HexSim: a modeling environment for ecology and conservation

Context

Simulation models are increasingly used in both theoretical and applied studies to explore system responses to natural and anthropogenic forcing functions, develop defensible predictions of future conditions, challenge simplifying assumptions that facilitated past research, and to train students in scientific concepts and technology. Researcher’s increased use of simulation models has created a demand for new platforms that balance performance, utility, and flexibility.

Objectives

We describe HexSim, a powerful new spatially-explicit, individual-based modeling framework that will have applications spanning diverse landscape settings, species, stressors, and disciplines (e.g. ecology, conservation, genetics, epidemiology). We begin with a model overview and follow-up with a discussion of key formative studies that influenced HexSim’s development. We then describe specific model applications of relevance to readers of Landscape Ecology. Our goal is to introduce readers to this new modeling platform, and to provide examples characterizing its novelty and utility.

Conclusions

With this publication, we conclude a > 10 year development effort, and assert that our HexSim model is mature, robust, extremely well tested, and ready for adoption by the research community. The HexSim model, documentation, worked examples, and other materials can be freely obtained from the website www.hexsim.net.

     

Heparanase - a novel regulator for cell and matrix interactions

Dynamic interactions between cells and underlying extracellular matrices are crucial for development, maintenance of cellular function, and response of tissure to injury and infection. Heparan sulfate proteoglycans (HSPG) are found in extracelular matrices and on the surface of most nuclrarated cells,and play critical roles in cell-cell and cell-matrix signal transduct ion by binding many molecules, such as growth factors and cytokines. Most of the biological properties of HSPG are conferred by heparan sulfate side chains, which can be degraded by heparanase. Changes of heparanase expression and activity may affect the biological processes above, which enables extravasation of inflammation cells, metastasis and neoangiogenesis of tumor cells invasion.     

Thresholds and hotspots for shrub restoration following a heterogeneous megafire

Context

Reestablishing foundational plant species through aerial seeding is an essential yet challenging step for restoring the vast semiarid landscapes impacted by plant invasions and wildfire-regime shifts. A key component of the challenge stems from landscape variability and its effects on plant recovery.

Objectives

We assessed landscape correlates, thresholds, and tipping points for sagebrush presence from fine-scale sampling across a large, heterogeneous area burned the previous year, where we were able to quantify soil surface features that are typically occluded yet can strongly affect recovery patterns.

Methods

Hypothesis testing and binary-decision trees were used to evaluate factors affecting initial sagebrush establishment, using 2171 field plots (totaling?~?2,000,000 m² sampled) over a 113,000-ha region.

Results

Sagebrush established in 50% of plots where it was seeded, a?>?12-fold greater establishment frequency than in unseeded areas. Sagebrush establishment was enhanced in threshold-like ways by elevation (>?1200 m ASL), topographic features that alter heatload and soil water, and by soil-surface features such as “fertile islands” that bore the imprint of pre-fire sagebrush. Sagebrush occupancy had a negative, linear relationship with exotic-annual grass cover and parabolic relationship with perennial bunchgrasses (optimal at 40% cover).

Conclusions

Our approach revealed interactive, ecological relationships such as novel soil-surface effects on first year establishment of sagebrush across the burned landscape, and identified “hot spots” for recovery. The approach could be expanded across sites and years to provide the information needed to explain past seeding successes or failures, and in designing treatments at the landscape scale.

     

Poor aeration in NFT and a means for its improvement

Because water can restrict rapid diffusive exchange of gases we have examined how far the nutrient solution is adequately aerated in NFT systems used for glasshouse tomato production. Measurements were at various places of: the concentrations of dissolved O₂ and dinitrogen oxide (nitrous oxide), the maximum rate of O₂ flow to an O₂-consuming sink (O₂ flux density), and the electrochemical (redox) potential. Whalehide pots containing peat-based or peat-sand based composts used to stand the plants in the NFT solution were found waterlogged and poorly aerated. Dissolved O₂ in solution drawn from the pots rarely exceeded 1-2 mg l^-1. This small amount of O₂ was associated with accumulations of dinitrogen oxide, a gaseous product of anaerobic microbial respiration. Oxygen flux density was also small but redox potentials remained above 300 mV which was too high to favour the formation of Phytotoxins such as Mn(II), Fe(II) or H₂S. Replacing the composts with more open structured inorganic media such as Perlite, Rockwool or Capogro almost completely eliminated the symptoms of poor aeration observed in the composts. On one occasion the O₂ dissolved in the flowing nutrient solution was found to be depleted by c. 50%. Thus the whole system can sometimes be subject to considerable O₂ deficits.     

争取重压下的突围——2007年蒜薹收购及贮藏形势分析

2007年轰轰烈烈的蒜薹收购终告结束，今年大蒜种植面积之大，蒜薹产量之多和收购价格之低。大大出乎所有人的意料。产地源源不断的蒜薹供应和有条件贮藏蒜薹的冷库几乎是全部爆满的大收购行动，令人瞠目结舌。蒜薹入库结束后，我们及时和各地的有关人员取得了联系，获取了第一手的资料。现籽有关情况汇总如下，希望对大家今年的经营工作有所帮助。     

梨育种数据管理和采集系统设计与实践

【目的】建立基于单株二维码标签的梨育种数据管理与采集系统,提高梨育种田间工作效率。【方法】通过对标签的制作材质、封装方法、悬挂方式等在田间适用性的观察试验,筛选出适宜梨育种群体使用的二维码标签;结合条码识别与移动终端App技术,开发出基于梨属植物种质资源数据标准的梨育种信息管理与采集系统,并与传统人工记录方式对比数据采集效率。【结果】适宜梨育种群体使用的单株二维码标签制作与悬挂方式为:红色覆膜铜版纸热转印树脂碳带条码,热塑封后用U型钉以统一方向固定;梨育种数据管理与采集系统实现了梨种质资源与杂交群体的基础数据存储、田间数据采集,以及文档、图片等档案的集中管理等功能;与手工采集数据方式相比,系统手持终端采集效率提高了约25%。【结论】设计的二维码标签成本低廉、经久耐用、田间辨识度高,可同时兼容常规编码体系和手持终端的扫码识别,适宜用作梨种质资源及杂交育种群体的身份标识;研制的系统实现了梨育种信息的田间快速采集与传输,确保育种数据的统一和完整性,提高数据采集记载效率。该系统也适用于苹果、桃、柑橘等其它木本果树。     

Estimation of metademographic rates and landscape connectivity for a conservation-reliant anuran

Landscape Ecology - Amphibian conservation efforts commonly assume populations are tied to waterbodies that collectively function as a metapopulation. This assumption is rarely evaluated, and there...     

Green roofs for a wide brown land: Opportunities and barriers for rooftop greening in Australia

There is increasing public, industry and government interest in establishing green roofs in Australian cities due to their demonstrated environmental benefits. While a small number of green roofs have been constructed in Australia, most are roof gardens or intensive green roofs. Despite their potential as a climate change adaptation and mitigation tool and their widespread use in the northern hemisphere, there are very few examples of extensive green roofs in Australia. One of the major barriers to increasing the prevalence of extensive green roofs in Australia is the lack of scientific data available to evaluate their applicability to local conditions. Relying on European and North American experience and technology is problematic due to significant differences in climate, available substrates and plants. This paper examines green roofs in Australia, discusses the challenges to increasing their use and the major information gaps that need to be researched to progress the industry in Australia.     

Control of water and nutrients using a porous tube: a method for growing plants in space

A plant nutrient delivery system that uses a microporous, hydrophilic tube was developed with potential application for crop production in the microgravity of space. The tube contains a nutrient solution and delivers it to the roots. Pumps attached to the tubing create a very small suction that holds the solution within the tube. This system was used to grow wheat (Triticum aestivum cv. Yecora Rojo) for 107 days in a controlled environment at suctions of 0.40, 1.48, or 2.58 kPa. The water absorbed through the pores of the tube by baby diaper sections decreased as suction increased. Correspondingly, final plant biomass, seed number, and spikelet number also tended to decrease as suction increased. The reduced yield at higher suction suggests that the plants experienced water stress, although all suctions were below those typical of soils at field capacity.     

Concepts and methods for landscape multifunctionality and a unifying framework based on ecosystem services

The potential of landscapes to supply multiple benefits to society beyond commodities production has received increasing research and policy attention. Linking the concept of multifunctionality with the ecosystem services (ES) approach offers a promising avenue for producing scientific evidence to inform landscape planning, e.g., about the relative utility of land-sharing and land-sparing. However, the value for decision-making of ES-based multifunctionality assessments has been constrained by a significant conceptual and methodological dispersion. To contribute towards a cohesive framework for landscape multifunctionality, we analyse case studies of joint ES supply regarding ten criteria designed to ultimately answer four aspects: (i) the multifunctionality of what (e.g., landscapes), (ii) the type of multifunctionality (e.g., based on ES synergies), (iii) the procedure of multifunctionality assessments, and (iv) the purpose of multifunctionality. We constructed a typology of methodological approaches based on scores for criteria describing the evaluation method and the level of stakeholder participation in assessments of joint ES supply. Surveyed studies and underlying types of methodological approaches (spatial, socio-spatial, functional, spatio-functional) differed in most criteria. We illustrate the influence of methodological divergence on planning recommendations by comparing two studies employing contrasting approaches (spatial and functional) to assess the joint supply of wildlife habitat and agricultural production in the Argentine Chaco. We distinguish between a pattern-based and process-based multifunctionality, where the latter can only be detected through approaches considering the ecological processes (e.g., ES complementarities) supporting the supply of multiple ES (functional and spatio-functional). Finally, we propose an integrated approach for assessing a socially-relevant process-based multifunctionality.     

花果两用观赏桃新品种——满天红的选育

满天红是以2-7(白凤×红寿星)自交育成的花果两用、高抗南方根接线虫的观赏桃新品种。该品种重瓣花,花红色,花冠大、花径4.4cm、花瓣4～6轮,花瓣数22～26枚;节间短,节长1.8cm,满树红艳。果实可以食用,单果质量130g,风味甜,可溶性固形物含量12%;郑州地区果实7月中下旬成熟,4月初开花,花期持续18d;需冷量800h,可用于盆景、庭院、公园、观光果园、插花艺术。     

柑橘加工鲜食兼用新品种——特罗维塔甜橙的选育

特罗维塔甜橙是从国外引种驯化并经品种比较试验获得的一个加工鲜食兼用的甜橙新品种。果实圆球形至扁圆形,平均单果质量180g,果皮橙黄色至橙红色,鲜艳,油胞大而突起,果肉柔软多汁,汁橙红色,风味浓郁,种子0～3粒,可食率69.1%,出汁率51.6%,可溶性固形物10.5%～13.0%,可滴定酸含量8g/L左右,固酸比13～16,维生素C500mg/L左右,12月下旬成熟,果实挂树延期采收性能良好,可到翌年3月中旬采收,果实耐贮藏。     

桃树"一边倒"树形的特点及其整形修剪技术

桃树"一边倒"树形树体结构简单,通过拉斜将主枝倒向一边,南北行向西倒,东西行向南倒,主枝倾斜45°.露地栽培株行距1～1.3m×2.5m,保护地栽培0.75～1m×1.8～2m.该树形具有结果早、产量高、果实品质好及便于管理等特点.同时介绍了该种树形的整形修剪技术.     

平潭水仙8189 新品种的选育

通过集团选择法,在平潭水仙群体中,经5年的反复选择、选出一批生长健壮、花葶数多的水仙鳞茎。利用该鳞茎后代的2年生鳞茎,在水仙花主产地漳州与当地水仙进行品种比较试验,结果表明,选育的平潭水仙具有鳞茎商品率高,每个鳞茎的花葶数比普通水仙多1～2葶,适应性强,性状稳定等特点。是一个种性优良的水仙新品种,已被命名为‘平潭水仙8189’。     

一株白桩菇属野生食用菌菌种分离鉴定与培养

以内蒙古锡林郭勒草原一株野生蘑菇为试材,采用形态特征和生态习性鉴定及分子鉴定的方法,对该蘑菇的菌丝体基因组DNA进行18S和ITS片段的扩增、测序,测序结果经Blast比对,从而对该蘑菇进行分离鉴定。结果表明:该野生真菌属于白桩菇属Leucopaxillus。另外,通过优化的MS平板培养基避光培养,在MS平板培养基上有原基形成,为日后对该菌种的驯化与栽培提供材料,为其开发与利用奠定基础。其ITS序列已上传GenBank,登录号为KY173356。     

Nitrogen and water use efficiency of zucchini squash for a plastic mulch bed system on a sandy soil

Zucchini squash (Cucurbita pepo L.) is an economically important vegetable crop in Florida. Typically, it is intensively managed with high inputs of fertiliser and irrigation water. Our objectives were to evaluate the interaction between fertilisation rates and irrigation treatments, and to quantify nitrate leaching in a plastic mulched/drip irrigated zucchini squash production systems. Three studies were carried out. The first study evaluated different depth placement of drip and fertigation lines on plant growth and fruit yield. Treatments included SUR (both irrigation and fertigation drip lines placed on the surface); S&S (both lines buried 0.15 m deep); and SDI (irrigation line placed 0.15 m below the fertigation line on the surface). The second and third studies compared three different N-rates and different soil moisture sensor-based irrigation strategies. Nitrate-N leaching was monitored by zero tension drainage lysimeters and soil samples. N leaching increased when irrigation and N-rates increased, with values ranging from 2 to 45 kg ha⁻¹ of N. Use of SDI increased yields by 16% compared to the S&S treatment, and reduced nitrate leaching by 93% while increasing the water use efficiency by 75% compared to a fixed 2-h irrigation event per day treatment. Application of N above the standard recommended rate of 145 kg ha⁻¹ did not increase yield, although yields were reduced at the lowest N-rate. The use of soil moisture sensors for automatic irrigation control reduced irrigation application and minimized nitrogen leaching. In addition, combining the soil moisture controlled SDI system that had surface applied fertigation resulted in similar or higher yields, while reducing both water use and potential N leaching because of improved nutrient retention in the root zone.     

Developing a complementary framework for urban ecology

Cities are characterized by dynamic interactions between socio-economic and biophysical forces. Currently more than half of the global population reside in cities which influence the global biogeochemical cycles and climate change, substantially exacerbating pressures on urban pollution, water quality and food security, as well as operating costs for infrastructure development. Goods and services such as aesthetic values, water purification, nutrient recycling, and biological diversity, that urban ecosystems generate for the society, are critical to sustain. Urban planners are increasingly facing the considerable challenges of management issues for urban ecosystems. Poor understanding of the complementary roles of urban ecology in urban infrastructure, and the functioning of ecosystems and ecological resilience of a complex human-dominated landscape has impeded effective urban planning over time, resulting in social disharmony. Here a complementary framework for urban ecology is proposed, in which ecosystems interact with land use, architecture and urban design – “E-LAUD” – affecting ecosystem and human health, and building on the concept that land uses in urban green areas, road-strips, wetlands, ‘habitat islands’ and urban architecture could synergistically benefit when clustered together in different combinations of urban landscapes. It is proposed that incorporation of the E-LAUD framework in urban planning forms the context of a new interdisciplinary research programme on ecological resilience for urban ecosystems and helps promote ecosystem services.