The concentration of grazing around artificial and natural watering points in an arid region produces a system known as a piosphere. This study focused on the Lajaneh Piosphere, located in a dry Zygophyllum eurypterum shrubland in north-east Iran. Vegetation and soil were sampled in Lajaneh Piosphere, to discern what amount of variation in plant species composition along a piosphere can be explained by environmental variables in addition to distance from the watering point. Elevation and geographical data were recorded along three transects extending across widely varied terrain up to 5 km from the piosphere. Redundancy Analysis (RDA) and partial Redundancy Analysis (pRDA) were used to evaluate the vegetation distribution as related to soil phosphorus (P), soil potassium (K), soil nitrogen (N), slope, aspect, elevation, and distance from water. Cover of palatable plant species increased with distance from the artificial watering point. Although the redundancy analysis resulted in much unexplained variation, we found the role of soil fertility factors and distance from water most important to plant species composition; soil nitrogen (N) (7.26%), soil phosphorus (P) (5.13%), soil potassium (K) (4.47%), and distance from water (1.77%) explained variations in vegetation community more than elevation (0.91%), aspect (0.42%) and slope (0.05%). Although the transects extended across a varied terrain through a gorge into an adjacent basin and onto a plateau ∼100 m above and below the watering point on the basin floor, distance from the piosphere still was more important in explaining plant species variance than topographic factors. In general, the grazing pressure decreased with distance from water and related with high concentration of soil nutrients. Understanding the magnitudes and orders of effects of different environmental variables on piospheres such as Lajaneh provides important understanding of environmental stresses in arid landscapes. Piospheres deserve further investigation to provide a basis for studying sustainable land management in arid and semi-arid regions.

在干旱地区，人工和自然浇水点周围的放牧集中产生了一个称为大气层的系统。这项研究的重点是位于干燥的Zygophyllum eurypterum中的Lajaneh油层伊朗东北部的灌木丛。在拉贾内（Lajaneh）大气层中对植被和土壤进行了采样，以识别沿大气层中植物物种组成的变化量，除了距浇水点的距离外，还可以通过环境变量来解释。沿三个横断面记录了海拔和地理数据，这些横断面分布在距球面5公里以内的多种多样的地形上。使用冗余分析（RDA）和部分冗余分析（pRDA）评估与土壤磷（P），土壤钾（K），土壤氮（N），坡度，坡向，海拔和距水的距离有关的植被分布。距人工浇水点的距离越大，可口植物的覆盖率就越高。尽管冗余分析导致了很多无法解释的变化，我们发现了土壤肥力因子的作用以及距水的距离对植物物种组成最重要；土壤氮（N）（7.26％），土壤磷（P）（5.13％），土壤钾（K）（4.47％）和与水的距离（1.77％）解释了植被群落的变化大于海拔变化（0.91％） ，长宽比（0.42％）和坡度（0.05％）。尽管横断面穿过峡谷延伸到不同的地形中，进入相邻的盆地，并流到盆地底部浇水点上下约100 m的高原上，但在解释植物物种变异性方面，距地层的距离仍然比地形因素更为重要。通常，放牧压力随距水的距离而降低，并且与土壤养分的高浓度有关。了解诸如Lajaneh之类的不同环境变量对太阳系圈的影响的大小和顺序，可以对干旱景观中的环境压力提供重要的了解。圈外圈值得进一步调查，为研究干旱和半干旱地区的可持续土地管理提供基础。