中国农田作物植被碳储量研究进展

作物植被碳储量是全球陆地生态系统碳库的重要组成部分。中国农田作物植被碳储量的估算主要采用参数估算法、遥感资料反演法和环境参数模型法。通过对中国近几十年来全国和区域尺度作物植被碳储量的估算研究,获得了一些作物的经济系数、含碳率和作物收获部分水分系数等估算参数值,探讨了遥感反演和环境参数模型方法,并提出加强农田基本建设、改进农业生产技术与管理、调整作物结构和加强作物秸秆利用等固碳措施。目前对中国农田作物植被碳储量的估算仍存在较大的不确定性,获取的估算参数尚不充分,估算方法和模型有待完善,对作物植被碳储量变化的源/汇效应尚未取得统一认识。虽然在农田生态系统中土壤碳储量（密度）普遍大于作物植被碳储量（密度）,但作物植被碳储量仍然是一个数量可观、并有增加潜力和可能的碳库,其大小及秸秆利用情况直接影响着土壤碳库。因此,对农田作物植被碳储量应分时段和区域具体分析,才能认识其源/汇效应。今后应在以下几方面进一步加强作物植被碳储量的研究：进一步完善和改进估算方法;加强作物植被碳储量估算及固碳措施的区域个例研究,探索不同空间尺度作物植被碳储量的尺度转换;开展作物碳储量动态及固碳机理的综合研究。此外,还应就气候变化与作物植被碳储量的相互耦合关系进行探讨。     

Recovery of Endemic Dragonflies after Removal of Invasive Alien Trees

Abstract:  Because dragonflies are very sensitive to alien trees , we assessed their response to large-scale restoration of riparian corridors. We compared three types of disturbance regime—alien invaded , cleared of alien vegetation , and natural vegetation (control)—and recorded data on 22 environmental variables. The most significant variables in determining dragonfly assemblages were percentage of bank cover and tree canopy cover , which indicates the importance of vegetation architecture for these dragonflies. This finding suggests that it is important to restore appropriate marginal vegetation and sunlight conditions. Recovery of dragonfly assemblages after the clearing of alien trees was substantial. Species richness and abundance at restored sites matched those at control sites. Dragonfly assemblage patterns reflected vegetation succession. Thus , initially eurytopic , widespread species were the main beneficiaries of the removal of alien trees , and stenotopic , endemic species appeared after indigenous vegetation recovered over time. Important indicator species were the two national endemics ( Allocnemis leucosticta and Pseudagrion furcigerum ) , which , along with vegetation type , can be used to monitor return of overall integrity of riparian ecology and to make management decisions. Endemic species as a whole responded positively to restoration , which suggests that indigenous vegetation recovery has major benefits for irreplaceable and widespread generalist species .     

养分管理与农田杂草生物多样性和遗传进化的关系研究进展

施肥被看作是一项潜在降低农田杂草对作物干扰的有效农作管理措施。不同施肥处理可形成具有不同养分状况的土壤条件,而土壤条件的差异是导致杂草生物多样性的重要因素。论证养分管理可显著改变农田杂草发生状况和杂草生物多样性,强调了深入开展不同养分管理模式对农田杂草生物多样性和遗传进化影响研究的重要性,提出了如何利用养分管理措施调节农田杂草,在控制杂草对农业危害的同时,保持一定农田可控杂草生物多样性的科学问题。长期N、P和K平衡配施,可维持杂草群落和杂草种子库的生物多样性与稳定性,兼顾杂草控制和杂草多样性保护,实现平衡施肥的经济效应与生态效应的统一。同时,农业生态系统中不同养分管理措施条件下的地表光辐射变化特征、不同光辐射变化对杂草种群种子萌发及植株建立的影响、优势杂草种群的确定及其生理生态和遗传进化规律是今后研究的重点和难点。     

Auswahl repräsentativer Standorte zur Modellierung der Ausbreitung von gentechnisch veränderten Pflanzen in Nord-Deutschland

Goal and Scope

The use of genetically modified plants (GMP) in agriculture is increasing rapidly. While GMP in North and South America are already established an extensive cultivation in Germany is yet to come. Risk assessment on possible effects of released GMP are mainly based on empirical studies with a small spatial extent (laboratories, small-scale field trials). The joint research project ‘Generic detection and extrapolation of genetically modified rape (GenEERA)’ aimed at estimating the dispersal and persistence of genetically modified oilseed rape (Brassica napus) by the use of individual based models. The objective of the article at hand is to give a detailed account of the spatial variability of climate in Northern Germany (German Federal States of Brandenburg, Lower Saxony and Bremen Mecklenburg Western Pomerania, Schleswig-Holstein and Hamburg). Based on this, a method was developed that includes both, the determination of representative oilseed rapefields for modelling the dispersal of GM oilseed rape at field scale, and the subsequent generalisation of the results to landscapes.

Data and Methods

The statistically founded selection of modelling sites was performed by a compilation of available indicators within a GIS environment which are supposed to be important for the dispersal and the persistence of oilseed rape. Meteorological data on precipitation (P), air temperature (T), and sunshine duration (S) collected at up to 1,200 monitoring sites from 1961–1990 were as well as data on wind conditions (W) aggregated multivariate-statistically by Ward cluster analysis. An ecoregionalisation was used for characterising Northern Germany ecologically. Phenological data on the start of the oil seed rape bloom differentiated in the monitoring periods 1961–1990 and 1991–1999, respectively, were regionalised by performing variogram analysis and kriging interpolation. These maps were used to select appropriate Landsat images to identify rape fields by remote sensing algorithms as well as to define the respective flowering periods for individual based modelling.

Results

The separately generated P-T-S-W-Cluster were aggregated to four homogenic climatic regions. In combination with agricultural clusters defining typical landuse patterns (crop rotation, cultivation management) eight model regions were derived which describe the climatic and agronomic variations in Northern Germany. For each of these regions a representative monitoring site was selected serving for individual based modelling. At last, the modelling results were extrapolated back to the model regions applying corresponding GIS queries.

Discussion

The generated climatic regions reflect the transition of marine climate at the North Sea to continental climate in Northeast Germany. The shift in flowering of oil seed rape coincides with other studies on phenological changes of agricultural crops and wild plants.

Conclusions

Due to the huge calculation efforts and the lack of adequate land registers it was not possible to simulate the potential dispersal of GM oil seed rape at farm scale. Thus, generalisations were used to describe the variations of relevant ecological drivers affecting the dispersal of GMP. It could be shown that the aggregation of those factors to homogenic climatic regions was a successful approximation.

Recommendations and Perspectives

Due to the limited empirical data base it is necessary to validate and substantiate the modelling results by a GMP monitoring. The EU Directive 2001/18/EC on the deliberate release of genetically modified organisms into the environment stipulates assessment of direct and indirect effects of GMP on humans and the environment by case-specific monitoring and general surveillance. It should be realised as soon as possible, since the release and the cultivation of GMP in Germany have been started, already. The monitoring should be complemented by the implementation of a web-based geoinformation system (WebGIS) which enables access to relevant geodata and monitoring data and assists in analysing possible GMP impacts.     

Allelopathy,a chance for sustainable weed management

The exploitation of crop allelopathy against weeds may be useful to reduce issues related to the use of herbicides. Several crops, such as alfalfa, barley, black mustard, buckwheat, rice, sorghum, sunflower and wheat, demonstrate strong weed suppression ability, either by exuding allelochemical compounds from living plant parts or from decomposing residues. As well as the positive effect on weed reduction, the introduction in agronomic rotations of allelopathic crops, their use as a mulch to smother crops or as a green manure may also be helpful in reduction of other agricultural problems, such as environmental pollution, use of unsafe products and human health concerns, through a reduction in chemical inputs. Knowledge of allelopathic properties of crops may also be advantageous in mitigation of soil sickness. Moreover, information on weed allelopathy may be profitable in preventing serious crop damage if the weed biomass is buried in the soil, and a crop susceptible to allellochemicals is planned for the following year. The use of allelopathic traits from crops or cultivars with important weed inhibition qualities, together with common weed control strategies, can play an important role in the establishment of sustainable agriculture.     

The People and Landscape Model (PALM): Towards full integration of human decision-making and biophysical simulation models

A model for simulating resource flows in a rural subsistence community is described. The People and Landscape Model (PALM) consists of a number of agents representing households, the landscape, and livestock. The landscape is made up of a number of homogeneous land units, or ‘fields’, each represented by an object containing data, methods and properties relevant to the field. Each field object consists of a number of soil layer objects, each of which contains routines to calculate its water balance and carbon and nitrogen dynamics. Organic matter decomposition is simulated by a version of the CENTURY model, while water and nitrogen dynamics are simulated by versions of the routines in the DSSAT crop models. The soil processes are simulated continuously, and vegetation types (crops, weeds, trees) can come and go in a field depending on its management. Crop growth and development are simulated by a generic model based on the DSSAT crop models, and which can be parameterised for different crops. Similarly, livestock growth and resource use is simulated by a generic model which can be parameterised for buffalo, cows, goats, sheep, chickens and pigs.     

Examining Fragmentation and Loss of Primary Forest in the Southern Bahian Atlantic Forest of Brazil with Radar Imagery

Abstract: The Atlantic rainforest of southern Bahia is one of the last remnants of the lowland forest of eastern Brazil that once covered the entire coastal area from Rio Grande do Norte to Rio Grande do Sul ( lat 8°–28° S) and has been deforested to a small fraction of its original cover (1–12%). All recent vegetation surveys have been based on optical satellite data, which is hampered by cloud cover and by southern Bahia's intricate mix of forest patches with other tree crops, especially cocoa. We describe the application of radar remote-sensing data to distinguish forest patches from cocoa planted in the shade of natural-forest trees. Radar, unlike optical sensors, is not obstructed by cloud cover and can acquire information about forest structure by penetrating into the vegetation canopy. The vegetation map generated from radar data clearly separates forest patches based on the degree of structural disturbance such as the density of shaded trees, the openness of the canopy, and the density of the monodominant Erythyrina shaded trees. The structural classification based on the radar data, and shown on the map, can help researchers assess the degree of fragmentation of the original Atlantic coastal forest and delineate areas of less disturbance with higher potential for conservation of biodiversity. This information can then be applied to conservation planning, especially the design and monitoring of nature reserves and the modeling of biological corridors.     

Uncertainty propagation in vegetation distribution models based on ensemble classifiers

Ensemble learning techniques are increasingly applied for species and vegetation distribution modelling, often resulting in more accurate predictions. At the same time, uncertainty assessment of distribution models is gaining attention. In this study, Random Forests, an ensemble learning technique, is selected for vegetation distribution modelling based on environmental variables. The impact of two important sources of uncertainty, that is the uncertainty on spatial interpolation of environmental variables and the uncertainty on species clustering into vegetation types, is quantified based on sequential Gaussian simulation and pseudo-randomization tests, respectively. An empirical assessment of the uncertainty propagation to the distribution modelling results indicated a gradual decrease in performance with increasing input uncertainty. The test set error ranged from 30.83% to 52.63% and from 30.83% to 83.62%, when the uncertainty ranges on spatial interpolation and on vegetation clustering, respectively, were fully covered. Shannon’s entropy, which is proposed as a measure for uncertainty of ensemble predictions, revealed a similar increasing trend in prediction uncertainty. The implications of these results in an empirical distribution modelling framework are further discussed with respect to monitoring setup, spatial interpolation and species clustering.     

Survival and growth of conservation shrubs and trees,with thin-cover reclamation on acid substrate,Iowa, USA

Many abandoned strip-mine sites in midwestern USA are highly acidic and require a separate layer of low-acidity cover materials for successful revegetation. Economics and logistics often constrain this reclamation to a very thin cover. Twenty-two species of shrubs and trees were tested for 6 years of survival and growth on a thin wedge of silt loess (up to 0.75m thick) emplaced over highly acid spoils, in south-central Iowa. No weed control or maintenance was provided. The performance of 21 of the species could be categorized into 3 groups: Group 1-consistent survival (10 species); Group 2-irregular survival and growth (6 species); Group 3-little suitability for survival (5 species). Mouldy nursery stock precluded evaluation of 1 species. For most species, the most favourable survival and growth was not on the thickest loess cover (0.75 meters) because weeds became too well established. In general, the shrubs survived severe weed competition in dwarfed form until they could break through the weed canopy. But the tree species had to penetrate the weed canopy within their first few years of growth or perish. There is evidence that if weed competition were reduced or eliminated, the species in Group 2 would probably have survival and growth equivalent to those in Group 1. The use of “tubelings” for establishing shrubs and trees on thincover reclamation sites is suggested.     

Model estimation of land-use effects on water levels of northern prairie wetlands.

Wetlands of the Prairie Pothole Region exist in a matrix of grassland dominated by intensive pastoral and cultivation agriculture. Recent conservation management has emphasized the conversion of cultivated farmland and degraded pastures to intact grassland to improve upland nesting habitat. The consequences of changes in land-use cover that alter watershed processes have not been evaluated relative to their effect on the water budgets and vegetation dynamics of associated wetlands. We simulated the effect of upland agricultural practices on the water budget and vegetation of a semipermanent prairie wetland by modifying a previously published mathematical model (WETSIM). Watershed cover/land-use practices were categorized as unmanaged grassland (native grass, smooth brome), managed grassland (moderately heavily grazed, prescribed burned), cultivated crops (row crop, small grain), and alfalfa hayland. Model simulations showed that differing rates of evapotranspiration and runoff associated with different upland plant-cover categories in the surrounding catchment produced differences in wetland water budgets and linked ecological dynamics. Wetland water levels were highest and vegetation the most dynamic under the managed-grassland simulations, while water levels were the lowest and vegetation the least dynamic under the unmanaged-grassland simulations. The modeling results suggest that unmanaged grassland, often planted for waterfowl nesting, may produce the least favorable wetland conditions for birds, especially in drier regions of the Prairie Pothole Region. These results stand as hypotheses that urgently need to be verified with empirical data.     

The Combined Effects of Remnant Vegetation and Tree Planting on Farmland Birds

Abstract:  Biodiversity conservation on agricultural land is a major issue worldwide. We estimated separate and joint effects of remnant native woodland vegetation and recent tree plantings on birds on farms (approximately 500–1000 ha) in the heavily cleared wheat and sheep belt of southern Australia. Much of the variation (>70%) in bird responses was explained by 3 factors: remnant native-vegetation attributes (native grassland, scattered paddock trees, patches of remnant native woodland); presence or absence of planted native trees; and the size and shape of tree plantings. In terms of the number of species, remnant native vegetation was more important than tree planting, in a 3:1 ratio, approximately. Farms with high values for remnant native vegetation were those most likely to support declining or vulnerable species, although some individual species of conservation concern occurred on farms with large plantings. Farm management for improved bird conservation should account for the cumulative and complementary contributions of many components of remnant native-vegetation cover (e.g., scattered paddock trees and fallen timber) as well as areas of restored native vegetation.     

Birds in agricultural mosaics: the influence of landscape pattern and countryside heterogeneity.

Agricultural environments are critical to the conservation of biota throughout the world. Efforts to identify key influences on the conservation status of fauna in such environments have taken complementary approaches. Many studies have focused on the role of remnant or seminatural vegetation and emphasized the influence on biota of spatial patterns in the landscape. Others have recognized that many species use diverse "countryside" elements within farmland, and emphasize the benefits of landscape heterogeneity for conservation. Here, we investigated the effect of independent measures of both the spatial pattern (extent and configuration) and heterogeneity of elements (i.e., land uses/vegetation types) on bird occurrence in farm-scale agricultural mosaics in southeastern Australia. Birds were sampled in all types of elements in 27 mosaics (each 1 x 1 km) selected to incorporate variation in cover of native vegetation and the number of different element types in the mosaic. We used an information-theoretic approach to identify the mosaic properties that most strongly influenced bird species richness. Subgroups of birds based on habitat requirements responded most strongly to the extent of preferred elements in mosaics. Woodland birds were richer in mosaics with higher cover of native vegetation while open-tolerant species responded to the extent of scattered trees. In contrast, for total species richness, mosaic heterogeneity (richness of element types) and landscape context (cover of native vegetation in surrounding area) had the greatest influence. These results showed that up to 76% of landscape-level variation in richness of bird groups is attributable to mosaic properties directly amenable to management by landowners. Key implications include (1) conservation goals for farm landscapes must be carefully defined because the richness of different faunal components is influenced by different mosaic properties; (2) the extent of native vegetation is a critical influence in agricultural environments because it drives the farm-scale richness of woodland birds and has a broader context effect on total bird richness in mosaics; (3) land-use practices that enhance the heterogeneity of farmland mosaics are beneficial for native birds; and (4) the cumulative effect of even small elements in farm mosaics contribute to the structural properties of entire landscapes.     

岷江干旱河谷典型地段整地造林效果评估

长期以来通过整地造林去恢复重建植被已在横断山区干旱河谷广为采用,然而这样的实践是否能有效提高植被覆盖率并改善土壤水源涵养能力仍不清楚.选择岷江干旱河谷3个典型地段,调查了多年(7～16 a)后整地造林地上植被覆盖、土壤物理性质以及目的造林树种岷江柏(Cupressus chengiana S.Y. Hu)的保存、生长与结实状况,以评价干旱河谷乡土树种造林成效及造林后的生态效果.结果表明:(1)岷江柏在栽植多年后仍有大量死亡,保存率明显下降,造林16 a后仅为38%;(2)不同年代栽植的岷江柏在造林后2～6 a即开始旱现直径年生长量下降趋势;(3)造林带内乡土植被总盖度、灌木盖度、草本盖度、地衣苔藓盖度均低于保留带,因此等高线水平沟整地造林措施未能有效促进乡土植被发育;(4)造林带土壤水分物理性质也不如保留带,整地造林也没有有效改善土壤水源涵养能力.综合分析发现,整地造林多年后岷汀柏造林不仅没有达到岷江干旱河谷预期的生态恢复重建效果,甚至有加剧生态退化的趋势.因此认为:(1)规模化整地造林并不是有效的干旱河谷生态恢复和保护措施;(2)尽管岷江柏是乡土树种,但并不是干旱河谷植被恢复的适宜种.图3表3参29     

Controlling annual weeds in cereals by deploying crop rotation at the landscape scale: Avena sterilis as an example

Weed control through crop rotation has mainly been studied in a nonspatial context. However, weed seeds are often spread beyond the crop field by a variety of vectors. For weed control to be successful, weed management should thus be evaluated at the landscape level. In this paper we assess how seed dispersal affects the interactions between crop rotation and landscape heterogeneity schemes with regard to weed control. A spatially explicit landscape model was developed to study both short- and long-term weed population dynamics under different management scenarios. We allowed for both two- and three-crop species rotations and three levels of between-field weed seed dispersal. All rotation scenarios and seed dispersal fractions were analyzed for both completely homogeneous landscapes and heterogeneous landscapes in which more than one crop was present. The potential of implementing new weed control methods was also analyzed. The model results suggest that, like crop rotation at the field level, crop rotation implemented at the landscape level has great potential to control weeds, whereby both the number of crop species and the cropping sequence within the crop rotation have significant effects on both the short- and long-term weed population densities. In the absence of seed dispersal, weed populations became extinct when the fraction of each crop in the landscape was randomized. In general, weed seed densities increased in landscapes with increasing similarity in crop proportions, but in these landscapes the level of seed dispersal affected which three-crop species rotation sequence was most efficient at controlling the weed densities. We show that ignoring seed dispersal between fields might lead to the selection of suboptimal tactics and that homogeneous crop field patches that follow a specific crop rotation sequence might be the most sustainable method of weed control. Effective weed control through crop rotation thus requires coordination between farmers with regard to cropping sequences, crop allocation across the landscape, and/ or the fraction of each crop across the landscape.     

华北地区几种冬闲覆盖作物碳氮蓄积及其对土壤理化性质的影响

充分利用华北地区冬季空闲耕地及光热资源,以冬闲耕地为对照,研究二月兰（Orychophragmus violaceus）、毛苕（Vicia uillosa Roth.）、黑麦草（Secale cereale L.）、草木樨（Melilotus officinalis）、紫花苜蓿（Medicago satiua L.）5种不同冬闲覆盖作物地上部、地下部以及总碳、氮的蓄积量及其对土壤理化性质的影响。结果表明：5种覆盖作物总干物质质量在4.6-8.82 t.hm-2之间,是冬闲田干物质质量的1.6-3.1倍。5种覆盖作物全碳蓄积量在1.80-3.14 t.hm-2之间,是冬闲田碳蓄积量的1.9-3.3倍。与对照相比,各覆盖处理均明显提高氮素蓄积,尤以苜蓿最佳,达到了202.8 kg.hm-2,差异显著。试验选择5种肥覆盖均可提高土壤有机质质量分数（0.90-2.86 g.kg）;黑麦草覆盖可明显降低土壤容重（0.08 g.cm3）;毛苕和苜蓿栽培均可显著降低土壤pH,但同时土壤盐分有所增加;二月兰和黑麦草栽培在提高土壤水分含量方面表现最好。     

Predicting a ‘tree change’ in Australia's tropical savannas: Combining different types of models to understand complex ecosystem behaviour

In this study, key ecological modelling limitations of a process-based simulation model and a Bayesian network were reduced by combining the two approaches. We demonstrate the combined modelling approach with a case study investigating increases in woody vegetation density in northern Australia's tropical savannas. We found that by utilising the strengths of a simulation model and a Bayesian network we could both forecast future change in woody vegetation density and diagnose the reasons for current vegetation states. The local conditions of climate, soil characteristics and the starting population of trees were found to be more important in explaining the likelihood of change in woody vegetation density compared to management practices such as grazing pressure and fire regimes. We conclude that combining the strengths of a process and BN model allowed us to produce a simple model that utilised the ability of the process model to simulate ecosystem processes in detail and over long time periods, and the ability of the BN to capture uncertainty in ecosystem response and to conduct scenario, sensitivity and diagnostic analysis. The overall result was a model that has the potential to provide land managers with a better understanding of the behaviour of a complex ecosystem than simply utilising either modelling approach in isolation.     

土壤酸化与油菜锰毒关系研究

对湖北省的主要旱地土壤种植多茬作物后油菜生产锰毒的原因进行了研究。结果表明,供试土壤pH值较原土样下降了1．0个单位。除石灰性土壤外,其它中酸性土壤交换性锰明显增加,造成油菜对锰吸收过量,同时由于吸收过程中锰铁拮抗作用的存在,植株在土壤锰毒发生后吸收的铁量下降,使体内锰铁比上升。     

Analyzing the spatial structure of a Sri Lankan tree species with multiple scales of clustering

Clustering at multiple critical scales may be common for plants since many different factors and processes may cause clustering. This is especially true for tropical rain forests for which theories explaining species coexistence and community structure rest heavily on spatial patterns. We used point pattern analysis to analyze the spatial structure of Shorea congestiflora, a dominant species in a 25-ha forest dynamics plot in a rain forest at Sinharaja World Heritage Site (Sri Lanka), which apparently shows clustering at several scales. We developed cluster processes incorporating two critical scales of clustering for exploring the spatial structure of S. congestiflora and interpret it in relation to factors such as competition, dispersal limitation, recruitment limitation, and Janzen-Connell effects. All size classes showed consistent large-scale clustering with a cluster radius of approximately 25 m. Inside the larger clusters, small-scale clusters with a radius of 8 m were evident for recruits and saplings, weak for intermediates, and disappeared for adults. The pattern of all trees could be divided into two independent patterns: a random pattern (nearest neighbor distance > 8 m) comprising approximately 12% of the trees and a nested double-cluster pattern. This finding suggests two independent recruitment and/or seed dispersal mechanisms. Saplings were several times as abundant as recruits and may accumulate several recruit generations. Recruits were only weakly associated with adults and occupied about half of the large-scale clusters, but saplings almost all. This is consistent with recruitment limitation. For approximately 70% (95%) of all juveniles the nearest adult was less than 26 m away (53 m), suggesting a dispersal limitation that may also be related to the critical large-scale clustering. Our example illustrates the manner in which the use of a specific and complex null hypothesis of spatial structure in point pattern analysis can help us better understand the biology of a species and generate specific hypotheses to be further investigated in the field.     

几种果粮间作人工植物群落生物生产力的动态变化及其优化调控

为解决果粮间作经营的中后期常出现的作物减产和资源浪费的矛盾,有必要分析果粮人工植物群落中各生态元的时空变化过程,揭示果粮间作经营中矛盾的产生、发展乃至激化的过程,寻求合理的间作作物组合,并进行优化调控,在岷江上游干旱河谷区,选择处于不同经营阶段（３ａ,５ａ,１０ａ,１８ａ,２８ａ）而经营管理条件基本一致的的９种苹果与粮食作物间作模式,调查测定了每一模式各阶段的果树的生长及其苹果产量,各间作粮食作物的生物量、总生物量、作物固定的总能量及其光能利用率、经济产量和经济收入等指标,揭示了苹果和各粮食作物２８ａ内的生物生产力的动态变化及其特点,找到了果树不同经营阶段的合理间作物组合,提出了该区不同经营阶段的最佳模式类型．对果粮间作的作用、理论基础及优化调控指标及其不确定性等问题也进行了讨论