Testing the stress-gradient hypothesis at the roof of the world: effects of the cushion plant Thylacospermum caespitosum on species assemblages.
Testing the stress-gradient hypothesis at the roof of the world: effects of the cushion plant Thylacospermum caespitosum on species assemblages.
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DOI：
10.1371/journal.pone.0053514
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Řeháková K
中科院分区：
文献类型：
--
作者：
Dvorský M;Doležal J;Kopecký M;Chlumská Z;Janatková K;Altman J;de Bello F;Řeháková K
许多垫状植物改善了它们栖息在高山生态系统中的恶劣环境，并作为护理植物，在它们的树冠内生长的物种比外面多得多。这些促进相互作用似乎增加了非生物胁迫，从而支持应力梯度假说。我们通过探索维管植物与占主导地位的垫植物Thylacospermum caespitosum（嘉鱼科）在干旱的跨喜马拉雅山，维管植物发生在全球海拔最高的限制之一的关联模式来测试这一预测。我们比较了1112对样地之间的植物组成放在垫和周围的开放地区，在社区从寒冷的草原到subindustrial地带沿着两个海拔梯度（东喀喇昆仑：4850-5250米和小西藏：5350-5850米）。我们使用PERMANOVA来评估物种组成的差异，基于弗里德曼的排列测试来确定单个物种的栖息地偏好，物种面积曲线来评估相互作用是否依赖于大小和竞争强度和重要性指数来评估植物-植物相互作用。没有迹象表明净促进被发现沿着海拔梯度。开阔地不仅物种丰富，但没有一个单一的物种喜欢只生长在垫内，而39-60%的56种检测到有一个显着的偏好垫外的栖息地。在T.在cespitosum中，物种的数量和丰度在缓冲区之外更大，这表明竞争性而不是促进性相互作用占上风。这是支持垫内土壤养分含量较低，表明资源抢占，并在海拔梯度的极端很少热改善。我们把这种负相关归因于对有限资源的竞争，干旱高山环境中强有力的环境过滤器选择了在其生命周期中不依赖于其他植物帮助的耐应力物种，以及缓冲垫不提供更好的微生境生长的事实。
Many cushion plants ameliorate the harsh environment they inhabit in alpine ecosystems and act as nurse plants, with significantly more species growing within their canopy than outside. These facilitative interactions seem to increase with the abiotic stress, thus supporting the stress-gradient hypothesis. We tested this prediction by exploring the association pattern of vascular plants with the dominant cushion plant Thylacospermum caespitosum (Caryophyllaceae) in the arid Trans-Himalaya, where vascular plants occur at one of the highest worldwide elevational limits. We compared plant composition between 1112 pair-plots placed both inside cushions and in surrounding open areas, in communities from cold steppes to subnival zones along two elevational gradients (East Karakoram: 4850–5250 m and Little Tibet: 5350–5850 m). We used PERMANOVA to assess differences in species composition, Friedman-based permutation tests to determine individual species habitat preferences, species-area curves to assess whether interactions are size-dependent and competitive intensity and importance indices to evaluate plant-plant interactions. No indications for net facilitation were found along the elevation gradients. The open areas were not only richer in species, but not a single species preferred to grow exclusively inside cushions, while 39–60% of 56 species detected had a significant preference for the habitat outside cushions. Across the entire elevation range of T. caespitosum, the number and abundance of species were greater outside cushions, suggesting that competitive rather than facilitative interactions prevail. This was supported by lower soil nutrient contents inside cushions, indicating a resource preemption, and little thermal amelioration at the extreme end of the elevational gradient. We attribute the negative associations to competition for limited resources, a strong environmental filter in arid high-mountain environment selecting the stress-tolerant species that do not rely on help from other plants during their life cycle and to the fact the cushions do not provide a better microhabitat to grow in.
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影响因子：
1.7
作者：
Arroyo, MTK;Cavieres, LA;Arroyo-Kalin, MA
通讯作者：
Arroyo-Kalin, MA
影响因子：
4.6
作者：
Badano, Ernesto I.;Cavieres, Lohengrin A.
通讯作者：
Cavieres, Lohengrin A.
影响因子：
4.8
作者：
Armas, C;Ordiales, R;Pugnaire, FI
通讯作者：
Pugnaire, FI
DOI：
10.1111/j.2517-6161.1995.tb02031.x
发表时间：
1995-01-01
影响因子：
5.8
作者：
BENJAMINI, Y;HOCHBERG, Y
通讯作者：
HOCHBERG, Y
影响因子：
2.8
作者：
Anthelme, Fabien;Buendia, Belen;Dangles, Olivier
通讯作者：
Dangles, Olivier