content and nitrogen fixation.Therefore,this study showed that increased concentration of arsenic in irrigation water had direct implications to the lentil （L.culinaris） plants overall performance.Moreover the use of bioassay demonstrated that mycorrhiza and clay particle reduced arsenic bioavailability in soil.