Some questions about landscape modelling

The paper discusses mainly about the modelling process and related problems with examples from Chinese and French cases. Five practical problems must be solved for modelling the functioning of any landscape: ( 1) The field data are necessarily taken with a sampling procedure that implies a spatial (and often temporal) scale. (2) Every landscape modelled has to be identified, delimited and characterised before application of the hierarchical theory. (3) The functioning of a landscape involves data of multiple types (climate, soil, vegetation, fauna, buildings, communications, economy, aesthetics, etc.) which must be integrated in a holistic approach. (4) Every landscape is spatially heterogeneous, and the structure of the model must be more or less isomorphic with its heterogeneity. ( 5) The evolution of the landscape must be modelled on a rather long period of time. For all these reasons, it is necessary to build ad hoc models. Object-oriented computing languages may be useful for this purpose.

Progress and prospect of research on forest landscape model

The Forest Landscape Model （FLM） is an efficiency tool of quantified expression of forest ecosystem＇s structure and function. This paper, on the basis of identifying FLM, according to the stage of development, summarizes the development characteristics of the model, which includes the theoretical foundation of mathematical model, FLM of stand-scale, primary development of spatial landscape model, rapid development of ecosystem process model as the priority, and developing period of structure and process driven by multi-factor. According to the characteristics of different FLMs, this paper classifies the existing FLM in terms of mechanism, property and application, and elaborates the identifications, advantages and disadvantages of different types of models. It summarizes and evaluates the main ap- plication fields of existing models from two aspects which are the changes of spatial pattern and ecological process. Eventually, this paper presents FLM＇s challenges and directions of development in the future, including： （1） more prominent service on the practical strategy of forest management＇s objectives; （2） construction of multi-modules and multi-plugin to satisfy landscape research demand in various conditions; （3） adoption of high resolution＇s spatial-temporal data; （4） structural construction of multi-version module; （5） improving the spatial suitability of model application.

The ideal landscape and its ecological planning approach in Mount Lushan National Park, China

This paper described the main four basic models of ideal landscape in the Mount Lushan National Park as Kunlunshan model, Xumishan model, Peach flower land model, Christian model. Five typical places in Mount Lushan with the ideal landscape characteristics like the East Grove Temple, White Deer Cave Academy, Simplicity and Tranquility Monastery, Lushan Valley, and Villa-cluster of the East Valley were analyzed, and the integration of the basic models for each place was discussed to make the realistic landscape conform to the ideal needs. Moreover, the discussions also involved the characteristics of ideal landscape that are featured in resource, culture, structure, function, process, scale and region. In conclusion, ideal landscape in the Mount Lushan National Park was the product of the interaction between human and nature. Mount Lushan inherits the essence of Chinese traditional culture with a history of more than 1000 years; and it also absorbs the manna of the Western culture as well as the exchanges between nature and humanities together with the conflict and adaptation among different cultures. The natural landscape could be satisfied with the survival demand and cultural taste of mankind by the way of ecological planning.

Predicting Ailanthus altissima presence across a managed forest landscape in southeast Ohio

Background: The negative impacts of the exotic tree, Ailanthus altissima(tree-of-heaven, stink tree), is spreading throughout much of the Eastern United States. When forests are disturbed, it can invade and expand quickly if seed sources are nearby.Methods: We conducted studies at the highly dissected Tar Hollow State Forest(THSF) in southeastern Ohio USA,where Ailanthus is widely distributed within the forest, harvests have been ongoing for decades, and prescribed fire had been applied to about a quarter of the study area. Our intention was to develop models to evaluate the relationship of Ailanthus presence to prescribed fire, harvesting activity, and other landscape characteristics, using this Ohio location as a case study. Field assessments of the demography of Ailanthus and other stand attributes(e.g., fire, harvesting, stand structure) were conducted on 267 sample plots on a 400-m grid throughout THSF,supplemented by identification of Ailanthus seed-sources via digital aerial sketch mapping during the dormant season. Statistical modeling tools Random Forest(RF), Classification and Regression Trees(CART), and Maxent were used to assess relationships among attributes, then model habitats suitable for Ailanthus presence.Results: In all, 41 variables were considered in the models, including variables related to management activities, soil characteristics, topography, and vegetation structure(derived from LiDAR). The most important predictor of Ailanthus presence was some measure of recent timber harvest, either mapped harvest history(CART) or LiDARderived canopy height(Maxent). Importantly, neither prescribed fire or soil variables appeared as important predictors of Ailanthus presence or absence in any of the models of the THSF.Conclusions: These modeling techniques provide tools and methodologies for assessing landscapes for Ailanthus invasion, as well as those areas with higher potentials for invasion should seed sources become available. Though a case study on an Ohio forest, these tools can be modified for use anywhere Ailanthus is invading.

Extrapolating plot-scale CO_(2) and ozone enrichment experimental results to novel conditions and scales using mechanistic modeling

Introduction:The Aspen-FACE experiment was an 11-year study of the effect of elevated CO_(2) and ozone(alone and in combination)on the growth of model aspen communities(pure aspen,aspen-birch,and aspen-maple)in the field in northern Wisconsin,USA.Uncertainty remains about how these short-term plotlevel responses might play out over broader temporal and spatial scales where climate change,competition,succession,and disturbances interact with tree-level responses.In this study,we used a new physiologybased approach(PnET-Succession v3.1)within the forest landscape model LANDIS-II to extrapolate the FACE results to broader temporal scales(and ultimately to landscape scale)by mechanistically accounting for the globally changing drivers of temperature,precipitation,CO_(2),and ozone.We added novel algorithms to the model to mechanistically simulate the effects of ozone on photosynthesis through ozone-induced impairment of stomatal control(i.e.,stomatal sluggishness)and damage of photosynthetic capacity at the chloroplast level.Results:We calibrated the model to empirical observations of competitive interactions on the elevated CO_(2) and O_(3) plots of the Aspen-FACE experiment and successfully validated it on the combined factor plots.We used the validated model to extend the Aspen-FACE experiment for 80 years.When only aspen clones competed,we found that clone 271 always dominated,although the ozone-tolerant clone was co-dominant when ozone was present.Under all treatments,when aspen clone 216 and birch competed,birch was always dominant or co-dominant,and when clone 216 and maple competed,clone 216 was dominant,although maple was able to grow steadily because of its shade tolerance.We also predicted long-term competitive outcomes for novel assemblages of taxa under each treatment and discovered that future composition and dominant taxa depend on treatment,and that short-term trends do not always persist in the long term.Conclusions:We identified the strengths and weaknesses of PnET-Succession v3.1 and conclude that it can generate potentially robust predictions of the effects of elevated CO_(2) and ozone at landscape scales because of its mechanistically motivated algorithms.These capabilities can be used to project forest dynamics under anticipated future conditions that have no historical analog with which to parameterize less mechanistic models.

Numerical simulation of landscape evolution and mountain uplift history constrain——A case study from the youthful stage mountains around the central Hexi Corridor,NE Tibetan Plateau

Landscape evolution models(LEMs)are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes.In this study we used a LEM to simulate the evolution of the mountains from the central Hexi Corridor in the northeastern Tibetan Plateau,where the climate is arid and the surface processes are relatively uniform.However,there are pronounced differences in the topography between the mountains around the central Hexi Corridor.The East Jintanan Shan,West Jintanan Shan and Heli Shan are located in the northern part of the corridor;and the Yumu Shan in the southern part.Firstly,several representative areas were selected from these mountains to analyze the topographic characteristics,including the uniform valley spacing,local relief,and the outlet number.Secondly,a LEM for these areas was constructed using the Landlab platform,and the landscape evolution was simulated.With uniform valley spacing and other topographic characteristics as the criteria,we compared the realistic and simulated terrain for different model ages.Finally,based on the similarity of the simulated and realistic terrain,we estimated the timing of the initial uplift and the uplift rate of the four mountain ranges.The results are consistent with previous geological and geomorphological records from these youthful stage mountains that have not yet reached a steady state.Our findings demonstrate that LEMs combined with topographic characteristics are a reliable means of constraining the timing of the initial uplift and the uplift rate of the youthful stage mountain.Our approach can potentially be applied to other youthful stage mountains and it may become a valuable tool in tectonic geomorphology research.

模拟中国四级行政尺度下耕地位移对粮食生产潜力的影响

Cropland displacement, as an important characteristic of cropland change, places more emphasis on changes in spatial location than on quantity. The effects of cropland displacement on global and regional food production are of general concern in the context of urban expansion. Few studies have explored scale-effects, however, where cropland is displaced not only within, but also outside, the administrative boundary of a certain region. This study used a spatially explicit model(LANDSCAPE) to simulate the potential cropland displacement caused by urban land expansion from 2020 to 2040 at four scales of the Chinese administration system(national, provincial, municipal, and county levels). The corresponding changes in potential cereal production were then assessed by combining cereal productivity data. The results show that 4700 km^(2) of cropland will be occupied by urban expansion by 2040, and the same amount of cropland will be supplemented by forest, grassland, wetland, and unused land. The potential loss of cropland will result in the loss of 3.838×10^(6) tons of cereal production, and the additional cropland will bring 3.546×10^(6) tons, 3.831×10^(6) tons, 3.836×10^(6) tons, and 3.528×10^(6) tons of potential cereal production in SN(national scale), SP(provincial scale), SM(municipal scale), and SC(county scale), respectively. Both SN and SC are observed to make a huge difference in cereal productivity between the lost and the supplemented cropland. We suggest that China should focus on the spatial allocation of cropland during large-scale displacement, especially at the national level.

XAANTAL2 （AGL14） Is an Important Component of the Complex Gene Regulatory Network that Underlies Arabidopsis Shoot Apical Meristem Transitions

In Arabidopsis thaliana, multiple genes involved in shoot apical meristem （SAM） transitions have been char- acterized, but the mechanisms required for the dynamic attainment of vegetative, inflorescence, and floral meristem （VM, IM, FM） cell fates during SAM transitions are not well understood. Here we show that a MADS-box gene, XAANTAL2 （XAL2/AGL14）, is necessary and sufficient to induce flowering, and its regula- tion is important in FM maintenance and determinacy, xal2 mutants are late flowering, particularly under short-day （SD） condition, while XAL2 overexpressing plants are early flowering, but their flowers have vege- tative traits. Interestingly, inflorescences of the latter plants have higher expression levels of LFY, AP1, and TFL1 than wild-type plants. In addition we found that XAL2 is able to bind the TFL1 regulatory regions. On the other hand, the basipetal carpels of the 35S：：XAL2 lines lose determinacy and maintain high levels of WUS expression under SD condition. To provide a mechanistic explanation for the complex roles of XAL2 in SAM transitions and the apparently paradoxical phenotypes of XAL2 and other MADS-box （SOCl, AGL24） over- expressors, we conducted dynamic gene regulatory network （GRN） and epigenetic landscape modeling. We uncovered a GRN module that underlies VM, IM, and FM gene configurations and transition patterns in wild- type plants as well as loss and gain of function lines characterized here and previously. Our approach thus provides a novel mechanistic framework for understanding the complex basis of SAM development.

Improving the knowledge of plant potential biodiversity-ecosystem services links using maps at the regional level in Southern Patagonia

Background:Biodiversity supports multiple ecosystem services,whereas species loss endangers the provision of many services and affects ecosystem resilience and resistance capacity.The increase of remote sensing techniques allows to estimate biodiversity and ecosystem services supply at the landscape level in areas with low available data(e.g.Southern Patagonia).This paper evaluates the potential biodiversity and how it links with ecosystem services,based on vascular plant species across eight ecological areas.We also evaluated the habitat plant requirements and their relation with natural gradients.A total of 977 plots were used to develop habitat suitability maps based on an environmental niche factor analysis of 15 more important indicator species for each ecological area(n=53 species)using 40 explanatory variables.Finally,these maps were combined into a single potential biodiversity map,which was linked with environmental variables and ecosystem services supply.For comparisons,data were extracted and compared through analyses of variance.Results:The plant habitat requirements varied greatly among the different ecological areas,and it was possible to define groups according to its specialization and marginality indexes.The potential biodiversity map allowed us to detect coldspots in the western mountains and hotspots in southern and eastern areas.Higher biodiversity was associated to higher temperatures and normalized difference vegetation index,while lower biodiversity was related to elevation and rainfall.Potential biodiversity was closely associated with supporting and provisioning ecosystem services in shrublands and grasslands in the humid steppe,while the lowest values were related to cultural ecosystem services in Nothofagus forests.Conclusions:The present study showed that plant species present remarkable differences in spatial distributions and ecological requirements,being a useful proxy for potential biodiversity modelling.Potential biodiversity values change across ecological areas allowing to identify hotspots and coldspots,a useful tool for landscape management and conservation strategies.In addition,links with ecosystem services detect potential synergies and trade-offs,where areas with the lowest potential biodiversity are related to cultural ecosystem services(e.g.aesthetic values)and areas with the greatest potential biodiversity showed threats related to productive activities(e.g.livestock).