1. Root, stem and leaf traits are thought to be functionally coordinated to maximize the efficiency of acquiring and using limited resources. However, evidence is mixed for consistent whole-plant trait coordination among woody plants, and we lack a clear understanding of the adaptive value of root traits along soil resource gradients. If fine roots are the below-ground analogue to leaves, then low specific root length (SRL) and high tissue density should be common on infertile soil. Here, we test the prediction that root, stem and leaf traits and relative growth rate respond in unison with soil fertility gradients. 2. We measured fine root, stem and leaf traits and relative growth rate on individual seedlings of 66 tree species grown in controlled conditions. Our objectives were (i) to determine whether multiple root traits align with growth rate, leaf and stem traits and with each other and (ii) to quantify the relationships between community-weighted mean root traits and two strong soil fertility gradients that differed in spatial extent and community composition. 3. At the species level, fast growth rates were associated with low root and stem tissue density and high specific leaf area. SRL and root diameter were not clearly related to growth rate and loaded on a separate principal component from the plant economic spectrum. 4. At the community level, growth rate was positively related to soil fertility, and root tissue density (RTD) and branching were negatively related to soil fertility. SRL was negatively related and root diameter was positively related to soil fertility on the large-scale gradient that included ectomycorrhizal angiosperms. 5. Synthesis. Root, stem and leaf tissue traits of tree seedlings are coordinated and influence fitness along soil fertility gradients. RTD responds in unison with above-ground traits to soil fertility gradients; however, root traits are multidimensional because SRL is orthogonal to the plant economic spectrum. In contrast to leaves, trees are not constrained in the way they construct fine roots: plants can construct high or low SRL roots of any tissue density. High RTD is the most consistent belowground trait that reflects adaptation to infertile soil.Key-words: determinants of plant community diversity and structure, leaf economic spectrum, plant economic spectrum, root branching, root diameter, root economic spectrum, root tissue density, soil fertility, specific root length, wood economic spectrum P erez-Ramos et al. 2012;Reich 2014;de la Riva et al. 2016). Investment in cheap tissue promotes fast growth, but comes at the cost of a short life span, whereas investment in expensive tissue produces long-lived organs that have slower metabolic rates. The hypothesis that leaves, stems and roots are coordinated is intuitive from both evolutionary and biophysical perspectives: being fast at acquiring and processing resources is only advantageous when all organs are operating
Categorical analysis of neo- and palaeo-endemism (CANAPE), phylogenetic diversity (PD) and phylogenetic weighted endemism (PWE) were used to explore patterns of diversity, endemism and biogeography in the indigenous vascular flora of the New Zealand archipelago. Distributional data comprising 213142 records for 436 genera and 2187 species and a phylogeny based mainly on rbcL sequences were used to calculate neo- and palaeo-endemism biodiversity metrics for 0.12° grid cells. Genus- and species-level analyses of PD revealed few significantly high-value cells mostly scattered in the northern North Island, and, for PWE, significantly high-value cells were concentrated in the northern North Island and northern offshore islands. CANAPE analyses suggested that palaeo-endemism is concentrated in northern North Island and the northern offshore islands, whereas neo-endemism is concentrated in South Island and the southern offshore islands. The areas of endemism highlighted by our analyses are compared with earlier biogeographic studies of endemism in the New Zealand flora. Some revision of previously suggested biogeographic boundaries is proposed, with the boundaries of the central South Island alpine gap being further north than previous studies have inferred, and the possibility that Pliocene marine transgression contributed to shaping the central North Island palaeo-endemism boundary is discussed.
The present study aimed to detect and quantify centres of vascular plant species and genus endemism and genus phylogenetic endemism in the New Zealand archipelago and to assess the representation of these in the conservation estate. The presence of 2187 vascular plant species, comprising 213141 georeferenced records, was mapped onto 0.12° grid cells and a genus-level phylogeny was constructed mainly from rbcL sequences used to calculate phylogenetic metrics. Previously identified centres of endemism were confirmed, and new areas of endemism were suggested. Patterns of endemism differ with taxonomic rank. Randomisations showed that the South Island mountains have greater species corrected weighted endemism (CWE) than expected, whereas the randomisations for genus CWE and genus corrected phylogenetic endemism (CPE) showed the northern half of the North Island and northern offshore islands to have greater endemism than expected. Consistent with the randomisations, the highest values of genus CWE and genus CPE predominantly occur in the northern North Island and offshore islands. Centres of species CWE, genus CWE and genus CPE, supported by randomisation analyses, overlap with the New Zealand conservation estate by 40.01, 29.52 and 19.12% respectively. Many areas of high endemism are often poorly protected, highlighting the urgency to consider the areas of endemism identified here in conservation policy, planning and management.
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